Latin American Coral Reefs
EXPLANATORY TEXT OF COVER 1) Coral reef and lagoon at Achutupo, San Bl~is Islands, Caribbean of Panam~i (see chapter by Guzm~in, map: Fig. 1, eastern region). Photograph by Jorge Cort6s. 2) Chapeiros and reef structures of Itacolomis, Bahia, Brazil (see chapter by Le~o et al., map: Fig. 18" Coral reefs of the Cabr~ilia~orto Seguro area, eastem region). These reefs are located near Mount Pascual, the first point of Brazil seen by a European, Pedro /klvares Cabral in 1500. Photograph by Ruy Kenji P. Kikuchi.
3) Punta Islotes, Golfo Dulce, Costa Rica (eastern Pacific) (see chapter by Cort6s and Jim6nez, Pacific of Costa Rica, map: Fig. 8). Photograph by Jorge Cort6s. 4) Colpophilia breviserialis from Cahuita, Costa Rica (see chapter by Cort6s and Jim6nez, Caribbean of Costa Rica, map: Fig. 3). Photograph by Jorge Cort6s. Cover created by Percy Denyer.
l~atin American Coral Reefs
Edited by Jorge Cortds CIMAR Universidad de Costa Rica San Pedro, Costa Rica
2003
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9 2003 Elsevier Science B.V. All rights reserved.
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Foreword The global decline in coral reefs during the last decades has provoked the most serious concerns about these remarkable ecosystems. If these declines were owing to a single worldwide cause, like influenza, plague and aids in humans, the focus of efforts to understand and remedy it would be clear. Instead, the causes of declines as well as the nature of reefs vary significantly from region to region and within regions. Thus the urgent need is to examine reefs and their declines regionally. This volume is one of the first of a new and much-needed series of compilations about reef regions of the oceans and their conditions. The collection offers comprehensive treatments of reefs of sixteen Latin American countries. For each, the Editor wisely established a standard format, which covers all the major aspects of reefs, the extent and nature of declines and their causes, and management efforts. The product is an in-depth characterization of the region's reefs, which will be of wide interest to reef scientists, managers and students. Coral Reefs of Latin America includes examples of an unusually wide range of oceanographic-tectonic settings. Caribbean reefs are interconnected by the Western Boundary Current (Gulf Stream System) such that the faunas and floras are the same over the entire regions. They have well-developed barrier, atoll and lagoonal reefs. They are frequently impacted by hurricanes, diseases and over-fishing and locally by runoff and sewage discharges. The southernmost reefs of the Western Atlantic off Brazil have an endemic coral fauna different from that of the Caribbean and some quite special morphologies; they are outside the influence of hurricanes, but subject to sediment stress in nearshore zones. Eastern Pacific reefs represent the global suboptimal endmember; they occur in the nearshore areas of a narrow shelf with extreme and often lethal temperature changes - upwelling and the elevated temperatures of E1 Nifio. The coral communities fringing remote Easter Island, which are bathed by subtropical sea conditions have a depauperate coral fauna; it is nevertheless surprisingly healthy, but has not produced significant relief over the surrounding sea floor. For anyone with a serious interest in coral reefs, this volume is an invaluable resource. For marine biologists, geologists and students it is on the one hand a welcome handbook. Each chapter provides summaries of previous research, through descriptions of subdivisions and even individual reefs. Included also are up-to-date information on declines and their presumed causes as well as management efforts. The tectonichydrographic explanation for the large-scale variability of Latin American reefs is a welcome framework, which may well apply to other reef regions. Moreover, the volume provides the necessary ingredients for other comparisons within and between the reefs of each country. University of Miami
Robert N. Ginsburg
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vii
CONTENTS Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
V
ix
INTRODUCTION Coral reefs of the Americas: An introduction to Latin American Coral Reefs J. Cort6s
BRAZIL Corals and coral reefs of Brazil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Z. M. A. N. Le~o, R. K. Kikuchi and V. Testa
CARIBBEAN The Cuban coral reefs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. M. Alcolado, R. Claro-Madruga, G. Men6ndez-Macias, P. Garcia-Parrado, B. Martinez-Daranas and M. Sosa
53
The coral reefs of the Dominican Republic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. X. Geraldes
77
Puertorican reefs: research synthesis, present threats and management perspectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J.R. Garcia, J. Morelock, R. Castro, C. Goenaga and E. Hern~ndez-Delgado
111
The Atlantic coral reefs of M6xico . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. Jord~n-Dahlgreen and R. E. Rodriguez-Martinez
131
Coral reefs of Guatemala . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. C. Fonseca E. and A. Arrivillaga
15 9
The reefs of Belize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J. Gibson and J. Carter
171
Nicaragua's coral reefs: status, health and management strategies ............ J. Ryan and Y. Zapata
203
Past, present and future of the coral reefs of the Caribbean coast of Costa Rica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J. Cort6s and C. Jim6nez
223
Caribbean coral reefs of Panama: present status and future perspectives .... H. M. Guzm~n
241
The Caribbean coral reefs of Colombia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J. Garz6n-Ferreira and J. M. Diaz
275
The corals and coral reefs of Venezuela . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. Weil
303
viii EASTERN PACIFIC Coral reefs of the Pacific coast of M6xico . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H. Reyes-Bonilla
331
Corals and associated marine communities from E1 Salvador ...................... H. Reyes-Bonilla and J. E. Barraza
351
Corals and coral reefs of the Pacific of Costa Rica: history, research and status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J. Cort6s and C. Jim6nez
361
Corals and coral reefs of the Pacific coast of Panama . . . . . . . . . . . . . . . . . . . . . . . . . . . J. L. Mat6
387
Corals and coral reefs of the Pacific coast of Colombia . . . . . . . . . . . . . . . . . . . . . . . . F. A. Zapata and B. Vargas-,iUagel
419
Coral communities and coral reefs of Ecuador . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. W. Glynn
449
Reef-building coral communities of Eastern Island (Rapa Nui), Chile ....... P. W. Glynn, G. M. Wellington, E. A. Wieters and S. A. Navarrete
473
Subject index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
495
ix
Acknowledgments The idea of this book originated at the 8th International Coral Reef Symposium in Panarn~ during the "Coral Reefs of Latin America Workshop" organized by Eric Jordan and myself. I thank the organizers of the 8th ICRS (Smithsonian Tropical Research Institute and the University of Panama) and specially H6ctor Guzm~n. Their generous support made it possible for a large number of Latin American reef scientists and students to attend the symposium and interact for the first time with colleagues from the region. During the workshop representatives from each country presented the state of knowledge of their coral reefs. The book on the coral reefs of Latin American took shape following the workshop and especially during the CARICOMP Site Directors Meetings. It was the possibility of these personal encounters that stimulated true transnational collaboration. For this, I thank funding organizations and all individuals who made possible this crucial initial phase. The goal of this book was to compile all the available information concerning the coral reefs in Latin America. Although in some countries there is a large amount of information about their reefs, it is in the form of reports, thesis or obscure journals and thus of limited circulation. Therefore, the best of that information has been included in this book in an effort of disseminating it to a wider sector of the scientific community. Whenever possible, local scientists working on coral reefs were asked to write about the history of reef research in their country, describe the reefs, point out natural and anthropogenic perturbations affecting those reefs, and outline management and conservation initiatives in relation to coral reefs in their area. I thank each and every one of the authors who submitted chapters for their effort and for making this book possible. I hope that this book stimulates more collaborative research, and increases the local and international awareness of the region's coral reefs. As pointed out in the Introduction to this book, there are three coral reef regions in the Americas: Brazil, Caribbean and eastern Pacific. Most, if not all the reef in each region, are found in Latin American countries. Fortunately, in the last decade or two the number of local scientists as well as the quantity and quality of the research has increased in most countries. From the chapters in this book we can learn about the types, size, species composition and conditions of the coral reefs in each country. And we can get a feel for the level of research in each country, which expands from a few isolated studies, to extensive, long-term research in many fields of reef ecology. Only one Latin American country with coral reefs, Honduras, is not presented in the book, which I regret; many people were contacted but a chapter was not produced. I greatly appreciate the excellent job done by reviewers of one or more chapters: R.B. Aronson, R.W. Buddemeier, G. Bustamante, A.G. Coates, A.I. Dittel, J. Geister, R.N. Ginsburg, P.W. Glynn, H.M. Guzrn~n, W.C. Jaap, B. Kjerfve, K. Koltes, J.H. Leal, C. Lotion, I.G. Macintyre, J. Ogden, K. Qualtrough, M. Reaka-Kudla, H. Reyes Bonilla, C.S. Rogers, K. Sullivan-Sealey, E. Villamizar, G.M. Wellington and J. Woodley. I thank Dr. Robert N. Ginsburg for accepting to write the Foreword to this book. I acknowledge the support of the Vicerrectoria de Investigaci6n, Universidad de Costa Rica, US-AID-CDR Project (TA MOU-97-C14-015), and M. Tupper. I thank Ms. Fenke Wallien of Elsevier Science, for her patience and support for this project. Finally, I salute my Mend and colleague Alberto Le6n who patiently and carefully did all the layout of the book up to the camera-ready version.
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Coral reefs of the Americas: An introduction to Latin American Coral Reefs Jorge Cortrs Centro de Investigaci6n en Ciencias del Mar y Limnologia(CIMAR), and Escuela de Biologia, Ciudad de la Investigaci6n, Universidad de Costa Rica, San Pedro, San Jos6 2060, Costa Rica
ABSTRACT: There are three main coral reef regions on the American continents: Brazilian, Caribbean and the eastern Pacific. Most coral reefs border Latin American countries, hence the title of this book. Corals and coral reef structures in these three areas vary largely in relation to plate tectonic activity and ocean circulation. Geologic separation of the Brazilian fauna from the Caribbean, due to Amazonian freshwater intrusion, dates from the end of the Cretaceous/early Tertiary, resulting in a highly endemic and relict coral fauna in the Brazilian region. The Caribbean and the eastern Pacific were separated by the Isthmus of south Central America about 3 million years ago. Due to the subsequent changes in amphiAmerican oceanographic conditions, the coral faunas of these two regions are dissimilar today. Although the faunas and reef structures are unique in each region, the natural and anthropogenic impacts affecting them are similar, resulting in marked reef degradation in most areas. Therefore, intercontinental collaboration between workers in North, South and Central America is necessary to study, protect and conserve the coral reefs of Latin America.
1. I N T R O D U C T I O N The American continents today contain three main reef areas: the Brazilian waters, the Caribbean and the eastern Pacific (Fig. 1). The reef area of Brazil extends from Atol das Rocas in the north, to the state of Bahia on the south, and from the mainland coast to Fernando de N o r o n h a offshore. The best-developed reefs are in the southern part o f the state of Bahia (Leao et al. chapter in this book). The Greater Caribbean or western tropical Atlantic, extends from Bermuda south to PanalTfi, and from Barbados in the Lesser Antilles to the coast of the Gulf of Mexico. The best r e e f development of this region is in the central Caribbean including Cuba, Jamaica and Belize (Goreau 1959; chapters on Caribbean reefs in this book). The eastern Pacific reefs extend from the Sea of Cortez south to Ecuador and oceanic Chile, and from Colombia west to Clipperton Island. The most extensive reefs are in Costa Rica, Panarn~, Colombia and on the oceanic islands of Cocos and Clipperton (Glynn et al. 1996; Cort6s 1997; chapters on Latin American Coral Reefs, Edited by Jorge Cortrs 9 2003 Elsevier Science B.V. All rights reserved.
1
jcr
EL MLVADOA’
,\&
NICARAGUA
‘
-,--
40.
.
COSTA R ICA PANAMA
-
Eastern Island
Fig. 1 . The American continent with its three main reef areas indicated.
Jorge Cortes
4
ECUAD
Coral reefs of the Americas: An introduction to the Latin American Coral Reefs
3
eastern Pacific reefs in this book). At Easter Island, the far southeastem Pacific outpost, incipient reef development has been observed recently (Glyrm et al. chapter in this book). All of the Brazilian, most of the eastern Pacific and a significant number of reef areas of the Americas are within Latin American jurisdiction, hence the focus of this book. Here, I will briefly describe the corals and coral reefs of the three regions noted above. Some possible explanations as to how each region acquired its present coral fauna will be considered. And finally, the common threats to corals and coral reefs of the Americas will be noted. It is necessary for the Latin American community to be well versed in the ecology of the regional coral reefs, since management of these important resources will require international collaboration in order to be effective. 2. BRAZILIAN There are two outstanding features of Brazilian reefs: their structure and coral composition. Reef structures called "chapeiros" are commonly observed on Brazilian reefs. They consist of several mushroom-shaped coral colonies fused above, some extending 20 m high and 50 m in diameter. Several chapeiros may fuse to form complex structures that the Brazilians call "reef banks". These reef banks are found along the southern range of Brazilian reefs, in the state of Bahia (Hetzel and Castro 1994). Calcareous algae predominate along the northern part of the Brazilian coast. Also unique to Brazilian reefs is their reef-building coral species composition. Close to one-half of the fifteen species are endemic and some are relics of the ancient coral fauna of the Tethys Sea. For example, Mussismilia hispida, an important reef builder in Brazil, is both an endemic and relict coral species. Recently have Brazilian scientists begun to study these reefs in detail and publish papers describing them (see chapter in this book by Leao et al.). 3. CARIBBEAN
The corals and coral reefs of the Caribbean are the most widely studied and best known of the three regions discussed herein (see Caribbean section in this book). A typical Caribbean reef has a shallow lagoon (few centimeters to 2 m deep), a reef crest where wave energy is dissipated (Geister 1977), a high diversity reef front and often a zone of spurs and grooves (Goreau 1959). The basements of many reefs occur to 35 m depth, but corals can be found as deep as 95 m (Fricke and Meischner 1985). A welldefined reef crest and lagoon are not present on either Brazilian or eastern Pacific reefs. 4. EASTERN PACIFIC Eastem Pacific reefs are relatively small, discontinuous and formed by only a few species of corals (see the eastern Pacific section in this book). Cort6s (1997) has referred to them as the minimum expression of a reef. There are two main types of reef structures and several minor geomorphologic variations. Reefs in M6xico, Panarn~, Colombia and in some areas in Costa Rica and Ecuador are built by species of Pocillopora. The branches of these corals grow interlocked, exhibiting virtually no submarine cementation
4
Jorge Cortes
or binding calcareous algae (Cortrs et al. 1994), which contribute to the stability of Brazilian and Caribbean reefs. Another major reef type in the eastern Pacific consists of the massive corals Porites lobata and Pavona clavus. The best expressions of this type are found at Cocos Island, Clipperton Island and the Gal~pagos Islands. Colonies may be enormous (several meters in diameter) and are sometimes not cemented to the substrate (Cortrs 1990). 5. DIFFERENCES AND POSSIBLE EXPLANATIONS Today, there are major differences among the three regions of the Americas with regard to coral reef structure and genetic/species composition of their reef-building corals (Table 1). The affinity between the Caribbean and Brazilian regions is high at the genetic, but less at the species level. The eastern Pacific and the Caribbean still have some genera in common, however, no species are shared between the eastern Pacific and either the Caribbean or Brazilian regions (Table 1). TABLE 1 Number of genera and species of reef-building corals in each region (Brazil, the Caribbean and the eastern Pacific) and those in common between region pairs. Sources: Brazil: Hetzel and Castro 1994, and chapter in this book by Le[io et al. Caribbean: Wells and Lang 1973, Budd 2000, and chapters in this book: Alcolado et al., Cortrs and Jimrnez, Fonseca and An'ivillaga, Garcia et al., Garzrn-Ferreira and Diaz, Geraldes, Gibson and Carter, Jord/mDahlgreen and Rodriguez-Martinez, Ryan and Zapata, Weil. Eastern Pacific: Glynn 1997, Glynn and Ault 2000, and chapters in this book: Cortrs and Jimrnez, Glynn, Glynn et al., Matr, Reyes-Bonilla, Zapata and Vargas-Angel. Region Brazil Caribbean E. Pacific Brazil - Caribbean Caribbean- E. Pacific E. Pacific- Brazil
Present Genera Species 10 21 8
In Common Genera Species
15 50+ 25 9 4 2
10 0 0
Differences in two oceanographic parameters may explain the obvious contrasts in coral species composition: plate tectonic events and ocean circulation. The position of the continents has changed over time, resulting in separation and isolation of the coral faunas. As a consequence, ocean current directional changes have remained the same or changed, thus creating new opportunities for speciation, which have resulted in the dissimilar coral faunas we now see in the Brazilian, Caribbean, and eastern Pacific regions. A circumtropical circulation existed during the Cretaceous, resulting in a relatively homogeneous coral fauna world-wide. With respect to the tropical American Seas, the first important fragmentation of the Tethys involved the separation of the proto-Mediterranean from the American continents. From this time onward, an entirely different coral fauna evolved in eastern American waters (Frost 1977; Budd 2000). At the end of
Coral reefs of the Americas: An introduction to the Latin American Coral Reefs
5
the Cretaceous (or early Tertiary), the Caribbean and Brazilian regions were separated as the South Atlantic Ocean widened. Around this time, the Andes were uplifted, changing the outflow of the Amazon River from the Pacific to the Atlantic Ocean, creating an enormous freshwater lens between the tropical Brazilian coast and the Caribbean. This freshwater lens presently remains an impassable barrier for corals. Also, in this region the Atlantic Equatorial current branches, moving north into the Caribbean and south to southern Brazil. Thus, ocean circulation also has enhanced the separation of these two regions, resulting in the unique Brazilian fauna. From 4 to 1 million years ago (mya), the evolution and divergence of the Caribbean coral fauna increased this dissimilarity (Budd et al. 1994). The presence of endemic Brazilian genera in the Caribbean fossil record, such as the relict M u s s i s m i l i a , fiu'ther provides evidence of the divergence of the Caribbean fauna (Budd et al. 1994). During this time of differentiation, the connection between the Caribbean and the eastern Pacific regions still persisted and coral faunas remained similar there. However, a tectonic event during the Pliocene epoch leads to the separation of the eastern Pacific and Atlantic American regions. The uplift of the Central American isthmus, some 3 mya (Coates et al. 1992), had fundamental oceanographic consequences as well as climatic and biological implications. The conditions for the generation of E1 Nifio events were created, resulting in warming disturbances in the eastern Pacific. Coastal upwelling also began, creating seasonal cool water centers as well (Cort6s 1997). Such thermal regimes are not conducive to coral growth and development. Additionally, sea level changes occurred during the Pleistocene (Cort6s 1986) initiating the extinction of reef-building corals in the eastern Pacific. Several workers suggest that shallow hard substrates were then colonized by corals that dispersed from the central Pacific, via eastward-moving ocean currents (Cort6s 1986; Glynn 1997; Glynn and Ault 2000). 6. NATURAL AND ANTHROPOGENIC IMPACTS The major coral reef regions of the Americas are distinct in structure and species composition, yet the environmental problems affecting these reefs are similar. Impacts from natural causes, such as coral bleaching (Glynn 1992; Glyrm and Colley 2001), have resulted in mass mortalities of corals in all three regions (see sections on Natural Disturbances in most chapters). Human impacts in marine environments have also taken their toll. Reef degradation in the American region is caused mainly by increased influx of terrigenous sediments (Rogers 1986; Cort6s 1990; Ginsburg 1994), primarily due to deforestation, uncontrolled coastal development and inappropriate agricultural practices (Cort6s and Risk 1985; Cort6s 1990). 7. CONCLUSIONS To prevent the further destruction of coral reefs world--~de, an accelerated program of education and training in reef science is necessary. Dissemination of information should occur within all user groups, from children to adults and at all custodial levels. More importantly, we must understand that coral reefs belong to all humankind and are not the property of any one nation. A cooperative, multinational program must be devel-
6
Jorge Cort~.s
oped in order to study, protect and rationally utilize these precious and fragile resources, these wonderful ecosystems we call coral reefs. ACKNOWLEDGMENTS This Introduction to the book Latin American Coral Reefs was enriched by the contributions of all the authors which I greatly appreciate. The critical reviews by several persons, and specially P. W. Glynn and S. Colley Theodosiou improved this chapter. REFERENCES Budd, A.F. 2000. Diversity and extinction in the Cenozoic history of Caribbean reefs. Coral Reefs 19: 25-35. Budd, A.F., T.A. Steaman & K.G. Johnson. 1994. Stratigraphic distribution of genera and species of Neogene to Recent Caribbean reef corals. J. Paleont. 68:951-977. Coates, A.G., J.B.C. Jackson, L.S. Collins, T.M. Cronin, H.J. DowseR, L.M. Bybell, P. Jung & J. Obando. 1992. Closure of the Isthmus of Panama: the near-shore marine records of Costa Rica and western Panama. Geol. Soc. Amer. Bull. 104: 814-828. Cort6s, J. 1986. Biogeografia de corales hermatipicos: el istmo centroamericano. Anal. Inst. Cienc. Mar Limnolog., U.N.A.M. 13: 297-304. Cort6s, J. 1990. The coral reefs of Golfo Dulce, Costa Rica: distribution and community structure. Atoll Res. Bull. 344: 1-37. Cort6s, J. 1997. Biology and geology of coral reefs of the eastern Pacific. Coral Reefs, 16(Suppl.): $39-$46. Cort6s, J. & M.J. Risk. 1985. A reef under siltation stress: Cahuita, Costa Rica. Bull. Mar. Sci. 36: 339-356. Cort6s, J., I. G. Macintyre & P. W. Glynn. 1994. Holocene growth history of an eastern Pacific fringing reef, Punta Islotes, Costa Rica. Coral Reefs 13: 65-73. Fricke, H. & D. Meischner. 1985. Depth limit of Bermudan scleractinian corals: a submersible survey. Mar. Biol. 88:175-187. Frost, S.H. 1977. Cenozoic reef systems of the Caribbean - Prospects for paleontologic synthesis. In: S.H. Frost, M.P. Weiss and J.B. Saunders (eds.), Reefs and Related Carbonates - Ecology and Sedimentology. AAPG Studies in Geology 4: 93-110. Geister, J. 1977. The influence of wave exposure on the ecological zonation of Caribbean coral reefs. Proc. 3rd Int. Coral reef Symp., Miami 1: 23-29. Ginsburg, R.N. (compiler). 1994. Proceedings of the Colloquium on Global Aspects of Coral Reefs: Health, Hazards and History, 1993. Rosenstiel School of Marine and Atmospheric Science, University of Miami: 240-246. Glynn, P.W. 1992. Coral reef bleaching: ecological perspectives. Coral Reefs 12:1-17. Glynn, P.W. 1997. Eastern Pacific reef coral biogeography and faunal flux: Durham's dilemma revisited. Proc. 8th Int. Coral Reef Symp., Panama 1: 371-378. Glynn, P.W. & J.S. Ault. 2000. A biogeographic analysis and review of the far eastern Pacific coral reef region. Coral Reefs 19: 1-23. Glynn, P.W. & S.B. Colley (eds.). 2001. A collection of studies on the effect of the 1997-98 E1 Nifio-Southern Oscillation event on corals and coral reefs in the eastern tropical Pacific. Bull. Mar. Sci. 69: 1-288.
Coral reefs of the Americas: An introduction to the Latin American Coral Reefs
Glynn, P.W., J.E.N. Veron & G.M. Wellington. 1996. Clipperton Atoll (eastem Pacific): oceanography, geomorphology, reef-building coral ecology and biogeography. Coral Reefs 15:71-99. Goreau, T.F. 1959. The ecology of Jamaican coral reefs, I. Species composition and zonation. Ecology 40: 67-90. Hetzel, B. & C.B. Castro. 1994. Corals of Southern Bahia. Editorial Nova Frontera, Rio de Janeiro, Brazil. 189 p. Rogers, C.S. 1986. Responses of coral reefs and reef organisms to sedimentation. Mar. Ecol. Prog. Ser. 62:185-202. Wells, J.W. & J.C. Lang. 1973. Systematic list of Jamaican shallow-water Scleractinia. Bull. Mar. Sci. 23: 55-58.
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Corals and coral reefs of Brazil Zelinda M. A. N. Leao a, Ruy K. P. Kikuchi a,b and Viviane Testa a a Laborat6rio de Estudos Costeiros, Centro de Pesquisa em Geofisica e Geologia, Universidade Federal da Bahia, Rua Caetano Moura 123,40210-340, Salvador, Bahia, Brazil b Departamento de Ci~ncias Exatas, Universidade Estadual de Feira de Santana, BR116 km 3 s/n, Campus Universit/trio, 44031-460, Feira de Santana, Bahia, Brazil ABSTRACT: The Brazilian coral reefs form structures significantly different from the well known coral reef models, because (i) they have a characteristic initial growth form of mushroom-shaped coral pinnacles called "chapeir6es", (ii) they are build by a very low diversity coral fauna, rich in endemic species, which are relic forms, remnant of an ancient coral fauna dating back in the Tertiary, (iii) incrusting coralline algae have an important role in the construction of the reef structure, and (iv) the nearshore bank reefs are surrounded and even filled with muddy siliciclastic sediments. The isolated reefs columns, the "chapeir6es", fuse together at their tops, forming large compound reef structures of varied sizes, with horizontal tops, and somewhat irregular shape. They can be completely exposed during low tides. These reef structures are distributed into three major sectors along the tropical coast of Brazil: the northern, the northeastern and the eastern coasts. There are different types of bank reefs, fringing reefs and an atoll. Corals, milleporids and coralline algae build the rigid flame of the reefs. The coral fauna, so far identified, comprises less than eighteen species, being some of them endemic to the Brazilian waters. Quaternary sea-level fluctuations affected the growth of the reefs in Brazil; transgressive and regressive seas marked different stages of reef development. The areas where the major coral reefs occur correspond to regions where nearby urban centres are experiencing accelerated growth and tourist development is increasing very fast. The major human impacts to the reef ecosystem are mostly associated with agricultural activities (sugarcane and timber), mineral and chemical industries and oil exploration. Increased sedimentation due to removal of the Atlantic rainforest and the disposal of industrial and urban effluents, are additional stresses to the coastal marine environment in Brazil. There are not many institutions concerned with preservation of the Brazilian coral reefs, and they are also fairly new.
1. I N T R O D U C T I O N Our k n o w l e d g e o f Brazilian coral reefs was limited c o m p a r e d to the Caribbean and the G u l f o f M e x i c o as prior to 1969, when the broadest description o f the Brazilian coral fauna b y the F r e n c h biologist Jacques Laborel was published (Laborel 1967; 1969a, 1969b), there were only reports about the corals o f Brazil b y visiting scientists (Spix and Martius 1828; Fitzroy 1832; Darwin 1851; Hartt 1868a, 1868b, 1869, 1870; Verrill 1868, 1901a, 1901b, 1912; Rathbun 1876, 1878a, 1878b, 1878c, 1879; Branner 1904; D e r b y 1907). These early works established the unusual characteristics o f the Brazilian reefs: their almost unique mushroom-like growth form (chapeirao) and the strong e n d e m i s m and low diversity o f the coral fauna. Latin American Coral Reefs, Edited by Jorge Cort6s 9 2003 Elsevier Science B.V. All rights reserved.
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Interest in studies about the Brazilian reefs expanded in the last two decades, due to the increased number of researchers working in this field of investigation, and to the increased degradation of reef areas. Recent researches include more detailed surveys of the reef environment, and the elaboration of quantitative databases found in numerous articles, thesis, dissertations, as well as technical reports. They consist, mainly, of: a) mapping of reefs areas (Leao 1982, 1994a, 1996; Araujo 1984; Nolasco 1987; Dominguez et al. 1990; Coura 1994; Testa 1996, 1997; Maida and Ferreira 1997); b) providing data on various aspects of the reef communities - fauna and flora (Oliveira-Filho and Ugadim 1976; Oliveira-Filho 1977; Nunam 1979; Pemch 1979; Rios and Barcellos 1980a; Bel6m at al. 1982; Hetchel 1983; Young 1984, 1986, 1988; Castro 1989, 1990a, 1994; Leao 1986a; Pitombo et al. 1988; Cutrim 1990; Ma~al and Amaral 1990; Luz 1991; Amaral 1991, 1992, 1994, 1997; Pires and Pitombo 1992; Pires et al. 1992; Schlenz and Bel6m 1992; Rohlfs and Bel6m 1994; Samos and Correia 1994, 1995; Ferreira et al. 1995; Maida and Ferreira 1995; Marques and Castro 1995; Nogueira 1995; Pires 1995; Pinto-Paiva and Fonteles-Filho 1996; Amaral et al. 1997; Correia 1997; Echeverria et al. 1997; Figueiredo 1997; Migotto 1997; Pinto and Bel6m 1997; Pires and Castro 1997; Rosa and Moura 1997; Santa-Isabel et al. 1998a; Villaga and Pitombo 1998; Castro and Pires 1999); c) characterizing the reef subenvironments and related sedimentary facies (Le~o 1982; Nolasco and Leao 1986; Leao et al. 1988; Kikuchi 1994; Leao and Ginsburg 1997; Testa 1997; Testa et al. 1997; Testa and Bosence 1998, 1999); d) studying the modem and Quaternary reef structures (Leao 1983; Leao and Lima 1983; Araujo et al. 1984; Leao et al. 1985, 1997; Kikuchi and Leao 1997, 1998; LeSo and Kikuchi 1999), and e) informing about reef conservation, protection and management in Brazil (Joly et al. 1969; Castro and Secchin 1981, 1982; Leao 1986b, 1994b; Ma~al 1986; Secchin 1986, 1991; Bel6m et al. 1986; Gonchorosky et al. 1989; IBAMA/FUNATURA 1991; Coutinho et al. 1993; Leao et al. 1994; Amado-Filho et al. 1997; Telles 1998). This chapter will focus on three main aspects of the Brazilian reefs: 1) characterization of the coral fauna, its endemism and the adaptation of a low diversity fauna to a highly siliciclastic muddy environment; 2) the classification and distribution of the major Brazilian reef systems and the aspects that influenced their Quaternary evolution and, 3) reviewing the major natural and anthropogenic impacts, which are threatening the Brazilian coral reef ecosystems. 2. REGIONAL SETTING 2.1. The continental shelf sedimentary facies The continental shelf along the tropical coast of Brazil varies considerably in shape and width. Along most of its extension it is very narrow, with an average width of 50 km. In its southern portion, however, it widens, particularly in the Abrolhos area, where it extends circa 200 km, as a result of a volcanic intrusive activity, an accretion to the shelf that was responsible for the formation of the Abrolhos Bank. The shelf break is commonly at an average depth of 80 m. Carbonate sediments dominate the entire tropical Brazilian middle and outer shelves, from north to south. Bioclastic carbonate gravel and sands (free-living non-
Corals and coral reefs of Brazil
11
articulated coralline red algae - maErl - Halimeda, benthic Foraminifera and mollusk debris), are also an important constituent in the inner shelf in many areas (Coutinho 1980; Dominguez and Leao 1994; Testa 1997; Testa and Bosence 1998, 1999), and not only in the middle and outer shelves as it was previously thought. More commonly, the inner shelf constitutes a typical mixing zone of siliciclastic and carbonate sediments; the siliciclastic originate from fiver discharges, coastal erosion, and reworked relict deposits of former lower sea-level stands, and the carbonates have as sources the locally-produced grains by the growth and transport of calcareous organisms, such as red and green algae. In the vicinity of the Sao Francisco River mouth (10030 , S) (Fig. 1), the largest river on northeast Brazil, the carbonate sediment production is interrupted, probably due to water turbidity (Tiltenot et al. 1994). Also, the inner shelf of the south part of the eastern region, between the Jequitinhonha (15~ and Doce (19~ rivers (Fig. 1) is influenced by river discharges, and plumes of fine sediments are seen to advance some 50 km offshore. In these areas bioclasts occur only on the middle and the outer shelves, and the main carbonate sediments are mollusk shells, benthic Foraminifera tests, debris of calcareous algae, bryozoans, echinoids and, more rarely, coral gravel. Reefs occur along the entire carbonate province, and are distributed along four geographic regions: northern, northeastern, eastern and southern (Fig. 1). The northernmost part is the poorest area, if reef buildups are taken into consideration. This perceived scarcity of reefs, already referred to by Laborel (1969a), may be a result of the lack of extensive research in the area. The Nautical Charts of the Brazilian shelf indicate that reefs are indeed rarer on the northern part of the country continental shelf compared to its northeastern and eastern parts, where reefs are more frequent. Near shore patch and bank reefs occur commonly within siliciclastic sandy to muddy sediments, both in the northeast (Testa 1996) and in the east coasts (Leao 1982; Araujo 1984; Nolasco 1987; Leao and Ginsburg 1997). This is one of the reasons why it is said that the reef building corals in Brazil are resistant to high rates of sedimentation and/or water turbidity. Furthermore, Milliman and Barreto (1975) and Kikuchi and Leao (1998) have documented the occurrence of drowned reefs at the shelf break.
2.2. Physical environment 2.2.1. Winds. The general atmospheric circulation pattem along the northeast and east Brazilian coasts is controlled by two elements (Bigarella 1972): (i) air masses generated in the South Atlantic high pressure cell and (ii) advances of polar air masses. Since the South Atlantic is devoid of hurricanes, only the above cited two elements, associated with the Intertropical Convergence Zone, define climate in the tropical coast of the country. The Brazilian eastem and northeastem coasts are therefore dominated by the southeasterly and easterly trade winds in this part of the Atlantic. A divergence zone of trade winds occurs in the southem part of the pressure cell, and northeastem winds blow to the south of this zone. A seasonal variation of this cell produces a north-south oscillation of the divergence zone between 10~ and 20~ This zone moves northward during summer and southward during winter. As a result, easterly and southeasterly winds dominate the coast far north of 13~ year-round, with speeds ranging from 5.5 to 8.5 m s~ (US Navy 1978). South of 13~ the easterly and southeasterly winds blow during fall and winter (April to September), and the northeasterly winds prevail during spring and summer (September to February); in this area the wind speed rarely surpass
12
Z.M.A.N. Leao et al.
Fig. 1. Map showing the majorreef zones, and the reefs described in the text and illustrated in figures 13 to 19. 5.5 m s -1 ( U S Navy 1978). The Antarctic polar front moves northward across the South American continent, east of the Andes Mountains, as great anti-cyclones, and splits into two branches. The eastern branch moves along the coast towards the Equator and can reach as far as 10~ during winter but, rarely, reaches latitudes lower than 15~ in summer (Dominguez et al. 1992). The advance of this polar front also generates additional south-southeasterly winds, which reinforce the southeasterly winds generated by the anti-cyclone high-pressure cell. Gale-force winds (25 m S"1) have been measured with the advance of these polar fronts (Bandeira et al. 1975). 2.2.2. Rainfall. The climate in the northeast coast of Brazil is classified as semi-arid and in the east coast is tropical humid. Considering the distribution of annual rainfall (Nimer 1989), the northeast coast from 4~ to 6~ is characterized by an excess of four to five dry months, and from 6~ to 12~ the coastal segments with less than two dry months
Corals and coral reefs of Brazil
13
altemate with areas with four to five dry months. The east coast from 12~ to 20~ has less than two consecutive dry months. A month is considered dry when its precipitation value in mm is equal to or smaller than twice the monthly average temperature in degrees Celsius (Gaussen et al. 1953 in Nimer 1989). 2.2.3. Sea surface temperature (SST). The range of maximum SST is the most conservative parameter along the Brazilian coast, varying in the northeast coast from 30~ during summer and fall (February to May) to 28~ from the end of winter to the beginning of summer (August to December), and in the east coast from 30~ (February to May) to 27~ (July and August). The minimum temperature, however, shows a marked decrease from north to south. On the northeast coast, it decreases from 25~ during summer and fall, to 23~ during winter and spring; on the eastern coast, during winter, the minimum temperature can reach 21~ (U.S. Navy 1978). 2.2.4. Waves. The wave pattem is conditioned by variations in the trade winds, i.e. related to movements of the offshore high-pressure centers. The Brazilian coast is mainly dominated by sea waves (locally generated waves with periods lesser than 7s), and those with heights above 1 m account for more than 50% of the observations referred to in the U.S. Navy Marine Climatic Atlas (U.S. Navy 1978). This is the kind of waves that Larcombe et al. (1995) found to be more effective in increasing turbidity of water in their four months of measurements, near the city of Townsville, Australia. In the Brazilian north and northeast coasts, the waves moving from southeast dominate the year round, and the waves from the east are important from January to May (summer-fall) and from September to November (spring). The southernmost part of the northeast coast and the east coast, on the other hand, are dominated by wave moving from east during the whole year. Waves from northeast are only important from November to February (summer), and from southeast occur from March to August (winter). Thus, waves are an effective process in water circulation in the southern part of the northeast coast and in the east coast. The north coast and the northernmost part of the northeast coast are protected from the main wave train during all year, being affected only by a secondary train (waves from the east) from September to May. 2.2.5. Tides. The Brazilian continental shelf has semi-diurnal tides. Due to the large latitudinal extent of the shelf, three different areas are defined, according to the tidal range classification proposed by Hayes (1979): m_acrotidal in the north coast, upper mesotidal in the northeast coast and the northernmost part of the east coast, lower mesotidal in most of the east coast and microtidal in the entire south coast. The most conspicuous effect of the tidal component is observed in the north coast, where it enhances the northwestward flow of the Brazilian Current (the North Brazilian Current), and periodically produces an intensification of this drift. 2.2.6. Ocean currents. The Brazilian Current (BC) and the North Coastal Brazilian Current (NCBC) are the main surface currents on the Brazilian continental margin (Stramma 1991, Silveira et al. 1994). They originate from the South Equatorial Current at about 5 ~ to 6 ~ S and flow to the south (BC) with average velocities of 50 to 70 cm s"I, and to the north and northwest (NBC) attaining velocities of 30 cm s1. Data from the Atlas de Cartas Piloto (DHN 1993) show that between 10~ and 13~ during July and
14
Z.M.A.N. Le~o et al.
August (austral winter) a reverse flow to the north can occur. North of 5~ the North Coastal Brazilian Current becomes stronger as a result of combining with the South Equatorial Current. 3. CORAL FAUNA The Brazilian coral fauna (Scleractinia) has three distinctive characteristics: a) it is a very low diversity coral fauna (18 species) compared with that of Caribbean reefs; b) the major reef builders are endemic species from the Brazilian waters, and c) it is composed predominantly of massive forms. The first descriptions of the Brazilian corals are from those collected during Hartt's voyage to Brazil (Hartt 1868a, 1869, 1870), which were identified by Verrill (1868, 1901a, 1912). Later on, Laborel (1967, 1969a) compared Verrill's taxonomy with contemporary forms and Tertiary fossils and corroborated Verrill's remarks that the Brazilian ahermatypic corals were all related to Caribbean species, but among the reef framebuilders (hermatypic species), the endemism is rather strong. More recently, Bel6m et al. (1986) and Castro (1994) confirmed and expanded Laborel's list of the Brazilian corals. Eighteen species of stony corals (madreporarians), four of hydrocorals, four of antipatharians, and eleven of octocorals constitute the cnidarian fauna of Brazil so far identified.
3.1. Stony corals Six of the reef-building Brazilian corals are endemic (Fig. 2), and among these endemic species some have affinities with Caribbean coral forms and some are related to a Tertiary coral fauna. These archaic species are the most common forms in almost all modem Brazilian reefs. They are the three species of the genus Mussismilia: M. braziliensis, M. hispida and M. harttii and the species Favia leptophylla. This archaism is an inheritance from a large endemic common fauna that existed up to the late Miocene and early Pliocene and was then isolated from the Caribbean area (Frost 1977). Apart from ocean water circulation, the elevation of the Andes and the consequent reversal of flow of the Amazon river to the Atlantic Ocean, may have contributed to the isolation of these two coral provinces, the Caribbean and the Brazilian (Souza 1994). In Brazilian waters these archaic corals were preserved, during Pleistocene low stands of sea level, in a refugium provided by the seamounts off the coast (Le~o 1983). The other two species considered endemic from Brazil are Siderastrea stellata and Favia gravida, both related to the Caribbean coral fauna. Most of the frame-building corals from Brazil are massive. Encrusting forms are present along the edges of the reefs. All reefs lack the branching acroporids that are major corals of the reef crest and fore reef slope of Caribbean reefs. The species Mussismilia harttii, an endemic species very abundant in most of the reefs, has corallites in dichotomous groups with the calyces separated, but it does not make branches. According to data from Laborel (1969a), Bel6m et al. (1986), Castro (1994) and Testa (1997) the Brazilian hermatypic corals are distributed along the coast of Brazil in four major geographic regions: northem, northeastem, eastem and southem (Figs. 1 and 3). The northern marginal area occurs between the Amazon fiver mouth and the Cape Sao Roque (0030 , to 5~ the northeastern area extends from Cape Sao Roque to the mouth of the Sao Francisco river (5029 , to 10~ the eastern area comprises the entire
Corals and coral reefs of Brazil
15
Fig. 2. The Brazilian endemic corals and hydrocorals: a) Mussismilia braziliensis; b) Mussismilia hispida; c) Mussismilia harttii; d) Favia leptophylla; e) Siderastrea stellata; f) Favia gravida; g) Millepora braziliensis; h) Millepora nitida. coast of the state of Bahia, from the mouth of the Sgo Francisco river to the Doce fiver (10~ , to 19~ and the southem marginal area extends from the mouth of the Doce river to the coast of the Santa Catarina state (19o30 , to 27~ The major reef core area
16
Z.M.A.N. Le6o et al.
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Fig. 3. Distribution of the Brazilian corals and hydrocorals along the coast of Brazil. A - Northern region; B Northeastern region; C - Eastern region; D - Southern region. (Based on data from Laborel 1969; Bel6met al. 1982; Castro 1994; Testa 1997). comprises the northeastern and eastern regions. The two marginal regions (northem and southern) were called by Laborel (1969a), the north and the south regions of impoverishment in hermatypic corals. Among the Brazilian endemic species M. braziliensis and F. leptophylla are the corals that show the greatest geographical confinement, because they are described only along the coast of the state of Bahia (the eastern region). On the other hand, the species M. hispida has the largest spatial distribution, because it occurs from Rocas Atoll (northeastern region) to the coast of the Santa Catarina State (southern region). The species Siderastrea stellata and Favia gravida are the most common corals in shallow intertidal pools of the reef tops and are considered as very resistant to variations in temperature, salinity and water turbidity. Siderastrea stellata has a broad distribution along the Brazilian coast, as it is known from the reefs of the northern region to the coast of the state of Rio de Janeiro. Favia gravida is a common species on the reefs from the northeastern and eastern regions. The cosmopolitan species Porites astreoides, P. branneri, Agaricia agaricites, A. fragilis, Montastraea cavernosa and Madracis decactis are species found in both Brazilian and Caribbean reefs. In the Brazilian reefs, they have a secondary role in the construction of the reefs located on the northeastern and eastern regions. The species M. cavernosa varies its forms in relation to depth. The shallow forms are hemispheric and the ones found on the lateral walls of the reefs at depths greater than 5 m may be flattened and encrusting. The species Meandrina braziliensis has two morphological variations: a free-living form that inhabits sandy
Corals and coral reefs of Brazil
17
bottoms and a fixed form attached to the reef walls. It has a wide distribution along the Brazilian coast from the northem region to the southernmost portion of the eastern region. The small corals Scolymia welsii, Phyllangia americana, Astrangia braziliensis and A. rathbuni do not contribute much to the construction of the reef structures. A. rathbuni occurs in the southem region (from the state of Rio de Janeiro to the coast of the Santa Catarina State) at depths from few meters to 90 m, attached to skeletal fragments. The madreporarian corals of Brazil coexist with an active siliciclastic sedimentation. Fine-grained terrigenous sediment input to the shelf is deposited within reef channels. During winter storms, a large portion of this sediment is resuspended reaching the reef areas. The coexistence of corals in this highly terrigenous environment contrasts with most other coral reef environments described in the literature, which require clear waters with minimum runoff from land for growth. How the Brazilian species succeed in these water conditions is still a question. There are suggestions that corals with larger polyps are more resistant to environmental stress than species with smaller polyps: a) corals with large polyps have developed a more efficient mechanism for cleaning themselves of sediment (Stoddart 1969; Dodge et al. 1974; Logan 1988); b) brain-shaped corals that have larger and deeper corallites with large polyps are much more resistant to desiccation during long exposures than micropolypal forms (Fishelson 1973), and c) different species have different capabilities of clearing themselves of sediment or surviving lower light levels (Rogers 1990). Some of the major frame builders corals of the Brazilian reefs, particularly the archaic species Mussismilia braziliensis, M. hispida, M. harttii and Favia leptophylla, have large corallites. Also the species Siderastrea stellata, that is widely distributed along the entire Brazilian coast, have larger corallites than its Caribbean counterparts. Considering these facts, it seems that the prevalence of corals with larger polyps in the Brazilian reefs may be a response to the stressful conditions of our turbid waters. Only the most resistant and the best adapted corals are able to withstand those conditions. 3.2. I-lydroeorals Of the three species of millepores reported from the Brazilian reefs, two are considered as endemic. They exhibit two major growth forms: branching and encrusting. Delicate, finger-like branches are characteristic of low energy environments. Irregular, short, rounded branches are common on the edges of the reefs, with the thick, massive branches in zones of higher energy. Encrusting forms are seen on reef tops or encrusting the axes of gorgonians. The cosmopolitan species Millepora alcicornis predominates on the windward borders of the reefs, a reef region that corresponds to the Acropora palmata zone of the Caribbean reefs. It is found along the entire tropical Brazilian coast. The endemic species Millepora braziliensis (Fig. 2g) was first described by Verrill in 1868, and confirmed by Boshma (1961). More recently Amaral (1997), using biochemical studies, has proved it to be a valid species. In zones of high energy, the colonies of this hydrocoral are more massive, but in protected zones, their branches are flattened. Laborel (1969a) located the zone of Millepora braziliensis immediately below the zone of Millepora alcicornis. It is found on the reefs from the northeastern and eastern regions. The species Millepora nitida (Fig. 2h) is also considered endemic to Brazil and up to the present time is recorded only along the coast of the state of Bahia. The specimens described by Verrill (1968), Boschma (1961) and Laborel (1969a), show similarities
18
Z.M.A.N. Leao et al.
with the species Millepora exaesae, from the Indo-Pacific fauna. The branches are short and fork-like, and their ends are much flatter than in Millepora alcicornis. Besides the millepores, a small hydrocoral, Stylaster roseus, is found in the protected parts of the reefs from the northeastern and eastern regions. It forms small colonies, a few centimeters high, which have a thick base covered with small pointed branches. 3.3. Black corals According to Castro (1994) four species of corals from the group of the antipatharians are recorded from the Brazilian waters: three of the genus Antipathes and one from the genus Cirripathes. The former forms flat, fan-shaped colonies, or have branches arranged like brush bristles; the later, also known as wire coral, forms long branched colonies up to several meters long. They have been recorded only on the reefs along the coast of the state of Bahia (eastern region). Their occurrence is poorly known because black corals still have not been properly studied in Brazil. 3.4. Octocorals Before 1980, only three species of octocorals were described on the Brazilian reefs. All of them belong to the group of the gorgonians, and two of those were considered endemic to Brazil. The Brazilian blade sea fan Phyllogorgia dilatata is found in reefs from the northeastern region to the coast of the state of Rio de Janeiro; the large octocoral Plexaurella grandiflora, is commonly found in the shallow reef areas from the northeastern and eastern regions; and the species Muriceopsis sulphurea, whose colonies have a characteristic yellow color, is frequently found among concentrations of soft algae. In Brazil, M. sulphurea occurs from the northeastern region to the coast of the Rio de Janeiro State. The latest reviews of the Brazilian octocorals by Castro (1989, 1990a, b) revealed eight new species: Plexaurella regia, Muricea flamma, Neospongodes
atlantica, Lophogorgia punicea, Carijoa risei, Heterogorgia uatumani, Ellisella barbadensis and Ellisella elongata. Among these newly described species, two are recorded only on the reefs located along the coast of the state of Bahia (eastern region): Plexaurella regia and Muricea flamma. Two other species are also considered endemic to the Brazilian reefs: N. atlantica, found on soft bottoms at the base of the reefs, and L. punicea, found in the sidewalls of the reefs from south Bahia to the coast of the state of Santa Catarina. C. risei, H. uatumani, E. barbadensis and E. elongata are also recorded from the reefs in the North Atlantic Ocean. In Brazil, C. risei, can be seen occupying the shaded areas of the reefs (caves and ttmnels), H. uatumani occurs l~om the state of Bahia (eastern region) down to Santa Catarina State (southern region), and the large species of the genus Ellisella, E. barbadensis and E. elongata, are found along the entire coast of Brazil. 4. REEF TYPES The description of the Brazilian coral reefs distinguish two grand groups of r e e f s Nearshore and Oceanic reefs, and both types are strongly influenced by the underlying substrate, such as older reef, Precambrian bedrock, volcanic intrusion, beachrock, etc. 4.1. The nearshore reefs These reefs are found on the inner and middle continental shelves. Taking in account two descriptive characteristics of the reef morphology: a) the reefs distance from the coast,
Corals and coral reefs of Brazil
19
and b) the reefs dimension (particularly the proportion between length, width and height), as well as a third aspect that is the reefs relationship with the coastal evolution, two major subcategories of reefs are distinguished: the reefs attached to the coast, and the reefs detached from the coast. Each one of these subcategories can even be subdivided into various reef types (Fig. 4 A to I). 4.1.1. Reefs attached to the coast. These reefs are, at present, adjacent to the coastline, and most commonly partially covered by siliciclastic sands. They include flinging reefs and attached bank reefs (Fig. 4 A to D). Fringing reefs (Fig. 4 A and C). These reefs usually border the shore of islands up to several kilometers (Fig. 5), developing above the island substrate as a continuous fringe. This fifnge became narrower with the lowering of sea level that occurred in late Holocene time and, thus, diminished the reef distance from the shoreline, and partially buried the back-reef lagoon. The fore-reef depths can vary from 5 to 10 m where an incipient spurand-groove system can develop. A very shallow lagoon (1 to 2 m of depth) is common in the back-reef area where small reefs, coral knolls (sensu Ginsburg and Schroeder 1969), are seen. Channels, that allow the exchange of water between the back-reef and the outer reef zone, may occasionally interrupt the reef crest. Attached banks (Fig. 4 B and D). These reefs occur also adjacent to the beach but are of limited lateral extent (Fig. 6). Generally these bank-type of reefs do not exceed more than 5 km long. The entire reef fiat is in the intertidal zone and no lagoon is formed. Tidal pools are common, generally of a reduced extent, say 5 to 10 m of width, usually not exceeding 1 m in depth. The reef front depth varies from 5 to 10 m and reef walls are generally abrupt. We differentiate these attached banks from the above described fringing reefs by their smaller dimensions, the absence of the typical back-reef zone with a lagoon, and their development in relation with the coastal evolution. The bank reefs sit on submerged rock exposures, of diverse composition, and generally occur on the shelf bottom facing small promontories along the coastline (Fig. 6). These attached bank reefs were isolated from the shoreline when reef growth initiate as suggests the contour of the reef substrate drawn in Figure 4 B, opposed to what is seen with the fringing reefs (Fig. 4 A). With the sea level lowering and/or coastline progradation these discontinuous banks are found closer to the coastline and some may even be found, at present, with the leeward portion covered by sandy beaches.
4.1.2. Reefs detached from the coast. These consist of reef structures of variable dimensions, from few meters to tens of kilometers. They occur from 1 to tens of kilometers off the coastline, in various depths. They do not form a lagoon, and sediment transport occurs freely on the leeward side of these reefs. Detached reefs can be divided into various reef types: Coral knoll, Patch and Bank reefs, and Pinnacle (Fig. 4 E to I). Coral knoll (Fig. 4 E). It can attain maximum dimensions and heights of a few meters (sensu Ginsburg and Schroeder 1969), and is found at variable shallow waters (usually less than 5 m deep), where they may alternate with patch reefs.
Z.M.A.N. Le8o et aL
20
Patch reef (Fig. 4 F). It has lateral dimemions of tens of meters with widths and lengths larger than heights. The lateral walls may have abrupt relief, around 5 m high. They are sparsely distributed over wide areas of the Brazilian inner shelf, i.e., in water shallower than 10 m.
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Corals and coral reefs of Brazil
21
Fig. 6. An attached bank reef of the Itacimirim beach, north coast of the state of Bahia (eastern region). See figures 1 and 16 for location.
Bank reef (Fig. 4 G and H). A reef structure whose horizontal dimension range from about 50 m up to some tens of kilometers, and their heights above the sea floor varies from 10 m (shallow banks) (Fig. 4 G) to more than 20 m (deep banks) (Fig. 4 H). This
22
Z.M.A.N. Leao et al.
reef type has variable shapes (irregular, circular, elongate, arc-like, etc.) and is related to its substrate or to its relative position to the present day sea level. Elongate reefs developed on lines of beachrock, features that are widely distributed along the northeast and east coasts of Brazil (Fig. 7). The larger and irregular bank reefs of the Abrolhos area (Fig. 8), which established on the topographic highs left by the erosion of older reefal carbonates, are also included in this category. Most are flat-topped reefs that were truncated during low sea level stands, favoring their lateral growth rather than their vertical development. Submerged banks, few meters high, are found in depths up to 10 rn, and they may be related to erosional phenomena followed by relative sea level oscillations. Pinnacle (Fig. 4 I). This distinctive reef type range in height above the sea floor from 5 to 25 m, and from 5 to 50 m in diameter of their tops. It can be of two types: 1) columnar, where the base is equally as wide as, or wider than, the top of the reef, and 2) chapeirao, where the flat top is wider, sometimes over three times larger than its base. Chapeirao (from the Spanish "chaperon", pl. in Portuguese "chapeir6es") is a term introduced by Charles F. Hartt in 1870, which alludes to hats with broad brims. It refers to the coral growth form unique of the Brazilian reefs and consists of isolated narrow pillars whose tops are expanded laterally, resembling flat mushrooms (Fig. 9). Seen from above, these structures have almost perfectly rounded shape and are easily mapped from aerial photographs (Fig. 10). 4.2. The oceanic reefs They are the reef structures that are located on the outer shelf and on oceanic sea mountains, including shelf edge reefs and an atoll. S h e l f edge reefs. Reefs growing at the border of the continental shelf, with widths up to 3 km and a relief of 35 m at depths of 50 rn, have been described in some portions of the Brazilian shelf edge (Kikuchi and Leao 1998) (Fig. 11). The reef initiation must have occurred earlier in the Holocene, at lower stands of sea level, and are now veneered with a deeper water commtmity. Atoll. It is an oceanic ring-shaped reef that encloses a lagoon (sensu Ginsburg and Schroeder 1969). Its dimensions can vary worldwide, from a few kilometers to tens of kilometers in the largest dimension. The only Brazilian atoll, Rocas, has dimensions of 3.5 km long by 2.5 km wide. Despite its small dimensions, the reef front, reef flat and a lagoon can be clearly distinguished and subdivided into discrete features (Fig. 12). Its construction is mostly due to non-articulate coralline algal growth (Kikuchi 1994; Kikuchi and Leao 1997; Gherardi 1997; Gherardi and Bosence 1999). 5. REEF DISTRIBUTION
As previously described, the corals and coral reefs of Brazil are found in four geographical regions: northern, northeastern, eastern and southern. 5.1. The northern region In this paper this region comprises the shelf between the eastern limit of the Amazon River mouth and the Cape Sao Roque including the coastline of the states of Maranhao,
Corals and coral reefs of Brazil
23
Fig. 8. The Prado isolated bank reefs on the coastal arc of Abrolhos. The long axis of the reef at the bottom of the figure is about 1km. For location see figures 1 and 19. Piaui, Cear~ and Rio Grande do Norte (Fig.l). This is a marginal realm where reefs are sparse and the community o f hermatypic corals is poor. The only reefs described in the literature are those o f the Parcel de Manuel Luis, on the shelf o f the state of Maranhao, 86 km off the coastline, around 0~ and 44~ These reefs grow as pinnacles in depths of 25 to 30 m and the top of the pinnacles reach up to 2 m water depth; during
Z.M.A.N. Le6o et aL
24
Fig. 10. Aerial view of giant isolated "chapeir6es" from the Parcel dos Abrolhos reefs (Eastern region). The diameter of the top of "chapeir6es" seen at the water surface can reach tens of meters. For location see figures 1 and 19. spring low tides some are at sea level. The reefs consist of coralline algae, hermatypic coral genera, such as Mussismilia, Siderastrea, Agaricia, Meandrina, and the hydrocoral Millepora (Coura 1994). From this area to the east, up to Cape Sao Roque, some patch and bank reefs are mapped in the inner shelf, no more than a few kilometers from the coast (Nautical Chart # 800). No detailed work has been carried out on these reefs.
5.2. The northeastern region This region comprises the shelf that extends from Cape Sao Roque to the Sao Francisco River mouth, along the states of Rio Grande do Norte, Paraiba, Pernambuco and Alagoas (Fig. 1). Reefs abound on the inner shelf, especially in its northem and southernmost parts, around Cape S~o Roque, and from the central part of the state of Pernambuco to south of the state of Alagoas, respectively. The coral buildups are generally patch or
Corals and coral reefs of Brazil
SE B'
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25
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Fig. 11. Echosounding profile at the shelf edge in the north part of the state of Bahia (Praia do Forte reefs). On the profile, (p) is the reef base, (t) is the top of the reef talus deposit, (h) is the inflection point at 55 m deep and (b) is the shelf break at 50 m. The photograph shows coralline algae rodoliths, macroalgae and sponges covering the sea bottom (modified from Kikuchi and Le~o 1998). For location see figure 16.
Fig. 12. Satellite image of Rocas Atoll (northeastem region). The longer axis is 3.5 km. For location and identification of morphological features see figure 15.
26
Z.M.A.N. Leao et al.
elongated bank reefs, but some attached banks are present, as well. The described areas are Sioba and Rio do Fogo reefs (Testa 1996, 1997) and Tamandar6 reefs (Laborel 1969a; Maida and Ferreira 1997). The reefs of Sioba and Rio do Fogo are coral knolls and patch reefs generally aligned longitudinally NW-SE, parallel to the coast (Fig. 13). They occur in the inner shelf at depths less than 10 m from 5 to 7 km from the coast and are restricted to a zone termed sublittoral turbid zone by Testa (1997). The coral knolls are about 0.5 rn high and the patch reefs can attain up to 6 rn high. The leeward, central and windward environ-ments present notable differences in reef morphology and composition of reef building organisms. The leeward area is characterized by a nearly vertical wall 6 m high. A 3 m high slope of mud built against the reef wall is found in this area. Sediments consist of 57% siliciclastic and 43% carbonate mud, rich in sponge spicules. The abundant Penicillus can be responsible for part of the carbonate mud. Close to these deposits, discoid rhodoliths composed of Spongites are found. The central area consists of patch reefs cut by channels approximately 0.5 to 1 m wide. Living rhodoliths found among seagrass beds in the channels are composed of Mesophyllum. In the windward area, patch reefs are about 4 m high. The Tamandar6 reef complex of elongated banks, patch and attached bank reefs, runs parallel to and close to the coast. According to Maida and Ferreira (1997), the reefs are arranged in three lines (Fig. 14). The first line is an alignment of elongated bank reefs, next to the beach, sometimes attached to the coastline, with tops exposed at low tide. The second-line reefs rise from depths between 1 and 8 m at different distances from the coast. They form elongated banks that delimit a backreef zone where patch reefs grow seaward of the attached bank reefs. Their tops may be either exposed at low tides or submerged just below water level. Though not cored, the spatial arrangement and elongation of these reefs suggest that they may have grown over lines of beachrock (Laborel 1969a; Dominguez et al. 1990). The third line of reefs forms a barrier-like reef
Fig. 13. Sioba and Rio do Fogoreefs, northeasternregion (modifiedfrom Testa 1997).
Corals and coral reefs of Brazil
27
structure that according to Maida and Ferreira (1997) is typical of the Tamandar6 reef complex. These reefs are narrow, elongated, with the back reef walls undercut by interconnected cavities and channels. The windward side has an irregular algal-vermetid ridge, and in some place channels that cut the ridge suggests a poorly developed spurand-groove system. Scattered pinnacles may be found seaward of these reefs.
Fig. 14. Tamandar6reefs, northeastern region (modified from Maida and Ferreira 1997). Rocas atoll is located about 270 km eastward off the coast of the State of Rio Grande do Norte (Fig. 1). It is built on the flat top of a seamount, with a surface depth ranging from 15 m to 30 m. It has an elliptical shape, opened on its western and northern parts. Its greater axis, oriented E-W, is about 3.5 km long and the minor axis, oriented N-S, is about 2.5 km long (Fig. 15). The reef is divided into two components: the reef proper and a sandy deposit. The reef proper is 100 to 200 m wide, interrupted occasionally by shallow pools. The sandy deposit is composed mainly of coralline algal debris of medium to fine-sand sizes. An algal ridge bounds the reef flat that is dominated by a coralline algae-vermetid association, growing as small linear ridges. A shallow lagoon, with maximum depth of 6 m, is seen inside the northwest part of the reef. The reef front has two distinct features: on the windward side (east and southeast sides) it is an abrupt, nearly vertical wall to depth of about 10 m where a talus deposit occurs. On the lee side a spur-and-groove system develops to depths of about 20 m. There are two sandy cays on the western side of the atoll: the Cemiterio islet that is 2 m high, and the Farol islet about 3 rn high. Although not widespread, corals and hydrocorals occur in protected areas, mainly in the lagoon, within the pools, and in some grooves of the reef front (Kikuchi 1994; Kikuchi and Leao 1997).
28
Z.M.A.N. Le6o et al.
Fig. 15. Morphological features of Rocas atoll (modified fromKikuchi and Le~o 1997).
5.3. The eastern region (the coast of the State of Bahia) This region comprises the shelf adjacent to the coastline that extends between the Sao Francisco and the Doce rivers. It spreads over 1,000 km subdivided into four major areas of coral occurrence as follows: the North Bahia coast, the Todos os Santos and Camamu bays, the CabrfiliaJPorto Seguro area and the Abrolhos reef complex (Fig. 1). All Brazilian reef types and reef building coral species are found in this region. The modem Brazilian shelf is not rimmed, instead reefs occur in various areas along its length. At the north part of the coast of the State of Bahia, bathymetric profiles (Fig. 11) reveal the occurrence of drowned reefs on the shelf edge along some tens of kilometers (Kikuchi & Leao 1998), and these data corroborate Milliman and Barreto's (1975) suggestion that the Brazilian carbonate shelf was rimmed on various portions. 5.3.1. The North Bahia coast (Fig. 16). Between the beaches of Praia do Forte and Abai, bank reefs and discontinuous attached bank reefs of variable sizes occur. The attached bank reefs usually slope downward into the beach sand, and water depth does not exceed 10 m in the forereef. The patch and bank reefs are located in water no deeper than 20 m and are generally 5 to 6 m high. The shallower banks (growing at 7 to 10 m water depths) generally exhibit an overhang on their edges, around 4 to 5 m above the sea bottom. Another type of reef structure found in this area is the superficial coral-algal constructions above beachrock that parallel the beaches located a few kilometers south of the coral reefs. These carbonate buildups have thickness no great than 1 m and developed after 5.9 ky BP, the youngest recorded ~4C date of the underlying beachrock (Nolasco 1987).
Corals and coral reefs of Brazil
29
Fig. 16. North Bahia reefs, easternregion (modified from Le~oet aL 1997). 5.3.2. The area of Todos os Santos and Camamu bays (Fig. 17). Shallow flinging reefs, which are more or less continuous, border the eastern and southeastem shores of the Itaparica Island and of the small islands located at the north part of the Todos os Santos Bay. Shallow seismic profiles and data from a core through a Holocene sequence about 10 m thick, suggests that the Itaparica reef accretion occurred on the top of an erosional unconformity, which formed the island substrate, a dark green shale of Cretaceous age (Araujo 1984; Araujo et al. 1984). Within the Todos os Santos Bay, in its north portion, there are also a series of 4 m high patch reefs growing in depths of 10. They generally have a rounded profile, with no widening of their tops. Fringing reefs also border the Tinhar6 and Boipeba islands and some other islands near the Camamu Bay. Although the coral reefs of the Bay of Camamu were the first cited in the literature about Brazilian coral reefs (Spix and Martius 1828), this is the area least known on the whole coast of the State of Bahia.
5.3.3. The Cabr~ilia / Porto Seguro area (Fig. 18). This area is characterized by the presence of bank reefs with varied shapes and dimensions, in water no deeper than 20 m, nmning parallel to the coastline. Thin elongated reefs may have grown on a submerged string of beachrock lying at about 10 m deep (Laborel 1969a). In both areas, parallel to the coast, reef communities colonize lines of beachrock. South of Porto Seguro, before reaching the Abrolhos area, there are some important attached bank reefs bordering the localities of Trancoso and Taquena. Furthermore, facing the Corumbau point, there are the Itacolomis reefs, which are the beginning of the occurrence of the giant chapeir6es, as well as isolated bank reefs separated from one another by irregular channels. These reefs have been very little studied so far.
30
Z.M.A.N. Le6o et al.
Fig. 17. Coral reefs from the bays of Todos os Santos and Camamu,eastern region. 5.3.4. The Abrolhos reef complex (Fig. 19). Nearly opposite to the town of Prado, the continental shelf suddenly widens to form the Abrolhos Bank, where the largest and richest coral reefs of the eastern Brazilian region are located (Le~o 1982). These reefs form two arcs. The coastal arc is composed of bank reefs of varied shapes and dimensions, whilst the outer arc, that borders the east side of the Abrolhos Islands, is formed by isolated chapeir6es in water deeper than 20 m. Incipient fringing reefs border the shores of the five islands that form the Abrolhos Archipelago. The coastal bank reefs form a complex of large reef structures consisting of coalescent chapeir6es, usually surrounded by isolated chapeir6es. Most of these bank reefs are oriented parallel or almost parallel to the coastline, probably as a result of the prevailing wind-driven currents in this region, which move from the northeast and east most of the year. Some reefs are protected from the dominant northeast and east winds but are exposed to winter storms from the south. In the northernmost part of the area, smaller bank reefs are found about 5 to 10 km off the coast, at about 10 to 15 m water depths. In the middle part of this coastal arc there is the Parcel das Paredes reefs, a complex of larger bank reefs and isolated chapeir6es spreading in a north-south direction
Corals and coral reefs of Brazil
Fig. 19. The Abrolhos reef complex, eastern region.
31
32
Z.M.A.N. Le6o et al.
for an extension of about 30 km. The largest reef of this complex, the Pedra Grande reef, is a very irregular structure about 17 km long by 10 km wide, formed by a network of isolated and fused chapeir6es with several deep channels. Southward, three smaller bank reefs complete this coastal arc of reefs. In one of them, the Coroa Vermelha reef, there is a small sand cay about 300 m long by 100 m wide. This carbonate islet is about 1.5 m above mean sea level and was formed by the accumulation of the detrital material derived from the erosion of the reef structure. Approximately 15 km east of the southemmost bank reef (the Vigosa reef), is the Popa Verde Bank, a group of nonemerging coral reefs, which due to the richness of its fauna and flora, is frequently visited by divers. The Parcel dos Abrolhos comprises the outer arc of reefs. It consists of isolated chapeir6es, which are surrounded by water depths exceeding 20 m. These chapeir6es do not coalesce to form bank reefs as in the coastal zone, and do not even emerge during low tides. Fringing reefs border the volcaniclastic rocks of Cretaceous age (Abrolhos Formation, Espirito Santo Basin) that constitute the islands of the Abrolhos Archipelago. These are not remarkable coral constructions, but are rather a veneer of reef organisms formed by the growth and cementation of coralline algae and other encrusting organisms, whose cavities are infilled with cemented sediment. These reefs extend from the low water level to depths of about 5 m.
5.4. The Southern region This is the southern marginal of the Brazilian shelf in relation to the growth of hermatypic corals. South of the latitude of the Doce River mouth (19~ no reef is known, though corals (Mussismilia hispida) are still found along the coast of the state of Santa Catarina (Castro 1994). At the Arraial do Cabo area in the state of Rio de Janeiro (Fig. 1), in the so-called "coral oasis" the coral species Siderastrea stellata and M. hispida are also found. 6. THE G E O L O G I C A L HISTORY OF THE REEFS The last post-glacial sea level fluctuations left distinctive imprints on the development of the Holocene coral reefs in Brazil. The relative sea level curves for the Brazilian coast, developed by Martin et al. (1979, 1985, 1996) (Fig. 20), are characterized by a transgressive phase that reached a maximum of 5 m above present sea level at 5.1 ky BP, followed by a general regressive phase since that time. It thus follows
0 .,510
I
2
3
# ~,
BP
Fig. 20. The Holocene sea level curve for the coast of the state of Bahia, during the last 7 ky (after Martin et aL 1979, 1985).
Corals and coral reefs of Brazil
33
the lineament of the "transgressive-regressive curve" of Davies and Montaggioni (1985), that is generally described in the southern hemisphere (Camoin et al. 1997), instead of the "transgressive curve" proposed for the Caribbean (Neumann and Macintyre 1985). During reef development in Brazil, four well-marked stages are recognizable: 1) reef initiation and establishment, 2) rapid upward reef accretion, 3) lateral growth of the reefs, and 4) reef degradation. The first two occurred in early Holocene time, during the transgressive sea, and the last two stages developed during the late Holocene sea level regression. Based on radiocarbon-dated corals and the rate of reef accumulation, two distinct reef growth patterns will be described: one that characterizes the reefs from the Eastern region (the coast of the state of Bahia) and the other the Rocas atoll.
6.1. Reefs from the eastern region Data obtained from two cores are used for describing the growth history of the coastal reefs. These were recovered from the Guarajuba reef, on the northemmost part of the eastem region (the north coast of the state of Bahia), and the Abrolhos reefs, on its southernmost part, because they are the ones with higher number of dated corals (Fig. 21 A to D). 6.1.1. Stage I - Reef initiation and establishment (from 7 to 5 ky BP, Fig. 21A). Data on sedimentation rates based on the age of a paleolagoon carved into the Abrolhos Bank on the southernmost part of the eastern region (Vicalvi et al. 1978), added to the Brazilian sea level curves (Martin et al. 1979, 1985, 1996), indicate that flooding of the continental shelf in Brazil occurred between 8 and 7 ky BP, indicating that reef growth in eastern Brazil could not have initiated earlier. The age of 6.66 ky BP for the oldest coral from the Abrolhos reefs, shows that the inner shelf reefs initiated their growth a little after 7 ky BP, following pattern similar to many present-day reefs (Macintyre and Glynn 1976; Davies and Montaggioni 1985; Montaggioni 1988; Cortes et al. 1994; Cabioch et al. 1995; Camoin et al. 1997). Reef initiation in Guarajuba was estimated by interpolating growth surface lines based on both the average rate of reef accretion of 7.3 mm y-1 and the Brazilian relative sea level curve. Similarly to the Abrolhos reefs, it must have initiated no later than 7 ky B P. For the shelf margin reefs, however, the rate of sea level rise must have outpaced reef growth, during early Holocene time. At the continental shelf of north Bahia, for example, submerged bank reefs about 5 m high, located 10 km offshore, at depths of 45 m, and at the shelf break (15 to 20 km off the coast, at a depth of 50 m) (Fig. 11), did not "keep-up" with sea level rise, and then a "give-up" facies of coralline algae rhodoliths developed at their drowned surface (Kikuchi and Le~o 1998). This characterizes a "giveup" reef growth phase of the Brazilian reefs. 6.1.2. Stage 2 - Rapid upward reef accretion (from 5 to 4 ky BP, Fig. 21B). It is characterized by a vigorous and rapid vertical growth of the reef structure, which is reflected by accumulation rates in the order of 7 mm y-l. Dated corals from the surface of both cores indicate that these reefs had already reached sea level before that time. The cored reefs were established on a reef foundation located at depths of at least 10 m below the present position of sea level, and initiated growth after 7 ky BP, thus growing
34
Z.M.A.N. Le~o et al.
10 m in less than 3 ky. The major framebuilders of the Brazilian reefs are massive coral heads, and the fast growing massive coral Mussismilia braziliensis, with annual growth band thickness of 8 mm (measured in X-radiographs), may be responsible for part of this stage of rapid reef upward growth, because it is the coral species that caps all studied reef structures from the Bahia reefs. In the offshore modem reefs of Abrolhos, this coral species is still abundant on the top of submerged chapeir6es (Laborel 1969a; Leao 1982). This period represents a "catch-up" mode of reef growth (sensu Newmann and Macintyre 1985) - the climax phase of reef development in Brazil. 6.1.3. Stage 3 - Lateral growth of the reefs (from 4 to 2 ky BP, Fig. 21C). The upward reef accumulation stopped when reef structures reached sea level. From then, up to the Present, the coastal reefs of Bahia passed the climax of their development, and reef growth was only possible laterally. In the two illustrated reefs, dated corals located a couple of meters from the drilled sites, with ages younger than the corals from the top of the cores (Fig. 21C), illustrate this phase of reef development in Brazil, where lateral growth of the reef structures surpassed their vertical accretion rate. Dated corals from the surface of reefs located in the southernmost part of the northeastern region (the reefs of Alagoas and Pernambuco, see Fig. 1 for location) have radiocarbon ages ranging between 3.9 and 5.7 ky BP (Barbosa et al. 1986; Dominguez et al. 1990), showing that these reefs also approached sea level before the present time, and lateral growth must then have occurred. This period characterizes a passage from a phase of reef aggradation to a dominantly progradation one. 6.1.4. Stage 4 - Reef degradation (from 2 ky BP to the Present, Fig. 21D). The fmal stage of development of the coastal reefs is characterized by an overall decline in reef growth. As a consequence of the sea level drop to its present position, all nearshore reefs in Brazil became emergent. A survey of the old coral community from the tnmcated reef tops and from the living coral community of the surface of modem shallow reefs from north Bahia (Leao et al. 1997; Kikuchi and Leao 1998), revealed that over the last 2.5 to 3.5 ky, corals have significantly declined in colony size (from average 60 to 12 cm), and the major reef building species have changed. The lowering of the sea level that occurred after 5 ky BP, placed the reefs closer to the coastline and mobilized the western continent-derived terrigenous sediment toward the eastern reef system. This exposed the nearshore reefs to heavy sedimentation, high levels of turbidity, and the intertidal reef community to intense solar radiation, and must have contributed to an increase in coral mortality. Higher live coral coverage (up to 30%) is found today only in the reefs located off the coastline, mainly in the southernmost part of the eastern region, the Abrolhos reefs (Pitombo et al. 1988). 6.2. The Rocas atoll Three factors differentiate the patterns of reef development in Rocas from the coastal reefs of the eastern region: the time of reef initiation, the reef accumulation rate and the time at which the reef approached sea level. Considering the ages of corals from the longest cored Holocene sequences (Rocas and Abrolhos, ca. 12 m, see Figs. 21 and 22), one sees that there is a time lag of almost 2 ky between reef initiation in Abrolhos (6.66 ky BP) and on Rocas atoll (4.86 ky BP). The time that the reefs approached sea level also appears to have been delayed in Rocas (2.02 ky BP) by 2 ky in comparison to Abrolhos (4.32 ky BP). The highest
Corals and coral reefs of Brazil
35
GUARAJUBA (m)
ABROLHOS
....---f
14-
.2J~L
I
o
...... -I~
-
PRESENT
Y Z _Z ~g
./ / f .,
12
, /
FROM 2 KY BP TO THE PRESENT SL 2 KY BP .............................................................................................................................................. o 2.05: l : O . 0 7 e ~ I_l
.
8
"03• 0.18 'k
.
12
C
FROM 4 TO 2 KY BP
SL 4 KY BP
,
y
8
12
B
FROM 5 TO 4 KY BP
SL 5 KY BP .....................................................................................................................................................................
f,~") M. braziliensis ?,~ M. harttii
o
LL
Massivecoral
~'y~- iillel~ora ,s..p 9 (14Cage ky BP "~
Corallinealgal crust
A
Core
[~
Precambrianbasalt Pleistocene reefal limestone 5.23•
A
FROM 7 TO 5 KY BP
Fig. 21. Reconstruction of reef growth on the Eastern region based on '4C dates and reef accumulation rate. A - reef initiation and establishment; B - rapid vertical accretion stage; C - lateral growth stage; D - reef degradation. MLWL --- mean low water level. SL= sea level according to Martin's Curve (Martin et al. 1979).
36
Z.M.A.N. Le~o et al.
rate of reef accumulation in Rocas is in the order of 3.10 m m gl, in contrast to the highest numbers of 7.14 to 7.85 mm y-i for the coastal reefs of north Bahia. This variation in growth rates between Rocas and the Bahia reefs may be explained by the difference in the building organisms. Rocas atoll, which has the lowest growth rates, is mainly built by coralline algae (Kikuchi and Leao 1997), whereas the reefs from Bahia are dominantly constructed by corals, and have at their upper parts the massive fast growing (8 mm yrl.) endemic species Mussismilia braziliensis. Even showing these differences from the coastal reefs, the initial stage of reef development in Rocas occurred, also, after 7 ky BP (Fig. 22 A). Since then, the vertical growth of the reef has been continuous (Fig. 22 B), but it appears that the reef had different rates of accumulation in its leeward and windward sides. The windward arc of the atoll approached to sea level by 2.02 ky BP (Fig. 22 C), while its leeward side, the site of the drill hole, reached the present position of sea level only by 0.84 ky BP (Fig. 22 D), much later than the other cored reefs. The radiocarbon ages of the top of Rocas Atoll are time coincident with the ages of the patch reefs from Rio Grande do Norte (1.28 to 0.45 ky BP) (Testa 1996), suggesting that the reefs from the northernmost part of the Brazilian coast are younger than the reefs from the southernmost part of the northeastern region and the whole eastern region. 6.3. Comparison with other reef areas Based on the two described examples we can conclude that the first stages of reef development in Brazil follow patterns similar to most growth history models described for many reef areas in the world - the highest reef growth rates coincide with the "keep-up" and/or "catch-up" stages of vertical accretion of the reef structures. The phase of highest rates of reef accumulation occurred in Brazil when sea level was akeady at or above its present position. The presence of fossil reef tops (31 dated corals with ages ranging from 0.45 to 6 ky BP) (Le~o et al. 1985; Martin et al. 1996) exhibiting truncated massive coral colonies up to 1 m of diameter (Lego et al. 1997), elevated reef spits (Kikuchi 1994; Kikuchi and Le~o 1997) and disseminated eroded algal ridges (Le~o 1982; Araujo 1984; Nolasco and Le~o 1986; Testa 1997; Maida and Ferreira 1997), are examples of high sea level peaks in Brazil. The final stage, however, is characterized by the prevalence of lateral growth of reef framework, and development of detrital facies, the signature of a regressive-still-stand phase of sea level. This is a feature not common in most reef models in the North Atlantic Ocean. 7. MAJOR ENVIRONMENTAL IMPACTS 7.1. Natural disturbances Because the Brazilian reefs experience no hurricanes and overlie a passive continental shelf, effects of natural disturbances recorded in our reefs are related only to the sea level oscillations that occurred during the last 5 ky, and the recently observed mass coral bleaching that occurred after a rise in sea surface temperatures.
7.1.1. Sea level oscillations. The history of sea level during late Holocene time shows that the Brazilian coast experienced considerable relative sea level fluctuations (Martin et al. 1979, 1985, 1996). These sea level oscillations had profound effects on the evolution of the coral reefs. The late Holocene regression that occurred during the last 5 ky was responsible
Corals and coral reefs of Brazil 3.5 km
ROCAS
PRESENT MLWL .....................
(m) 0.84• o .................
v, 1f v v, v v, .v_ v._ v . + v . . v
v....v ..v v
v
FROM 2 KY BP TO PRESENT
(m) o
SL 2 KY BP .................................................................
-++-
'"..... - 16
......
. . . . . . . . . . . . . . . .
4
8
12
C
FROM 3 TO 2 KY BP
(m)
SL 4 KY BP o ....................................................................................
4
/4 3.06:1:0.18. ~
8 ,,
4.41•
]
k- ~
~|
4.86+0.20./~b_,,.,_r,_ ~. \
B
FROM 5 TO 3 KY BP
(m)
+OJ_ Massive coral
Coralline algal crust I ~
Volcanic rock 9 14Cage ky BP
SL 5 KY BP ",u~. ~ Coralline algae A Core 0 .....................................................................................
FROM 7 TO 5 KY BP
Fig. 22. Reconstruction of reef growth on Rocas atoll based on ~4C dates and reef accumulation rate. A - reef initiation; B - vertical growth; C - windward truncation; D - leeward truncation. M L W L = mean low water level. SL = sea level according to Martin's Curve (Martin et al. 1979).
37
38
Z.M.A.N. Leao et al.
for the degradation phase of the nearshore reefs. As previously described, the lowering of sea level exposed the reef tops to marine erosion, dissolution and extensive bioerosion. Furthermore, the reef communities dwelling on these tops experienced stress resulting, chiefly, from strong solar radiation and high levels of sedimentation and water turbidity. Several laC dates from the tops of the coastal bank reefs, ranging from 3.18 to 6.00 ky BP (Leao et al. 1985; Martin et al. 1996; Kikuchi and Leao 1998), are evidence that the reefs reached heights higher than the present sea level, and that they were truncated by erosion due to sea level drops. On these flattened reef tops, which are totally subaerially exposed during low tides, living corals occur only within tidal pools. There, variations of water temperature and salinity, as well as long exposures to strong solar radiation, are stress factors for most of the coral species. Small colonies of the endemic species Siderastrea stellata and Favia gravida are the only corals that inhabit this reef environment. Increased coastal sedimentation during the regression subjected the reefs to the influence of a highly siliciclastic sediment influx. Data from several areas along the northeast and east coasts of Brazil shows that the nearshore reefs are located in a sedimentary province dominated by terrigenous sediments, either relict or modem. In the northeastern region, for example, the sediments onshore the reefs of Rio do Fogo and Sioba (Fig. 13), at the coast of the state of Rio Grande do Norte, have more than 55% of relict siliciclastic constituents (Testa 1997). Along the whole coast of the state of Bahia (the eastern region, Figs. 16, 17, 18 and 19), on the nearshore reefs, 40 to 80% of the perireefal sediments have terrestrial sources (Leao 1982; Araujo 1984; Nolasco and Leao 1986; Leao and Ginsburg 1997). All these terrigenous sediments are unconsolidated muddy sands derived from ancient deposits that cover most of the hinterland and outcrops along the coast, mostly of the Tertiary Barreiras Formation that can also occur submerged on the inner shelf, and to a minor degree, from fiver outputs that are carried to the reefs during winter storms. These environmental conditions, such as strong solar radiation, low light levels and high sediment influx exceed the tolerance levels of most of the Brazilian coral species. Only the most resistant and the best adapted species withstand the stressful conditions of our coastal waters.
7.1.2. El Nifio-Southern Oscillation (ENSO) and coral bleaching. Although coral bleaching has long been observed along the Brazilian coast, no systematic studies about its cause were made until 1993, when an extensive bleaching of the species Mussismilia hispida and Madracis decactis occurred in the coast of the state of S~o Paulo (the southern region) (Migotto 1997). The author points out an anomalous rise of the sea surface temperature as the major cause for the bleaching, and reported that after six months all bleached colonies had recovered. The strong ENSO event that begun at the end of 1997, in the Pacific ocean, caused a rise of the sea surface temperature in some regions of the Brazilian coast as well, especially in the eastern region. The sea temperature rise started in mid January 1998 (summer in the southern hemisphere), attained its climax in mid March and the beginning of April, and faded away at the end of May (data obtained from the Monthly Climatology Charts produced by Dr. Allan Strong - NOAA/NESDIS, available at http://psbsgil.nesdis.noaa. gov: 8080/PSB/EPSSST/climo&hot.html, Fig. 23). Two hot spots were registered at the coast of the state of Bahia, one at its north coast (around 13~ - 39~ Fig. 16), and the other at the Abrolhos region (around 18~ - 39~ Fig. 19). In both areas the
Corals and coral reefs of Brazil
39
1,00
0,75
? 0,50 o
0,25
0,00
Date
Fig. 23. Sea surface temperature anomaly of the north coast of the state of Bahia (Eastern region) in 1998, based on hotspot charts produced by Dr. Alan Strong (NESDIS/NOAA). TABLE 1 Environmental parameters measured in 1998. Temperature (~ Surface Bottom
Salinity Surface
Bottom
14/Apr
30.5
29.0
38.0
38.0
17/Apr
29.5
28.5
37.0
38.0
24/Apr
29.0
28.5
37.0
36.0
01/May
29.5
-
39.0
-
estimated sea surface temperature anomaly, of about I~ matched with measured temperatures in the field, which ranged between 29.5 ~ and 30.5~ (Table 1), about one degree higher than the value of 28.5~ that is commonly found at that time of the year. Two reefs were surveyed, one in each area (north Bahia and Abrolhos), in order to estimate the degree of bleaching. An average of one hundred coral colonies were counted and identified in each reef, and they were classified into three categories: healthy, partially bleached and bleached. At the north Bahia area, the survey was performed weekly during the first month (April 14th, 17th, 24 th and May 1st), and monthly until September, when the first signals of recovery were observed. The Abrolhos reef was surveyed only once (April 29th). In the North Bahia reefs extensive coral bleaching was observed. Three coral species were the most affected: Agaricia agaricites showed an average of 80% of its colonies totally bleached; 60 to 20% of the Mussismilia hispida colonies were bleached and Siderastrea stellata had between 45 to 15% of its colonies affected. From the end of the temperature anomaly, in late May, to September, the frequency of bleached colonies
40
Z.M.A.N. Leao et aL
declined until no bleached Siderastrea stellata was seen, and M. hispida colonies were observed in process of recovery (only less than 10% of its colonies were affected), but more than 60% of A. agaricites colonies were still bleached (Fig. 24). After six months no bleached coral was seen and recently dead colony was not observed. In Abrolhos the degree of bleaching was also considerable. The most affected species were: Porites branneri with more than 80% of its colonies totally bleached, M. hispida with 85% affected (45% totally and 40% partially bleached), M. harttii with an average of 75% of its colonies affected, and P. asteroides from which no one healthy colony was seen. Although A. agaricites did not show a totally bleached colony, more than 90% of them had a pale color (Fig. 25). Additional data of a bleaching event in Abrolhos recorded an anomalous high sea surface temperature during the summer of 1994, which affected 51-88% of Mussismilia colonies (Castro and Pires 1999). There is no available data about recovery after these two events.
7.2. Human induced impacts 7.2.1. Coastal runoff. Despite the fact that Brazilian coastal reefs have been coexisting with a muddy siliciclastic influx, they seem to be, in recent time, clearly under a higher stress, mainly due to the increased coastal nmoff. This can be attributed to the increasing deforestation of the Atlantic coastal rainforest for agricultural and industrial purposes, ftrst for sugar cane and coconut plantations, then to allow timber exploitation, and as of the last few decades, to cultivate eucalyptus for industrial use. In the north eastern region, for example, the sugar cane monoculture forms a belt about 60 km wide and almost 100 km long, and is located a few kilometers inland in the area where the nearshore reefs are more numerous (Maida and Ferreira 1997). Along the eastern region, carbon isotope data from living coral species showed that there is a strong continental influence upon the reefs located nearest the shores (Azevedo et al. 1992). Also, a recent survey of the coral community of shallow coastal reefs from north Bahia showed that the endemic species inhabiting the tidal pools in the attached bank reefs experience chronic bleaching (Santos 1998), which is probably due to the harmful effects of the high rates of sedimentation on the reefs. Those inhospitable conditions are related to the decrease of light intensity that inhibits the photosynthetic function of the coral symbiotic micro algae, as well as the coral filter feeding mechanism.
Fig. 24. Frequency of bleached colonies of the three main coral species through 1998 in the north coast of state of Bahia (Eastern region).
Corals and coral reefs of Brazil
41
Fig. 25. Frequency of bleached colonies assessed on April 29, 1998 at Abrolhos (Eastern region).
The other most common anthropogenic agents that are threatening the coastal reefs of Brazil, as already pointed out in several publications (Ma~al 1986; Coutinho et al. 1993; Dominguez and Le~o 1994; Leao 1994b; Leao et al. 1994; Amado Filho et al. 1997; Maida and Ferreira 1997), are directly related to coastal zone development, marine tourism, trading of reef organisms, predatory fishing, the installation of industrial projects, and exploitation of fossil fuels. 7.2.2. Urban development. Unrestrained urban development in coastal areas, mainly on the outskirts of the municipalities that already offer an infrastructure for tourism, such as the cities and small villages located from the state of Rio Grande do Norte (the northeastern region) to the south part of the state of Bahia (the eastern region), an extension of almost 2,000 km, is a potential threat to the reefs. The untreated urban garbage and organic sewage coming from those areas adjacent to the reefs is causing, in some places, an abnormal increase of nutrients in the reefs biota, with dramatic consequences to the ecological balance of the environment. Measurements of the nutrient levels of the ground water of the Guarajuba Beach, at the north coast of the state of Bahia, for example, show levels much higher than the normal conditions of coastal sea waters (Costa Junior 1998). 7.2.3. Marine tourism. Allied to the disorderly growth of the coastal towns and representing, in some cases, the main reason for their expansion, is the marine tourism industry in Brazil that has recently experienced extensive growth, particularly in the marine protected areas. An example of this is the number of visitors to the Abrolhos National Marine Park, in the south part of the Bahia coast, which during a period of five years (1988/92) increased over four hundred percent (Le~o et al. 1994). This activity, if not properly controlled, may cause serious impacts to the reef ecosystem, especially on account of the careless anchoring of boats, the dumping of non-biodegradable garbage overboard, leaks from motor boats, the removal of reef organisms for collections, (both as souvenirs and for aquariums), the breaking of reef organisms caused by the impacts of diver's gear, unrestrained underwater fishing by amateurs, and even occasional shipwrecks.
42
ZM.A.N. Le6o et al.
7.2.4. Overexploitation of reef organisms. Because their proximity to the mainland, the coastal reefs have been heavily threatened by coral trading and the exploitation of both the artisanal and the commercial fisheries. In the northeastern region, for many years, corals were extracted for the commerce of souvenirs (Ma~al 1986) as well as to supply sugar refineries with lime, which was used as a clarifying agent in the preparation of the sugar cane syrup (Maida and Ferreira 1997). In many coastal cities along the whole coast, particularly in the historical villages, as for example in south Bahia, we can verify that for more than centuries corals have been mined for building material, both in the construction of old fortresses, dating back to the 16th century as well as nowadays, in building rustic beach resorts. The predatory fishing occurs mostly as a consequence of the use of explosives in both artisanal and commercial fishing, and of chemicals in the indiscriminate catching of aquarium fishes and other marine organisms. Those activities can be responsible for the mass mortality of a great part of the reef biota. Although forbidden and widely combated, explosives are still used, particularly in the area of the Todos os Santos Bay, in the state of Bahia, which accounts for many reports in the press. 7.2.5. Industrial projects. The development of industrial projects is a constant threat to the coral reefs of northeast and east Brazil, if a strict control of the final disposal of the industrial waste is not managed appropriately. Some examples are the petrochemical outfalls on the littoral north of Salvador City (Fig. 16), and the paper plants on the southern part of the state of Bahia. Those industrial effluents must bring to the water (river and/or sea) toxic elements. Data from Amado Filho et al. ( 1 9 9 7 ) shows that in the south part of the Abrolhos reefs (south Bahia), there are already signs of contamination by heavy metals, which must probably be due to the chemical effluents of the paper plant located nearby. Petroleum exploration in areas where coral reefs exist can cause serious damage to these ecosystems. In the Todos os Santos Bay, for example, the operation of petroleum tanks has been responsible for numerous accidents regarding oil spills in the last years. The offshore drilling in south Bahia is a threat to the nearby reefs of the Abrolhos National Marine Park (Fig. 19), either from the impacts caused by their activities, such as boat collisions with the reefs, and/or the increasing water turbidity and spills. 8. P R O T E C T I O N AND MANAGEMENT Though there has been scientific information about the coral reefs of Brazil over a century, knowledge about the actual condition of the reefs is still scarce, and some areas are virtually tmknown. There are only a few well protected reefs. In the coastal zone, only the reefs located in areas with low levels of urban development can still be considered pristine. These include the ones located along the Tamandar6 area (Pernambuco state) in the northeastern region (Maida and Ferreira 1997, Fig. 14), the ones around the Camamu Bay area (Fig. 17), in the state of Bahia, and the reefs located offshore on the continental shelf, due to their inaccessibility and/or theft designation as protected areas are not affected by human impacts. The institutions concerned with preservation of the coral reefs in Brazil have only recently been created. In the northern region, a state marine park established in 1991 protects the offshore Manuel Luiz Bank, located between 0046 , - 0~ and 44009 , - 44~ 'W
Corals and coral reefs of Brazil
43
(Fig. 1). But it does not prevent crossing by large ships in route to the Sao Luiz harbor, which exposes the reefs to oil spills and grounding. Along the coast of the northeastern region, a recently designated (1998) environmental marine protected area covers a great part of the coast of the states of Pemambuco and Alagoas, between 8~176 and 3 5 ~ 1 7 6 It is called the Coral Coast Environmental Protected Area, the largest protected area of shallow coastal reefs so far created along the coast of Brazil. Offshore, the Biological Reserve of Atoll das Rocas and the Femando de Noronha National Marine Park control the illegal lobster fishing in the atoll and marine tourism in the Femando de Noronha Archipelago. The Biological Reserve of Atoll das Rocas, designated in 1979, is located between 3~176 and 33~176 (Fig. 15). The Femando de Noronha National Marine Park was created in 1988, and is located about 80 nautical miles eastward the Rocas atoll (between 3~ '3~ and 32~176 Fig. 1). In the eastern region, one national and two municipal marine protected areas have been created. The oldest of them is the Abrolhos National Marine Park that protects the richest area of coral reefs in Brazil. It comprises two units: the area of the Abrolhos Archipelago and the outer arc of "chapeir6es" (between 17~176 and 38~ '38~ Fig. 19), and the Timbebas reef on the coastal arc of reefs (between 17027 '17~ and 38~176 Fig. 19). The two recently created municipal areas are the Pinaunas Reef Environmental Protected Area, along the eastern coast of the Itaparica Island, at the entrance of the Todos os Samos Bay (between 12~176 and 38~176 Fig. 17) designated in 1997, and the Recife de Fora Municipal Marine Park, created in 1998, which is located between 16~176 and 38~176 (Fig. 18), at about 5 nautical miles off the coast of the city of Porto Seguro, on the south part of the coast of the state of Bahia. It is a small reef with an area of approximately 20 square kilometers that has been heavily used for the marine tourism. With the exception of the last three recently designated areas, all reef areas have management plans, with conservation programs already in action. The marine resource management plans of the new ones are now in the early phase of implementation. Along the coast of the state of Bahia even the reefs not included in the park areas are protected by law, since the State Constitution in its Article 215, Chapter VIII, declares that coral reefs are areas of permanent protection. However, legislation enforcement is not yet effective. 9. CONCLUDING REMARKS The Brazilian coral reefs have some common characteristics with the Caribbean reefs, but they also present unique features when compared with the well-studied reef systems. These particular aspects of the Brazilian reefs are related to the reef growth form, the reef building fauna, the control of the underlying substrate on reef distribution and morphology, the reef surrounding depositional setting and the influence of sea level on the evolution of the reef structures. The reef growth form. The reefs in Brazil initiate growth with a peculiar architecturecoral pinnacles with a mushroom-like form, the "chapeir6es" of Hartt (1870). The expanded top or brim that forms the mushroom head is constructed by the photophile corals and millepores. They may initiate growth very early as young "chapeir6es" can be as
44
Z.M.A.N. Leao et al.
small as 1 m in height and 1 to 2 m in diameter in their tops. These "chapeir6es" are not a common growth form of coral reefs in other parts of the tropical seas, but they can be roughly compared with the algal cup reefs of Bermuda (Ginsburg and Schroeder 1973). The coral fauna of Brazil. The coral fauna of the Brazilian reefs has a very low diversity and a significant endemism. The major reef building species are remnants of a most strong relict fauna dating back from the Tertiary, which was probably preserved during Pleistocene low stands of sea level in a refugium provided by the seamountains off the Abrolhos Bank, in south Bahia (Leao 1983). This stronger endemic fauna, more resistant and better adapted, has been withstanding the periodically turbidity of the Brazilian waters. The reefs morphology and distribution. Most of the nearshore reefs of Brazil were formed through the coalescence of adjacent "chapeirres", by their tops. These larger compound reef structures do not form a classical barrier reef. They are, instead, isolated shallow bank or patch reefs with varied shapes and dimensions, and each type is differently distributed on the entire tropical coast of Brazil. Along great part of the northeastern region, where the continental shelf is very narrow, the most common type of reef are the elongate banks, which parallel the coastline forming one, two or sometimes three chains of reefs. Many of these elongate bank reefs are localized by relict beachrock. Where the continental shelf widens, i. e. the Abrolhos area, isolated banks are irregularly distributed on the inner and middle shelves, and they are established on eroded older reefs. Attached to the coastline, shallow bank reefs developed on the top of Precambrian outcrops facing headlands. The interreefal sediment. In contrast with most of the world's living coral reefs, the nearshore reefs of Brazil are an example of reefs that are surrounded by sediments containing amounts of siliceous sand and mud that range from 30 to 70% (Le~o and Ginsburg 1997). The siliciclastic fraction is derived from river loads and coastal erosion, and the carbonate content is predominantly skeletal in origin. This muddy sediment is resuspended from the bottom by the energy of wind-induced waves, during winter storms, causing periodic turbid waters in the reefs area. The most important effect of these turbid waters on the reefs is the variation in light intensity available for the hermatypic corals. But the Brazilian coral fauna succeed in such water conditions, maybe due to two major reasons: a) strong runoff occurs only periodically (during winter storms), and thus, there are interim periods for coral growth, and b) the prevalence, in Brazil, of corals functionally adapted and more resistant, which have larger polyps and, then, have developed a more efficient mechanism of cleaning themselves of sediment. Origin and development of the reefs. The Brazilian reefs initiate growth after 8,000 years BP, an ecological phenomenon that was widespread in the whole tropical world. But the last post-glacial sea level fluctuations that occurred along the coast of Brazil, left distinctive imprints on the development of the reefs, which recognize well marked phases of reef growth. A drowning phase must have occurred during early Holocene, before the 5,100 years BP maximum sea level, which characterizes the "give-up" reefs found on the shelf edge. In the shallower zones (inner and middle shelves), the "catch-
Corals and coral reefs of Brazil
45
up" stage of vertical accretion of the reefs occurred when sea level was already at or above its present position. An ultimate stage, which is marked by the widely presence of lateral growth of the reef framework over its upward accumulation, occurred during the regressive phase of sea level, and it also responds for the subaerial exposure of the top of the nearshore reefs, a feature that is not common in most of the Caribbean reefs. ACKNOWLEDGMENTS We acknowledge Dr. Jorge Cort6s for inviting us to write this chapter, and several of our colleagues who supplied copies of their publications on the Brazilian reefs. We are also deeply indebted to Dr. Robert Ginsburg and three other anonymous reviewers for their insightful suggestions, which greatly improved the f'mal version of the manuscript. The chapter is based on previous studies that were partially supported by grants to the authors, from the "Conselho Nacional do Desenvolvimento Cientifico e Tecnol6gico" - CNPq/Brazil, and to V.T. from the Natural Environmental Research Council, UK. Jos6 Edvaldo Silva Moitinho drew the maps. REFERENCES
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Stramma, L. 1991. Geostrophic transport of the South Equatorial Current in the Atlantic. Mar, Res. 49:281-294. Telles, M.D. 1998. Modelo trofodingmico dos recifes em franja do Parque Nacional Marinho dos Abrolhos, Ba. M.Sc. thesis, Funda~go Universidade do Rio Grande. 150 p. Testa, V. 1996. Quaternary sediments of the shallow shelf, Rio Grande do Norte, NE Brazil. Ph.D. dissert., Royal Holloway University of London. 411 p. Testa, V. 1997. Calcareous algae and corals in the inner shelf of Rio Grande do Norte, NE Brazil. Proc. 8th Int. Coral Reef Symp., Panarnfi 1" 737-742. Testa, V. & D.W.J. Bosence. 1998. Carbonate-siliciclastic sedimentation on a highenergy, ocean-facing, tropical ramp, NE Brazil. In: V.P. Wright & T. Burchette (eds.), Carbonate Ramps: oceanographic and biological controls, modeling and diagenesis. Geol. Soc. London, Spec. Pub. 149: 55-71. Testa, V. & D.W.J. Bosence. 1999. Biological and physical control on the bedform generation in the Rio Grande do Norte inner shelf, Brazil. Sedimentology 46:279-301. Testa V., D.W.J. Bosence & M.L. Viana. 1997. Submerged lithologies as indicators of relative sea-level oscillations in Rio Grande do Norte, NE Brazil. Anais VI Congr. Est. Quatem.: 155-160. Tiltenot, M., T. Jennerjahu, G. Irion, J.O. Morais & A. Brichta. 1994. Sedimentological and geochemical indicators of fiver supply along the Brazilian continental margin. 14th Intern. Sedim. Cong. IAS Abstract: D77. U.S. Navy 1978. Marine Climatic Atlas of the World, Volume I V - South Atlantic Ocean, Washington, D.C. 325 p. Verrill, A.E. 1868. Notes of the radiate in the Museum of Yale College, with descriptions of new genera and species. 4. Notes of the corals and echinoderms collected by Prof. C.F. Hartt at the Abrolhos reefs, Province of Bahia, Brazil. Connecticut Acad. Arts Sci. Transact. I: 351-371. Verrill, A.E. 1901a. Variations and nomenclature of Bermudian, West Indian and Brazilian reef corals with notes on various Indo-Pacific corals. Connecticut Acad. Arts Sci. Transact. XI: 66-116. Verrill, A.E. 190 lb. Comparison of the Bermudian, West Indian and Brazilian coral fauna Connecticut Acad. Arts Sci. Transact. XI: 169-206. Verrill, A.E. 1912. The gorgonians of the Brazilian coast. J. Acad. Nat. Sci. Philadelphia 2: 373-404. Vicalvi, M.A., M.P.A. Costa & R.O. Kowsmann. 1978. Depressgo de Abrolhos: uma paleolaguna Holocanica na plataforma continental leste brasileira. Bol. Tec. Petrobr~is, 21" 279-286. Villaga, R. & F.B. Pitombo. 1998. Benthic communities of shallow-water reefs in Abrolhos, Brazil. Rev. Bras. Oceanogr. 45: 35-43. Young, P.S. 1984. An~lise qualitativa e quantitativa da fauna associada aos corais hermatipicos Mussismilia hartti, Mussismilia hispida e Siderastrea stellata (Coelenterata, Scleractinia) nos recifes de Jogo Pessoa, PB. M.Sc. thesis, Universidade Federal da Paraiba. 120 p. Young, P.S. 1986. An~ilise qualitativa e quantitativa da fauna associada a corais hermatipicos (Coelenterata, Scleractinia) nos recifes de Joao Pessoa, PB. Rev. Bras. Biol. 46: 99-126. Young, P.S. 1988. Recent cnidarian-associated barnacles (Cirripedia, Balanomorpha) from the Brazilian coast. Rev. Bras. Zool. 5: 3.
53
The Cuban coral reefs P. M. Alcolado, R. Claro-Madruga, G. Men6ndez-Macias, P. Garcia-Parrado, B. Martinez-Daranas and M. Sosa Instituto de Oceanologia, Ave. 1a, No. 18406, Playa, Ciudad de La Habana, Cuba
ABSTRACT: Trends in species diversity and density, and zonation patterns of several reef communities
were observed in Cuban reefs, and are described herein for sponge, scleractinian, gorgonian, and fish communities. Cuban coral reefs are suffering deterioration. The broad sections of the shelf, with chains of bordering keys, act as a buffer, limiting the terrestrial impact on coral reefs (e.g. pollution, sedimentation, direct human influence, etc.). However, in some places algae are proliferating and dominating at the expense of corals, perhaps because of the synergistic influence of black urchin dieoff with relatively high local concentrations of phosphates. Intense mortality of Acroporapalmata was observed in several places along the north and south coasts of Cuba. Over-fishing has affected some fish populations (Nassau grouper and several sharks). Until now, management of coral reefs has not been specifically focused, nor did it have a holistic approach. Recently, a joint resolution of the Ministry of Fisheries Industry and the Ministry of Science, Technology and Environment established important regulations for the protection and sustainable use of coral reefs. In addition, some degree of protection has been achieved by fishing regulations, the existing legislation on pollution, collecting, and environmental impact assessment, and the commitment to international treaties such as CITES and Agenda 21. The Cuban Environmental Agency is currently formulating plans and new legislation for the protection of marine ecosystems. Reef research in Cuba is considered of great importance by the Ministry of Science, Technology and Environment, but is still fragmentary and insufficient due to the lack of resources.
1. I N T R O D U C T I O N
1.1 History of research on coral reefs of Cuba The "stony coral" and "coral reef " are necessarily and tightly linked terms, at least when writing the recent history of coral reef research. In their excellent and concise revision of the history of Cuban stony corals and coral reef research, Zlatarski and Martinez-Estalella (1980, 1982; consult for further information) mention how Arango y Molina (1877) recognize Pourtales as the first to mention corals in Cuban waters. They also refer to several papers from the late 19 th century and the first half of the 20 th where stony corals from Cuba are mentioned in an incomplete fashion, and with an unsystematic gathering of data. Also cited is Duarte-BeUo (1949, doctoral thesis) and his popular work on Cuban stony corals (1963). Lastly, after mentioning other authors that also refer to Latin American Coral Reefs, Edited by Jorge Cortfs 9 2003 Elsevier Science B.V. All rights reserved.
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scleracfinians, and to the richness and diversity of Cuban coral reefs, they cite several papers by Kiihlmann on the morphology, origin, and ecology of Cuban coral reefs (1970a, b, 1971a, b, c, d, 1974a, b). Wells (1988), in her compilation of coral reefs of the world also mentions early descriptions of Cuban coral reefs by Agassiz (1894) and Vaughan (1919). Zlatarski and Martinez-Estalella's (1980, 1982) monographic book on Cuban Scleractinia was a significant contribution to the knowledge of the systematics, zonation, distribution, ecology, zoogeography, and associated biota of Cuban stony corals. The book (in Russian, 1980, and French, 1982) provides a great insight into the different types of reefs in southern and northwestern Cuba. More recently, the number of papers on coral reefs has increased. We can mention, for example, Ndfiez-Jim6nez (1984a, b), with general information about Cuban coral reefs; Su~ez (1989) on macrophytobenthos; Trelles et al. (1997) on reef macroalgae communities; Martinez-Estalella (1986), Herrera-Moreno and Martinez-Estalella (1987), MartinezEstalella and Herrera-Moreno (1989), Herrera et al. (1991) on Scleractinian communities; Alcolado (1978, 1979, 1985, 1989, 1990, 1994, in prep.), Alcolado and Herrera-Moreno (1987), Alcolado and Gotera (1985) on reef sponge communities; Alcolado (1981), Alcolado et al. (1980), Herrera-Moreno and Alcolado (1983, 1986, 1988), Herrera et al. (1997) on reef gorgonian communities; Alcolado (1984, 1992), Herrera-Moreno and Alcolado (1985, 1986), Herrera-Moreno (1991), Alcolado et al. (1994) on coral reef biomonitors; Ibarzfibal (1993) on reef vagile macrofauna; De la Guardia and Gonz~ilezSans6n (1997a, b, c) on reef fauna symbiotic associations; Herrera-Moreno (1983) on the meiobenthos of polluted reef; Alcolado et al. (1997, 1999) on the status of Cuban coral reefs; Mochek and Vald6s-Mufioz (1983), Vald6s-Mufioz and Garrido (1987), Final6G6mez et al. (1989), Claro et al. (1990), Claro and Garcia-Arteaga (1994), Aguilar et al. (1997), Gonzfilez-Sans6n et al. (1997 a, b), Claro et al. (1998) on reef fish communities; Plante et al. (1989) on redox potential in coral reefs; Martinez-Iglesias and Garcia-Raso (1999) on decapod crustacean reef communities; Espinosa and Rams (1987) on mollusk reef communities, and Espinosa and Abreu (in prep.) on reef echinoderm communities and Gonzfilez-Sans6n (1997c) on reef fauna. 2. DESCRIPTION OF CORAL REEF AREAS 2.1. Distribution of Cuban coral reefs
Cuban coral reefs can be found along almost the entire border of the Cuban shelf, and extend inshore across broad areas of the shelf (Figure 1-7). The shelf edge extends approximately 3200 km (Alcolado et al., 1997). The northern shelf is completely fringed by fore reefs, and the southem shelf, along 1631 km, which gives a total rough estimate of 3781 km of fore reefs. Zlatarski and Martinez-Estalella (1980, 1982) have classified Cuban reefs into three types: fringing, barrier, and reefs on muddy substrates. Ktihlmann (1974a) descrybes a more diverse system of reef types: barrier reefs, crossbar reefs, cluster reefs, complex reefs, coral canyons, incision reefs, spur and groove reefs, and horst reefs. We prefer to use the term reef crests or reef fiat to refer to what Zlatarski and MartinezEstalella (1980, 1982) and Kiihlmann (1974a) call barrier reefs, and Wells (1988) and others call reef banks. The entire Cuban shelf edge is virtually continuously fringed by fore reefs (>95%). These fore reefs exhibit great variation in their profiles and ecological zones. In most cases, following a shallow limestone terrace (poorly covered by corals), a slope 10-15 m
The Cuban coral reefs
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Fig. 2. Location of coral reefs in the westem end of Cuba (north and southwest of the Pinar del Rio Province). descends to a deeper, rocky-sandy terrace often with some dispersed patch reefs. Further out on this terrace, a spur and groove system often occurs. Sometimes on the deep terrace, just before the "drop off", a transverse sand corridor develops in front of an elevated coralline threshold. Examples include: fore reefs sheltered from shelf out flowing currents by the Los Indios and San Felipe keys in the western Gulf of Bataban6; Cayo Diego P&ez reef (east of Gulf of Bataban6); Cayo Rosario reef (south of Gulf ofBataban6); Bajas reef
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Fig. 4. Location of the coral reefs in the north-central shelf of Cuba, from de east of the province of Villa Clara to the province of Camagtiey.
(Colorados reefs); Cayo Levisa reef, Cabafms Bay reef, and Momllo reef (northwest of Cuba). In many places these reefs bear reef crests at their shallowest zone (we propose the term "crest reefs" for the complex reef crest-fore reef). Reef crests in Cuba tend to be more abundant at the edge of the four broad sections of the Cuban shelf. These sections are the
The Cubancoralreefs
57
Gulf of Guanahacabibes (northwest Cuba); Sabana-Camagiiey Archipelago (central north Cuba); Gulf of Ana Maria-Guacanayabo (southeast Cuba) and, Gulf of Bataban6 (southwest Cuba). However, in the narrow shelf of northeastern Cuba, reef crests are also widespread and quite long. Reef crests can be linear or patch-like. The linear type is the most common and varies greatly in its species composition and zonation. The patch type has an irregular to subcircular outline, and is characterized by being densely fringed by Acropora palmata along the entire margin. The latter type is common along the border of the Gulf of Guanahacabibes (Colorados reefs), and along the east edge of the Gulf of Bataban6 (Mddano
Vizcaino reefs). Zlatarski and Martinez-Estalella (1980, 1982) found reefs on muddy substrates in the Gulf of Guacanayabo. These structures are up to 25 m high, and are covered mainly by Oculina and Cladocora arbuscula, along with many sponges that give the reef what they say a "gelatinous" appearance. Its shallow zone (2-5 m) is usually dominated by Acropora cervicornis, and the reef flat is a usually barren, with fragment of coral or covered by
Thalassia testudinum. Inshore patch reefs are found dispersed on the northwestern (Gulf of Guanahacabibes), southwestern (Gulf of Bataban6), and southeastern (Ana Maria-Guacanayabo Gulf) sections of the shelf of Cuba. 2.2. Some features of the flora and fauna of Cuban coral reefs
2.2.1. Flora. Up to now, 526 species of marine macroalgae of the Divisions Chlorophyta, Phaeophyta, and Rhodophyta have been registered in Cuba (A. M. Suhrez per. com.), and approximately 60% of them have been found on coral reefs (data from C. Jim6nez, B. Martinez-Daranas, A. M. Su~irez, J. Trelles and D. Zfil~ga). In shallow reefs (less than 5 m deep) and back reefs, Halimeda opuntia, Sargassum spp., Turbinaria spp., Padina spp., and Stypopodium zonale tend to be the commonest species. Thalassia testudinum beds with algae of the orders Siphonocladales, Caulerpales, and many species of red algae of the family Rhodomelaceae dominate in reef lagoons. On deep coral reefs, Halimeda goreauiL H. discoidea and H. tuna are usually abundant. Brown algae are mainly represented by Sargassum hystrix, Lobophora variegata and Dictyota spp. Red algae are common and mainly represented by the genera Galaxaura, Jania and Amphiroa as well as by many species of the order Ceramiales and crustose genera (Peyssonnelia, Litophyllum and Mesophyllum). These algae live attached to the rocky substrate competing for space with sessile invertebrates, while rhizophytic genera (Rhipocephalus spp., Penicillus spp., Udotea spp. and Avrainvillea spp.) mainly dwell on sandy bottoms. Some species of the order Ulvales, Amphiroa sp., Dictyopteris delicatula, and cyanobacteria were abundant in polluted areas of the coast of Havana City. At stations located between the back reef and 20 m, the number of species of macro algae varied from 9 to 49 (excluding crustose calcareous algae). Margalef's species richness index (calculated with dry biomass as sample size) varied between 1.56 and 6.18 (including data from the Sabana-Camagiiey Archipelago and C. Jim6nez's data from the reefs of Juan Garcia, Cantiles and Diego P6rez keys, southwest of Cuba). There was not a clear trend of species richness with regard to depth on the before mentioned reefs southwest of Cuba, while in the Sabana-Camagiiey Archipelago species richness tended to be slightly higher at 5-10 m. In the southwestern reefs, Shannon's heterogeneity index
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Fig. 6. Location of the coral reefs in the southwestern shelf of Cuba. varied between 0.04 and 3.05 nats, and the evenness index between 0.01 and 0.83. These indices did not show any trend with depth. Higher values of algal biomass are expected where there is nutrient enrichment. Low values of dry biomass between 0.01 and 0.21 kg rn-2 (with a maximum wet biomass of 0.6 kg m -2) were found at the above mentioned reefs of Juan Garcia, Cantiles, and Diego P6rez keys in the spring of 1987 and the summer of 1988. In those sites, Halimeda scabra and Dictyota menstrualis were the dominant species (C. Jim6nez, per. com.).
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In December 1997, in the reefs of the Jardines de la Reina Archipelago (a relatively pristine zone, far from land influence), low values of dry biomass (0.01 - 0.11 kg m -2) were obtained in stations at depths of 5 and 10 m. The maximum wet biomass was 0.54 kg m 2. Lobophora variegata, Dictyota spp. and Halimeda spp. were the dominant species. In contrast, in Playa E1 Chivo (very close to Havana City, and heavily polluted by sewage) the wet biomass values in August 1997 at 10-20 m were close to 0.8 kg m 2. An algal mat dominated by Amphiroa spp. and Dictyota spp. was noticed here. Values were not higher, perhaps because of the very low water transparency. Unexpectedly, high values of biomass were found (0.1-1.5 kg/m2 of dry biomass and 0.3-3.1 kg/m 2 of wet biomass) in a research survey conducted on the reefs of the SabanaCamagiiey Archipelago (at 37 stations distributed along 10 reef profiles, from the back reefs to 20 m deep in April-May 1994). The highest values of dry biomass were found to be higher than 0.69 kg m "2 (biomass refers to coral free space). This frequency was 60% at 10 m, and 20% at 20 m. Unforttmately, there are not previous values for intra site comparisons. Sea urchin Diadema antillarum was very scarce. Phosphate concentrations were fairly high, and greater than Lapointe's et al. (1992) threshold values for excessive algal proliferation. It seems to be the consequence of some influence from the nutrient rich inshore water bodies. Cladophora catenata, Microdyction marinum, Dictyota spp. and Lobophora variegata were the dominant species in the entire studied area. On western Cayo Largo fore reefs, dense algal mats dominated by Microdyction marinum, lobophora variegata and Dictyota spp. were observed during the spring of 1998, when water temperature was already high (29~ in May). This mat was partially covered by a red slimy coat of an as yet unknown composition (t)rsula Rehfeld, per. corn_). Phosphate and ammonium concentrations were high. The intensity of aerobic mineralization process of heterotrophic microorganisms was higher than primary water productivity (Miravet et al. 1999). Wet biomass values in Playa E1 Chivo reef were lower than in the Sabana-Camagfiey reefs, probably due to the high water turbidity, and the different seasons in which sampling was conducted. In Cuban reefs an increase in the biomass of algae usually takes place between spring and early summer, followed by a reduction in late summer. 2.2.2. Sponges. About 160 sponge species have been collected from Cuban reefs. Of these, 144 were identified to species. In shallow reef zones, down to 7 m, Aplysina
fistularis, Clathria virgultosa, Cliona caribbea f. aprica, Chondrilla nucula, Scopalina ruetzleri, Cliona vesparia and Spirastrella coccinea are the most common and dominant species. In deep reefs (7-35 m), the most frequent and dominant sponges are Aplysina cauliformis, C. caribbea f. aprica, Ectyoplasia ferox, Iotrochota birotulata, Mycale laevis, Niphates amorpha, Aiolochroia crassa and S. ruetzleri. Other common but rarely dominant sponges are A. fistularis, Callyspongia vaginalis, C. nucula and Niphates digitalis. At greater depths (30- 35 m), A. cauliformis, Ircinia felix and E. ferox are the most common and dominant species (sometimes comprising 10% or more of the total number of individuals). On the fore reef slope, where the bottom is covered by a thin layer of sand, Phoriospongia (?) rubra, Oceanapia stalagmitica and Tectitethya crypta are common species. In organically polluted areas, Alcolado and Herrera-Moreno (1987) noted a remarkable dominance of Clathria venosa and Iotrochota birotulata s musciformis (a slimy, wine-colored, encmsting form described by Duchassaing and Michelotti, 1864) at depths of 10-15 rn.
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Fig. 7. Locationof the coral reefs in the ArchipelagoJardines de la Reina (southeastern shelf of Cuba). In general, species richness and heterogeneity tend to increase with depth as a result of the reduction in both hydrodynamic stress and light intensity. This trend can be locally disrupted by (1) sedimentation, (2) poor substrate quality (sand) and (3) the unpredictable action of storm turbulence at a given depth along the depth gradient. Complexity of bottom relief, which as a rule increases with depth within the reef range, seems to enhance diversity. A very slight reduction in species richness and heterogeneity is often observed from 20 rn to deeper zones of the reefs. Evenness index (J') varies greatly at shallow zones, becoming less variable towards greater depths. The value of J' increases with depth. Sponge density also varies greatly at shallower depths (from 0 to 44.2 sponges m-Z), but at 30-35 m reaches approximately steady values of 7-11 sponges rn-2. Sponge cover becomes more variable with increasing depth, with a maximum of 29.3% found at 20 m in the Rinc6n de Guanabo reef, east of Havana City (Alcolado 1989, 1994). 2.2.3. Stony corals. Cuban stony corals are represented by 41 species (40 scleractinians and one hydrocoral species with three forms) according to the Zlatarski and MartinezEstalella (1980) classification. This figure rises to 60 if some coral forms of Acropora
cervicornis (cervicornis and prolifera), Agaricia agaricites (agaricites, fragilis, grahamae, tenuifolia, undata and lamarcla'), Scolymia lacera (lacera, cubensis and wellsi), Mycetophyllia lamarckiana (lamarckiana, aliciae, ferox and danaana), Montastraea annularis (annularis, faveolata and franksi), Siderastraea radians (radians and siderea), Porites porites (porites, furcata and divaricata), Madracis decactis (decactis and mirabilis), Isophyllia sinuosa (sinuosa and rigida) and Millepora alcicornis (alcicornis, complanata, squarrosa) are considered as different species. Taking into account Zlatarski and Martinez-Estalella's (1980) monograph and our own data, the most frequent reef dwelling stony corals (considering all depths) are M. annularis,
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Porites astreoides, A. agaricites (f. massiva and bifasciata), Montastraea cavernosa, S. radians (f. radians and siderea), Stephanochoenia intersepta, Diploria strigosa, Dichocoenia stokesi, Meandrina meandrites, Eusmilia fastigiata, Acropora cervicornis, M. lamarckiana, Manicina areolata and Millepora alcicornis. In shallow reefs (0-5 m deep) the most frequent stony corals are Acropora palmata, M. alcicornis (f. complanata), P. astreoides, M. areolata, A. agaricites, S. radians (f. siderea), D. strigosa, P. porites and M. annularis. A. palmata, M. annularis, A. agaricites and P. astreoides tend to be dominant species. A. palmata and M. alcicornis f. complanata are the most dominant and common species on reef crests. Plate-shaped M. annularis and A. agaricites (f. unifasciata) usually dominate at slopes below 25 m deep. Herrera-Moreno and Martinez-Estalella (1987) observed small S. radians (forms siderea and radians) dominating the polluted reefs of Havana City. In the organically polluted areas, containing excess of suspended particles, the most common corals were S. radians (f. siderea and radians), D. stokesi, S. intersepta, P. astreoides, and M. cavernosa. D. stokesi was once found to be a locally dominant species at 10 and 20 m depth at Cayo Frances reef, central north of Cuba. Shannon's diversity (in natural bells) of stony corals in Cuban reefs (using Zlatarsky and Martinez-Estalella's classification system) was observed to vary from almost zero (0.59 at 4 m deep in the National Aquarium reef, Havana City) to 2.59 at 20 m in the Cayo Guillermo reef, north-central Cuba (2.81, if considering the alternative classification scheme with 58 species of scleractinian corals). As a general rule, it increases from the shallow zones (0.5-5 m) to medium depths (15-20 m) and decreases toward deeper zones where dominance of one species occurs. Coral diversity was observed to be lower in organically polluted places near Havana Bay and some polluted rivers of Havana City (Herrera-Moreno and Martinez-Estalella 1987). Species richness (R1 using natural logarithms) tends to increase with depth: it attained values of up to 3.69 at 10 m in Cayo Caballones reef (Jardines de la Reina Archipelago, southeast Cuba). If using the alternative classification system, species richness reaches a value of 4.89 at 20 m in the Cayo GuiUermo reef). The species evenness index (J') is highly variable at shallow depths, and becomes more constant with increasing depth (below 10 m). The maximum value (0.91) was found at 20 m deep in Cayo Sabinal, northeastern Cuba (Zlatarsky and Martinez-Estalella's classification system). Population density varied from 0.07 colonies m "2 (in the back reef of Cayo Sabinal, central north Cuba) to 36.75 colonies rn-z (at 10 m deep in Cayo Cachiboca reef, Jardines de la Reina Archipelago). Coral cover varied from almost zero to 75 %. The highest coral cover of A. palmata thickets (up to 75%) was found in Rinc6n de Guanabo, west Havana City (Martinez-Estalella and Herrera-Moreno 1989) and in reef escarpments at 11-35 m deep (up to 40-60%). In some back reefs, rock pavements, and sandy/rocky terraces of deep fore reef slopes, density and coral cover exhibit their lowest values. A. palmata populations in most of the places visited in the north and south of Cuba have been strongly affected, presumably by white diseases (white band, coral bleaching, white pox). Hurricane Gilbert (1988) in the south of Cuba produced extreme damage of A. palmata thickets.
2.2.4. Gorgonians. Sixty-eight gorgonian species have been recorded in Cuba, of which 55 species are reef dwellers. Some of them are typically found below 25 m, as they do not rely on the symbiosis with zooxanthellae for nourishment, and hence their larvae
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P.M. Alcolado et al.
search for places with weak illumination for settling. Among these species the most common are Iciligorgia schrammL Ellisella elongata and Ellisella barbadensis (GuitartManday 1959; Alcolado 1981; Behety 1975; Garcia-Parrado and Alcolado 1998). As with most sessile reef organisms, gorgonians display a zonation pattern related to depth across the reef (Alcolado et al. 1980; Alcolado 1981;). In the back reef, Eunicea mammosa, E. flexuosa and Briareum asbestinum are typically dominant or most frequently found. Species number and relative abundance vary depending on the degree of protection provided by the reef crest. In low-energy back reefs, some species that are typical of 1020 m depth are also found. Plexaura homomalla f. typica is a common species of the back reefs, mainly in the Canarreos Archipelago (southwest Cuba) where it frequently dominates. In the surf zones of the reefs (Acropora palmata zones) or at 1-3 m deep in nearshore fringing reefs, Gorgonia flabellum tends to dominate. Muricea muricata, E. mammosa, E. tourneforti and E. flexuosa are also common species in this reef zone. At 5 m, where a limestone pavement prevails, the most frequent species are E. mammosa, E. tourneforti, E. flexuosa, Plexaurella dichotoma, Pseudopterogorgia americana and Gorgonia ventalina. At a depth of 10 m, P. americana, E. mammosa, E. flexuosa, P. dichotoma and Muriceopsis flavida tend to be the commonest species. In more quiet and higher relief bottoms, at depths between 15 and 20 m, Plexaura kuekenthali, Eunicea calyculata f. coronata, B. asbestinum, P. americana and E. flexuosa are very often conspicuously abundant (and also sometimes Eunicea clavigera). Sometimes this zonation pattem of species dominance with depth does not occur. Even an extremely rare species like Muriceopsis sulphurea was found to dominate at 2 m in the Cayo Esquivel reef (Sabana-Camagtiey Archipelago, central north of Cuba). Some species, such as Iciligorgia schrammi, which usually display very low population densities in Cuba have been observed to form monospecific thickets in a deep fore reef near Anc6n Beach (Jardines de la Reina Archipelago). In the organically polluted reefs of Havana City, Herrera-Moreno and Alcolado (1983) found that E. flexuosa, P. kuekenthali, Pseudoplexaura flagellosa, E. tourneforti, Eunicea calyculata f. typica and E. calyculata f. coronata were among the dominant or common species. The first three species were frequently the most dominant. Species richness indices and the heterogeneity index (H') of gorgonian communities increased from the shore to 10-12 m in depth. In contrast to what is observed with sponges and stony corals, gorgonian diversity diminishes slightly with increasing depth across the reef. It is likely that a synergy of factors occurs at 10 m, favoring the development of more diverse gorgonian communities. These factors include: (1) light intensity necessary for zooxanthellae, (2) hydrodynamic stress for most gorgonian species relative to the remaining sessile taxa that compete for space, and (3) reduction in sedimentation events. The same occurs with evenness (J'). Density varies from values lower or slightly higher than 1 colony m z, which are typical for the back reefs, to more than 14 colonies m z. Higher densities are typically found on the back reef, and 10 and 15 m in depth. 2.2.5. Vertebrates. Turtles, dolphins, and fish are the major vertebrates associated with Cuban coral reefs. Turtles are represented by four species which are considered endangered throughout the Caribbean: the hawksbill (Eretmochelys imbricata), the loggerhead (Caretta caretta), the green (Chelonia mydas), and the leatherback (Dermochelys coriacea). The hawksbill seems to have local populations in Cuban waters and to spend all its life cycle in
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a limited area. The other species are migratory, utilizing the reefs mostly as refuges, adjacent seagrass beds for feeding, and beaches for reproduction. The leatherback turtle is rare in Cuban waters, but is seen during reproductive migrations. Fishing of all turtle species has been banned in Cuba since 1992. Only a very small quota is still permitted, in the northeastern shelf and south of Isle of Youth. The dolphin, Turciops truncatus, is common in coral reefs where they feed intensively on reef fish. It is the only mammal associated with this habitat in Cuban waters. A small controlled amount of dolphins is catched and exported for aquaria. Fish are the most diverse, abundant (in number and biomass), and biologically dynamic group of organisms associated with coral reefs. The Cuban reef fish fauna seems to be one of the richest of all the Caribbean islands. About 350 fish species live or spend part of their life on coral reefs. Some species are not obligate reef fish, but have a much wider distribution in association with marginal habitats, such as sand patches, lagoons, mangroves, or seagrass beds. Many species are considered residents of the reefs, but many others are transients. Both play an important role in the flux of energy of reef ecosystems. Resident species, particularly territorial species, are usually small fish that use the reef for refuge, feeding, and in many cases reproduction. Many reef fish are primary consumers on epilithic algae, or in the adjacent seagrass beds. This is the case for surgeon and parrotfishes (Acanthuridae and Scaridae). Most of the carnivorous fishes (Lutjanidae, Haemulidae, Carangidae, Sparidae and others) use the reef as refuge during daytime, but feed in seagrass beds at night. This fish play an in~ortant role in the transportation of energy from seagrasses to the reef in the form of feces. There is a larger difference in fish community structure between different reef types than between regions with the same kind of habitat. In shallow bank reefs, with low physical complexity, fish species richness is lower than on the slope, crest, or patch reefs, and evenness is higher, although fish density and biomass are minimal. Dominant species in bank reefs are Thalassoma bifasciatum, Acanthurus spp., Haemulon flavolineatum, H. plumieri and Abudefduf saxatilis. On reef crests, the most frequent and abundant species are Haemulon flavolineatum, Thalassoma bifasciatum, Sparisoma viride and surgeonfish (Acanthurids). In patch reefs, the most frequent and abundant species are grunts, particularly Haemulon plumieri, H. flavolineatum and H. sciurus. Snappers (Lutjanus griseus, L. synagris and L. analis) are very important in patch reefs in the Gulf of Bataban6, particularly because of their biomass. Surgeonfish are also present and abundant in this habitat. Fish diversity on patch reefs is usually higher than on reef crests and bank reefs. However on remote reefs far from the edge of the shelf, as in some regions of the Gulf of Bataban6, the number of species tend to be lower, and their biomass higher. The highest fish diversity was found on reef slopes, at 15-30 m depth. The most abundant species here is Chromis cyanea, but the grunts (H. plumieri, H. sciurus and H. flavolineatum) are also abundant and dominant in biomass. The species Gramma loreto, Stegastes partitus and Clepticus parrai are characteristic (and also abundant) on the reef slope, but are poorly represented in shallow reefs. Thalassoma bifasciatum, Scarus croicensis, Sparisoma viride, Halichoeres garnotti and Lutjanus ehrysurus are also important species on this reef type. Sharks and some other large predators are more commonly found in this habitat than in others (Claro et al. 1990; Claro and Garcia-Arteaga 1994). A comparison of fish community structure between Cuban reefs and those from Martinique and Guadeloupe showed that diversity is higher in Cuba. In contrast, fish density is
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higher in Martinique, due to a large number of small fish; fish biomass is two fold greater in Cuban reefs (Claro et al. 1998) than in Martinique. Medium and large-sized fish are still common in Cuba, but rare in the Lesser Antilles reefs, as a result of over-fishing. 3. NATURAL DISTURBANCES 3.1. Sedimentation Natural stress resulting from sedimentation has been detected along extensive areas of the eastern portions of the gulfs of Bataban6 (southwest Cuba) and Ana Mafia (southeast Cuba), and is due to outflowing currents coming from the shelves, which are often heavily loaded with free sediment. The same was observed at the reef of Cayo Cantiles (south of the Gulf of Bataban6). 3.2. Cyclones and cold front winds Because of the high frequency of cyclones, the reef communities of the southwestem and northwestern (Archipelago Los Colorados) parts of Cuba are comparatively more shaped by these events. There is a remarkable dominance of species resistant to sedimentation and water movement, mainly in the unsheltered western and southern borders of the Gulf of Bataban6. Annually the northwestern shallow reefs of Cuba are highly influenced to varying degrees (frequency and intensity), by strong waves generated from winds accompanying the winter cold fronts. 3.3. Natural nutrification The presence of natural nutrification caused by physical oceanic processes might be present as follows (Marcelino Hemfindez, per. com.): 9 Intermittent cyclonic gyre in the northeast of Pinar del Rio Province (north of Los Colorados reefs and in the southeast of the Gulf of Bataban6 ("Fosa de Jagua"). Possibly, there is another cyclonic gyre in north of Holguin (very northeast of Cuba). 9 Divergence of currents with upwelling of nutrient rich waters in the southwest of the Gulf of Bataban6, but far from the shelf edge. Those systems and their influence on coral reefs of Cuba deserve more research. According to some satellite images, the coral reefs of the Sabana-Camagiiey Archipelago are exposed to the comparatively photosynthetic-pigment rich waters of the Bahamas Strait. It can be the effect of the influence of the shelves of Bahamas and Cuba upon the narrowness and relatively slow transportation of waters of that strait. 3.4. Climate change impact and El Nifio-Southern Oscillation An increase of 0.2-0.29 cm yr of sea level rise around Cuba has been estimated (Hernfindez et al. 1998). This can involve an increase in coastal erosion rates and consequently more sedimentation stress on coral reefs. An average temperature rise of 0.13~ per decade in the south west of Cuba (at Cayo Largo) was estimated in Alcolado et al. (1999). Repeated coral bleaching events in Cuba have been associated to ENSOs by Carrodeguas et al. (in press). For that reason, an increase in frequency and intensity of seawater warming associated to ENSO has to be a matter of great concern for coral reef survival. A "La Nifia" event was responsible of a widespread coral bleaching in Cuba, in 1998.
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4. ANTHROPOGENIC IMPACTS, PROTECTION AND MANAGEMENT 4.1. Sedimentation and pollution About half of the Cuban shelf edge (54%) is separated from the mainland by broad shallow-water bodies and groups of keys which prevent anthropogenic influences from reaching the reefs (Figs. 1-7). Large extensions of the mainland coasts are only slightly urbanized or industrialized. However, watersheds have been extensively deforested for a long time enhancing sediment runoff to the sea. For these reasons, pollution affects coral reefs only in a few localized places, while some degree of sedimentation (including that of natural origin) appears to be common (Alcolado et al. 1994). Deforestation-induced sedimentation may affect roughly 20% of the coral reefs on the shelf edge. As mentioned previously, in the Sabana-Camagiiey Archipelago reefs in the spring of 1994, values of dry and wet algal biomass were high and dominated by filamentous and foliose forms, which according to Littler, Littler et al. (1989) and Steneck and Dethier (1994) are typical of nutrient-rich environments. This algal proliferation is probably due to the synergistic action of the observed relatively high nutrient concentrations (dissolved phosphate concentrations were higher than Lapointe et al. (1992) threshold values for enhancement of algal proliferation) and the massive mortality of the black sea urchin Diaclema antillarum (whose population is showing a marginal degree of recovery in some places). Herbivorous fish populations was not significantly affected in that area in the early 90s. Organic and chemical pollution have been observed to affect the coral reefs off Havana City due to the heavily polluted waters of Havana Bay and the Almendares and Quibfi rivers, together with the underwater sewage outfall point located east of the Havana Bay entrance (Playa E1 Chivo). Nutrient enrichment produces a large proliferation of fleshy and filamentous algae in the reefs located near Havana Bay, Rio Quibfi, Playa E1 Chivo (Havana City), and near the entrance of Mariel Bay (at the northwestern end of Havana Province). At Playa E1 Chivo, the wet biomass value of macroalgae was 0.83 kg m2 in August 1997. On the reefs of Havana City, diversity of scleractinians, sponges and gorgonians has dropped to low values, and their communities are dominated by the scleractinian Siderastraea radians, the sponges Clathria venosa and Iotrochota birotulata f musciformis, and the gorgonian Plexaura kuekenthali, Eunicea flexuosa or Pseudoplexaura spp. The dominance of these species, only when accompanied with low species diversity is considered to be an indicator of organic pollution (Alcolado et al. 1994). The population density of stony corals and gorgonians is very low, and is variable for sponges (Alcolado et al. 1994). As a consequence of the degradation of these reefs, shelter capacity and food availability are considerably decreased, thus leading to a dramatic decrease in fish diversity and abundance. Thermal pollution caused by the cooling system of a power plant located east of Mariel Bay has killed a shallow reef area, producing extensive coral bleaching. Mechanical pollution by fiber wastes from a henequen (an agave plant used to produce ropes) fiber processing factory was observed at a shallow reef near Mosquito River (east of Mariel Bay), causing abrasion of stony corals, sponges, and gorgonians (Alcolado et al. 1994). Some degree of pollution may be affecting the reefs near the entrance of Cienfuegos (south central region), Santiago de Cuba (southeastern Cuba), Nuevitas, Nipe (northeastern Cuba), and Matanzas (northwestern Cuba) bays, as well as near Baracoa City (northeastern
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Cuba) and some other locations, although it has not yet been assessed. We estimate that roughly less than 3% of the shelf border is affected by a notable degree of organic pollution. An environmental assessment recently conducted by Bustamante et al. (in prep.) in the reefs near Guant~namo Bay revealed the absence of significant pollution. 4.2. Tourism Tourism in Cuba, in spite of its great potential, is still poorly developed and thus has had a limited impact on coral reefs. Up to the present day, regulations on the protection of coral reefs from tourist visitation are not yet fully enforced. For this reason, mechanical damage and extraction of stony corals and other organisms (fish, octopuses, gorgonians, etc.) are degrading reef to some extent in sites where tourists and locals engage in diving and boating activities. Two examples of this situation are the once beautiful scenic reefs of Rinc6n de Guanabo, Puerto Escondido (northeast of Havana Province), and the one at Km 14 of Varadero (east of Matanzas Bay). Anchoring on coral outcrops has been and continues to be a practice in fishery and nautical activities. In 1998, mooring buoys were used in at least 25% of tourism reef-dive sites m Cuba. There were other reef diving sites, near human settlements (19%), where mooring buoy deployment was stopped because buoys were frequently stolen. More buoys are being currently deployed in diving centers. 4.3. Coral reef fisheries
In islands surrounded by broad shelves, like Cuba, fmfish fishery takes place in seagrass beds, coral reefs, and mangrove ecosystems, which together constitute an ecological ensemble. After a period of high increases in fish catches from 1960 to 1975, some commercial species became over-fished. Examples are the lane snapper (Lutjanus synagris) in the Gulf of Bataban6; the Nassau grouper (Epinephelus striatus) in virtually the entire Cuban shelf (Claro et al. 1994); mullets (Mugil spp.) and shrimps (Penaeus spp.) in the southern shelf; and the queen conch (Strombus gigas) also in many places around Cuba. As a result of shifts in target fish, the partial replacement of these species led to increases in the catches of other species, such as rays (Dasyatis spp.), gray snappers (L. griseus), jacks (Carangidae) and grunts (Haemulidae), amongst others. Bathoid fishing yields later dropped. Shark fishing yields have also decreased in recent years, due to a long period of sustained low-profile over-fishing (Claro et al. 1994). Cuban coral reef ichtyofauna, as revealed by its higher biomass, species richness, and average size, is in a better condition than those from other Caribbean islands such as Martinique, Guadeloupe and Jamaica (Claro et al. 1998). Most of the damage to the f'mfish fisheries was caused by the use of massive and low-selective fishing gear (e.g. set nets) and by heavy fishing of spawners during the reproductive periods. In this case, the most significant event was the over-fishing of the lane snapper in the Gulf of Bataban6, which induced extreme changes in the structure of reef fish communities. The lane snapper population was replaced by grtmts (Haemulidae), which are a species of lower quality and commercial value. The proliferation of grunts prevented recuperation of the lane snapper stocks in the Gulf, despite the enforcement of drastic fishery-management regulations. Now, more than 20 years later, the lane snapper stocks are recuperating. After the first collapse of conch stocks in 1978, following an authorized capture of 2578 tons in 1977, the Ministry of Fishery Industry (MIP) established a permanent closed season throughout the entire Cuban shelf from 1978 to 1981. Since 1990, a closed repro-
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ducfive season in north and southwestem Cuba (April-September), prohibition of catching juveniles, and smaller local fishing quotas were also established. This stock reduction was produced mainly by the over-fishing due to the illegal harvesting of meat for bait (with a rough estimate of more than 1500 tons of complete animal wet weight per year), or for selling the shells as souvenirs. Two stock assessments carried out in 1984 (all around Cuba) and 1987 (north central Cuba) and a qualitative survey in 1991 (north central Cuba) showed that these measures did not stop the decline in conch populations in those years, at least on the north coast. Two stock assessments suggested a slight recovery in the south of Cuba, one in Cabo Cruz (Southeast Cuba) in 1990, and another in the south of the Gulf of Bataban6 (Southwest Cuba) in 1991. Very rarely, did the percentage of juveniles in the assessed populations exceed 20%. A drop in larvae recruitment coming from upstream is suspected (Ferret and Alcolado 1994). The Queen Conch fisheries were again opened for domestic consumption in the central south of Cuba after some fishery data analysis as well as in the Northeast after fishermen reported some population increase in 1998. For accomplishing CITES regulations, assessments of conch populations in 1999 and 2000 revealed increased densities (> 0.3 ind rn2) in the Northeast (north of Camagfiey Province) and Southeast (Cayos Doce Leguas) of Cuba (M. Formoso per. com.). Now, local fishing quotas require a license from the Environmental Agency of the Ministry of Science, Technology and Environment (CITMA). Spiny lobster Panulirus argus is an important resource closely linked to coral reefs. This marine resource is considered to be the best regulated and the most sustainable in Cuba. Since 1978, catches have varied between 11000 and 13000 metric tons per year and were mainly based upon lobsters inhabiting the seagrass beds of the Cuban shelf, and not just upon those dwelling in the reefs, where an important reproductive potential remains. In the last years total catch varied between 9000 and 10000 metric tons due to some decrease in recruitment since 1989 (R. Cruz, in prep.). Baisre (2000) also documents this decline. Private lobster fishing is not allowed, but some poaching for the black market takes place. Variable catches of turtles on the order of 500 to 1300 tons per year were obtained from 1968 to 1992, with values higher than 1000 tons only before 1975. Since this year catches began to diminish down to 44 tons in 1997. The National Program for the Conservation of Turtles gradually diminished the legal harvesting of turtles since 1992, in accordance with the Convention for the International Trade of Endangered Species of Flora and Fauna. Measures included the prohibition of the private catching of turtles and the egg collection, as well as their transportation and consun~fion. Among other measures, the program establishes the protection of beaches where turtles nest. Since 1997, a total quota of 45 tons was established for two places (Nuevitas in the northeast of Cuba and Cocodrilo in the southwest). There is some poaching for local consumption through the black market. Research to test the hypothesis that Cuba has a resident hawksbill turtle (Eretmochelys imbricata) population is being conducted. Research on the artificial rearing of the hawksbill turtle, green t t ~ e and loggerhead has been carried out for the establishment of turtle farms. Financial constraints have limited the possibility of implementation of the two existing turtle farm programs of Cayos Doce Leguas and Cocodrilo (formerly Jacksonville). Some harvesting of the gorgonian Plexaura homomalla has taken place along two reefs at the southeast end of the Isle of Youth (southwest Cuba) to obtain prostaglandin. This collection was carried out in a sustainable way, by pnming 50% of the "mature" (>30 cm tall) colonies, with a subsequent "resting" of the harvested areas.
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Recently, craftsmen and some local state mini-enterprises for the manufacturing of jewelry, handicrafts, and imitation black coral have illegally collected several species of gorgonians (from some individual sellers). This has led to the devastation of gorgonian gardens in the shallow reef zones of Havana City and Varadero Beach (as far as we know). Commercial stocks of black coral (Anthiphates caribbeana) were discovered in 1960. From the 70's, they were collected in an unregulated manner. The official exploitation of black coral (mainly directed to Anthiphates caribbeana) began in the second half of the 80's. The harvesting of this resource was regulated in 1990, but continued in an ineffectively coordinated and poorly controlled fashion by a few state enterprises. Very recently, there has being a significant improvement in control, by using permanent harvest inspection on-board fishing boats. Illegal harvesting has taken place since the 70's, despite the fact that this activity is forbidden. As a consequence, adult black coral stocks have been depleted in some locations (at the shallower depth ranges of black coral) along the north of Pinar del Rio Province, in Matanzas Bay (northeast Cuba), Puerto de Sagua (north-central Cuba) and Cazones Gulf (east of the Gulf of Bataban6), amongst others. In 1998 an official estimate was that 1468.6 kg of black coral has been extracted at depths of 20-55 m by four enterprises. The regulated minimum size for black coral collected in Cuba is 1.20 m tall and 2.5 cm in diameter at the base. Due to the lack of knowledge on the abundance, biology, ecology and distribution of black coral, a research project partially supported by the UNDP has been conducted, in order to investigate black coral ecology and assess its populations.
4.4. Management prospective Since the 1970's more attention began to be paid to Cuban coral reefs research. However, real possibilities for a differentiated, comprehensive, holistic and legally supported reef management did not exist up to recent times. Rather, management was fragmentary and regulatory measures poorly enforced. A certain degree of protection and sustainability was then achieved through: 9 Some fishery regulations. 9 Existing legislation on the protection of natural resources, flora and fauna, on the prevention of pollution, on marine collecting, and on environmental impact assessment. In that legislation, the term coral reef was not expressed, but included within the genetic concept of fragile ecosystems. 9 Regulatory measures for tourism development in natural areas, required for the acquisition of environmental licenses. 9 Commitments with international treaties such as Agenda 21, MARPOL, SPAW, and CITES. To advance towards an Integrated Coastal Zone Management, a complex and difficult yet vital issue for coral reef conservation, is the current target of the Ministry of Science, Technology and Environment (CITMA). In 1994 a process of institutional improvement took place in which CITMA and its subordinate Environment Agency (AMA) were created. Since 1996 the legislation relevant to protection and rational use of fragile ecosystems improves year after year (Resolution 111/96 Rules about Biological Diversity, 1996; Resolution 168 Rule of Environmental Impact Assessment and for obtaining Environmental Licenses, 1996; Law 81 of Environment, 1997; National Environmental Strategy, 1997; the National Strategy for the Conservation and Sustainable Use of
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Biological Diversity, 1999 and others). CITMA, AMA and MIP are more aware of the urgent need for action for the conservation and sustainable use of coral reefs and they are formulating plans, regulations and a new legislation for the achievement of these goals. AMA and MIP are discussing specific regulations for coral reef use and protection. In 1996 the first explicit regulations for coral reefs appeared (Decree-law 164 Rules of Fishery, 1996; Resolution 33 on Black Coral, 1996; Joint Resolution MIP-MCTMA No. 1/97 of the Ministry of Fishery Industry and CITMA; and the draft bill of the Decree-Law of Biological Diversity). Among these regulations are the prohibition of collecting, anchoring, dredging, pouring sediments, pollutants and solid wastes, and using explosives in coral reefs and their vicinities. Fines are to be imposed for violations of those regulations according to the Decree-law of Contravention System on Environmental Issues, 1999. A recently approved Decree-law on Protected Areas (1999) paves the way to the urgent protection of several coral reefs in Cuba. The Ministry of Science, Technology and Environment is working to improve education and awareness on coral reef value and vulnerability. The UNDP/GEF SabanaCamagiiey Ecosystem Project on biodiversity protection of the Sabana-Camagiiey Archipelago, the Institute of Oceanology (Instituto de Oceanologia), the National Aquarimn, the Center of Environmental Information, Management and Education, the Coastal Ecosystem Research Center, the Marine Research Center, the National Center of Protected Areas, the National Enterprise for the Protection of Flora and Fauna, the ONG "Sibarimar" and the Cuban participants in the CARICOMP Project (Caribbean Coastal Marine Productivity) are working in that direction. Cuba has the necessary professional capability and the institutional capacity for the research and management of its coral reefs. However, the present economic difficulties seriously limit the fmancial resources available to implement and enforce such conservation actions. Although CITMA considers coral reefs in Cuba to be important, coral reef research is still fragmentary due to the lack of resources. The Project General Assessment of the Ecological Status of Cuban Coral Reefs and Monitoring of the Cuban Regional CARICOMP Station is being executed with many limitations. It is aimed at the assessment of the status of coral reefs throughout Cuba, and at identifying the natural and anthropogenic stressors involved, as well as giving relevant management recommendations to the Environmental Agency. It is also engaged with the monitoring of the coral reef station of the Cuban CARICOMP site in Cayo Coco (northern Cuba) and with the "Atlantic and Gulf Rapid Reef Assessment" initiative (AGRRA). 5. CORAL BLEACHING AND DISEASES Coral bleaching and diseases are treated as a separate section (apart from natural disturbances and anthropogenic impacts) because of uncertainty regarding the extent to which human activity may be directly or indirectly involved. The first mass coral bleaching event in Cuba was recorded in 1983 (N. Capetillo and C. Carrodeguas per. com.). Until 1994, coral bleaching was fragmentarily documented, with no reliable information about the extent of the events. In the late summer of 1995, widespread and intense coral bleaching was reported at many locations in the north of Cuba, from Cayo Jutia (Pinar del Rio Province) to Santa Lucia Beach (east of Camagtiey Province). This intense coral bleaching extended from very shallow reef (1 m) to 30 m
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deep. Affected corals were Montastraea annularis; Diploria strigosa," Agaricia agaricites; Porites astreoides; Acropora palmata; Millepora alcicornis; Palythoa caribbaea. Surprisingly, Siderastraea siderea were not bleached, at least in Cayo Guillermo. Recovery of many colonies was reported in January from Santa Lucia Beach reef. Some signs of recovery were also seen in October in a shallow reef at Cayo Guillermo. Before 1995, such intense coral bleaching and other diseases were recorded by the authors at the following times and locations: 9 North of Cayo Pared6n Grande (northern central Cuba) on October 12, 1989: affected corals were Acropora palmata (white band or predation?) at a reef crest, and Meandrina meandrites (coral bleaching) at 10-15 m depth. 9 Three miles west of the mouth of Cabafias Bay (northwest Cuba) on a reef crest (1.2 m depth) on September 29, 1990: Millepora alcicornis f. complanata was about 90% bleached. 9 Near Guardalavaca Beach, Banes (northeast Cuba), on a fore-reef about 15 rn in depth, on August 20, 1993): stands of Agaricia spp. had suffered bleaching (N. Capetillo per. corrL). Surveys conducted on one cruise in April-May 1994, along the north-central part of Cuba (Sabana-Camag4iey Archipelago), and another cruise in the first half of June 1995, along the southern coast of the Isle of Youth (southwest), did not reveal the occurrence of any massive coral bleaching events. During the first survey (in April-May, 1994) some partially bleached colonies of Montastraea annularis and M. cavernosa were observed on a reef at Cayo Coco (12-20 m deep), as well as some colonies of Acropora palmata with big white patches on the back reef in Cayo Guillermo (west of Cayo Coco). On the reef of Cayo Caimfin Grande (west of Cayo Guillermo), at 18-20 m deep, some colonies of Stephanochoenia intersepta and Dichocoenia stokesi were fully bleached, while a few M. annularis were partially bleached. On the reef of Cayo Fragoso (west of Cayo Caimfin), some partially bleached colonies of M. annularis were also detected at a depth of 5 m. On the second survey (June 1995), some Siderastraea exhibited dark spot disease at a depth of 30 m (D. lbarzfibal per. corn.), and some isolated Montastraea were completely bleached at about 20 m depth (J. P. Garcia-Arteaga per. com.). Periodic monitoring of the Cuban CARICOMP reef sites (twice a year since September 1993 to the early summer of 1995) at Cayo Coco (northern Cuba) has not revealed massive coral bleaching. In November 1995 coral bleaching was recorded at the site for many coral colonies. The most affected species, in decreasing order, were Mycetophyllia lamarckiana, Agaricia agaricites, Montastraea annularis, Colpophyllia natans and Diploria strigosa. An almost full recovery was reported at visited reefs. In the late summer of 1997, intense coral bleaching took place in the north of Cuba, but not in the south where several places were visited. It seemed to be the most intense coral bleaching event recorded in Cuba. We do not know the fate of the affected corals. Many colonies of Helioseris cucullata, which is considered a species resistant to bleaching, were bleached. Again, Siderastraea siderea did not suffer bleaching. Further coral bleaching also took place in the late summer of 1998. This was reported at Havana City reef, Cayo Coco (north-central Cuba), Cayo Largo (southeast of the Gulf of Bataban6, Dr. l)rsula Rehfeld per. com.), Cienfuegos (Dr. Jos6 Espinosa, per. com.), Trinidad (south of Cuba), and Santiago de Cuba (southeast of Cuba, down to 35 m depth in May, C6sar Garrido, per. com.). At Punta Franc6s (southwest of Gulf of Bataban6), no massive coral bleaching was observed in October (Jos6 R. Larralde per. com.), yet in the
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same month 30% of corals were bleached in the CARICOMP site reef of Cayo Coco (10 m depth). Many corals were not white, but paler, revealing that the event was just beginning. A cropora palmata populations were observed to have deteriorated to a large extend, presumably as a result of the joint action of "white band" disease, "coral bleaching" and/or predation (Coralliophilla snails) in several locations in the north and south of Cuba (Paraiso and Levisa keys in the northwest of Cuba; Coco, Sabinal, and Guajaba keys in the Sabana-Camagtiey Archipelago; Cayo San Felipe, Punta Francfs, and Cayo Cantiles in the southwest of Cuba; from Bajo de la Vela to Cayo Caguama at Jardines de la Reina Archipelago). In other locations visited in 1994 (e.g. Punta Francfs, Punta del Este, Cayo Matias, Cayo Campos and others, in the southwest of Cuba, and south of the provinces of Gramma, Santiago de Cuba and Guantfinamo) A. palmata stands were in good condition. Now they are predominantly dead. Acropora cervicornis mounds in front of Playa Siboney, at 15-20 m, (south of Santiago de Cuba) was said to still be healthy in 1997. Craig Quirolo from the NGO "Reef Relief' (per. com.) has observed and photographed the occurrence of "black band" disease and what he calls "white pox" in Punta Mafia la Gorda (northwestern end of Cuba) and in Coco and Guillermo keys (central-north Cuba) in 1997. In the north of Pinar del Rio (northwest of Cuba, between Bahia Honda Bay and Cayo Jutia) he reported the occurrence of "white band", "black band", "yellow band", "white pox" and "white plague" diseases, as well as "aspergillosis" in sea fans (Quirolo 1998). He also observed a frequent occurrence of the snail Coralliophila abbreviata on Acropora palmata. ACKNOWLEDGMENTS We are very grateful to Craig Quirolo (Reef Relief) for his valuable information on coral reef diseases in some Cuban reefs, and to Georgina Bustamante (The Nature Conservancy's Marine Conservation Center), Yair Lichtenztajn and Jorge Cortfs for reviewing the manuscript and for their invaluable advice. REFERENCES
Agassiz, A. 1894. A reconnaissance of the Bahamas and the elevated reefs of Cuba. Bull. Mus. Comp. Zool. 26: 1-203. Aguilar, C., G. Gonz~ilez-Sansfn, J. Angulo & C. Gonz~lez. 1997. Variaci6n espacial y estacional de la ictiofaunaen un arrecife de coral costero de la regifn noroccidental de Cuba. I: Abundancia total. Rev. Invest. Mar. 18: 223-232. Alcolado, P.M. 1978. Ecological structure of the sponge fauna in a reef profile of Cuba. In Colloques Intemationaux du C.N.R.S. Biologie des Spongiaires 291: 297-302. Alcolado, P.M.1979. Estructura ecol6gica de las comunidades de esponjas en un perfil costero de Cuba. Cien. Biol. 3: 105-127. Alcolado, P.M. 1981. Zonaci6n de los gorgon~iceos someros de Cuba y su posible uso como indicadores comparativos de tensi6n hidrodin~imica sobre los organismos del bentos. Informe Cient.-Tfc., Inst. Oceanol., Acad. Cien. Cuba 187: 1-43. Alcolado, P.M. 1984. Utilidad de algunos indices ecol6gicos estrucmrales en el estudio de comunidades marinas de Cuba. Cien. Biol. 11:61-77.
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Alcolado, P.M. 1985. Estructura ecol6gica de las comunidades de esponjas de Punta del Este, Cuba. Rep. Inv. Inst Oceanol., Acad. Cien. Cuba 38: 1-65. Alcolado, P.M. 1989. Estructura ecol6gica de las comunidades de esponjas del arrecife de Rinc6n de Guanabo, Cuba. Rep. Inv. Inst. Oceanol., Acad. Cien. Cuba 10: 1-16. Alcolado, P.M. 1990. General features of Cuban sponge communities: 351-357. In: K. Riitzler (Ed.), New Perspective in Sponge Biology. Smithson. Inst. Press, Washington, D.C. Alcolado, P.M. 1992. Sobre la interpretaci6n del medio marino mediante el empleo de los indices de diversidad y equitatividad. Cien. Biol. 24: 124-127. Alcolado, P.M. 1994. General trends in coral reef sponge communities of Cuba: 251255. In: R.W.M. Van Soest, T.M.G. Van Kempen & J.J. Vermeulen (Eds.), Sponges in time and Space. Balkema, Rotterdam. Alcolado, P.M. & G.G. Gotera. 1985. Estructura de las comunidades de esponjas en los arrecifes cubanos. Contrib. Simp. Cien. Mar y VII Jornada Cient. Inst. Oceanol. XX Aniversario, Ciudad de la Habana 1: 11-15. Alcolado, P.M. & A. Herrera-Moreno. 1987. Efectos de la contaminaci6n sobre las comunidades de esponjas en el litoral de La Habana, Cuba. Rep. Inv. Inst. Oceanol., Acad. Cien. Cuba 68: 1-17. Alcolado, P.M., A. Corvea & A. Gonzfilez. 1980. Variaciones morfol6gicas internas y extemas de los abanicos de mar (Gorgonia spp.) y su valor adaptativo. Cien. Biol. 5: 47-56. Alcolado P.M., A. Herrera-Moreno & N. Martinez-Estalella. 1994. Sessile communities as environmental bio-monitors in Cuban coral reefs, 1993: 27-33. In: R.N. Ginsburg (compiler), Proc. Colloq. Forum Global Aspects of Coral Reefs: Health, Hazards, and History. RSMAS, Univ. Miami. Alcolado, P.M., R. Claro, G. Men6ndez & B. Martinez-Daranas. 1997. General status of Cuban coral reefs. Proc. 8th Int. Coral Reef Sym., Panamfi 1" 341-344. Alcolado, P.M. and 6 authors. 1999. Evaluaci6n diagn6stica preliminar de los arrecifes coralinos del oeste de Cayo Largo del Sur: 1998-1999. Instituto de Oceanologia (Report). Arango y Molina, R. 1877. Radiados de la Isla de Cuba. Real Acad. Cien. Med., Fis. Nat., Habana 14: 272-284. Baisre, J. 2000. Chronicle of Cuban marine fisheries (1935-1995): Trend and fisheries potential. FAO Fisheries Technical Paper. Behety, P.A. 1975. Nuevos reportes de gorgonficeos (Coelenterata) para Cuba. Serie Oceanol6gica 33" 1-9. Bustamante, G., M. Chiappone, K. Sullivan Sealey, E. Webb, G. Delgado, K. Bayer, J. Kelly, A. Lowe & R. Wright. In prep. Marine resources In: Rapid ecological assessment of the southern part of the Guantanamo Bay. Am6rica Verde, Arlington (Virginia). Carrodeguas, C., G. Arencibia, N. Capetillo & M. Garcia. Decoloraci6n de corales en el Archipi61ago Cubano. Rev. Inv. Pesq. Claro R. & J.P. Garcia-Arteaga. 1994. Estructura de las comunidades de peces en los arrecifes del grupo insular Sabana-Camagiiey, Cuba. Avicennia 2: 83-107. Claro, R., J.P. Garcia-Arteaga, E. Vald6s-Mufioz & L.M. Sierra. 1990. Caracteristicas de las comunidades de peces en los arrecifes del Golfo de Bataban6: 1-49. In: R. Claro (ed.), Asociaciones de peces en el Golfo de Bataban6. Editorial Academia, La Habana.
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Claro R., J.A. Baisre & J.P. Garcia-Arteaga. 1994. VIII. Evoluci6n y manejo de los recursos pesqueros: 435-492. In: R. Claro (ed.), Ecologia de los peces marinos de Cuba. CIQRO, Chetumal, M6xico. Claro, R., J.P. Garcia-Arteaga, Y. Bouchon, M. Louis & C. Bouchon. 1998. Caracteristicas de la estructura de las comunidades de peces en los arrecifes de las Antillas Menores y Cuba. Avicennia 8/9: 69-86. De la Guardia, E. & G. Gonz~lez-Sans6n. 1997a. Asociaciones de esponjas, gorgonias y corales en un arrecife en la costa noroccidental de Cuba. I: Distribuci6n espacial de biotopos. Rev. Inv. Mar. 18: 198-207. De la Guardia, E. & G. Gonzhlez-Sans6n. 1997b. Asociaciones de esponjas, gorgonias y corales en un arrecife en la costa noroccidental de Cuba. II: Variaciones espaciales del cubrimiento y la densidad. Rev. Inv. Mar. 18: 208-215. De la Guardia, E. & G. Gonz~lez-Sans6n. 1997c. Asociaciones de esponjas, gorgonias y corales en un arrecife en la costa noroccidental de Cuba. III: Variaci6n espacial de la diversidad. Rev. Inv. Mar. 18: 216-222. Duarte-Bello, P.P. 1949. Contribuci6n al estudio de los madreporarios de las costas de Cuba. B.Sc. thesis, Universidad de La Habana. 159 p. Duarte-Bello, P.P. 1963. Corales de los arrecifes cubanos. Acuario Nacional, Serie Educacional 2: 1-85. Espinosa, J. & A. Rams. 1987. Malacocenosis de los arrecifes coralinos de la Playa Santa Lucia, Camagiiey. Garciana 5: 3-4. Ferrer, L., P.M. & P.M. Alcolado. 1994. Panor~imica actual de Strombus gigas en Cuba: 7378. In: R.S. Appeldom & B. Rodriguez (eds.), Biologia, pesqueria y cultivo del caracol Strombus gigas. I Cong. Latinoamer. Malacologia, Editorial Ex Libris, Caracas. Final6-G6mez, E., C. Aguilar & A. Barroso. 1989. La comunidad de peces de un arrecife artificial: comparaci6n con la comunidad de peces naturales adyacentes. Rev. Invest. Mar. 10: 143-154. Garcia-Parrado, P. & P.M. Alcolado. 1998. Nuevos registros de Octocorales para la plataforma cubana. Avicennia 8/9:105-108. Gonz~ilez-Sans6n G., C. Aguilar, J. Angulo & C. Gonz~lez. 1997a. Variaci6n espacial y estacional de la ictiofauna en un arrecife de coral costero de la regi6n noroccidental de Cuba. I: Diversidad. Rev. Invest. Mar. 18: 233-240. Gonz~ilez-Sans6n G., C. Aguilar, J. Angulo & C. Gonz~lez. 1997b. Variaci6n espacial y estacional de la ictiofauna en un arrecife de coral costero de la regi6n noroccidental de Cuba. III: An~lisis multidimensional. Rev. Invest. Mar. 18:241-248. Gonz~ilez-Sans6n, G., E de la Guardia, C. Aguilar, C.Gonz~dez & M. Ortiz. 1997c. Inventario de los componentes m~is comunes de la fauna en un arrrecife de coral costero de la regi6n noroccidental de Cuba. Rev. Invest. Mar. 18: 193-197. Guitart-Manday, D. 1959. Gorgonias del litoral de la costa norte de Cuba. Publ. Acuario Nac., Serie T6cnica 1" 1-24. Hem~ndez, M., P. Garcia & M. Izquierdo. 1998. Preliminary considerations on the probable impact of sea level rise and water temperature in some localities of the coastal zone of the Cuban Archipelago. Proc. Conference on National Assessment Results of Climate Change. San Jos6, Costa Rica, 1998" 183-202. Herrera, A., D. Ibarzabal, G. Gotera, G. Gonz~lez, R. Brito, E. Diaz & C. Arrinda. 1991. Ecologia de los arrecifes del borde de la SW cubana y su relaci6n con la langosta Panulirus argus. Rev. Invest. Mar. 12: 163-171.
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Herrera-Moreno, A. 1983. Efecto de residuales industriales sobre el patr6n estacional y las caracteristicas del meiobentos en Santa Cruz del Norte. Rep. Inv. Inst. Oceanol., Acad. Cien. Cuba 20: 1-35. Herrera-Moreno, A. 1991. Efectos de la contaminaci6n sobre la estructura ecol6gica de los arrecifes coralinos en el litoral habanero. Ph.D. dissert., Academia de Ciencias de Cuba. 110p. Herrera-Moreno, A. & P.M. Alcolado. 1983. Efecto de la contaminaci6n sobre las comunidades de gorgon~ceos al Oeste de la Bahia de La Habana. Cien. Biol. 10: 69-86. Herrera-Moreno, A. & P.M. Alcolado. 1985. Monitoreo de la contaminaci6n mediante el anfilisis de la estructura comunitaria de los gorgon~iceos. Contrib. Sin~. Cien. Mar y VII Jomada Cient. Inst. Oceanol. XX Aniversario, Ciudad de la Habana: 253-257. Herrera-Moreno, A. & P.M. Alcolado. 1986. Estructura ecol6gica de las comunidades de gorgon/lceos en el arrecife de Santa Cruz del Norte. Rep. Inv. Inst. Oceanol. 49" 1-27. Herrera-Moreno, A. & P.M. Alcolado. 1988. Estructura de las comunidades de gorgon/~ceos en el litoral de Mariel y su comparaci6n con el litoral habanero. Cien. Biol. 15: 55-69. Herrera-Moreno, A. & N. Martinez-Estalella. 1987. Efectos de la contaminaci6n sobre las comunidades de corales escleractineos al Oeste de la Bahia de la Habana. Rep. Inv. Inst. Oceanol. 62: 1-29. Herrera, A., P. Alcolado & P. Garcia-Parrado. 1997. Estructura ecol6gica de las comunidades de gorgon~ceos en el arrecife de barrera del Rinc6n de Guanabo. Avicennia 6/7: 73-85. Ibarz/lbal, D. 1993. Distribuci6n y abundancia de la macroinfauna bent6nica v/lgil en tres arrecifes de la plataforma suroccidental cubana. Avicennia 0: 84-111. Kiihlmann, D.H.H. 1970a. Die korallienriffe Kubas. 1. Genese und evolution. Int. Revue Hidrobiol. 55: 729-756. Ktihlmann, D.H.H. 1970b. Studien fiber physikalische un chemische factoren in kubanischen Riffgebieten. Acta Hydroph. 15: 105-152. Ktthlmann, D.H.H. 1971a. Die entstehung des west-indischen korallenriffgebietes. Wiss. Zeitschr. D. Humboldt-Univ. Berlin, Math.-Nat. R. 29: 675-695. Ktihlmann, D.H.H. 1971b. U-ber einige physicalische und chemische factoren in kubanischen korallenriffgebieten. Wiss. Zeitschr. D. Humboldt-Univ. Berlin, Math.Nat. R. 29:707-719. Kiihlmann, D.H.H. 197 lc. Untersuchungen zur Okologie und entstehung kubanischer banlrifle Kubas. Wiss. Zeitschr. D. Humboldt-Univ. Berlin, Math.-Nat. R. 29:721-775. Kiihlmann, D.H.H. 1971 d. Die korallienriffe Kubas. II. Zur Okologie der bankriffe und ihrer korallen. Int. Revue Hidrobiol. 56:145-199. KiJhlmann, D.H.H. 1974a. Die korallienriffe Kubas. III. Die rigelriff und korallenterasse, sweiverwandte erscheinungen des bankriffes. Int. Revue Hidrobiol. 59:305-325. Ktihlmann, D.H.H. 1974b. The coral reefs of Cuba. Proc. 2nd Int. Coral Reef Symp., Australia 2: 69-83. Lapointe, B.E., M.M. Littler & D.S. Littler. 1992. Modification of benthic community structure by natural eutrophication: the Belize barrier reef. Proc. 7th Int. Coral Reef Symp., Guam 1: 1323-334. Littler, M.M., D.S. Littler & P.R. Taylor. 1989. Evolutionary strategies in a tropical barrier reef system: functional groups of marine macroalgae. J. Phycol. 19: 229-237.
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Martinez-Estalella, N. 1986. Distribuci6n y zonaci6n de los corales cubanos (Scleractinea). Rep. Inv. Inst. Oceanol., Acad. Cien. Cuba 46: 1-24. Martinez-Estalella, N. & A. Herrera-Moreno. 1989. Estructura ecol6gica de las comunidades de corales escleractineos en el arrecife de barrera del Rinc6n de Guanabo. Rep. Inv. Inst. Oceanol., Acad. Cien. Cuba 9: 1-15. Martinez-Iglesias, J.C. & J E. Garcia-Raso. 1999. The Crustacean decapod community of three coral reefs from the southwestern Caribbean Sea of Cuba: Species composition, abundance and structure of the communities. Bull. Mar. Sci. 65: 539-557. Miravet, M.E., M. Lugioyo, S. Loza E. Perig6 & M. Montalvo. 1999. Indicadores microbiol6gicos del estado de salud de los arrecifes coralinos y fondos blandos de la plataforma suroeste de Cuba. Inf. parcial, Arch. Cien. Inst. Oceanol, 20 p. Mochek, A.D. & E. Vald6s-Mufioz. 1983. Acerca de la conducta de los peces de las comunidades costeras en la plataforma cubana. Cien. Biol. 9: 87-106. Ndfiez-Jim6nez, A. 1984a. Cuba: La naturaleza y el hombre. Vol. 2. Bojeo. Editorial Letras Cubanas, La Habana, Cuba. 702 p. N6fiez-Jim6nez, A. 1984b. Cuba Jardin Coralino. Catey, Ediciones Turisticas de Cuba, Instituto Nacional de Turismo de Cuba, La Habana. 44 p. Plante, R., P.M. Alcolado, J.C. Martinez-Iglesias & D. Ibarzabal. 1989. Redox potential in water and sediments of the Gulf of Bataban6, Cuba. Est. Coast. Shelf Sci. 28: 173-184. Quirolo,C. 1998. Reef Relief' s 1998 Cuba Expedition. Reef Relief(report): 1-47. Steneck, R.S. & M.N. Dethier. 1994. A functional group approach to the structure of algal-dominated communities. Oikos 69: 476-498. Su~rez, A.M. 1989. Ecologia del macrofitobentos de la plataforma de Cuba. Rev. Invest. Mar. 10:187-206. Trelles, J. A.M. Suhrez & L. Callado-Vides. 1997. Macroalgas del arrecife de la Herradura, Costa NO de La Habana. Revista de Investigaciones marinas 18(3): 191192. Vald6s-Mufioz, E. & O.H. Garrido. 1987. Distribuci6n de los peces en un arrecife costero del litoral habanero. Rep. Inv. Inst. Oceanol., Acad. Cien. Cuba 61: 1-22. Vaughan, T.W. 1919. Fossil corals from Central America, Cuba and Puerto Rico with accounts of the American Tertiary, Pleistocene and Recent coral reefs. Bull. U.S. Nat. Mus. 103: 189-524. Wells, S.M. 1988. Coral reefs of the world. Vol. 1: Atlantic and eastern Pacific. UNEP, Nairobi & IUCN, Gland. 373 p. Zlatarski, V. & N. Martinez-Estalella. 1980. Scleractinians of Cuba, with data on associated organisms. Bulgarian Academy of Sciences Press, Sofia (in Russian). 312 p. Zlatarski, V. & N. Martinez-Estalella. 1982. Scleractiniaires de Cuba. Acad6mie Bulgare des Sciences, Sofia. 290 p.
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The coral reefs of the Dominican Republic F r a n c i s c o X. G e r a l d e s Centro de Investigaciones de Biologia Marina, Universidad Aut6noma de Santo Domingo and Fundaci6n Dominicana Pro - Investigaci6n y Conservaci6n de los Recursos Marinos, P.O. Box 748, Santo Domingo, Dominican Republic
ABSTRACT: The Dominican Republic has a land area of 48,484 km 2, with a coastline of 1,389 km, of these 166 km or 11% are coral reefs. The continental shelf, averages 7.5 km wide and covers 8,130 km 2. There are two submerged offshore banks, two barrier reefs, as well as many fringing reefs. Dominicans in general recognize the importance of coral reefs as they provide safe ports, shelter and habitat for biodiversity, food and beaches. The first report of reefs in the Americas was from Hispaniola by C. Columbus in 1492, calling them "baxas" or "roqueiros". Other early naturalist worked with specimens from this island, and research continues until our days. The reef setting varies depending on the location and distance form the numerous river discharges. Dry areas and shallow platforms are favorable for reef growth at: Montecristi, Macao-Punta Cana, Parque Nacional del Este, Parque Nacional Jaragua, as well as the Silver Banks located some 170 km to the north of the island. The coral coverage varies from 40% to 9%, reflecting not only natural causes, but also anthropogenic impacts. There are reports of 64 coral species. The coastal marine habitats including the reefs of all the marine protected areas in the country have been studied, cataloged and mapped, the information produced have been important for their management and conservation. Some reefs are under threat by development of ports such is the case of Boca Chica, the most studied reef site in the island. Sedimentation along the coast has increased, and has become a threat to reef growth, occurring on 1/3 of the coastline, and now reaching reef sites such as Juan Dolio and Barahona. Coral bleaching has been found mainly on areas near urban development. The 1980's mass mortalities occurred as in the rest of the Caribbean. The reefs of the southern and eastern coasts of the Dominican Republic are usually exposed to hurricanes. The reef tracks near urban development are more impacted by habitat degradation due to physical damage and from nearby sources of pollution transported by currents. Non-adequate beach use in some tourists centers have caused reef degradation in the past, lessons learned have induced the tourism sector to become involved in reef conservation. The main problem reefs are facing is overfishing of several essential species such as Strombus sp., Panulirus sp., and fishes of the Serranidae, Lutjanidae, and Scaridae families. Several non-official institutions as well as the recent created Secretaria de Medio Ambiente y Recursos Naturales (Ministry of the Environment and Natural Resources) have programs for conservation of marine and coastal habitats, communities and species.
1. I N T R O D U C T I O N T h e c o r a l r e e f s o f the D o m i n i c a n R e p u b l i c are an i m p o r t a n t r e s o u r c e , a n d it is a c k n o w l e d g e d b y the citizens that t h e y p r o v i d e safe ports, shelter, a n d food. C o r a l reefs h a v e r e c e n t l y b e e n a s s o c i a t e d w i t h the t o u r i s m industry. W h i l e in the past, D o m i n i c a n s t o o k c o a s t a l a n d m a r i n e r e s o u r c e s for granted, a n d c o n s i d e r e d t h e m e v e r l a s t i n g , t h e r e is Latin American Coral Reefs, Edited by Jorge Cortrs 9 2003 Elsevier Science B.V. All rights reserved.
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today an awareness of their fragility, and of the fact that they need care and good management to ensure their health and function. At present, coastal and marine environments, as well as forest habitats, have national economic, political and aesthetic value. Nevertheless, overfishing, pollution and urban growth still pose very relevant and real threats to these ecosystems. In order to minimize these, the country has set aside four large coastal regions as marine protected areas: Parque Los Haitises, Parque Montecristi, Parque del Este and Parque Jaragua. The last three are located downstream of oceanic currents and receive minimal river influence. In all coral reefs, seagrasses, and mangroves constitute important habitat reserves. Other coastal features of the Dominican Republic include emerged reef terraces, shorelines of terrigenous origin, estuaries and sandy beaches. This chapter includes a description of the coral reefs of the Dominican Republic, as well as maps of the most important reef sites: two barrier reefs (Montecristi and MacaoBavaro-Punta Cana), and several fringing, hard base, high energy marine-coastal communities. Finally, a short review of the environmental hazards that coral reefs face in the Dominican Republic is presented.
1.1. Natural history The island of Hispaniola, situated at 17040 ' and 19~ and 68020 ' and 70~ is the second largest in the Caribbean (78,000 km2), and located in the north-central boundary of the Caribbean Sea. The deep Windward Passage (4,000 m) separates it from Cuba, to the north-northwest, and the Jamaica passage separates it from Jamaica, to the west-southwest (3,000 m). It is separated from Puerto Rico, to the east, by the shallow Mona Passage (350-400 m). Oceanic currents and winds are primarily governed by the easterly trade winds. Hispaniola is politically divided into two countries: Haiti to the west, and the Dominican Republic to the east (Fig. 1). The Dominican Republic has a land area of 48,484 km 2, with a coastline of 1,389 km. Of these, 376.7 km (or 27%) are mangroves, and 166 km (or 11%) are coral reefs. Emerged reef terraces and cliffs, are the main coastal features found along the coast, especially on the southeastern region of the island. The continental shelf has a mean width of 7.5 km, and covers an area of 8,130 km 2. There are two submerged offshore banks: La Navidad and La Plata, 70 and 150 km 2 respectively, located north of Cabo Saman~ (Fig. 1). 1.2. Geography The island topography is diverse, with three large valleys and four mountain chains. These have a directional trend northwest to southeast, with broad valleys in between. Two outstanding features of the Dominican Republic are: that it contains the deepest zone in the Caribbean (the Valle de NeybaJLago Enriquillo, at 48 m below sea level), and the highest peak (Pico Duarte/La Pelona, 3,087 m above sea level) (De la Fuente 1976). The island also has a very complex tectonic and geological history, being seismically active. 1.3. Climate and oceanography The climate of Hispaniola is considered to be tropical marine dry, with an annual average temperature ranging from 18 to 32~ at the lower elevations. There are regional variations in climate and rainfall, influenced by the predominant northeasterly trade winds,
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as well as cold fronts from the northwest, and sporadic hurricanes and summer storms from the southwest. Rainfall tends to decrease from east to west. The annual average rainfall is 980 mm, with May and November having the highest precipitation, and December to April having the lowest. The oceanic circulation patterns in coastal waters are dominated by the Northem Equatorial Current, which flows westward and divides itself into northem and southem branches at Mona Passage (Metcalf et aL 1977). Counter currents, usually associated with tides, are common near to the coast. Tides are semi-diumal, with mean spring tidal ranges of 90 and 30 cm on the northern and southem coasts respectively. 1.4. Culture, population, and development The people of the Dominican Republic form an agricultural and farming society, which is presently moving towards light industry and tourism. Historians indicate that deforestation and human intervention in the natural setting has occurred since the 15 th century. Severe environmental changes occurred during the early to middle 20 th century, when the sugarcane industry boomed and large areas of forest were cut down, increasing soil erosion and sedimentation, and hence ultimately affecting the nearby marine ecosystems.
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Another major impact to the environment has been the recent population rise, from 2.5 million in the 1960's to the present 8.5 million today. This rise has increased the degradation of watersheds, river systems, and marine and coastal habitats. 1.5. Coral reef research
The study of reefs in Hispaniola began in 1492, when Christopher Columbus described these submerged structures as "roqueiros", "baxas" and "restringas" (confinements) in his navigation log (Col6n 1492). Later, in 1525, Gonzalo Femfindez de Oviedo (in Chardon 1949) mentions these strange formations on his Sumario de la Natural Historia de las Indias. Several early naturalists, such as Carlos Plumier (1695 in Chardon 1949) and George L. Leclerc (1770 in Chardon 1949) made collections for the Muse6 de Historie Naturelle de Paris. In 1776, Luis Nicolson published his Essai sur l'Histoire Naturelle de St. Domingue (Chardon 1949), where he mentions madreporaria, corals, crustaceans, and other invertebrates. Also worth mentioning is the work of Moreau de Saint-M6ry during 1796 (Chardon 1949) and his Description Topographique et Politique de la Partie Espagnole de L'Ile de Saint Domingue. Later in the 19th century, more works followed such as those of William Gabb (1868, in Chardon 1949), who published "On the Topography and Geology of San Domingo". In the early 1900's, other scientists such as Vaughan (Vaughan 1900; Vaughan et al. 1921), Wells (1956), and William Hassler, who published "From Sea Base to Mountain Top at Santo Domingo" (1933, in Chardon 1949), collected and worked either on living and fossil reefs of the Dominican Republic. More recent studies, including those of Sir W. Halcrow and Partners's reports on the environmental impacts at Boca Chica (1976); Geister's (1980), and Schubert and Cowart's (1980) work on the paleontology of reef terraces on the south coast of the Dominican Republic; the studies of Galzin and Renaud-Mortand (1983) on pollution effects on coral reefs; and the work on the reef conditions after hurricanes (Barnwell 1983). Dominican contributors to reef studies include Bonnelly de Calventi (1974), who published a taxonomic coral list. Gonzfilez-Nufiez (1974) located reefs sites and lists species collected in "Operaci6n Madre Perla". In 1973, F. X. Geraldes began his research on coral reefs, publishing in the local newsletters of the Museo Nacional de Historia Natural, Centro de Investigaciones de Biologia Marina, and the Herbario de la Universidad de Santo Domingo. These early works included the first Dominican scientific reef study with descriptions of reef types, species, and locations, the results of which were later summarized and published (Geraldes 1976, 1978). Rathe (1981) produced the first systematic study of sponges in Dominican coral reefs. Geraldes (1982) also studied the effects of hurricanes on Dominican reefs. More recent studies include reef characterizations, ecological assessments, and species lists (Geraldes 1994a, 1996a, b, c; Vega 1994; Vega et al. 1994, 1997; Geraldes and Vega 1995a, b; Geraldes et al. 1997), as well as reef conservation efforts made by creating volunteer networks for reef monitoring (Cintr6n et al. 1994; Geraldes 1994b). 2. DESCRIPTION OF CORAL REEF AREAS Most coral reefs of the Dominican Republic are fringing reefs. There are also two barrier reefs, numerous patch reefs, and four large offshore banks; their distribution is associated with the coastal profile and depth of the ocean platform. In places like Macao
The coral reefs of the Dominican Republic
81
-Puma Cana and Momecristi, broad platform barrier reefs are found. Not so in Palenque, Saman~ Bay, and the Bahia Escocesa, where reefs are unable to establish due to the high turbidity caused by numerous river discharges. There are also unnatural conditions that are affecting the reefs such as increasing coastal development, pollution, untreated waste, water discharges, and beach erosion. This chapter describe the reefs found in the coasts of the Dominican Republic, starting with the offshore bank reefs (Silver Banks). The coastal reefs are described beginning at the northwestern shores bordering Haiti at Rio Masacre (Montecristi), and moving clockwise around the island to the southwestern border with Haiti at Rio Pedernales. 2.1. Offshore bank reefs: The Silver Banks, National Sanctuary of Whales The Silver Banks (Fig. 1), at 20~ 69~ l'W, and 140 km north of Puerto Plata in the Dominican Republic, have an area of 3,740 km 2. In the northern portion of this bank the barrier is composed of a series of patch reefs bound together near the surface. This area is shallower and shaped like a triangle. The reef extends for 30 km to the southeast; it is exposed at low tide: on its ocean side to a great depth, over a distance of less than 100 m. The coral patches are pillars of cemented coral skeletons ascending from the rubble and sandy base 15 to 25 m up the surface. The living coral species found here follow the zonation pattems described by Goreau (1959). A. palmata is found occupying the top portion of the reef down to the 6 m depth contour. Below that zone, most corals are typical of the lower palmata and buttress zones. The substrate of the Silver Banks is mainly sand and coral gravel. At the southern portion of the breaker zone, the mean depth is 40 m, and corals grow only where suitable substrate is present. The turbidity of the water tends to increase to the south and away from the reef crest. A reduction of coralline columns or pillars is obvious to the south of the reef crest. The mean coral cover in the Silver Bank is 40%. There is a low density of sponges (2%). Turf algae covers 51% of the sampled substrate. The rugosity of this reef is relatively high (1.3%) due to the magnitude of the coral columns or pillars, some of which reach the surface of the water. 2.2. Coastal reefs 2.2.1. Montecristi barrier reef (Fig. 2.). The Montecristi region in the northern coast of the Dominican Republic has the largest reef formation of the country with a length of 64.2 km, which grows on the nearshore areas of the Montecristi Shoals (1,181 km2). The coastline consists of a low mountain range of sedimentary (Miocene) origin. At the northwestern end is the landmark of E1 Morro (273 m) and the city of Montecristi, and 2 km to the west is the Yaque del Norte River estuary with its large mangrove forest. The climate and land ecology of the area is dry to very dry tropical forest, conditioned mainly by the lack of river runoff and the steady easterly winds (15 to 30 knots). The reef begins at E1 Morro and extends westward reaching Punta Rucia. Along the coast and protected by the barrier and lagoon, extensive nearshore seagrass beds and frondose growths of red mangroves (Rhizophora mangle) thrive. The reef system of Montecristi can be considered as a barrier reef in active expansion. High relief features and large living coral colonies with sizes exceeding 10 m in diameter are common. The deep reef
82
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Atlantic Ocean 20007N
Montecristi Shoals 100 m
F.X. G e r a l d e s
R i o Yaque del Nolte
-
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Breakers
@ Deep reef
0 Mangrove
Fig. 2. Parque Nacional de Montecristi
0
Reef flat Seagrass Hard bottom exposed cornunities
1 5 h
The coralreefs of the DominicanRepublic
83
has different characteristics depending on location and position relative to currents, waves, wind direction, and tidal channels. A representative portion of this setting is shown on Fig. 3, at Punta Mangle. Reef lagoon: The reef lagoon can be between 20 m and 2 km wide, and up to 20 m deep. In association with it there are sandy beaches, mangrove forests and terrigenous cliffs. In hard base areas (1 to 5 m deep), small coral patches (5 to 800 m 2) are found with Gorgonia spp. and Plexaura spp. as the dominant soft corals, associated with the M. annularis complex, Diploria spp., Manicina spp., A. cervicornis, Porites spp. and Millepora spp. The main feature in this lagoon is the dense to sparse seagrass beds of Thalassia and Syringodium on a sandy or sand-mud base. Other coral species found in the reef lagoons are: P. divaricata, M. areolata, S. siderea, S. radians and A. cervicornis. Reef flat and back reef: There is an extensive and diverse back reef followed by a reef fiat. In areas closer to tidal channels a more vigorous growth of corals occurs: Porites porites, Porites divaricata, the M. annularis complex, A. cervicornis, A. palmata and Millepora complanata are present with octocorals and sponges as well. Near to the reef crest a harder, more consolidated base is found, where calcareous algae Amphiroa spp. and Jania spp. are dominant. Thalassia and Syringodium grow in patches. Reef crest: Skeletal remains of poorly lithified Acroporids form the reef crest. Millepora is dominant although a few young A. palmata are also found. This change in dominance patterns could be attributed to the Acroporid disease, with Millepora substituting the previously dominant A. palmata and Porites spp. structures. In most of the reef area, the crest is narrow and crossed by tidal channels. Here, the waves from oceanic swells barely reach the reef. This may be due to the effect of the precedent shoal which reduces their force. The energy here is mainly represented by wind-generated waves with a short lifespan producing choppy seas, which conditions a low energy environment. On its ocean side the crest abruptly drops to 6 - 10 m in less than 30 m, allowing a clear view of its basal structure, which is composed of large skeletons of A. palmata, A. cervicornis, Porites spp. and Montastraea spp. Some of these skeletons have broken loose and lie at the base of the crest, serving as suitable substrates for future colonization, as well as refuge for other reef inhabitants. Outer reefs: In exposed areas, there is evidence of a lower Palmata zone consisting mostly of large, dead colonies of A. palmata. Seaward is a low relief spurs and grooves formation, with large colonies of the dominant Montastraea complex are also found. There are variations to this zonation pattern: when tidal channels divide the reef crest, there is usually a portion of the breaker zone, facing away from the predominant forces (wind and waves); this creates a very calm and protected portion on the reef. In this setting, the reef crest can sometimes abruptly drop into a sandy channel with seagrass, often down to 30 m deep. As this portion receives some of the ocean's energy, the coral growth can be found forming patches 10 to 5,000 m 2 in size. This set-up then continues either towards the shore where it connects to the backreef, or seaward, where it is followed by spurs and grooves or hard grounds. In the majority of the cases for Montecristi, the reef crest slopes towards a hard base (10 m deep), where octocorals are
84
F.X. Geraldes
N
Hardbottom
71O30 ~
~~
Fig. 3 Punta Mangle, Parque Nacional Montecristi
The coralreefs of the DominicanRepublic
85
dominant. The hard base ends in a wall, dropping to the 25 m contour where large coral colonies are found. The M. annularis complex, M. cavernosa, Diploria spp. and Agaricia spp. amongst others cover most of the bed, with a total coral cover exceeding 60%. In these places, the colonies form gigantic structures, some occupying up to 100 m E, formed by coral heads of multiple colonies forming a single structure. Among these, broad caves and deep crevices (14 m) are common. In the deepest portion (30 m), coral pinnacles are found. Live corals and other hermatypic organisms use the large boulders and debris that have precipitated down from shallower regions as substrate to grow vertically in a pillar-like fashion. When several of these pinnacles grow close together, they sometimes join to create a larger base. In most cases the dominant species is Montastraea, and it covers all previous growth. In other cases some of these are dominated by octocorals and coralline algae such as Halimeda goreaui, Halimeda discoidea and Dyctiota spp. The encrusting octocoral, Erythropodium caribaeorum, and the red calcareous algae Porolithium caribeaeum are also common features of the pillars at the Montecristi reefs. Another type of reef formation found here are deep reefs, which form buttress systems. These are characterized by large to very large dominating colonies of the M. annularis complex, as well as M. cavernosa, Siderastrea spp., D. strigosa, D. labyrinthiformis, D. stokesiL Madracis spp., M. meandrites, A. agaricites, A. cervicornis and the sponge Cliona langae. These buttress systems are usually found in association with the tidal channels located throughout the extension of the reef.
Offshore keys Punta Rucia keys. In the eastern end of the Montecristi Barrier Reef at Punta Rucia, there are 16 offshore coral keys. These are small (800 to 5,000 m2), submerged, mountlike features that rise from a sandy platform 45 to 100 m deep. They have an arch-like shape, with the convex side facing the incoming winds. There is a significant difference in coral growth pattern between the exposed and protected sides of these keys. On the protected side of the keys, at 15 m depth, there is sparse marine vegetation, with Syringodium and fleshy algae dominating; as this reaches the flat, a back reef may form. Here P. caribaeorum, and the corals P. astreoides, D. strigosa and M. annularis are found with small colonies. In these places the long-spined black sea urchin Diadema antillarum is common, hiding amongst the crevices of the healthy reef found here. Moving towards the reef crest, on its windward side and at 2 m deep, a breaker zone is evident; species diversity increases, as do organisms adapted to stronger waves and currents. On some of the keys the breaker zone occupies the entire key. The dominant species found here are: A. palmata, Millepora spp. the, M. annularis complex and D. strigosa. In some of the other keys in these high-energy areas, there are large areas of hard substrate without any coral growth; instead, large algae mats of Lobophora sp. and other algae cover most of the area. The frontal reefs usually end at approximately 12 m depth, sometimes followed by a sand plateau or by a forereef slope to deeper waters. Hermatypic corals dominate this reef slope. Numerous healthy colonies of the M. annularis complex, A. palmata, M. cavernosa, P. porites, A. agaricites, together with the sponges Cliona langae and Aplysina fistularis are found. Due to currents induced by heavy swells at the base of the exposed side (forereef slope), a detrital area is found.
86
F.X. Geraldes
Here octocorals such as Plexaura homomalla, P. americana and P. flexuosa and the coral M. alcicornis become dominant species. Siete Hermanos keys. These keys are not part of the Montecristi barrier reef system. They are located 25 km west of El Morro, at the western and distal end of the Montecristi Shoals, on a ocean floor rise (5-30 m deep) and at the edge of the Manzanillo submarine canyon (>800 m deep). The keys occupy an area of 10 km 2, and vary in size between 3,000 to 40,000 m z. All are composed of sand and unconsolidated coral debris with arid vegetation, where nesting populations of Tula leucogaster (buN) are commonly found. Water turbidity and salinity show influences of the Yaque del Norte river estuarine system about 20 km upstream. The sea bed is sand-mud. Despite these conditions, the shallowness of these seven shoals offer enough light penetration for fringing reefs to form on the windward sides, as well as patches on the leeward sides of the keys. In shallow areas between the keys, there are numerous patch reefs. In some cases these are vaguely connected and form large structures, especially between Cayo Rata and Cayo Muerto. Coral reef formation is least at Cayo Tourur6, this being the most easterly key and thus closer to the estuary. Nevertheless, the river plumes can reach as far away as Cayo Arenas, located furthest to the west. It is considered that water quality, mainly its turbidity and salinity, have influenced this region to conform a unique reef formation. The coral structure on these keys is of a l~inging reef type down to 20 m, consisting of a sandy beach followed by a narrow reef flat 10 to 50 m wide. The species composition on the back reefs is similar to Punta Rucia back reefs. The breaker zone, however, presents differences between the keys. Most of them rise from a sand-mud base at 10 - 12 m. In keys facing surf and currents, the hard base substrate is bare and covered by cementing and boring sponges, and octocorals. In those keys where the currents and surf are not as strong, vertically growing species are found together with large to gigantic coral colonies. These grow sparingly, and are surrounded by finger-like corals such as Porites spp. Sometimes, gigantic round coral forms can be found which comprise most of an area, with very few if any other accompanying benthic species.
Biodiversity of the Montecristi barrier reef Recent studies done in Montecristi (Geraldes 1996a, b, c; Geraldes et al. 1997) have produced updated information about this area, a community and substrate map (1:40,000) of the coastal region, and the first biodiversity list for the region's marine and coastal habitats. The biodiversity sampled here includes 22 Classes, 285 Families, 525 Genera, and 742 species. The highest species richness is found in the hard base communities, which is related to substrate rugosity and complexity. Of these hard base community types, coral patches, high relief spur and grooves, and reef keys represent the refuges for biodiversity. 2.2.2. Luper6n reef, Luper6n Bay, Puerto Plata. Eastward of Montecristi, the coast is characterized by a diversity of habitats: a reef terrace extends from Punta Rucia to Luper6n, and the coast is then mainly of terrigenous origin until it reaches Puerto Plata. Luper6n Reef is a fringing reef located 250 m offshore. It grows over a narrow drowned reef terrace, which borders a shallow submarine canyon at the entrance of a bay (Bahia de Luper6n), where mangroves and a small town are found. The reef grows on a hard base, with low relief and high gorgonian cover up to 10 m deep. The reef slope ends at
The coral reefs of the DominicanRepublic
87
40 m depth near a submarine canyon. Coral cover is 12%, with algae dominating (67%). The growth is mainly of hard and smooth substrates, with very little reefrugosity (1.04%). 2.2.3. Playa Dorada reef, Puerto Plata (Fig. 4.) Patchy coral growth with low cover by live corals, dominated by encrusting turf and fleshy algae, are characteristics of a sedimentary coastal region of calcareous origin, which is washed by numerous torrential streams that form sedimentary plumes; rip currents are common here. Offshore (18 m deep) a hard basal community grows on top of a sandstone substrate. In areas where coastal features provide shelters, like Playa Dorada, the coast was originally fringed by healthy mangroves and marshes (now replaced by golf courses and hotels), which acted as sediment and nutrient barriers, and allowed the formation of patch reefs. These often formed small mounts and pillars, with rose vertically from a 15 m base to the surface. A small fringing reef of A. palmata and Porites sp. developed. These structures protected the coast and created a large stretch of beach, which is now intensely utilized by the tourism industry. At present, this reef is severely degraded due to environmental misuse by the resorts (over 5,000 rooms) and the golf course built here: all these infrastructures have exceeded their sanitary infrastructures capacity, thus streams and ground water pollution, together with nutrient runoff, have seriously affected the nearby reefs and coastal regions. There is little hope of recovery unless the activities that maintain this present level of pollutants are controlled. Studies shows that there is an 80% coral mortality, and that 92% of the basal and reef substrate is covered by algae, especially Gracilaria spp., Dyctiota spp., Turbinaria spp. and Codium spp. Eastward of Playa Dorada, the coastal features of the coast change to reef terraces followed by a narrow flinging reef that extends eastward for 3 km. The distance from shore to the reef crest reef varies from 10 to 200 m away, where the breakers begin; A. palmata skeleta are found here covered with algae. Millepora spp. now dominates this breaker system. In deeper water (15 - 25 m), irregular sandstone structures with many crevices and pillars, covered with scattered coral growth, rise up to 5 m high from the sandy beds. 2.2.4. Sosfia reef, Puerto Plata. SosOa reef is located in a small bay open at the northeast. The base is composed of beach rock. The calm waters and white sandy beaches off the coast make this a preferred tourist destination. High reef terraces encompassing a unique view surround the beach. Underwater, a patch reef surrounded by sand occupies approximately 30% of the center of the small bay. A prairie of octocorals with sparse growth of A. palmata, M. alcicornis, D. clivosa, and D. cylindrus begins at the 4-m contour. Deeper, at the 10 m contour, the diversity and cover by coral species increases, covering 28% of the substrate. Intense visitation by tourists has caused severe impacts on this site. Continuous visitation creates large sediment plumes. Algae cover is 43%, possibly due to some undetermined nutrient input. In terms of species diversity, the absence of large predatory fish species is noticeable. The sponges occupy 6.4%, and are mainly of the encrusting and burrowing types. 2.2.5. Reefs of the northern shore of the Samanfi Peninsula Reef Las Ballenas keys. This reef surrounds a carbonate outcrop in the coast of Las Terrenas, on the northern shore of the Samanfi peninsula. The base is a hard pavement
88
I
7 1 0454
100 rn
Punta Soslja
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kgantin 20rn
sand/rn~
AEROPUERTO
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i
Beach rock Seagrass
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0 Reefs
E?Reef terraces
Fig. 4. Playa Dorada - Punta Sosua, Puerto Plata.
I l
Hard Bottom Communities
5m
F.X. Geraldes
fi
20055'-
The coral reefs of the Dominican Republic
89
eroded relict reef, where sparse medium-sized coral colonies, mainly of Diploria spp. and Meandrina, establish themselves in crevices and grow. There are also octocorals, and a thick carpet of fleshy and turf alga covers this basic substrate. The species richness is not high, and comprises 11 species of algae, 9 sponges, 9 octocorals and 2 hard corals. E! Portillo reef. This reef is located on the northern shore of the Saman~i peninsula. The coastline is composed of high and steep carbonate mountain slopes and terraces. The climate is very humid. Since the 1940s, most of the coastal lands have been turned into coconut farms, deforesting the area in the process. The reefs here are fifnging, growing very close to shore in sparse patches with a tendency to close at the breaker and to form lagoonal environs. On these lagoons, and very close to the shore in shallow waters, the patches have coral remains of A. palmata, the M. annularis complex, Millepora spp., and Diploria spp. Most are fully covered by fleshy and turf algae; very few, if any, live corals are found on them (Geraldes and Vega 1995b). Further out to sea, approximately 9 km offshore, there are numerous shoals (15 m deep), that rise from the surrounding oceanic waters. These are carbonate terraces, eroded either by bioerosional processes or by exposure to weathering during past geological times. The species of corals found in these shoals are few and low in coverage (11.7%). More dominant is turf algae (44%), fleshy algae (20%), and encrusting sponges (18%) (Geraldes and Vega 1995b). The lack of large predators and the scarcity of large herbivores and sea urchins are affecting coral recruitment on these reefs, giving the opportunity for more active erosional processes to Occur.
Puerto Escondido. This site is the northermost shore in the east of the Saman~i peninsula. It is located very close to a terrigenous rocky shore with falling boulders, and to the edge of the narrow continental shelf. Corals here grow without any apparent anthropogenic influences. Runoff and springs in the past, which are now reduced, have created small, narrow, protected coves where corals flourish, and where A. palmata grows vigorously. In deeper waters, on a terrigenous base, a young fringing reef can be found with 25 coral species, 15 species of sponges, 11 species of octocorals and 18 species of algae (Geraldes and Vega 1995b). Cabo Cabr6n reef, Las Galeras. The reef near Cabo Cabr6n offers a spectacular wall dive. It is located at the tip of the Saman~ peninsula. The coastal region is formed by Tertiary rocks (marble), and is steep and high (400 m). The water depth right off the coast surpasses 150 m. In some areas where landslides have occurred, narrow terraces can be found formed by large boulders. In those places coral grows from the surface to 50 m deep in a 30 ~ incline. The coral forms are of the encrusting and massive type, and coral cover is approximately 40%. Tube sponges follow with a 28% coverage (Geraldes and Vega 1995b). Large fish are frequently found here. During winter, humpback whales are often encountered, here and in the Portillo and Terrenas reef sites. 2.2.6. Miehes reef. This region on the eastern coast of the Dominican Republic is very humid. Numerous rivers and streams loaded with sediments join the ocean near Miches. The Yuna river system discharges to the west in Saman~ bay, and together with the Los Haitises and the Sabana de la Mar watersheds, they form the largest estuarine system of the Caribbean islands. The waters in the entire region are generally murky due to the high loads of sediments, limiting coral growth. Near the town of Miches, at Punta Hicacos, a
90
F.X. Geraldes
68115,
Punta
Atlantic Ocean
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.....
o. . . .
,.
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. ~
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Fig. 5. Macao- Bavaro- Punta Cana.
small fringing reef has developed. To the west there are small patch reefs. Extending towards the center of the bay to the north, there are offshore shoals, which are dangerous for navigation and where important 16 th century wrecks are found (Tolosa and Concepci6n). This coral region has not been documented. 2.2.7. Bfivaro- E! M a c a o - Punta Cana barrier reef system (Fig. 5). On the Eastern shores of the Dominican Republic, facing the Mona Passage, is the B~ivaro-E1 MacaoPunta Cana barrier reef system. This portion of the island has a configuration resembling a bold arrowhead. B~ivaro faces northeast into the Atlantic, E1 Macao is to the east (Mona Passage), and Punta Cana to the southeast (the Caribbean). The coastline is sandy, with mangroves, coastal lagoons, and swamps behind the coastal dune. These humids drain into the sea through numerous outlets or underground springs. The watershed is a coastal plain in the B~varo region. At E1 Macao and Punta Cana, reef terraces are usually found close to shore mainly at Cabo Engafio and near the airport. The reefs of E1 Macao, B~ivaro and Punta Cana extend for 70 km. There are marked structural differences between them. While E1 Macao and B~varo face northeasterly winds and high swells, Punta Cana faces southeasterly winds and waves. Thus E1 Macao and B~ivaro are high energy reef complexes with hard bases and eroded profiles, while Punta Cana has the characteristics of a low relief reef.
The coralreefs of the DominicanRepublic
91
El Macao (Arena Gorda) reef. This reef is located in the north central portion of the Mona Passage, close to Cabo Engafio, and has Atlantic reef characteristics. Its appearance is similar to the one described for Puerto Plata and E1 Portillo in Saman~t. The smooth and solid limestone rises from the sandy surroundings up to 10 m, forming a high relief reef. There are no spur and groove formations here: the rocky formations are more like reef relicts from the late Quaternary period. The substrate where the reef has established itself is covered with algae (23%, of which 1.3% are encrusting and boring algae). The basal reef rocks of this reef have become brittle through bio-erosional processes, forming sediments and sand and creating temporary sediment plumes that affect coral recruitment and growth. This explains the low coral coverage (5.5%), most of which consist of small colonies no larger than 20 cm in diameter. B~ivaro reef. The breaker zone at B~ivaro can be as far as 3.5 km from shore, creating a wide lagoon (2-5 m deep) with coral patches and an extensive seagrass bed, followed by a broad porous and shallow back reef that reaches gradually onto the reef fiat. Coral species commonly found in this area are P. porites, P. astreoides, S. radians, M. complanata, A. cervicornis, Diploria spp., C. natans and the M. annularis complex. A. palmata skeletons covered with algae in association with Millepora sp. dominate the windward side of the breaker zone, which is narrow and steep. At 4 m, there are large dead stands of A. palmata as well as large boulders of the M. annularis complex and Diploria sp. Reaching the 13 m depth there is an irregular and wide sand channel, ending on its seaside in a rise of 8 m, which continues to form a smooth sandstone shoal, mostly covered by turf algae; during stormy events, this area becomes the first breaker region on the reef complex. These shoals are uneven, with crevices 2-5 m deep. Between them, shallow sand pockets appear and interconnect with others. Towards the deeper regions and on the frontal face of this shoal, the 10 m contour is reached with a gentle slope. The reef base then flattens and low-relief spurs (1.5 rn high) with sand and rubble-filled grooves begin to extend for 800 m or more, to about the 18 m depth. The coral cover for this portion of the reef is 16%. Punta Cana Reef. This reef is located in the southern portion facing the Mona Passage, and begins on its northern side following the cornering of Cabo Engafio by deep seas. Here, isolated patch reefs may be found close to shore. The Punta Cana reef grows closer to shore, characteristic of the fringing reef type, and is oriented towards the southeast. This zone is frequently hit by hurricanes. The Punta Cana sandy beaches are interspersed with low coral cliffs, which tum into high escarpments towards the south where the reefs end and there are deep nearshore waters. The reef lagoon region is shallow with rubble and sparse seagrasses. Several freshwater springs discharge underwater, thus influencing the type of biological diversity found here. The breaker zone at 5 m is narrow and composed of large, compacted skeletons of A. palmata; algae cover is high and few live corals are present. Seaward of the breaker zone, there is a sand and rubble area, with large boulders comprising the base of this frontal structure. The spur and groove area is of low profile and highly eroded. The 50 rn contour line is very close, and there are some areas where it is possible to find features used as dive destinations. The Macao-B~ivaro-Punta Cana Barrier Reef is now facing large impacts and threats from a steadily growing tourism industry. In a 30 km stretch of coast, about 11,000 hotel rooms have been constructed. The intense use of some hotel front sites and dive destinations has inflicted obvious damage on the reefs. In those areas close to shore, coral cover-
92
F.X. Geraldes I
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,'" . . . . . . . .
, .... . ...............
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age is less than 5%, and the seagrass beds as well as the lagoon patch reefs and backreefs are clearly degraded. There has been a rapid and unplanned development, without environmental impact assessments on the potential impacts of several activities, such as dredging and intense beach use creating sediment plumes, which mainly affect the backreefs, the reef flats, and the reef crests at Macao, B~ivaro and Cabeza de Toro. There are other impacts that have affected this reef, such as anchors, environmentally unconscious diving and snorkeling, and increased fishing pressure. The result of these actions has induced the algae growth, which has reached to 58% of substrate cover. Beside the sediment effect described above, there exists no control over the release of detergents and other water treatment chemicals that are usually associated with hotel operations. The evidence of a stressed system is clear, and there is an unusually noticeable presence of the black band disease, affecting several coral species.
The coral reefs of the Dominican Republic
93
2.2.8. Reefs of Parque Naeional del Este (PNE) (Fig. 6). The reefs of this protected area are basically low relief systems, found either as small, fringing, deep (20-30 m deep) patches, or as banks. Most of them are on the leeward side, protected by a land mass of Pleistocene and Recent reef terraces. Southeasterly trade winds are dominant. The reef on the leeward side can be divided into two distinct areas: that along the southern coast of Saona Island (influenced by oceanic currents,) and that along the western side of the Catuano Passage (more protected). The bases of the Saona reefs are consolidated hard bases and octocorals and sponges dominate the benthic communities. Hard corals are abundant only at the specific places where they concentrate, forming small, dispersed coral patches. Here the waves and currents are strong, and are in part responsible for sculpturing the reefs. The reefs west of Catuano mainly have sandy bases with patch reefs. Large amounts of sediment and biogenic sands are transported from the Catuano Passage and deposited along this coastline towards the west, with large seagrass meadows covering most of the nearshore areas. Corals mostly grow in patches from 12 to 30 rn deep. Further to the west, away from the influences of the Catuano Passage, coral patches increase in frequency and grow as deep-water fringing reefs, these being the most common reef structures of the southern coast of the Dominican Republic. Parque Nacional del Este (PNE) is the most studied marine site in the Dominican Republic (Vega 1994; Vega et al. 1994, 1997). Six categories of hard base substrate have been identified for this area: low relief spur and groove formations, reef flats, transitional reef communities, patch reefs, low relief rocky shoals, and rocky coasts. The basal substrate for these formations is consolidated carbonate reef, in addition to sediments and rubble.
Fringing Reefs Catalinita reef (Fig. 7.). This reef is located at the eastern end of a channel that separates the mainland f~om Saona Island. The base rises abruptly at the edge of the channel. In the deep portions, high relief spurs and grooves with large, rounded coral forms are common, while in shallower areas a hard base virtually without sand deposits, serves as a substrate for a large octocoral prairie. Following the 10 m contour depth, the base is covered by a wide frontal section of large skeletons ofA. palmata which project to the surface. In some areas where live colonies still exist, patches of Montastraea spp. and M. complanata form, mainly on the leeward side of the breaker zone and near Catalinita Island, which is a deposit of coral debris. Arreeife del Troneo (Catalinita reef). This is a leeward reef located to the north of Pasa Grande and south of Catalinita Island. Porites sp. is the dominant species at 0.5 m depth. At 3 m coral diversity increases. Algae (27 species) cover 50% of the area, sponges (16 species) occupy 5% of the area, octocoral (7 species) growth is sparse, and corals (14 species) cover 25% of the benthos. P. fureata is the dominant species. This setting forms a low frontal wall that ends in a narrow sand-gravel base, colonized by a dense seagrass bed of T. testudinum. Reef Crest, Catalinita Reef. Due to the act that this reef geographically faces the westbound currents, it is common to fred large amounts of solid waste from the heavy traffic of the Mona Passage and other offshore territories to the east. Dominating the top of the crest in 0.2 rn of water, is the short leaf type of Thalassia. There are also some live colonies of A. palmata, A. cervicornis, M. complanata, D. strigosa, M. areolata and S.
94
F.X. Geraldes !
18o12'
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ISLA SAONA
Fig. 7. Catalinitareef, ParqueNacional del Este.
radians. Below this, large, unconsolidated pieces of A. palmata lie like non-cemented tiles. At the 2 m deep, a patchy seagrass bed is established on top of coarse gravel (>25 cm diameter) substrate. In this zone, 8 species of algae cover 50% of the base. Sponges and octocorals are rare: There are 5 species of sponge and 3 species of octocoral. Hard corals are represented by 10 species, growing sparsely as small colonies. Adamanay Reef. This narrow fringing reef starts at E1 Faro to the West, and runs very close to shore along the village of Mano Juan, ending at Canto de la Playa in the central southern portion of Saona Island. The reef crest is separated by a shallow and narrow (30-50 m) sandy channel with seagrasses. Sporadic coral aggregations form the narrow reef fiat, which then continues into a Acropora-Montastraea zone; this is the basal structure of the breaker. In the seaward direction lies a hard carbonate platform, where gorgonians and coral grow in depths and configurations similar to other Saona Island sites. The Adamanay Reef protects the only human settlement in Saona Island, which dates back to the 1700s as a pirates' village, and is now a fishing settlement and a tourist destination.
The coralreefs of the DominicanRepublic
95
Low relief spur and groove communities
The low relief spur and groove communities are mainly found to the west of Mano Juan, in a somewhat protected region of PNE, and in the south of Saona Island. They are located between 0.5 - 3 km away from the coast at 15 to 30 m deep. Sponges are dominant, as are octocorals and algae. Coral colonies are medium-sized and scarce. M A M M A ' s reef. This reef begins 18 m in front of Punta E1 Faro. The reef system is a continuation of a patch reef near the coast, in 3 to 8 m of water, dominated by live A. palmata and the M. annularis complex. Going seaward from this patch reef, a broad sand channel occurs, ending where the spur and grooves begin, with an orientation facing East towards the incoming waves and winds. Coral cover is low (7.5%), octocorals are the dominant benthic forms (17% coverage), and algae occupy 25% of the base. Parque Naeional. This reef is located westward of the mainland, at 15 m depth. It has small, narrow spurs (6-9 m wide and a length up to 25 m), and the grooves are narrow (3-5 m wide) and filled with fine sediments. The basic orientation of this reef is east to west. The algae are dominant with 15 species, forming patches with Halimeda opuntia and H. tuna as the dominant species. Twenty-nine species of sponge have been documented, with ,4gelas, Xestospongia and Verongula constituting the most common genera. Octocorals are abundant with 10 species, Pseudopterogorgia acerosa and P. americana being the most common species. Twenty-five species of hard corals have been observed, with relatively low coverage. The most common species are medium sized colonies of D. labyrinthiformis, S. siderea and M. cavernosa. El Pefi6n (CARICOMP/site). E1 Pefi6n has a hard base, with sparse sand-clay sediments at 15 m. This eroded spur and groove formation gently slopes towards a 2 m cut reminiscent of ancient shores, and into a sand channel where seagrasses grow. The dominant benthic fauna are the octocorals, with 18% coverage and 16 species, Briareum, Eunicea and Pseudopterogorgia being the most common genera present. Sponge coverage is 11%, with a diverse sponge composition (36 species), Agelas, Verongula, and Xestospongia being the most common. The corals account for 8% of basal coverage with 26 species (the highest species count for the whole PNE). Algae cover is significant; 24%, with 15 species represented. This location has been chosen as the CARICOMP permanent reef monitoring station for the country. Arrecife de Rub6n. This reef lies on the 20 m contour line that extends from Mano Juan westward. The reef's loose substrate is formed by sand, clay, and rubble. The benthic biodiversity is dominated by algae, with 14 species covering 25% of the substrate. Sponge diversity is also high, with 34 species covering in some cases up to 50% of surveyed areas. The most common genera present are again ,4gelas, Verongula and Xestospongia. Coral coverage is low (5%), and only 18 species have been documented. El Toro. This reef is found in the southwestern shore of Saona Island, at the 20 m contour depth. The orientation and position of this site faces the incoming currents and seas from the southeast. A spur and groove system forms its basic design, ending abruptly in the cut of an old shore terrace at 26 m depth, where large gravel and reef debris accumulate from the bioerosional processes occurring in the living portion of the reef. Algae cover (50%) is dominant, followed by octocorals with 22 species. Corals (25 species) grow, but cover no more than 5% of the base.
96
F.X. Geraldes
Bayahibe Reef. This reef is located at the northwestern limit of Parque Nacional del Este, 800 m away from shore, on top of a submerged terrace 18 m deep. It has a welldef'med spur and groove system, with relief up to 2 m high. The reef orientation is eastwest, perpendicular to the shore. The coverage by corals is 34%, with 25 species; sponges 11% with 37 species; and algae 35%, with 16 species. Hard base carbonate reef flat communities This reef type is characterized by a hard base flat carbonate substrate. These reefs are low relief, and are associated with high energy seas and currents. They are most common in the eastern portion of the park facing the incoming surge and waves from the open seas. In terms of diversity, turf and brown algae, and/or a co-dominance of algae and corals dominate them. Pasa Grande (Catalinita Reef). Algae, with 36 species, dominate this hard base. The most conspicuous genera are Dictyota, Turbinaria, Stypopodium and Halimeda. Coral colonies grow sparsely forming large individuals. Octocorals are few in number, represented by Gorgonia ventalina, Pseudoplexaura poros and Plexaura flexuosa: all are species adapted to high-energy conditions. Seven sponge species are present, encrusting and boring forms (Chondrilla nucula and Cliona langae) dominating. The corals are more diverse with 12 species, the most common being A. palmata, D. clivosa, P.
astreoides and P. porites. Transitional reef communities E! Faro. To the northwest of the Adamanay reef crest, somewhat protected by an extension of the southern coast of Saona Island, a low relief-high energy occurs at 7 m depth, mostly colonized by: algae, corals, and octocorals. It may be considered a transitional reef with accumulations of sediments and rubble. There are 24 species of algae, with Halimeda, Dictyota and Amphiroa dominating, and a cover from 25 to 50%. There are 22 octocoral species, with Eunicea, Plexaura, Plexaurella and Pseudopterogorgia being the most abundant, and encompassing 25% of the basal coverage. Hard corals are present, with 23 species growing scattered along the fiat bottom, covering 5% of it. Patch reef communities These are located in protected waters in the western portion of the leeward side of the park, and inside the Catuano Passage, protected by the fringing reef and reef crest of Catalinita Island. Arrecife del Angel 1. This reef is located in shallow water (1.8-5.4 m), in the western entrance of the Catuano Passage, and is surrounded by a large seagrass bed. The structure is dome-shaped, with a diameter of 30 m, and is collapsed in its middle portion; hence the name that reminds one of a halo. In this middle portion Porites rubble accumulates. In its most exposed portion, large coral heads are found, with a tendency to link to the back reef by a rubble and deposition bed. Algae is the dominant form here with 50% coverage representing 21 species, the common ones being Halimeda opuntia, Caulerpa racemosa, Titanoderma sp., Stypopodium zonale, Amphiroa tribulus and Dictyota sp. Sponges here are scattered with a 5% coverage, but with 20 species present, of which Cliona langae and Iotrochota birotulata are the most obvious ones. Octocorals are very sparse, with 7 species found only in the periphery of the patch structure. Corals
The coralreefs of the DominicanRepublic
97
represent >5% coverage with 11 species present. P. porites, the M. annularis complex and M. cavernosa are the most common. Arrecife del Angel 2. Again in the Catuano Passage, at 5 rn depth, there is a patch reef with low relief, surrounded by a seagrass bed, sand, and gravel, with spotted and patchy coral colonies. Algae are dominant with 50% coverage and 15 species. Sponges have only 5% coverage with 18 species, with C. langae, Amphimedon compressa, I. birotulata and Aplysinafistularis being the most commonly seen species. Besides algae, the most dominant group is octocoral, with 13 species and large colonies (>50cm) of Eunicea, Plexaurella, Pseudoplexaurella and Pseudopterogorgia. Here coral cover is >5% of the substrate, with 15 species. There are moderate to large colonies (> 25 cm) of the M. annularis complex, M. cavernosa, D. labyrinthiformis and S. siderea. There are also acroporids present. Los Flamencos. This reef is located near E1 Faro reef, in the protected waters of the small cape which the coastline forms here. The reef is at 6 m depth and consists of a series of coral patches separated by sediments and rubble. The physical relief is medium to low in a hard substrate, where corals congregate to form outcrops of growth with large heads intercepted by the sand channels surrounding them. In some cases A. cervicornis is found, initiating the settling process and patch formation. Algae are represented by 21 species, dominated by Dyctiota sp. Octocoral fauna is common, with Eunicea, Plexaurella, Pseudoplexaurella, Pseudopterogorgia and Pterogorgia being the most commonly seen. Also common are the hard corals with 23 species. There are large (>2 m diam.) colonies of A. palmata serving as a basal structure for other species to settle on, such as A. tenuifolia and the rare M. squarrosa. Large numbers of Montastraea, Colpophyllia and Dendrogyra are also found in these coral patches. Hard base carbonate platform communities Arrecife de Los Cocos. At 4 m depth, in the western portion of the Catuano Channel, there is a tidal channel frequently washed by strong currents generated from tides and winds, which structures the benthic community. Due to the strong currents, the dominant biota found are algae and octocorals, and in a lesser quantity, sponges and corals. Algae cover is above 50%, with 29 species present, the most common being Hypnea cervicornis, Acanthophora spicifera, Jania rubens and Laurencia intrincata. Of these, H. cervir represents more than 25%. Halimeda opuntia, H. tuna, Coelothryx irregularis, Amphiroa brasiliana and Galaxaura oblongata are also common. It is notable that the red algae are dominant in this location. Sponges are sparse around this reef site, occupying 5% of the base with 28 species. It is interesting to note that some of them can reach sizes up to 1.2 m, and the most commonly found species here are Amphimedon compressa, Pandaros acanthifolium and Callyospongia vaginalis. Octocorals are the most conspicuous group on this reef, with some individuals reaching up to 2 m high. They are well represented by 23 species, the largest number of species found in the park nevertheless their basal attachment or foot only covers 5% of the base. The common species are: P. acerosa, E. clavigera and E. calyculata, representing 60% of the total. Corals cover 1% of the base, with small colonies (<100 cm 2) of 14 species growing mainly in aggregations surrounded by rubble. The dominant species found are: M. alr P. astreoides, D. stokesii and D. labyrinthiformis, which represent 90% of the population.
98
F.X. Geraldes
2.2.9 Playa de la Isla Catalina reef, La Romana. On the southern coast of the Dominican Republic, to the south of the town of La Romana is a small island named Catalina, with two reef sites: one is a leeward reef, the other is a wall. The leeward reef lies seaward after a seagrass bed, sloping to 5 m depth; then a spur and groove system begins, ending at 14 m. Below this is a wide sandy area with coral patches. Recently this area has been turned into a cruise ship and tourist port, impacting the reefs there. Open water anchoring structures were deployed to tie these large vessels. Assessment studies have found a reduction of more than 80% in the overall benthic cover, due to the physical effects of these structures. Here, coral cover has been reduced from 12% to 4%; similar values have been found for sponge and octocoral cover, and algal cover increased from 15 to 27%. The solid reef platform has been transformed into rubble substrate. In general terms, this reef site is one of the most affected and damaged in the country. In nearby undisturbed areas, the average coral cover is 8%, with 31 species; octocorals cover 3%, with 14 species; sponges cover 8%, with 33 species; and algae cover 21%, with 19 species (Geraldes 1994b). The wall site is located on the northern tip of Catalina island, and extends some 500 m along the shore. It is separated from shore by a narrow (20 m) and shallow (2-3 m) zone. At 2-5 m depth a dense and healthy coral conglomerate is found, where A. palmata, the Montastraea complex, Diploria spp., M. decactis, Porites spp., M. miriabilis, many sponges such as Xestospongia spp. and Cliona spp. and octocorals cover most of the base. The wall starts abruptly at the eastward margin, and vertically extends over 40 m, ending at a sandy base. On the wall Halimeda spp. and plate forms of Agaricia spp., together with P. astreoides and Montastraea spp., are common. In the deeper areas, anthipatharian and octocorals are also common, in crevices and along the vertical hangings. 2.2.10. Reefs of Juan Dolio - Guayacanes, San Pedro de Macoris On the south coast and 25 km to the west of the Higuamo and Soco rivers is the fringing reef of Juan Dolio-Guayacanes, extending for 10 km, close to the shore. This reef protects a narrow sandy beach on a low-laying terrace. Due to the proximity of major cities, tourist installations have been developed along this coast in excess of its carrying capacity. In turn, beach intervention has deteriorated the reef setting and created conflict between users of this region. Tunnel Reef. The coastline near this reef is composed of porous and calcareous reef terraces, and sandy shores. The Higuamo River influences the area. This reef is made up of a crest, with sparse patches. Seaward from the reef crest and parallel to it there is a rubble and sand channel; upon reaching 7 m depth, a high relief spur and groove system begins with relatively healthy coral growth covering 33% of the base. This is one of the few places in the country where coral cover surpasses algal cover (26%). Villas del M a r - Juan Dolio reefs. The breaker zone of this area is composed of A. palmata, D. strigosa, the M. annularis complex, M. complanata, P. porites and P. astreoides. Most are dead colonies covered by turf algae. They are not cemented, but are placed in situ. They are heavily used by beach goers and are usually covered by free sediments and detritus, together with solid waste and garbage. Encrusting and boring sponges, such as Anthosigmella varians and C. langae, thrive here. The deterioration of this reef crest has created a stronger shore current, which has increasing beach erosion and
The coralreefs of the DominicanRepublic
99
sand transport inside the reef lagoon. The lower Palmata zone has started to receive large amounts of sediment coming from the lagoon region, where the presence of encrusting and boring organisms has also increased. Towards the deeper region (12 m), the reef has not yet suffered, due to the buffering effect of an 80 rn sand channel. A high relief reef begins with the following basic benthic composition: coral 33%, 8% octocorals, 2% sponges, and 26% algae. Stresses are evident due to bleaching and black band disease being present in some of these colonies. Punta Garza. This system is a unique reef front formed by a Porites-Montastraea association, without acroporids. It grows towards the shoreline and connects with it by a very shallow and often exposed (at low tides) sand accumulation, where Syringodium dominates. Eight species of algae, 10 species of octocorals, 7 species of sponges, and 21 corals represent the most common benthic organisms there. This region is being severely impacted by dredging and jetties deployed to sustain the development of tourism. This has also increased the turbidity of the coastal waters, and it is now common to find large amounts of sediments covering coral colonies, with discoloration and death of organisms found in some cases. Guayaeanes Reef. The conditions of the shore near this reef are similar to the ones described for the other reefs in this coastline" they are severely impacted, due to urban and tourist development. The reef is divided into two portions. The eastern portion is a very shallow (0.2 - 1 rn deep) reef fiat hard platform (10 - 40 m wide), that connects to the beach. The cemented remains of Porites and Montastraea are the main components of the base of this reef crest. Seaward, this platform drops abruptly (2 m) to a hard substrate, which continues into a shallow sand channel; there, MiHepora and octocorals appear. Further east, at Punta Cadillo, this reef type changes back to a typical A. palmata breaker, although it is equally highly impacted and covered by algae such as Mycrodictyon sp. and A canthophora sp., in addition to zoanthids (Zoanthus pulchellus). 2.2.11. Boca Chica reef, Bahia de AndrOs, Santo Domingo (Fig. 8) This reef has the longest history in the country, as a study case. The Boca Chica reef is located in the center of a bay, and has a south-southeasterly orientation, facing dominant winds and swells. The coast is a dissolution basin of the carbonate terraces that are characteristic of the south coast. At this site, several underground springs emerge from the Rio Brujuelas, creating a shallow sand deposit suitable for a f~ingingbarrier reef establishment. In the mid-1930s the lagoonal area of this reef was dredged, and the material used as landfill in the coastal mangrove swamps, to reclaim the land and convert this into a resort town. Since then, hotels, sugar mills, and port facilities have been installed, sheltered by the reef barrier. In this process, Isla la Piedra was created using the by-products of port construction and dredging. There is also a small natural mangrove key called La Matica. Today, the region hosts 150,000 permanent residents and 5,000 hotel rooms, in a stretch of less than 3 km of coast, thus creating intense pressure and impacting the coastal and marine resources and habitats found here. The reef of Boca Chica may be described as an eroded spur and groove formation, with a clearly defined zonation pattern as regards depth: sandy beach, back reef lagoon, reef crest, breaker zone, lower palmata zone, spurs and grooves, sand channel, buttress zone, and drop-off. All these reef regions are impacted either by natural stresses (3 hurri canes in 25 years) or by anthropogenic activities (overfishing, coral extraction, dredging,
1O0
F.X. Geraldes
Boca Chica ~:,.:.,:,:,,:,,:::,,:,,:,,:,:.,:,,:,,:,,:,:,:.,:,,:,,:,,:,,~--; ~'*'~' ',',', ', ',',',','| ',',
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pollution, divers, etc.). The regions where this is most evident are: La Matica key, the backreef, reef fiat, the breaker zone, and the spurs, which in some places are well eroded and have a slow cementation. At approximately 10 m depth, there are large concentrations of loose rocks and reef debris, with rubble covering 20% of the base. Nevertheless, this reef's benthic composition still has a predominance of coral coverage with 20%. Sponges are also present, with a 5% cover. Algal cover is high (56%). The major groups of benthic organisms found here are represented by: 12 species of algae, 6 species of octocorals, 22 sponges and 30 corals. Agaricia spp. and the M. annularis complex are the most common species found. Algae such as Laurencia sp., and encrusting sponges (Cliona sp. and A. varians) are also common. In the shallows, at the breaker zone (1-4 rn deep), large colonies of A. palmata, the M. annularis complex surrounded by P. astreoides, P. divaricata, P. porites, M. complanata, and G. flavellum, are still present. Nevertheless, the seascape seems catastrophic. Pieces of coral lie all around, and degradation by physical with bioerosional processes is obvious. Diadema antillarum and tunicates, boring sponges, and large amounts of turf algae cover all available basal surfaces. Amongst all this, small colonies of A. palmata appear. At the breaker zone, the Acropora barrier is dead, but still in place and functional. Encrusting algae (Porolithon pachydermun) and zoanthids fill the surface area of this zone. The reef crest and reef fiat contains large amounts of reef debris. The intense erosional process found here produce sand for the Boca Chica beach. In deeper waters, at about 30 m, plate forms of Agaricia spp., the M. annularis complex, C. natans, M. meandrites, M. angulosa and Mycetophyllia spp. accompany a
The coral reefs of the DominicanRepublic
101
massive growth of Halimeda sp. and Amphiroa sp. At 20 m, Erythopodium spp. appear with the encrusting sponges C. langae and Ectyoplsia ferox. Some large Xetospongia muta are also found. Corals are not the dominant features in this seascape, but there are well-developed colonies of A. cervicornis, D. cylindrus, P. astreoides, P. furcata, M. alcicornis and Agaricia spp. 2.2.12. Parque Nacional Submarino La Caleta, Santo Domingo. This is an 18 krn2 marine protected area located on the leeward side of the Caucedo Peninsula. Rocky shores surround the area. Nearshore, there is a sandy base with patchy corals. This continues into seagrasses, and at 10 m spurs and grooves appear. At greater depths (18 m) there is an abrupt drop to 25 - 40 rn, where there are low and medium relief spurs and grooves. Here, there are hard base reef-fiat carbonate platforms, reef walls, and sunken structures deployed there to serve as artificial reefs and fish aggregation devices. The main benthic organisms recorded for this area are: 32 species of coral, (A. agaricites, D.
strigosa, L. cucullata, M. decactis, M. meandrites, M. alcicornis, M. cavernosa, P. astreoides, S. siderea and Stylaster roseus, amongst others), 20 species of octocorals (G. flabellum, is the most common, followed by E. caribaeorum and P. bipinnata, together with P. homomalla and P. americana), 50 species of sponges (Amphimedon compressa, Aplysina cauliformis, Ircinia strobilina and Pseudoceratina crassa are found at almost all depths, followed by Agelas conifer, Callyospongia vaginalis, Ectyoplasia ferox, Iotrochota birotulata and Xetospongia muta), and 45 species of algae. The benthic coverage is as follows: algae 41%, sponges 13%, octocorals 13%, and corals 28% (Geraldes 1994a; Geraldes and Vega 1995a). 2.2.13. Najayo-Palenque Reef. On the southem coast, a large open bay is found between Punta Caucedo to the East (La Caleta) and Punta Najayo to the West, where the NajayoPalenque Reef is located. The site sits after the Ozama - Haina- Nigua river complex. These three rivers discharge in Santo Domingo's (Capital City) coastline, which is composed mostly of reef terraces until reaching the Nigua River. These rivers do not form a tree estuary, due to the great ocean depth found nearshore (>300 m). The water discharged is polluted, and enriched with sediments from the cities of Santo Domingo and San Crist6bal and the surrounding sugar cane and farm areas. The coastal currents flow westward towards the Najayo-Palenque Reef. These reefs are typical of high energy conditions, with low profiles dominated by a hard, current swept base, and sparse octocoral growth. It is assumed that the substrate is non-uniform due to tectonics or erosional processes caused by catastrophic events that have altered it, leaving boulders and uplifted tile-like structures where corals attach in the leeward domain. 2.2.14. El Derrumbao Wall, Las Salinas, Bani. From Najayo and Palenque westward, the climate changes to very dry. The Derrumbao Wall is located near a coastal desert with large sand dunes. The shore is composed of dark sand and coarse gravel of terrigenous origin. Through bio-cementation processes, sandstone is found close to the shore, serving as appropriate substrata for corals and other life forms to establish themselves. This shallow, seagrass-dominated feature terminates some 30 m from shore, where there is an abrupt drop towards a submarine fault (> 1,500 rn deep). Cemented sand rectangular blocks, measuring 3-5 m by 2 m, form the wall. Madracis sp., P. porites, P.
102
F.X. Geraldes I
70049 '
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i 1.5km
Fig. 9. Puerto Viejo, Azua_
the M. annularis complex, M. cavernosa, C. natans and Siderastrea siderea are common species found in the first 10 m. Then at this depth, an overhang occurs and cryptic species abound. Several large sponges, such as Cliona sp., E. ferox and X. muta can also be found. After the overhang, the wall turns into sand, with a large angle of slope, which is usually covered with f'me sediments that are easily stirred by divers. 2.2.15. Puerto Viejo, Azua, Bahia de Oeoa (Fig. 9). This reef site lies in a dry region on the southwestern coast. The reef forms a small barrier with an 8 km 2 lagoon. Due to its sheltering features, it has been used as a natural port since the 1500s. In 1957, a modem port was built which altered the reef. At the breaker zone there are several keys formed by reef deposits that are now colonized by mangroves. Near the shore tidal fiats with Halodule and Syringodium are common. Corals are found in the sand depressions or erosional pits, the most common being M. aerolata, P. porites, P. divaricata, S. radians and D. strigosa. The lagoon has a variable depth of 0.5 to 14 m, and T. testudinum is dominant. Corals grow in patches, and Diploria spp. and Siderastrea spp. dominate. Others, such as A. cervicornis, M. complanata, P. astreoides, A. agaricites, P. furcata and the rare
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Acropora prolifera are sparsely found. Strong tidal currents flow and influence the circulation of this lagoon, enhancing coral growth especially in the back reef, where A. cervicornis, P. astreoides, P. divaricata, D. strigosa, S. siderea, M. areolata, S. radians and M. alcicornis are the common species. The reef fiat is dominated by zoanthids growing on top of coral debris. Corals like P. astreoides, D. clivosa and very large colonies of Acropora palmata dominate in the breaker zone. In deeper waters (10 m), a hard basal carbonate platform is found, with sand pockets. Large tree-like colonies of A. palmata, as well as large boulders of C. natans, are found here creating intricate structures where other reef creatures seek refuge and nourishment. These coral patches tend to grow closer together in deeper water. At 13 m deep, they usually merge to form low relief spurs and grooves. 2.2.16. Barahona reef. The reef at Barahona is a fringing reef that has not been thoroughly studied. It consists of a well developed spur and groove system, breaker zone, reef fiat, and islets that surround a lagoon, which has been converted into a port. The reef barrier was cut, dredged, and enlarged to allow for port transit and ship movement. On the protected coast lies the town of Barahona. Nearby and upstream there is the Yaque del Sur River estuary with considerable sediment loads that sometimes reach this reef and affect it. 2.2.17. Parque Nacional Jaragua. Parque Nacional Jaragua is located at the southwestern end of the Dominican Republic. This is a dry region, where cacti and desert-like vegetation dominate. No rivers or surface runoff is found in these Pleistocene carbonate reef terraces. On its windward side strong seas, medium-sized cliffs, and high energy pebble and pocket beaches with fringing reefs are found. On its leeward coast, protected by high cliffs, sheltered, long, white sandy beaches are common, with consolidated hard carbonate offshore, where coral cover and density is high. There is not a well developed fringing or bank reef in most of the zone, except near Cabo Rojo (Weil 1997). At the southern tip Beata Island is found, and further out is Alto Velo Island. Moving towards the southwest, at the edge of the continental shelf, there is an elevation of the seafloor called Los Frailes Shoals. Other descriptive studies of this area are included in Borrell (1981) and Vega (1981). Beata Island reefs. This island is formed by reef terraces and has a low relief. On its windward side at its northeastern end, coral reefs are located offshore forming bank reefs (Weil 1997). On the leeward side there are seagrass beds, followed by a hard carbonate base with sparse coral, sponge, and octocoral growth, and with a high cover of algae. The most abundant corals are Porites, Undaria (Agaricia), Diploria, S. siderea and M. cavernosa. Alto Velo Island. This small island, located 20 km. away from the mainland, is an oceanic island of volcanic origin. Its slopes are bare and drop steeply into the ocean depths. In the shallows on the leeward side (west), one can find large boulders and caves/crevices formed by land slides. Here, cryptic reef creatures, mostly of crustose and flattened forms, are sparsely located. Los Frailes Shoals. Located 12 miles southwest of Cabo Rojo, Los Frailes shoals is a seafloor intrusive elevation, that rises from the seafloor, and surfaces in a similar manner to Alto Velo Island. These rock outcrops receive clean oceanic waters, which allow the establishment of a diverse community. There are boulders and submerged walls 10 m
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high, covered by Tubastrea aurea. Large Montastraea, Diploria and Colpophyllia colonies, as well as sponges, are present on the other side (Weil 1997). Cabo Falso to Bahia de Las Aguilas. In the Beata Canal, where there is protection from the incoming ocean lies a platform that reaches a depth of 18 m. It is covered with algae, hydrozoans, gorgonians and Cliona, as well as some A. palmata colonies (Weil 1997). The deeper areas have a highly diverse community associated with large boulders, where octocorals, zoanthids, and sponges predominate. At Lanza Zo to the north, in 15-25 m of water, there is a bank reef located some 800 m offshore which runs parallel to the shoreline. Here algae such as Dyctiota, Lobophora, and Halimeda are abundant. Sponge diversity and abundance is also significant, but corals are sparse. At Bahia de Las Aguilas the reef has a higher coral diversity and coverage, with Montastraea, Porites, Undaria (Agaricia) and Agaricia being dominant. Rare species such as Mycethophyllia reesi are uncharacteristically abundant (Weil 1997). Cabo Rojo. This reef is located a few kilometres northwest of Cabo Rojo, where the continental shelf forms a submarine canyon. The reef begins at 18 m on a wide platform covered by seagrasses. The reef then drops to 45 m, to a sandy base. There is a large degree of cover by the plate-like Montastraea, Agaricia, and Undaria, and large Colpophyllia colonies can be found. The blue-green algae Schyzothrix is also abundant between 13 and 18 m. Octocorals are scarce and scattered along the slopes. Sponges are abundant and diverse. Millepora is common in the shallow areas, where A. cervicornis patches are common. Signs of white band disease are present. M. franksi and A. lamarcki are the dominant coral species in the deep area of the reef (Weft 1997). 3. NATURAL DISTURBANCES 3.1. Sedimentation The Dominican Republic occupies a fairly large land mass. There are large rivers and streams washing extensive watersheds, and there are usually no coral formations directly downstream from them. The Caribbean coast is basically composed of carbonate reef terraces, allowing shallow fringing reefs to develop. On the northeastern region there are mountainous terraines close to the shore, associated with increased rainfall, which in turn cause short torrential streams that drain into the adjacent sea, loading it with sediments, and limiting reef growth. This occurs for approximately one third of the coastline. Along the rest of the coast, reef growth is of the fringing or barrier type. These usually occur in association with the dry regions of the country, where waters are clear. Nevertheless, even in these dry regions there are three places that have natural sediment inputs and restrict reef settlement: Punta Martin Garcia in Barahona, Punta Salinas in Peravia, and El Morro in Montecristi. 3.2. Coral bleaching Coral bleaching events have been associated with abnormal water temperatures and other undetermined stresses. There has not been a country-wide study of bleaching for the Dominican Republic. There are, however, reports of its occurrence at most reefs, the most evident being the reef sites near major urban settlements which are more heavily visited or overfished, such as Puerto Plata, Sos~a, Las Terrenas, Macao, B~ivaro, Guayacanes, Boca Chica, and La Caleta.
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3.3. Mass mortalities and other stresses The mass mortalities of A. palmata and D. antillarum have triggered major ecological changes in the coral reef ecosystem. These no longer resembles the classical description of coral reefs by Goreau and Goreau (1973). The breaker and lower palmata zones have been specially affected by the mortality of this coral. This causes, the urchin to die off, and this in association with overfishing and increased nutrient pollution has enabled algae to flourish and cover the eroding reef environment, which perpetuates reef erosion. In some reefs Millepora sp. and Zoanthus sp. are seen at the breaker zone, substituting for A cropora. 3.4. Hurricanes and tropical storms Hurricanes and tropical storms are common in Hispaniola. There have been more than 200 of these events recorded since the fifteenth century. These phenomena are more common for the Caribbean southern coast, rarely affecting the Atlantic coast. Nevertheless, all major reef sites have been affected by at least one of these events. The major direct effect is the initial impact and there is massive destruction of the coral stands. Large portions of living material are usually transferred and deposited on top of the reefs. This debris accumulation later turns into suitable substrate for furore colonization of corals, and may form islets on the reef fiat, to be colonized by a succession of mangroves and other coastal vegetation. In the deeper portions the debris is accumulated in two regions of the reef: at the deepest portion of the spur and groove in the sand channel, and at the end and deep portion of the buttress zone. This debris is either consolidated, serving as base for future growth, or bioeroded and turned into sand and pebbles. Other effects are those caused by the increment in water turbidity and reduced salinity, due to the large volume of downpour rains and excessive runoff due to deforestation on the nearby watersheds. This increases river flooding as well as sediment loads, which reach distant reef sites. In these locations, it is common to f'md stresses in corals, where bleaching and other stress-related symptoms are obvious amongst the reef inhabitants. These reefs usually remain in a delicate condition. For their mitigation, there is a need for ample reforestation programs of the watersheds, as well as an integrated approach to coastal zone management. Reefs that are in this situation and described in this work are: Juan Dolio-Guayacanes, Boca Chica, E1 Portillo, Playa Dorada, and Puerto Viejo reefs.
4. ANTHROPOGENIC IMPACTS Destruction and degradation of coral reefs now appears near most human settlements, due to the increase in negative environmental impacts to the aquatic and coastal environments. There is also clear evidence that some of these impacts are caused by remote human activities such as agriculture, animal husbandry, and industrial development. In general, land-based fertilizers, pesticides, domestic and industrial trash, and wastes from the mining industries are all reaching the river mouths, estuaries, and adjacent marine ecosystems like coral reefs (Puerto Plata, Sosua, Las Terrenas, Miches, Juan Dolio-Guayacanes, Boca Chica, La Caleta, Palenque) via runoff. Coastal development has led to the destruction of wetlands and mangroves for landfills, coastal construction, and dredging. Ports and shipping activities, recreational boats and marinas, some localized and rare reef-based coral mining, can also be found in Montecristi, Luper6n, Puerto Plata, Sosua,
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Las Terrenas, Macao, B~ivaro, Punta Cana, Bayahfbe, Guayacanes-Juan Dolio, Boca Chica, La Caleta, Palenque, and Barahona. Overfishing is also heavily affecting Dominican reefs. Overharvesting of commercially important species such as Strombus gigas, S. pugilis, Panulirus argus, and fish of the Serranidae, Lutjanidae, and Scaridae families, is a problem. Lately, there has been an increase in the harvesting of other reef creatures such as black corals, hermit crabs, and omarnental reef fishes, starfish, sea urchins, and live-rocks for the souvenir industry. Most of these activities are prohibited or regulated by Dominican laws, but there is a lack of political and financial support to achieve the proper enforcement and personnel training. In order to minimize the negative effects on reefs, non-government organizations have contributed with conservation actions. 5. CONSERVATION AND MANAGEMENT Actions in this regard have been implemented since 1962, due to efforts of the Centro de Investigaciones de Biologia Marina of the Universidad Aut6noma de Santo Domingo, which is the pioneer institution on marine and coastal issues and studies in the country. Later, in 1984, the Fundaci6n Dominicana Pro-Investigaci6n y Conservaci6n de los Recursos Marinos (MAMMA), promoted conservation actions on behalf of coastal and marine resources, especially issues regarding coral reefs and fisheries. All these activities motivated the Government to decree the presidential act (No. 112/96) that specifically protects coral reefs in the Dominican Republic. The Governmental bodies in charge of protecting this natural resource are: the Dominican Navy and its Coast Guard unit, the Subsecretaria de Recursos Naturales of the Ministry of Agriculture, and the Instituto Nacional de Protecci6n Ambiental (INPRA). As part of the country's conservation efforts, there exist on its coasts three relatively large representative coastal-marine protected areas, with big tracks of coral reefs, in good natural conditions, however they are under fishing pressure. These parks are: Montecristi in the North shore, del Este in the Eastern portion, and Jaragua in the South West; all shelter important biodiversity resources, and create nurseries for economically species of interest as well as unique tropical marine and coastal habitats and representative ecosystems. ACKNOWLEDGMENTS I am particularly grateful to my wife and colleague M6nica B. Vega for her help in review and editing of this manuscript, as for her companionship on field expeditions. I would also like to thank Enrique Pugibet, Rub6n Torres, Yira Rodrfguez, Kathleen Sullivan, John Tschirky, Mark Chiappone, as well as the staff of CIBIMA and Fundaci6n MAMMA, Inc. for their support.
REFERENCES Bamwell, F.H. 1983. Impacto del Hurac~ David (1979) sobre los corales de la cresta del arrecife de Boca Chica, Bahia de Andr6s, Repfiblica Dominicana. Contribuciones del CIBIMA, Santo Domingo, Dominican Republic 15: 1-10.
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Bonnelly de Calventi, I. 1974. Corales P6treos de la Rept~blica Dominicana. Estudios Biologia Pesquera. Colecci6n Ciencia y Tecnologia, UASD 1" 1-3. Borrell, P. 1981. La Isla Beata: 111-123. In: Investigaciones en las Islas Beata y Alto Velo. Museo del Hombre Dominicano y Marina de Guerra. Editora Amigo del Hogar, Repfblica Dominicana. Chardon, Carlos E. 1949. Los Naturalistas en la Am6rica Latina. Tomo I. Secretaria de Estado de Agricultura, Pecuaria y Colonizaci6n. Ciudad Trujillo, Repfblica Dominicana. 386 p. Cintr6n G., J.R. Garcia & F. Geraldes. 1994. Manual de m6todos para la caracterizaci6n y monitoreo de arrecifes de coral. World Wildlife Fund, Washington, D.C. 67 p. Col6n, C. 1492. Diario de Navegaci6n. In: Los Precursores 1: Crist6bal Col6n Diario de Navegaci6n y Otros Escritos. 1988. Biblioteca de Cl~isicos Dominicanos I. Ediciones de la Fundaci6n Corripio, Inc. Santo Domingo, Rep~blica Dominicana. 370 p. Femandez de Oviedo, G. 1950. Sumario de la Natural Historia de las Indias (1525). Edici6n Biblioteca Americana serie Cronistas de Indias. Fondo Cultura Econ6mica, Mexico D.F. 279 p. Galzin, R. & J. Renaud-Momant. 1983. Le lagon de "la Bahia de Andr6s" a Saint Domingue et son eventuel desequilibre (extraction de sediment, pollution). Contribuciones del CIBIMA 37: 1-19. Geister, J. 1980. Pleistocene reef terraces and coral environments at Santo Domingo and near Boca Chica, south coast of Dominican Republic. IX Conf. Geol. Carib. 2: 14. Geraldes, F.X. 1976. Ecologia y taxonomia de los arrecifes de coral Dominicanos 1: Costa Sur. Thesis, Departamento de Biologia, Facultad de Ciencias, Univ. Aut6noma de Santo Domingo. 124 p. Geraldes, F.X. 1978. Los arrecifes de coral de la costa sur Dominicana. In: Conservaci6n y Eeodesarrollo. Editora Alga & Omega. Santo Domingo. 125 p. Geraldes, F.X. 1980. Arrecifes f6siles de la costa sur de la Repfiblica Dominicana. IX Conf. Geol. Carib. 2: 6. Geraldes, F.X. 1982. Los efectos del Hurac~n David y la Tormenta Federico en el arrecife de coral de Boca Chica. Contribuciones del CIBIMA 27: 1-8. Geraldes, F.X. (Ed.). 1994a. Inventario y elaboraci6n del plan de manejo del Parque Nacional Submarino La Caleta. Primer informe parcial. Fundaci6n Dominicana ProInvestigaci6n y Conservaci6n de los Recursos Marinos, Inc. (MAMMA). Documento de proyecto. PRONATURA/FMAN/PNUD. 150 p. Geraldes, F.X. 1994b. Iniciativa para la conservaci6n de los arrecifes coralinos del Caribe. Informe Final CIBIMA/WWF. 150 p. Geraldes, F.X. 1996a. Los ecosistemas costeros marinos del litoral de la Provincia de Montecristi, lnforme Segundo Semestre, Proyecto CIBIMA-UASD/GEF-PNUD/ONAPLAN. Centrode Investigaciones de Biologfa Marina, Univ. Aut6noma de Santo Domingo. Geraldes, F.X. 1996b. Bit~icora del Crucero Montecristi 96. Proyecto CIBIMAUASD/GEF-PNUD/ONAPLAN. Centro de Investigaciones de Biologfa Marina, Univ. Aut6noma de Santo Domingo. 35 p. Geraldes, F.X. 1996c. Reporte sobre los sistemas arrecifales del litoral de la provincia de Montecristi. Crucero Montecristi 96. Reporte Proyecto CIBIMA-UASD/GEFPNUD/ONAPLAN. Centro de Investigaciones de Biologfa Marina, Univ. Aut6noma de Santo Domingo. 65 p.
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Geraldes, F.X. & M. Vega. 1995a. Evaluaci6n ecol6gica, pesquera y socioecon6mica. Plan de Manejo del Parque Nacional Submarino La Caleta. Informe Final Proyecto FMAN/PNUD/PRONATURA. Fundaci6n Dominicana Pro-Investigaci6n y Conservaci6n de los Recursos Marinos (MAMMA). 152 p Geraldes F.X. & M. Vega, 1995b. Reporte sobre evaluaciones ecol6gicas en los ambientes arrecifales y zona costero-marina de Las Terrenas, E1 Portillo, Puerto Escondido, y Cabo Cabr6n, Peninsula de Saman,-i, Repfiblica Dominicana, 24-25 de septiembre del 1995. Fundaci6n Dominicana Pro-Investigaci6n y Conservaci6n de los Recursos Marinos, Inc. 54 p. Geraldes F.X., M. Vega, V. Alvarez, E. Pugibet, L. Alm~inzar, T. Vargas, H. Ramirez, C. Mateo, Y. Rodriguez, R. Torres, A.L. Franco, V. Rivas & R. Castellanos. 1997. Reconocimiento e inventario de las principales comunidades del litoral de Montecristi. Crucero MC96. Informe de 2do. Semestre. Proyecto GEF-PNUD/ ONAPLAN, CIBIMA-UASD. 350 p. Gonz~lez Nffiez, C. 1974. Operaci6n Madre Perla (1960). Bol. Soc. Dom. Geo. 4:13-31. Goreau, T.F. 1959. The ecology of Jamaican coral reefs I: Species composition and zonation. Ecology 40: 67-90. Goreau, T.F. & N.I. Goreau. 1973. The ecology of Jamaican coral reefs II: Geomorphology, zonation and sedimentary phases. Bull. Mar. Sci. 23: 400-464. Metcalf, W.G., M.C. Stalcup & D.K. Atwood. 1977. Mona Passage drift bottle study. Bull. Mar. Sci. 27:586-591. Rathe, L. 1981. Estudio sistem~itico de las esponjas (Porifera) del litoral de la Rep~blica Dominicana. Thesis, Departamento de Biologia, Univ. Aut6noma de Santo Domingo. 123 p. Schubert C. & J. Cowart. 1980. Terrazas marinas del Pleistoceno a lo largo de la costa suroriental de la Repfblica Dominicana. Cronologia preliminar. IX Conf. Geol. Carib. 2: 8. Vaugham, T.W. 1900. The stony corals of Porto Rican waters. Bull. U.S. Fish Comm. 20:291-319. Vaugham T.W., W. Cooke, D.D. Condit, C.P. Ross, W.P. Woodring & F.C. Alkins. 1921. Geological survey of the Dominican Republic I. U.S.G.S., Gibson Brothers Press, Washington, D.C. 268 p. Vega, B. 1981. Aspectos hist6ricos de las Islas Beata y Alto Velo: 13-16. In: Investigaciones en las Islas Beata y Alto Velo. Museo del Hombre Dominicano y Marina de Guerra. Editora Amigo del Hogar, Santo Domingo, Rept~blica Dominicana. Vega, M. 1994. Evaluaci6n ecol6gica r~ipida del ~ea marina del Parque Nacional del Este, Repfblica Dominicana. Informe Final, Acuario Nacional. 100 p. Vega, M., G.A. Delgado & K.M. Sullivan. 1994. Rapid Ecological Assessment. Parque Nacional del Este, Dominican Republic. 151 p. Vega M., M. Chiappone, G. Delgado, R. Wright & K. Sullivan 1997. Evaluaci6n ecol6gica integral del Parque Nacional del Este, Rep~blica Dominicana 2: Recursos marinos. The Nature Conservancy Media Publishing, Bahamas. 93 p. Wells, J.W. 1956. Treatise on Invertebrate Paleontology F. Coelenterata. 328-444. Geol. Soc. Amer., Univ. Kansas Press. Weil, E. 1997. Coral, octocoral and sponge diversity on reefs of the Jaragua National Park, Dominican Republic. Report to Grupo Jaragua, Project Marine Biodiversity of the Dominican Republic, GEF-PNUD/ONAPLAN. 9 p.
The coral reefs of the Dominican Republic
TAXONOMIC LIST OF STONY CORALS OF THE DOMINICAN REPUBLIC Class Hydrozoa Order Athecatae Family Stylasteridae Stylaster roseus Family Milleporidae Millepora alcicornis (Linnaeus) M. complanata Lamarck M. squarrosa Lamarck Class Anthozoa Order Scleractinia Family Astrocoeniidae Stephanocoenia michelinii Milne Edwards and Haime S. intersepta Family Pocilloporidae Madracis decactis (Lyman) M. formosa Wells M. mirabilis Wells M. pharensis (Heller) M. pharensis (Heller) forma luciphilia Wells M. senaris Wells Family Acroporidae Acropora cervicornis (Lamarck) A. palmata (Lamarck) A. prolifera (Lamarck) Family Agariciidae ~ Agaricia agaricites forma agaricites (Linnaeus) forma carinata Wells forma danai Milne Edwards and Haime formapurpurea (Lesueur) A. fragilis forma fragilis Dana A. humilus Verrill A. lamarcki Milne Edwards and Haime A. grahamae Wells A. tenuifolia Dana Leptoseris cuculIata (Ellis and Solander) Family Siderastreidae Siderastrea radians (Pallas) S. siderea (Ellis and Solander) Family Poritidae Porites astreoides Lamarck P. branneri Rathbun P. porites (Pallas) P. furcata Lamarck P. divaricata Lesueur Family Faviidae Colpophyllia natans (Houttuyn) C. breviserialis C. amaranthus Diploria clivosa (Ellis and Solander) D. labyrinthiformis (Linnaeus) D. strigosa (Dana) Favia fragum (Esper) Manicina areolata forma areolata (Linnaeus)
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forma mayori Wells The Montastraea annularis complex (Ellis and Solander) M. cavernosa Linnaeus M. franksi Solenastrea bourmoni Cladocora arbuscula (Leseur) Family Rhizangiidae Astrangia solitaria (Lesueur) Phyllangia americana Milne Edwards and Haime Family Oculinidae Oculina difussa Lamarck Family Meandrinidae Dendrogyra cylindrus Ehrenberg Dichocoenia stellaris Milne Edwards and Haime D. stokesi Milne Edwards and Haime Meandrina meandrites forma meandrites (Linnaeus) M. memorialis M. braziliensis Milne Edwards and Haime Family Mussidae Isophyllastrea rigida (Dana) Isophyllia sinuosa (Ellis and Solander) Mussa angulosa (Pallas) Mycetophyllia aliciae Wells M. danaana Milne Edwards and Haime M. ferox Wells M. lamarckiana Milne Edwards and Haime M. ressi Wells Scolymia cubensis Milne Edwards and Haime S. lacera (Pallas) S. wellsi Family Caryophylliidae Eusmilia fastigiata (Pallas) Family Dendrophylliidae Tubastrea coccinea Lesson T. aura Rhyzosmilia maculata
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Puertorican reefs: research synthesis, present threats and management perspectives Jorge R. Garcia a, Jack M o r e l o c k a, R o b e r t o Castro a, Carlos G o e n a g a a and E d w i n H e r n f i n d e z - D e l g a d o b
aDepartment of Marine Sciences, University of Puerto Rico, Mayaguez, P. O. Box 908, Lajas, Puerto Rico, 00667 bBiology Department, University of Puerto Rico, Rio Piedras Campus, San Juan, Puerto Rico
ABSTRACT: This work provides a synopsis of scientific research undertaken in characterization of coral reef systems from Puerto Rico. A data set on the sessile-benthic community structure and coral taxonomy from 52 reefs surveyed with quantitative sampling protocols over a 15 year period (19841999) is here included. These data are analyzed in the context of the contrasting oceanographic conditions of the Puertorican shelf and the history of man-induced and natural environmental stressors potentially affecting the ecological condition of reefs at the sites studied. A total of 93 coral taxa, including 43 scleractinian (stony) corals, 42 octocorals (gorgonians), 4 species of black coral (antipatharians) and 4 hydrocorals have been reported from Puertorican waters. Coral reefs from La Parguera (Turrumote, Media Luna, Shelf-edge), offshore Mayaguez Bay (Tourmaline Reef), Naguabo (Algodones Reef), and La Cordillera de Fajardo (Cayo Diablo, Cayo Palominitos) showed the highest live coral cover (>30 %). These reefs lie on protected sections of the shelf, upstream from large riverine discharges and are the ones farthest from shore. The Montastrea annularis complex was the dominant coral taxa among reefs with high live coral cover. Hard-ground and rock reefs with very low coral cover are ex-posed to very strong wave action (e.g. Caja de Muertos) and/or receive heavy loads of sediments from large riverine discharges (e.g. Morrillos, Boca Vieja, Mameyal, Cerro Gordo). Montastrea cavernosa, Porites astreoides and Diploria strigosa were the most abundant corals from reefs under heavy sediment stress. Dead coral reefs (Hojitas, Guayanilla, Rio, Algarrobo) are associated with a history of combined impacts such as dredgings, ship traffic, domestic sewage and industrial (mostly organic) discharges in semi-enclosed environments (e.g. Guayanilla Bay, Ponce Bay, Mayaguez Bay). Desig-nation of coastal areas with high coral development as Natural Reserves, with prospective plans for establishment of closed fishing regulations within reserve areas stands as the main strategy for protection and management of coral reefs in Puerto Rico. At present, several monitoring programs are in place to document changes in the community structure of coral reefs in Puerto Rico.
1. I N T R O D U C T I O N
1.1. Research background R e s e a r c h on the P u e r t o r i c a n coral reefs started in the 1 9 6 0 ' s and has p r o c e e d e d at a slow p a c e until present. Initial qualitative surveys by A l m y and C arri 6n T o r r e s (1963), Latin American Coral Reefs, Edited by Jorge Cortrs 9 2003 Elsevier Science B.V. All rights reserved.
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Glylm et aL (1965) and Glynn (1968) provided taxonomic accounts of corals and guidelines for their identification, which stimulated research on aspects of their ecology during the 1970's. The vertical zonation of coral species on reefs from the north and south coasts were reported by Pressick (1970) and Szmant-Froelich (1973), respectively. In his analysis of Western Atlantic coral reefs, Glynn (1973a) noted the low diversity of scleractinian corals in Puerto Rico relative to other regions in the Caribbean. One of these descriptions included the reef flat biotope from Laurel Reef in La Parguera (Glynn 1973b). Loya (1976) performed studies relating the community structure of hermatypic corals to sedimentation and established the first quantitative assessments of coral cover and diversity patterns from Puertorican reefs. The relationship between live coral cover and sedimentation stress was further examined by Rogers (1983). Her work also included the first measurements of community metabolism for Puerto Rican coral reefs (1979). Acevedo and Morelock (1988) expanded knowledge on coral degradation and sedimentation stress in their studies of coral reefs from the south and southwest coasts, providing at the same time fia'ther characterizations of community structure for several reefs in the region. The first geographical inventory of Puertorican reefs was prepared by Goenaga and Cintr6n (1979). This work, along with subsequent qualitative surveys of reef geomorphology and commtmity structure (Cintr6n et al. 1975; Colin 1978; Canals and Ferrer 1980; Canals et al. 1983) established criteria for designation by the government of Puerto Rico of marine areas with coral reef development as Natural Reserves. With this ini-tiative, the government of Puerto Rico recognized the exceptional ecological value of coral reef systems, but provided feeble mechanisms for their protection and management. Intensified utilization of the coastal zone stimulated problem oriented research involving coral reef communities, which allowed further quantitative characterizations during the late 1970's, 80's and 90's. Rogers et al. (1978) evaluated the impacts of military operations on the coral reefs of Vieques and Culebra, on the northeast coast. Rogers (1985) associated the degradation of western Atlantic and Caribbean coral reefs to the decline in reef fisheries. Subsequent characterizations of coral reef communities in shallow reefs around Puerto Rico have included fish assemblages as an integral part of the reef community (Garcia et al. 1985; Castro and Garcia 1996, 1997; Hem~ndezDelgado 1992; Webb et al. 1998). Positive correlations between fish species diversity and live coral cover were reported from belt-transect surveys in shallow reefs around Puerto Rico (Garcia and Castro 1999). Unfortunately, these studies have been unable to evaluate shifts in fish community structure over time for any particular reef. A preliminary assessment of the decline in coral reef associated fisheries was prepared by Appeldora et al. (1992). During the last decade, coral reef research in Puerto Rico has largely focused on community characterization and monitoring programs, marine reserve feasibility studies, environmental impact assessments, coral diseases and mitigation programs. For example, CARICOMP (Garcia et al. 1988) is a Caribbean-wide coral reef monitoring program set up to examine changes in the ecological health of coral reefs and associated ecosystems (e.g. fringing mangroves, seagrass beds) across a network of laboratories and marine reserves (including the Puertorican site of La Parguera). As part of the U. S. Coral Reef Initiative Program for P. R. (from NOAA) a series of coral reefs in Natural Reserves of Puerto Rico have been recently selected as priority sites for establishment of characterrization and monitoring programs. Baseline characterizations of coral reef communities
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based on quantitative sampling protocols are available for Jobos Bay, La Parguera, Guanica, La Cordillera de Fajardo, E1 Tourmaline Reef, and Caja de Muertos (Garcia & Castro 1997; Garcia et al. 1988, 1999). Other initiatives have included characterization efforts in support of the coral reefs occurring within the Rio Espiritu Santo Natural Reserve (Hermindez-Delgado 1995), Isla de Mona Natural Reserve (Canals et al. 1983; Hemfindez-Delgado 1994a) and La Cordillera de Fajardo Natural Reserve (Hem~indezDelgado 1994b). At least two major efforts were launched during the 1990's to protect coral reef associated fishery resources and the ecological integrity of important coral reef systems. A feasibility study for establishment of a Marine Fishery Reserve in La Parguera, southwestern Puerto Rico (Garcia 1996) included a baseline characterization of sessile benthic and fish communities of the Turrumote, Media Luna and San Cristobal Reefs. More recently, on the northeastern side of the island, Hemfindez-Delgado et al. (1988) described the marine biological resources associated with the coral reef at the Isla de Culebra Fishery Reserve. Additional quantitative and qualitative characterizations of reef communities have been included as part of environmental impact studies of submarine outfall discharges (Regional Wastewater Treatment Plants of the P. R. Aqueducts and Sewers Authorithy) at 11 sites around the island of Puerto Rico (Garcia et al. 1985). Other characterizations of coral reef communities were performed in relation to operations of thermoelectric power plants in Jobos Bay (Szmant-Froelich 1973), San Juan Bay (Garcia and Castro 1995) and Guayanilla-EcoElectrica (Castro and Garcia 1996, 1998). Mass mortalities of corals and related reef organisms have also received research attention in Puerto Rico. Vicente and Goenaga (1984) reported on the mass mortality of the black sea-urchin, D i a d e m a antillarum, around the coastline of Puerto Rico, and provided a general description of dying specimens from direct observations in the field. A series of reports of massive coral bleaching from the waters of Puerto Rico were produced in the late 1980's (Bunkley-WiUiams and Williams 1987; Goenaga et al. 1989; Williams and Bunkley-Williams 1989, 1990; Bunkley-Williams et al. 1991). These studies evidenced permanent damage by the bleaching phenomena on reef corals and associated the periodic bleaching events to elevated sea surface temperatures. 1.2. Oceanographic features of the Puertorican shelf Corals grow throughout most of the insular shelf of Puerto Rico, yet the physical, climatic and oceanographic conditions that affect coral reef development vary markedly among insular shelf segments. The north and northwest coasts are narrow (< 3 km) and shallow communities are subjected to high wave action during winter, as cold fronts from the North Atlantic reach the Caribbean Antilles. The north and west coasts also receive substantial sediment and nutrient loading from the discharge of some of the largest rivers in Puerto Rico. The north coast features abundant formation of sand dunes, some of which are now submerged eolianites. Others fringe the coastline, forming rocky beaches with rich intertidal communities (e.g. Isabela, Arecibo, Loiza). The northeast coast has a wider shelf, partially protected from wave action by a chain of small emergent rock reefs aligned east- west between the main island and the Island of Culebra. The northeast coast is upstream from the discharge of mayor rivers resulting in more appropriate conditions for
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coral reef development. The east coast is characterized by extensive unconsolidated sand deposits which limit coral reef development, but scattered rock formations within this shelf section have been colonized by corals. Isla de Culebra and Isla de Vieques lie at the eastern boundary of the Puertorican shelf. The south coast is a coastline of lower wave energy and the insular shelf is generally wider than at the north coast. Rivers with smaller drainage basins discharge on the southeast coast and only small intermittent creeks discharge on the southwest coast, which has been classified as a semi-arid forest. The south coast also features a series of embayments and submarine canyons (Acevedo and Morelock 1988). Small mangrove islets fringe the south coast and many of these provide hard substrate for coral development. The shelfedge drops off at about 20 meters with an abrupt, steep (almost vertical) slope. At the top of the shelf-edge lies a submerged coral reef formation (Morelock et al. 1977) which gives protection to other reefs, seagrass and mangrove systems of the inner shelf. The southwest coast is relatively wide and dry, with many emergent and submerged coral reefs that provide adequate conditions for development of seagrass beds and fringing mangroves. Toward the central west coast lies Mayaguez Bay, one of the largest estuarine systems of the island and partially influenced by wave action from North Atlantic swells during winter. Mona and Desecheo are oceanic islands between Puerto Rico and the Dominican Republic which belong to Puerto Rico. The northern sections of the islands are strongly affected by wave action and their insular platforms are virtually reduced to steep walls, whereas the southern coastal sections of these islands are more protected and have wider platforms where coral reefs develop. There are no rivers in either of the islands, which are surrounded by waters of exceptional transparency (Cintr6n et al. 1975). 2. TYPES OF REEFS AND GEOGRAPHICAL DISTRIBUTION Modem shelf-edge reefs formed in Puerto Rico some 8,000 years ago. Inner reefs, formed on top of submerged banks and sandy bottoms of the flooded shelf are believed to be about 5,000 years old (Adey 1978). The rise in sea level associated with the last Pleistocene glaciation (Wisconsin) flooded the lower limestone ridges of the shelf, providing appropriate sites for coral growth and subsequent reef development (Goenaga and Cintr6n 1979). Cross-shelf seismic profiles provided by Morelock et al. (1977) support the theory of Kaye (1959), which state that reefs on the southwest coast developed on drowned calcarenite cuestas formed as eolianite structures parallel to the coastline during the Wisconsin glacial period. Proper substrate, depth, and water transparency conditions in the southwest coast allowed for extensive development of coral reefs during the mid-Holocene period (Goenaga and Cintr6n 1979). At least three mayor types of reefs are recognized within the Puertorican shelf, although different coral reef formations have been reported (Goenaga and Cintr6n 1979; Hem~indez-Delgado 1992; Morelock et al. 1977). The distribution of the mayor reef types as updated from different sources is shown in Figure 1. 2.1. Rock reefs
Rock reefs are submerged hard substrate features of moderate to high topographic relief with low to very low coral cover, mostly colonized by turf algae and other encrusting biota. Coral colonies are abundant in some cases (e.g. Diploria spp., Porites astreoides,
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Acropora palmata, Dendrogyra cylindrus) but grow mostly as encrusting forms, providing minimal topographic relief. These types of reefs fringe the west and northwest coastlines of Rincon, Aguada, Aguadilla, Isabela and Quebradillas. Also lie between Dorado and San Juan on the north coast, to the northeast off Fajardo forming a chain of reefs between Fajardo and Isla de Culebra, and on the East Coast off Yabucoa and Humacao (Fig. 1). These are coastlines subjected to high wave energy, abrasion and sedimentation stress. Rock reefs are important habitats for fishes and macroinvertebrates since they are usually the only available structure providing underwater topographic relief in these areas. Some have developed atop of submerged rocky headlands and are characterized by the development of coralline communities adapted for growth under severe wave action and strong currents. Examples of these include the granodiorite rock reefs located between Humacao and Yabucoa, off the southeast coast. A second type of "rock reef' is formed atop of basaltic extrusive rocks. Most of these are fairly shallow (1-6 m), not extending more than 10-50 m horizontally and showing moderate to steep irregular slopes. Examples include the reefs of Cabezas de San Juan at Fajardo and Cabeza de Perro Island at Ceiba. There are deeper basaltic rock reefs, such as the submerged out-crops of the Culebra Island archipelago, which forms an extensive and complex system of slabs, boulders, overhangs, crevices, cracks and channels. These structures may support deeper reef coral fauna (e.g. red corals, Icilligorgia schrammi, and black coral, Anthipathes spp.) in waters as shallow as 10-12 m (Hem~indez-Delgado pers. obs.). In other cases, rocky bottoms form long and narrow ridges parallel to the shelf-edge, arising from depths of 22 to 40 m which support some coral growth, but these systems have not been studied yet. 2.2. Hard Ground Reefs Hard ground reefs are mostly flat, eolianite platforms ranging in depth from 5 to 30 meters largely covered by turf algae, encmsting sponges and scattered patches of stony corals. Coral colonies are typically encmsting forms, perhaps an adaptation to the extremely high wave energy that prevails seasonally on the north coast. Many of the encmsting coral colonies grow over vertical walls in crevices among the hard ground. The barrel sponge, Xestospongia muta, is usually abundant in hard ground reefs, where it represents one of the main features contributing topographic relief. Low-relief sand channels aligned perpendicular to the coast cut through the hard ground platform in many areas providing topographic discontinuities. The sand is generally coarse and mostly devoid of biota, evidencing short deposition times and highly dynamic movements across the shelf due to the high wave action. These systems are found off the central north (off Arecibo) and northeast coastlines. 2.3. Coral Reefs Coral reefs are mostly found as fringing, patch, bank and shelf-edge formations in Puerto Rico. Fringing coral reefs are by far the most common. These are located throughout most of the northeast, east and southem coastlines associated with erosional "rocky" features of the shelf. Coral is not the main component of the basic reef structure, but its development has significantly contributed to its topographic relief, influencing the sedimentology of adjacent areas and providing habitat for a taxonomically diverse biological assemblage that is consistent with a coral reef community. Examples of these flinging
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reef types include the formations along the leeward side of the Cordillera de Fajardo reefs. One of the best developed flinging reefs along that chain is Cayo Diablo, where a dense growth of coral is present, including very large colonies of massive and branching coral growth types. These reefs show a variable spur-and-groove growth pattern which is probably most evident at the reef off the southeast section of Isla Palominitos, where the distance between the top of the "spurs" and the bottom of sand channels at the "groove" can exceed 6-7 m. Examples of fringing reefs in the west coast include those at Mayaguez Bay (Manchas Interiores, Manchas Grandes, Rodriguez and E1 Negro Reefs) and Cabo Rojo (Isla Ratones, E1 Ron, Boquer6n and other smaller ones). On the south coast, coral reefs fringe many small islands or keys, such as those of La Parguera, Gufinica, Guayanilla, Ponce, Guayama and Salinas, or may be found as fairly extensive coral formations associated with the shoreline at the mouths of coastal embayments (Gu~nica, Guayanilla, Pefiuelas). In some instances, coral growth has been primaryly responsible for the formation of emergent island reefs, or keys, such as the reefs off La Parguera. In these keys, well developed coral formations typically fringe the windward (forereef) section of the islet and a reef flat colonizedby a Porites porites biotope is generally found with intermixed turtle seagrass (Thalassia testudinum) and scattered coral colonies of small size and low relief (Glynn 1973). Development of the reef fiat leads to establishment of red mangrove growing towards the water, with its aquatic root system providing habitat for a diverse assemblage of juvenile reef fishes and invertebrates. The reef grows continuously as wave action breakes up coral colonies and fragments and deposits them on the emergent section of the reef. These keys grow notoriously during hurricanes, as abundant coral fragments are detached from the substrate and deposited on land. Fringing reefs are also found off the northeast coast at Rio Grande, Luquillo, Fajardo, Culebra and Vieques. Many of these systems resemble barrier reefs, but according to the strict definition of barrier reefs (emergent reefs separated from the shoreline by a wide and deep lagoon), these are not barrier reefs because only shallow (< 20 m depth) lagoons separate these reefs from the shoreline (Goenaga and Cintr6n 1979). Northern fringing reefs are characterized by the presence of shallow (0.5-3.0 m depth) back-reef communities dominated by Porites porites biotopes and scattered colonies of different species. Shelf-edge reefs are the best developed (but least studied) coral reef ecosystems in Puerto Rico. An extensive reef formation is found at the shelf-edge off the south coast, from Guayanilla to Cabo Rojo. This reef displays the typical "spur-and-groove" growth pattern with sand channels cutting through the shelf perpendicular to the coastline. Off La Par-guera, the reef starts at a depth of about 18 m and continues down the shelf slope to depths of at least 35 m. Optimal development is found just at the shelf-break, at a depth of 20 m. Another less extensive system, but very well developed is the shelf-edge reef at the northern Tourmaline Reef off Bahia Mayaguez. This reef begins at a depth of about 10 m, increasing the height of its "spurs" towards the shelf-edge. Both of these shelf-edge reefs grow in waters of moderate to high transparency. Perhaps the best developed reef within Puerto Rican waters is the shelf-edge reef found off the southwestem section of Isla de Mona. Although limited quantitative data is available to characterize this reef in terms of its live coral cover (Cintr6n et al. 1975; Canals et al. 1983), it is evident that extensive sections surpass 60% of live coral cover. The waters that surround this oceanic reef receive minimal terrigenous inputs.
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3. REEF COMMUNITY STRUCTURE, CORAL TAXONOMY AND DISTRIBUTION Puertorican coral reefs were initially described in terms of their taxonomic composition by Almy and Carfi6n Torres (1963). This initial survey identified a total of 35 species of scleractinian corals from La Parguera, southwest coast of Puerto Rico. Later surveys have been reported by Mckenzie and Benton (1972), Rogers et al. (1978), HemandezDelgado (1992, 1994a, b), Hemandez-Delgado and Alicea-Rodriguez (1993a, b) and Hemandez-Delgado et al. (1996a, b). A compendium of coral taxa from Puertorican waters was prepared from different sources (Mckenzie and Benton 1972; Goenaga 1977; 1985a, b; Goenaga and Cintr6n 1979; Goenaga et al. 1989). Table 1 presents a taxonomic listing of 93 species of coral taxa, including octocorals, black corals and hydrocorals from Puertorican reefs. Quantitative assessments of sessile-benthic reef communities were performed between 1985 and 1999 on 54 reefs around the island of Puerto Rico. Characterizations were performed using various techniques rendering information of the percent cover by reef substrate categories. These included continuous measurements along 10 m linear transects (Porter 1972; Loya 1976), phototransects, and 1.0 m z standard quadrat techniques. Data on reef community structure and coral taxonomic composition has been separated into three depth strata (1 - 5 m; 6 - 12 m; 15 -25 m) representing different reef types and physiographic zones within a given reef. Only live coral cover and taxonomic composition is available for the deeper reefs studied (15 - 20 m). Percent cover data are means from replicate line transects or quadrat surveys (n = 4 or 5) on each reef. Percent cover by sessile-benthic substrate categories at shallow reefs (1 - 5 m) are presented in Figure 2. Algae was the dominant substrate type in terms of percent cover in seven out of the nine reefs surveyed, ranging in cover between a minimum of 31.8% at Algodones Reef in Naguabo, and a maximum of 82.1% at Pta. Bandera Reef in Luquillo. The mean cover of algae on shallow reefs was 65%. Live coral at shallow reefs varied between a maximum of 48.9% at Algodones Reef and a mini'mum of 3.7% at Pta. Bandera Reef (Fig. 2). Mean live coral cover was 15.5%. Shallow reefs with live coral cover of 20% or higher were both from the southeast coast (Algodones and Pta. Fraile), whereas reefs with live coral cover below 10% were all from the northeast coast, including the island of Vieques. The taxonomic composition of stony corals at shallow reefs was characterized by a mixed assemblage of species (Fig. 3). Between four and 10 species of corals were intercepted by linear transects at each reef. The Porites astreoides, P. porites, Siderastrea radians, S. siderea assemblage represented more than 50% of the total coral cover at shallow reefs surveyed. Porites astreoides and Siderastrea radians were present at all reefs surveyed in the 1 - 5 m depth range. Other common taxa included Diploria spp. and the hydrocorals, Millepora spp. The encrusting octocoral, Erythropodium caribaeorum, was present in five out of eight reefs surveyed with maximum cover (44%) at Gallito Beach Reef in Vieques (Fig. 2). Zoanthids, particularily the encrusting, colonial form Palythoa sp., and sponges were the other main biotic components of the shallow reef benthos. Abiotic cover (sand, holes, overhangs, etc.) averaged 8% at shallow reefs. Live coral cover varied from 0.6 to 49.1% at reefs surveyed in the intermediate depth range (6-12 m). Mainland reefs from the north and northeast coastlines (Mameyal, Bajios, Boca Vieja, MorriUos, Siete Mares, Pta. Candelero) evidenced low coral cover (Fig. 4).
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TABLE 1 List of coral taxa reported from Puertorican waters. Phylum Cnidaria
M. sulphurea
Leptoseris cucullata
Class Hydrozoa
M. flavida
Siderastrea siderea
Order Milleporina
Plexaura flexuosa
S. radians
Millepora alcicornis
P. homomalla
Porites astreoides
Millepora complanata
Pseudoplexaura porosa
P. porites
Millepora squarrosa
P. flagellosa
P. branneri
P. wagenaari
Favia fragum
P. crucis
Diploria clivosa
Plexauretla dichotoma
D. strigosa
P. nutans
D. labyrinthiformis
P. grandiflora
Manicina areolata
Gorgonia mariae
P. grisea
M. mayori
G. ventalina
P. fusifera
Colpophyllia natans
G. flabellum
Ellisella sp.
Cladocora arbuscula
Order Stylasterina
Stylaster roseus Class Anthozoa Subclass Octocorallia -.
Order Gorgonacea
Pseudopterogorgia acerosa
Subclass Hexacorallia
Montastrea cavernosa
P. americana
Order Antipatharia
M. annularis
P. bipinnata
Antipathes pennacea
M. faveolata
P. rigida
A. tanacetum
M. franksi
P. albatrossae
A. furcata
Phillangia americans
Stichopathes sp.
Astrangia solitaria
Pterogorgia anceps P. citrina
Order Alcyonacea
Meandrina meandrites
Eunicea mammosa
Erythropodium caribaeorum
Dichocoenia stokesi
E. succinea
Iciligorgia schrammi
Dendrogyra cylindricus
E. axispica
Briareum asbestinum
Mussa angulosa
Telesto riisei
Scolymia lacera
E. fusca E. laciniata E. touneforti
Order Scleractinia
S. cubensis
Stephanocoenia michelinii
Isophyllia sinuosa
E. clavigera
Madracis decactis
Isophyllastrea rigida
E. knighti
M. mirabilis
Mycetophyllia lamarckiana
E. calyculata
Acropora palmata
M. aliciae
Muricea atlantica
A. cervicornis
M. danaana
M. muricata
A. prolifera
M. ferox
M. pinnata
Agaricia agaricites
Eusmilia fastigiata
M. laxa
A. fragilis
Tubastrea aurea
M. elongata
A. tenuifolia
Oculina diffusa
Muriceopsis sp.
A. lamarcki
Las Cabezas Reef in Fajardo was the only mainland reef from the northeast coast-line with live coral cover above 10%, ranking 15 th among reefs studied at intermediate depths. Hard-ground and rock reef communities of the north coast are subject to very strong wave
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Fig. 3. Taxonomic distribution of linear cover by reef corals. Reef depth: 1-5 m.
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Fig. 4. Mean linear cover by sessile-benthic substrate categories. Reef depth 96 - 12 m.
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action and heavy loads of sediment from large river plumes. Reefs from the south coast located close to shore in Ponce Bay (e.g. Hojitas) and Guayanilla Bay (e.g. Guayanilla, Cayo Rio, Cayo Unitas) also ranked very low in terms of live coral cover. These are inshore coral reefs in advanced state of degradation. An increasing pattern of live coral cover associated with distance from shore was observed in Mayaguez Bay, where a series of dead coral reef structures, such as Algarrobo Reef and other submerg-ed patch reefs (not included in this survey) are found close to shore. Mid-shelf reefs in Mayaguez Bay varied in live coral cover between 10.6% at Media Luna and 29.3% at Las Coronas. Tourmaline Reef, in the outer shelf of Mayaguez Bay showed the highest live coral cover of all reefs studied (e.g. 49.1%). Tm'nunote and Media Luna Reefs in the south-west coast (La Parguera), and Cayo Diablo and Isla Palominitos reefs from the northeast island chain (Cordillera de Fajardo Reefs) followed Tourmaline Reef in terms of live coral cover. The reefs of the Cordillera de Fajardo are subject to very strong wave action during winter, but are located upcurrent from major rivers and do not receive large sediment loads. Well developed coral reef communities are present along the protected (leeward) sections of the chain of islets. Algae was the dominant substrate on 35 out of the 38 reefs studied at intermediate depths, ranging in cover from 28.2% in Turrumote to 98.0% at Mameyal Reef. A mixed assemblage of short filamentous algae, forming an "algal turf' was the most common type of algal cover, although substantial fleshy algae was observed at La Barca and Cayo Caribes Reefs from Jobos Bay, and at Mameyal and Cerro Gordo reefs in Dorado. Calcareous algae (mostly Halirneda sp.) was an important component of the algal cover at Cayo Rio and Guayanilla Reef. The encrusting octocoral, Erythropodium caribaeorum, was observed in variable percent linear cover at 29 reefs surveyed at intermediate depths (6 - 12 m). The highest cover was observed in the Caribes Reef at Jobos Bay (9.9%) and Pta. Maguey in Isla Culebra (8.7%). Conversely, encrusting gorgonian was absent from the high energy hard ground and rock reef communities from the mainland north coast (Fig. 4). Zoanthids (Palythoa sp.) and sponges were the other main biotic components of the reef benthos at intermediate depths. Abiotic cover (sand, holes, overhangs, etc.) ranged from 0 - 26.8%. The taxonomic composition of corals at reefs of intermediate depth (6 - 12 m) is presented in Fig. 5. The Montastrea annularis complex was the predominant scleractinian coral at 19 of the 22 reefs with highest live coral cover within this depth range. Conversely, M. annularis complex was absent in 12 out of the 13 reefs with lowest live coral cover among the reefs surveyed. Montastrea cavernosa and Porites astreoides occurred in more reefs than any other coral taxa and were the main components of the live coral assemblage of highly degraded reefs, such as Mameyal, Cayo Rio, Morrillos and Guayanilla Reef. Live coral cover at the deeper reefs studied (15 - 25 m) was highest at the shelf-edge reef off La Parguera (44%). Other reefs from the southwest coast (Penuelas, Turrumote) surveyed at depths between 15 and 25 m depths ranged in live coral cover from 16 to 27%. Manchas Interiores, Manchas Exteriores and Manchas Grandes Reefs at the middle-shelf of Mayaguez Bay presented live coral cover ranging between 0 and 7% (Fig. 6). Montastrea annularis complex, M. cavernosa, Porites atreoides and Agaricia spp. were the most common coral taxa at the deeper reefs studied.
Puertorican reefs
Fig. 5. Taxonomic distribution of linear cover by reef corals. Reef depth 96 - 12m.
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Fig. 6. Taxonomic distribution of linear cover by reef corals. Reef depth: 15-25 m.
4. E N V I R O N M E N T A L STRESSORS TO CORAL REEFS The present status of Puerto Rican coral reefs may be one of the most critical in the Caribbean (Goenaga and Boulon 1991). This is perhaps the result of our highly accelerated urban and industrial coastal development during the last four decades and (still) the lack of effective management policies to protect the ecological integrity of these resources. Superimposed on this local scenario are global and regional stressors presently affecting coral reefs. On a local scale, anthropogenic activities, such as the massive deforestation of mangroves in the north coast, dredging of our principal bays for ocean cargo, runoff from large scale agricultural developments in the coastal plain, deforestation of large fiver watersheds for urban development, raw sewage disposal into rivers and establishment of thermoelectric power plants on the north and south coasts represented an important combination of factors acting as potential stressors to coral reefs in the 1950's. One decade later, the f'irst (taxonomic) observations on coral reef systems were undertaken (Almy and Carri6n Tortes 1963). Two decades later, the first inventory of Puertorican coral reefs was performed (Goenaga and Cintr6n 1979). Thus, no one really knows what the "pristine" condition of our coral reefs ever was. In absence of baseline data on live coral cover, massive overgrowth by algae and other encrusting biota of coral skeletons has been used as an indication of "reef degradation" in Puerto Rico. Mackenzie and Benton (1972) were the first to document the massive algal cover and low live coral in reefs of the north coast. Sedimentation and high turbidity has been associated with coral reef degradation in a variety of reef systems in Puerto Rico
Puertorican reefs
125
by different authors (Kaye 1959; Garcia et al. 1985; Hem~ndez-Delgado and Alicea Rodriguez 1993a; Garcia and Castro, 1995, 1997; Hem~ndez-Delgado 1995; Castro and Garcia 1996; Hem~ndez-Delgado et al. 1996a). In their qualitative inventory of reefs, Goenaga and Cintr6n (1979) noted the high sedimentation affecting reefs of the north coast and those in the south and west coasts in bays used for ocean cargo (e.g. Guayanilla, Mayaguez). Acevedo and Morelock (1988) provided a quantitative assessment of sediment impact on south coast coral reefs by measuring reductions of live coral cover from reefs located close to sediment point sources. Combined contamination sources, perhaps with synergistic effects, have been a major threat to coral reefs in Puerto Rico. Dead coral reefs with massive colonies completely overgrown by algae and other encmsting biota are found in Ponce, Guayanilla and Mayaguez Bays. These systems share a combination of environmental stressors that probably acted together as causal factors of the irreversible damage to coral reefs in these bays. Before any large scale manipulations of drainage basins by man, coral reefs co-evolved with riverine runoff discharges into these bays. But, sediment loads probably increased dramatically when fiver drainage basins were deforested for urban development. Furthermore, these bays were dredged repeatedly in order to allow large ship traffic inside the bays. It is possible that the magnitude of sediment stress alone could have killed the reefs in these bays, but it is uncertain at this point. In addition to the stress associated with sediment abrasion and increased turbidity, primary treated domestic sewage and industrial (mostly organic) waste water from tuna factories were discharged into the inner sections of Ponce and Mayaguez Bays for many years, which promoted the process of eutrophication. It is to be inferred that the increased productivity further limited water column light penetration in these bays and perhaps favored growth of algae and other encrusting biota over corals. Other major anthropogenic activities that have been associated with reef degradation in Puerto Rico include: 1) oil spills (Cerame-Vivas 1969), 2) anchoring of large oil cargo vessels (Hem~indez-Delgado pers. obs.), 3) overfishing (Appeldom et al. 1992), 4) uncontrolled recreational activities (Hem~indez-Delgado 1992, 1994a), 5) eutrophication (Kaye 1959), 6) mechanical destruction by ship groundings (Glynn 1973b; Hem~ndez-Delgado et al. in prep), 7) thermal pollution (Hem~mdez-Delgado 1992), and 8) military bombing activities, particularly at Vieques and Culebra Islands (Rogers et al. 1978; Antonius and Weiner 1982). In the particular case of Culebra and Vieques islands, historical bombing during military training activities have caused severe destruction of coral reef fisheries and reef frameworks (Rogers et al. 1978). A total of 76% of the surface of Vieques Island has been part of a U.S. NAVY training facility since 1941. Most coral reefs located in the eastern half of the 35 km long Vieques Island are still suffering from the i n , acts of military training activities. For the last two decades, there had been no reliable monitoring records of ecological changes in Vieques easternmost coral reefs, although 8 to 50% declines in coral cover from coral reefs located within maneuver areas in Vieques have been reported (Antonius and Weiner 1982). Such decline in coral mortality has been attributed to hurricanes, concluding that the impact of bombing in the coral reef was negligible (Antonius and Weiner 1982). Unfortunately, deep reef sections that are typically unaffected by hurricanes were not included in the assessment of bombing effects. Natural factors that have been associated with coral reef degradation include: 1) hurricanes (Glynn et al. 1965), 2) coral bleaching (Williams and Bunkley-Williams 1989,
126
J.R. Garciaet al.
1990; Goenaga et al. 1989; Hemfindez-Delgado and Alicea Rodriguez 1993b), 3) coral diseases (i.e., white band disease, black band disease, white plague and seafan fungus disease (Bruckner 1999), 4) predation by territorial pomacentrid fishes, mostly Stegastes planifrons (Williams and Bunkley-Williams 1990; Hemfindez-Delgado and Alicea Rodriguez 1993a), and 5) the Caribbean-wide massive mortality of the sea-urchin Diadema antillarum (Lessions et al. 1984). The decline in abundance of large fishes along with the massive mortality of the black sea-urchin represents a major shift in the community structure of Puertorican reefs. It can be hypothesized that the reduction of grazing pressure by the black sea-urchin has promoted algal overgrowth of corals and other hard ground substrates. The absence of large fish predators includes parrotfishes, which are in~ortant herbivores in the coral reef system and carnivores, which consume small fishes. Some authors believe that the lack of large fish predators has stimulated a proliferation of small fish farmers, such as damselfishes (e.g. Stegastes planifrons) which bite and kill coral polyps to promote new growth of algae to feed their young. Likewise, the persistent and ever increasing fishing pressure over spiny lobster (Panulirus argus) has reduced substantially the abundance of this predator from shallow reefs. Consequently, there has been a proliferation of one of its favorite prey, corallivorous gastropods. The increased abundance of these gastropods is having large scale coral predation effects on Acropora palmata in La Parguera (Bruckner, pers. com.). 5. MANAGEMENT APPROACH OF CORAL REEF RESOURCES The presence of well developed coral reef communities stands as one of the main criteria in designation of coastal areas as Natural Reserves by the Department of Natural Resources of the Commonwealth of Puerto Rico. Natural Reserves which present coral reef systems include: 1) Espiritu Santo River Estuary Natural Reserve, Rio Grande 2) Cabezas de San Juan Natural Reserve, Fajardo 3) La Cordillera Natural Reserve, Fajardo 4) Mosquito Bay Natural Reserve, Vieques 5) La Parguera, Lajas, 6) Caja de Muertos, Ponce 7) Mona Island 8) Tourmaline Reef 9) JOBANERR, Salinas. All of these Natural Reserves are under the jurisdiction of the Puerto Rican government. There are also protected lands owned by the United States federal government, e.g. Culebra National Wildlife Refuge, which protects many of the coastal lands and cays in the Culebra Island archipelago. Natural Reserves bring only a minor degree of protection to coral reefs, but effective management is limited by the lack of laws regulating fishing activities and recreation. There are at present other candidate sites for the establishment of Natural Reserves and Marine Fishery Reserves. These include E1 Covento Beach (Natural Reserve), Tumamote Marine Fishery Reserve, and Culebra Island Marine Fishery Reserve. Management perspectives for protection of coral reef resources must address integral ecosystem approaches including permanent fishing closure inside critical reef sections as
Puertorican reefs
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part of the management strategy. The decline of large fishes from Puertorican reefs represents a major threat to the integrity of the reef ecosystem and has been shown to have direct consequences upon live coral cover. It may be argued that due to the offshore larval dispersion patterns of most coral reef fishes (Sale 1970; Leis and Miller 1976; Johannes 1978; Roberts 1997) closed fishing areas would not have any fishery enhancement effects on local scales. Ramirez and Garcia (in prep.) have shown that important predatory fish families, such as Lutjanids, have mostly neritic larval dispersion patterns, and as such, present good potential for self-recruitment. Many other reef fish families have shown neritic larval cycles and could benefit directly from an expected increment in parental stock biomass due to closed fishing laws in coral reefs. Also, direct escape of large fishes and lobsters from closed fishing areas could benefit adjacent areas open to reef fisheries. The abundance of large fishes increases the recreational value of coral reefs for ecotourism which, in turn, serves to support the local economy. With establishment of closed fishing areas in selected reef areas of already designated Natural Reserves, a network of protected areas could allow for an additional level of connectivity that some reef fishes and lobsters need for replenishment of their populations (Roberts 1997). The next step would be the establishment of such management policies on a larger, regional (northern Caribbean) scale. Public awareness is the driver for these initiatives to become reality. REFERENCES
Acevedo, R. & J. Morelock. 1988. Effects of terrigenous sediment influx on coral reef zonation in southwestern Puerto Rico. Proc. 6th Int. Coral Reef Symp., Australia 2: 189-194. Adey, W.H. 1978. Coral reefmorphogenesis: a multidimensional model. Science 202:831. Almy, C. Jr. & C. Carri6n Tortes. 1963. Shallow water stony corals of Puerto Rico. Carib. J. Sci. 3: 269-279. Antonius, A. & A. Weiner. 1982. Coral reefs under fire. Mar. Ecol. 3: 255-277. Appeldorn, R., J. Beets, J. Bohnsack, S. Bolden, D. Matos, S. Meyers, A. Rosario, Y. Sadovy & W. Tobias. 1992. Shallow water reef fish stock assessment for the U. S. Caribbean. NOAA Technical Memorandum NMFS-SEFSC-304:70 p. Bruckner, A.W. 1999. Black-band disease of scleractinian corals: Ocurrence, impacts and mitigation. Ph.D. dissert., Univ. Puerto Rico, Mayaguez. 87 p. Bunkley-Williams, L. & E.H. Williams. 1987. Coral reef bleaching peril reported. Oceanus 30:71. Bunkley-Williams, L., J. Morelock & E.H. Williams. 1991. Lingering effects of the 1987 mass bleaching of Puerto Rican coral reefs in mid to late 1988. J. Aquat. Animal Health 3: 242-247. Canals, M. & H. Fetter. 1980. Los arrecifes de Caja de Muertos. Dept. Natural Resources, San Juan, Puerto Rico, Report. 39 p. Canals, M., H. Fetter & H. Merced. 1983. Los arrecifes de coral de Isla de Mona. Proc. 8th Symp. Dep. Natural Resources, San Juan, Puerto Rico: 1-26. Caslro, R. & J. R. Garcia. 1996. Characterization of marine commtmities associated with reefs and seagrass/algal beds in GuayaniUa and Tallaboa Bays. Report to EcoElectrica/ Gramatges and Associates, Inc. Dept. Mar. Sci., Univ. Puerto Rico, Mayaguez. 171 p.
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Cerame-Vivas, M.J. 1969. The wreck of the Ocean Eagle. Sea Frontiers 15:224-231. Cintr6n, G., J. Thurston, J. Williams & F. MacKenzie. 1975. Caracteristicas de la plataforma insular de Isla de Mona. Proc. 2nd Symp., Dept. Nat. Resources, San Juan, Puerto Rico: 69-91. Colin, P. 1978. Caribbean Reef Invertebrates and Plants. T.F.H. Publications. 152 p. Garcia, J.R. 1996. La Parguera Marine Fishery Reserve. Sea Grant Program, UPRM, Report. Dept. Mar. Sci., Univ. Puerto Rico, Mayaguez. 111 p. Garcia, J.R. & R. Castro. 1995. Characterization of marine communities associated with reefs and seagrass/algal beds in San Juan Bay and Ensenada Boca Vieja, Palo Seco. Report to Grammatges and Associates, Inc. Garcia, J.R. & R.L. Castro. 1997. Characterization of coral reef, seagrass beds and mangrove root communities at the Jobos Bay Natural Estuarine Research Reserve JOBANERR-DRNA. Report, Dept. Mar. Sci., Univ. Puerto Rico, Mayaguez. 69 p. Garcia, J.R. & R.L. Castro. 1998. Pre-construction survey of marine communities associated with coral reefs and seagrass/algal bed habitats in Guayanilla and Tallaboa Bays, southwestern Puerto Rico. Report to Grammatges and Associates, Inc. Dept. Mar. Sci., Univ. Puerto Rico, Mayaguez. 83 p. Garcia, J.R. & R.L. Castro. 1999. Fish-coral associations in shallow reefs around Puerto Rico. Proc. Int. Conf. Scient. Aspects of Coral Reef Assessment, Monitoring and Restoration. NCRI, Fort Lauderdale, FL. Abstract: 89. Garcia, J.R., C. Goenaga, & V. Vicente. 1985. Characterization of marine communities in the vicinity of PRASA submarine outfalls. Report to Metcalf & Eddy, Inc. Dept. Mar. Sci., Univ. Puerto Rico, Mayaguez. 220 p. Garcia, J. R., C. Schmitt, C. Heberer & A. Winter. 1988. La Parguera, Puerto Rico, USA: 195-212. In: B. Kjerfve (ed.), CAR/COMP - Caribbean Coral Reef, Seagrass and Mangrove Sites. UNESCO, Paris. Garcia, J.R., R. Castro & J. Sabater. 1999. Coral reef communities from Natural Reserves in Puerto Rico. Vol. 1. Isla Caja de Muertos, Bosque Seco de Guanica, Bahia de Mayaguez, Cordillera de Fajardo. JOBANEER, DNR-PR/USCRI, Report. San Juan, P. R. 162 p. Glyma, P.W. 1968. Mass mortalities of echinoids and other reef fiat organisms coincident with midday, low water exposures in Puerto Rico. Mar. Biol. 1: 226-243. Glynn, P. W. 1973a. Aspects of the ecology of coral reefs in the Western Atlantic region: 271-324. In: O.A. Jones, and R. Endean (eds.), Biology and Geology of Coral Reefs, Vol. 2. Academic Press, New York, N.Y. Glynn, P. W. 1973b. Ecology of a Caribbean coral reef. The Porites reef-fiat biotope: Part I. Meteorology and hydrography. Mar. Biol. 20:297-318. Glynn, P.W., L.R. Almod6var & J.G. Gonz~ilez. 1965. Effects of hurricane Edith on marine life at La Parguera. Carib. J. Sci. 4: 335-345. Goenaga, C. 1977. Two new species of Stichopathes (Anthozoa: Antipatharia) with notes on their biology. M.Sc. thesis, Univ. Puerto Rico, Mayaguez. 69 p. Goenaga, C. 1985a. Assessment of precious coral fisheries potential south of Guanica Bay, Puerto Rico, using the submersible RV Johnson-Sea Link. National Marine Fishery Service, NOAA, Report. Dep. Mar. Sci., Univ. Puerto Rico, Mayaguez. 15 p. Goenaga, C. 1985b. The distribution and growth of Montastrea annularis (Ellis and Solander) in Puerto Rico platform reefs. Ph.D. dissert., Univ. Puerto Rico, Mayaguez. 215 p.
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Goenaga, C. & R.H. Boulon, Jr. 1991. The State of Puerto Rican and U.S. Virgin Islands Corals. Caribbean Fishery Management Council, Hato Rey, Puerto Rico, Report. 66 p. Goenaga, C. & G. Cintr6n. 1979. Inventory of the Puerto Rican Coral Reefs. Dept. Natural Resources, San Juan, Puerto Rico, Report. 190 p. Goenaga, C., V.P. Vicente & R.A. Armstrong. 1989. Bleaching induced mortalities in reef corals from La Parguera, Puerto Rico; a precursor of change in the community structure of coral reefs? Carib. J. Sci. 25: 59-65. Hemfindez-Delgado, E.A. 1992. Coral reef status of northeastern and eastern Puertorrican waters: recommendations for long-term monitoring, restoration and management. Caribbean Fishery Management Council, Hato Rey, Puerto Rico. Report: 87 p. Hem~ndez Delgado, E.A. 1994a. National Marine Sanctuary Site Nomination: Mona and Monito Islands. NOAA, Washington, D.C. Report: 18 p. Hemfindez-Delgado. E.A. 1994b. Preliminary inventory of the coral reef systems and hard ground communities from La Cordillera Natural Reserve, Puerto Rico. Project ReefKeeper, Miami, FL. Report: 38 p. Hem~ndez-Delgado, E.A. 1995. Inventario preliminar de las comunidades coralinas de la costa de Rio Grande, incluyendo la Reserva Natural del Estuario del Rio Espiritu Santo. Junta de Planificaci6n, San Juan, Puerto Rico. Report: 25 p. Hemfindez Delgado, E.A. & L. Alicea-Rodriguez. 1993a. Estado ecol6gico de los arrecifes de coral en la costa este de Puerto Rico: I. Bahia Demajagua, Fajardo, y Playa Candelero, Humacao. Proc. 12th Symp. Carib. Fauna Flora, Univ. Puerto Rico, Humacao. Abstract: 2. Hem~ndez Delgado, E.A. & L. Alicea-Rodriguez. 1993b. Blanqueamiento, p6rdida de pigrnentos y recuperaci6n en los cnidarios de la costa este de Puerto Rico entre el 1992 y 1993. Proc. 12th Symp. Carib. Fauna Flora, Univ. Puerto Rico, Humacao. Abstract: 73. Hem~indez-Delgado, E.A., L. Alicea-Rodriguez & J.E. Martinez-Sufirez. 1996a. Las comunidades coralinas de Playa Los Gallitos, Vieques, Puerto Rico: I. Descripci6n cualitativa. Uni6n de Protecci6n del Medio Ambiente de Vieques, Report. 24 p. Hemfindez-Delgado, E.A., E.O. Rodriguez-Class & J.E. Martinez-Sufirez. 1996b. Evaluaci6n biol6gica del arrecife Cayo Ahogado, Bahia Algodones, Naguabo, Puerto Rico. Environmental Quality Board of Puerto Rico, San Juan, P.R., Report. 41 p. Hemfindez-Delgado, E.A., A.M. Sabat, L. Alicea-Rodriguez, J.E. Martinez-Sufirez, A.L. Ortiz-Prosper, E.O. Rodriguez-Class, C.G. Toledo-Hem~ndez & R.N. Ginsburg. 1988. Descripci6n de las comunidades arrecifales dentro de la propuesta Reserva Pesquera Marina de la Isla de Culabra. Proc. 23 ra Symp. Dept. Natural Resources, San Juan, Puerto Rico. 20 p. Johannes, R.E. 1978. Reproductive strategies of coastal marine fishes in the tropics. Envir. Biol. Fish. 3: 65-84. Kaye, C. 1959. Shoreline features and quaternary shoreline changes, Puerto Rico. U.S.G.S. Prof. Paper. 317-B: 49-140. Leis, J. & J. M. Miller. 1976. Offshore distributional patterns of Hawaiian fish larvae. Mar. Biol. 36: 359-367. Lessions, H. A., D. R. Robertson & J. D. Cubit. 1984. Spread of Diadema mass mortality through the Caribbean. Science 226: 335-337.
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Loya, Y. 1976. Effects of water turbidity and sedimentation on the community structure of Puertorican corals. Bull. Mar. Sci. 26: 450-466. McKenzie, F. & M. Benton. 1972. Biological inventory of the waters and keys of northeast Puerto Rico. Dept. Natural Resources, San Juan, Puerto Rico. Report: 90 p. Morelock, J., N. Schneiderman & W.R. Bryant. 1977. Shelf reefs, southwestern Puerto Rico: In: S.H. Frost, M.P. Weiss & J.B. Saunders (eds.), Reefs and Related Carbonates- Ecology and Sedimentology. Studies in Geology 4:17-28. Porter, J.W. 1972. Patterns of species diversity in Caribbean reef corals. Ecology 53: 745-748. Pressick, E.C. 1970. Zonation of stony corals on a fringe reef southeast of Icacos Island, Puerto Rico. Carib. J. Sci. 10:137-139. Roberts, C.M. 1997. Connectivity and management of Caribbean coral reefs. Science 278: 1454-1457. Rogers, C. S. 1979. The productivity of San Cristobal Reef, Puerto Rico. Limnol. Oceanogr. 24: 342- 349. Rogers, C.S. 1983. Sub-lethal and lethal effects of sediments applied to common Caribbean reef corals in the field. Mar. Poll. Bull. 14: 378-382. Rogers, C.S. 1985. Degradation of Caribbean and western Atlantic coral reefs and decline of associated fisheries. Proc. 5th Int. Coral Reef Congr., Tahiti 6:491-496. Rogers, C.S., G. Cintr6n & C. Goenaga. 1978. The impact of military operations on the coral reefs of Vieques and Culebra. Dept. Natural Resources, San Juan, Puerto Rico, Report. 26 p. Sale, P.F. 1970. Distribution of larval Acanthuridae off Hawaii. Copeia 4: 765-766. Szmant-Froelich, A. 1973. The zonation and ecology of Jobos Bay coral reefs. Ann. Rep., Puerto Rico Nuclear Center-DOE. Environmental Studies. PRNC-162:174-224. Vicente, V. & C. Goenaga. 1984. Mass mortalities of the sea-urchin Diadema antillarum in Puerto Rico. Center for Energy and Environment Research. CEER-M-195: 1-26. Webb, R.P., D. Collar, W.C. Schwab, C. Goenaga, J.R. Garcia & R. Castro. 1998. Assessment of the biota, sediments, and water quality near the discharge of primary treated effluent from the Mayaguez regional waste water treatment plant: Bahia de Anasco Puerto Rico: December 1990 through January 1991. U.S.G.S., Water Resources Investigations Report 98-XXXX, San Juan, Puerto Rico. 73 p. Williams, E.H., Jr. & L. Btmkley-Williams. 1989. Bleaching of Caribbean coral reef symbionts in 1987-1988. Proc. 6th Int. Coral Reef Symp., Australia 3: 313-318. Williams, E.H., Jr. & L. Bunkley-Williams. 1990. Coral reef bleaching alert. Nature 346: 225.
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The Atlantic coral reefs of Mexico Eric J o r d f i n - D a h l g r e n and R o s a Elisa R o d r i g u e z - M a r t i n e z ICML, Universidad Nacional Aut6noma de Mexico. Ap. Postal 1152, 77500 Cancfin, Quintana Roo, Mexico ABSTRACT: Well-developed coral reefs are found along the Mexican Atlantic margin from the western Caribbean to the Gulf of Mexico. This work briefly characterizes the wide array of coral reefs found in this area and the coral communities that colonize them. Differences in oceanic connectivity and terrestrial influence result in the delineation of three major reef subregions: Caribbean, Campeche Bank and southwest Gulf of Mexico reef systems. The environmental settings of these reefs, as well as the climatic and biological perturbations to which they have been subjected, are also summarized. A review of anthropogenic influences from fisheries to coastal development and a gross assessment of coral community condition in these reefs are also made. We described the coral reef protection in Mexico up to 2001 and comment on its problems and effectiveness.
1. I N T R O D U C T I O N T h e M e x i c a n Atlantic coast extends f r o m the w e s t e m C a r i b b e a n to the G u l f o f Mexico. This is a s u b t r o p i c a l e n v i r o n m e n t w h e r e s h a l l o w seas are s t r o n g l y i n f l u e n c e d b y the
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tourism-associated coastal development is generating multiple conflictive uses as well as threatening the well being of the reefs themselves. Finally a word of explanation. There are several unreferenced statements and conclusions on this review. All of these are personal observations (EJD), mostly based on unpublished data on Gulf and Caribbean coral reefs gathered through a lengthy observational period as EJD has had the good fortune of being able to work on these reefs for more than twenty years. 2. HISTORY
Mayan and Mexican pre-Hispanic cultures were familiar with coral reef biota. Scleractinian corals, gorgonians and gastropod shells were common items used at burial offerings in these ancient cultures (L6pez and Polanco 1991). Also seafaring Mayas trading from the Gulf of Mexico, along the coast, down to Honduras, apparently built navigational aids on shore to indicate reef passages (Farris and Miller 1977). Charts published in the early 19th century are the first known technical accounts of reefs in the Gulf of Mexico. The majority of the surviving charts from these times were made after the Mexican independence in 1810, although most likely Spaniards had previously charted the Gulf reefs, as navigational hazards, because Veracruz and Campeche were busy ports during colonial times. The English Admiralty charted the majority of reefs in the Gulf of Mexico in the mid 1800s and also charted Banco Chinchorro, in the southern Mexican Caribbean. Most modem navigational charts of Mexican reefs are based on these charts, and/or modifications of them carried out by the US National Ocean Survey and the Mexican Navy Office for Oceanography. The first scientific observations of Mexican reefs were made by Humboldt (1861) on the Gulf of Mexico, while the first formal contribution is that of Heilprin (1890) on the reefs of Veracruz in the SW Gulf. Darwin's (1984) comments on the eastern Yucatfin reefs were based on available maps, but he did not visit the area, and made no comment about the reefs in the southern Gulf of Mexico. It was not until the 1960s that a systematic effort was made to study Mexican coral reefs basically in the SW Gulf of Mexico, where reefs growing in areas of heavy sedimentary influence add new insights to the issue of how coral reefs grow (Chamberlain 1966; Emery 1963; Moore 1958; Morelock and Koening 1967; Rigby and Maclntyre 1966). This effort was followed by biological, sedimentological and geological studies in the offshore Campeche reefs (Kornicker et al. 1959; Logan 1969). In contrast, although some reports (Boyd et al. 1963) were produced in the 1960s, systematic geological (Ward et al. 1985; Spaw 1978) and ecological (Jordfin 1979a, b) studies of Caribbean reefs in Mexico were not initiated until the late 1970s. During the last 30 years, scientific studies shifted from foreign to Mexican scientists mainly at the Instituto Polit6cnico Nacional (Huerta 1961; Ch/Lvez 1973), and the Universidad Nacional Aut6noma de Mexico (Villalobos 1971; Bonet 1967). This belated interest in coral reef studies in Mexico arises from two related facts: a) that marine sciences in general did not become a priority in Mexico until the 1970s, and b) coral reefs are but a small part of the vast marine ecosystems of the country. Nowadays, many other academic institutions and individuals are contributing significantly to coral reef studies, such that papers in scientific journals and reports are
The Atlantic coral reefs of Mexico
133
numerous. This effort reflects the growing interest of the Mexican academic commtmity, government agencies, and of the public in general, for coral reefs. Our list of references may be incomplete but it includes almost 600 contributions, both scientific and technical related to coral reef ecosystems in Mexico (Table 1). Close to 50% of these references are scientific contributions, and of these the great majority concern biological aspects, from species lists to ecological aspects of benthonic, nektonic and planktonic species. There are also a large number of undergraduate (17%) and postgraduate (6%) level theses, a good number of which are of high quality. Reports and bulletins constitute almost 30% of the contributions. TABLE 1 Scientific and technical works related to coral reefs in Mexico 1882-1998 (data obtained from the Coral Reef Systems Laboratory, ICMyL, UNAM). Scientific journals Oceanography and hydrology Geology
7
Proceedings/ Memoirs
B.Sc
4
4
Thesis M.Sc./Ph.d. 2
Reports/ Bulletins 9
Books 1
26
6
1
4
5
2
146
64
85
26
91
11
Fisheries
3
4
2
1
6
3
Management
1
8
Pollution
2
2
1
Other
9
6
4
1
6
194
94
97
34
149
Coral community
TOTAL
29 3
17
3. REEF SYSTEMS 3.1. Reef morphology There are scleractinians in all three Mexican seas: the Pacific, the Gulf of Mexico and the Caribbean. However, well developed reefs appear only in the Atlantic region, although some authors argue that the Cabo Pulmo reef in Baja California may qualify as a fully developed reef (see Reyes-Bonilla in this volume). In the Atlantic region of Mexico coral reefs occur in three major areas: SW Gulf of Mexico, Campeche Bank, and in the Caribbean (Fig. 1). Whereas in the Caribbean coral reefs are a common feature, in the Gulf of Mexico, both in the SW Gulf and Campeche Bank, distribution of reefs is restricted to small areas. All coral reefs in the Gulf of Mexico, with the exception of Alacranes reef, are bank-reefs of small size. Some are open-reefs while others show a shallow internal platform instead of a lagoon, a feature that may be related to the small reef size (Hopley 1982) (Table 2).
3.1.1. SW Gulf of Mexico reefs. There are four reef groups: Isla Lobos, Tuxpan, Veracruz and Ant6n Lizardo (Fig. 1; Table 2). The bank reefs that constitute these groups
Jordim-Dahlgren & Rodriguez-Martinez
134
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~ i ~~ ........... . . . . . . . . . . .
B. C h i n c h o r r o Fig. 1. Reef systems off the Atlantic coast of Mexico. Ix)cation map only, individual reefs not drawn to scales (for proper scaling see Fig. 2). Barrier/fringing reefs along the Caribbean coastline are not evident at this scale, see Figure 5. Black areas indicate reefs.
are generally less than 10 km 2 in area (Fig. 2), lie close to shore (Fig. 3) and are distmctly isolated. This fact suggests that underwater features upon which the reefs were able to rise control their development, however the nature of these reef's foundations is unknown. For some of these reefs the inferred foundation are basalt (FreelandLockwood 1971) and/or salt dome elevations (Antoine 1972). There are distinct morphological variations between leeward and windward sectors, and the main reef builder species are Acropora palmata (mostly dead at present (Jordfin-Dahlgren 1993a) and Montastraea annularis, although other species may play an important additional role (Table 3). Corallinaceae algae are quite common and may play an important binding role, and in some reefs, there is relatively high abundance of sediment-producer algae of the genus Halimeda. These reefs are directly affected by the silt-laden discharge of large rivers, particularly intense during the rainy season from June to September. Notwithstanding this apparently stressful situation reef development is surprisingly good and scleractinian species richness is relatively high (Horta-Puga and Carricart-Gavinet 1993). However, at Isla Lobos reefs (the northernmost nearshore emerged reefs in the Gulf) there are fewer species than in the southern reefs (unpubl. data). 3.1.2. Campeehe Bank reefs. Most of these reefs follow the outer fringes of the extensive Yucatfin shelf, some 80 to 130 km offshore (Fig. 1, Table 2). These reefs, also of the bank type, are slightly larger than those at the SW Gulf (Figs. 2 and 3), varying from under 3 km 2 (Tri~ingulos Oeste reef) to over 20 km 2 (Cayos Arcas reefs). There are also a number of submerged reefs reaching to within 10 m of the surface, as well as a few inshore reefs found close to the NW corner of the Yucatfin peninsula (Fig. 1; Table 2).
The Atlantic coral reefs of Mexico
135
TABLE 2 Main morphological characteristics of Mexican Atlantic coral reefs. Fr.: fringing; Ba-At: Atoll like bank; Bar.: Barrier. H: high; M: medium; L: low; N: nil; ?: unknown;. *: numerous submerged small banks and unaccounted for pinnacles. **: Mean (Std. deviation) when more than one reef. ***: Includes shallow and deep shelf edge reefs. - : Not applicable. Distances along reef tracts are approximate. S W G U L F of M E X I C O Reef type Reefs per system (n) *
Isla L o b o s
Tuxpan
Veracruz
Bank
Bank
Bank, Fr.
A. Lizardo Bank
3
3
7
8
0.9 (0.6)
2.8 (3.5)
1.9 (0.4)
3.1 (3.3)
25 (3)
20 (2)
20 (6)
29 (9)
Windward slope
< 20 ~
> 20 ~
> 20 ~
> 20 ~
Leeward slope
> 20 ~
> 20 ~
> 20 ~
> 20 ~
8.4 (2.9)
9.8 (1.3)
3.8 (2.2)
11.7 (7.9)
M
H
H
H
Unit size (km 2) ** Depth at base (m) **
Distance to shore (km) ** Terrestrial influence
CAMPECHE BANK
Emerged
Setting
Offshore
Reef type Reefs per system (n) * Unit size (km 2) **
Bank
Submerged
Ba-At
Offshore
Inshore
Bank
Bank
4
1
11
4
5.0 (2.5)
680
<1 to >8
<1 to >2
Depth at top (m) **
-
-
16 (10)
6 (5)
Depth at base (m) **
38 (7)
50
36 (9)
16 (8)
Windward slope
< 20 ~
< 20 ~
> 20 ~
< 20 ~
Leeward slope Distance to shore (km) ** Terrestrial influence
> 20 ~
> 20 ~
> 20 ~
> 20 ~
175 (21)
124
182 (16)
35 (11)
N
N
N
CARIBBEAN Setting
North
N
Central
South
Continental
Island
Submerged
Bar-Fr.
Fr. ***
Bank
Bar-Fr.
Bar-Fr.
Ba-At
60
50 +
-
110
100
-
Unit size (km 2) **
-
-
> 400
-
-
700
Depth at top (m) **
-
-
25
-
-
Depth at base (m) **
20-60
10-400
360
30-60
30-65
400 +
Windward slope
< 20 ~
< 20 ~
> 20 ~
< 20 ~
< 20 ~
> 20~
-
-
> 20 ~
-
-
> 20~
Reef type Reef tract length (km)
Leeward slope Distance to shore (krn) **
-
-
58
-
-
30
Terrestrial influence
N, L
N
N
L
N, L
N
Upwelling
L, M
?N
?L
?
?
9
136
Jordhn-Dahlgren & Rodriguez-Martinez
Fig. 2. Details of selected reefs in the Gulf of Mexico, Campeche Bank and Caribbean (see Fig. 1). Atoll-like bank reefs (Chinchorro and Alacranes), offshore bank reefs (Cayo Arenas and Cayo Arcas), offshore bankbarrier reefs (Trihngulos),and inshore reefs on the western Gulfcoast. All drawings are North-oriented.
All the offshore reefs rise from the shelf surface at depths of 30 to 40 m, and those of the northern sector may have developed, during a marine transgressive phase, from remnants of ancient sand dunes (Logan 1969). There are distinct morphological variations between leeward and windward sectors. An extensive and shallow reef flat is a common feature in most of leeward part of these reefs. Corallinaceae algae are quite abundant in these flats, and binding of coral skeletons in ample dead beds of Acropora cervicornis is evident. Some reefs have extensive spurs (Cayos Arenas, Tri~ngulos reefs), and deep moats on the fore reef zone (Cayos Areas, Tri~ngulos reefs). Main spur builder species are Acropora palmata (mostly dead at present) and Montastraea annularis in the deeper sections, although other species may play an important additional role (Table 3). Halimeda species abundance is scarce in these reefs, and in Cayos Arcas three separate surveys, from 1969 (Farrell et al. 1983) to 1997 (Jordan per. obs.) have failed to detect its presence. In contrast with the Caribbean shallow reef environment (-1 to-10 m) sandy areas are not colonized by seagrasses.
137
The Atlantic coral reefs of Mexico
TABLE 3 Characterization of reefs off the Atlantic coast of Mexico. Dom. (Dominant bio-constructor species or association): Aaga: Agaricia agaricites; Acer: Acropora cervicornis; Apal: A. palmata; AL: algal (corallines or fleshy); CA: coral-algal (crustose); CBA: branched coral-algal (unconsolidated); CG: Coral grounds, communities dominated by gorgonians, scattered corals (maybe abundant, but small) and sponges, that contribute in small measure to the reef relief; Cnat: Colpophyllia natans; Dcli: Diploria clivosa; Dstr: D. strigosa; Mann: Montastraea annularis; Mcav: M. cavernosa; Mfav: M. faveolata; MC: mixed corals; Mcom: Millepora complanata; Ssid: Siderastrea siderea; Past: Porites astreoides; Pfur: Porites furcata; OT: others. Cond. (bio-constructors condition): d: diseased; h: healthy; r: recovering (recovery of live tissue in standing colonies); x: dead (not-recently). Overg. (Overgrowth on dead bio-constructors): 1: consolidating (crustose algae); 2: stabilizing (zoanthids, Erythropodium caribbaeorum); 3: temporary non-consolidating (fleshy and filamentous algae). Sdom. (Sub-dominant bio-constructor species or association). Relief (Dominant reef features that provide relief to a given reef zone): b: Acropora belt; ch: coral heads; cms: complex multiple structures; icc: isolated coral colonies; lc: low-lying crests; n: no significant relief over substrata, as with coral grounds; o: open, porous matrix; pi: pinnacles; sg: spur and grooves. The relative importance of reef features is indicated as follows: +High; + Medium; - Low; 9not applicable. Reef Zone
Dom.
Cond.
Overg.
Sdom.
Relief
Mann
d, x
3, 1
Dstr
ch, pi
+
Lagoon/flat
Dcli
h, d
1, 3
pfur
pi
-
Reef crest
Apal
x
1, 2
CA
lc
-
Fore reef (shallow)
Apal
x
3
Dcli
n
-
Fore reef (deep)
Mcav
h
Ssid
o
+
Leeward
Mann
h
Cnat
ch, pi
+
Lagoon/fiat
Dcli
h
CBA
n, o
SW GULF REEFS Isla Lobos Leeward
9 Tuxpan 9 1, 2, 3
9
Reef crest
Apal
x
CA
b
+
Fore reef (shallow)
Dstr
h
9
Mfav
o, pi
•
Fore reef (deep)
Mfav
h
9
Ssid
o
+
Leeward
Acer
x
Mcav
ch, pi
+
Lagoon/fiat
Dcli
h
Past
n, ch
-
Reef crest
Apal
x
1,3
CA
B
+
Fore reef (shallow)
Apal
x
1,3
Mann
ch, lc
+
Fore reef (deep)
Cnat
h
9
Mfav
pi, ch
+
Leeward
MC
h
Mcav
pi, ch
+
Lagoon/flat
Apal
x
1
Mann
cms
+
Reef fiat
Acer
x
2, 1
AL
n, ch
-
Reef crest
Apal
x
1, 2
CA
n
-
Fore reef (shallow)
CG
h
9
Dstr
ice
+
Fore reef (deeper)
Mcav
h
9
Ssid
ch
•
Veracruz and Ant6n Lizardo 3
CAMPECHE BANK REEFS Banks 9
138
Jo rd6n-Dah lgren & R odriguez-Martinez
Table 3 cont.
Reef zone
Dom.
Cond.
Leeward
Mann
h
Lagoon/fiat
Mann
h
Reef flat
Dcli
h, d
Reef crest
Apal
x
Fore reef (shallow)
CG
h
Fore reef (deeper)
Mfav
h
Overg.
Sdom.
Atoll-Bank (Alacranes) 9 Mcav 9 1, 2
9
Relief pi, ch
OT
cms
CBA
n, ch
AL
lc
Dcli
icc
Ssid
CARIBBEAN REEFS Continental Leeward
9
9
.
Lagoon/channel
Mfav
h
9
MC
ch
-
Back reef/fiat
Mfav
h
9
Apal
ch
•
Mcom
lc
+
Mcav
icc-sg
+
MC
icc-sg
+
ch,pi
+
Apal
x, r
Fore reef (shallow)
CG, Mfav
h
Fore reef (deeper)
CG, Mfav
h
Reef crest
3 9
Island (Cozumel) Leeward
MC
h
OT
Fore reef (shallow)
CG, Mfav
h
Mcav
icc-sg
+
Fore reef (deeper)
CG, MC
h
OT
icc-sg
+
+
Lagoon/channel Back reef/flat Reef crest
Chinchorro Bank Leeward
MC
h
Lagoon/channel
Mfav
h
Back reef/flat
Mfav
h
9
OT
oh, pi
MC
cms
+
9
Apal
ch, lc
+
CA
h
9
Mcom
lc
+
Fore reef (shallow)
Apal
h
9
Aaga
sg
+
Fore reef (deeper)
CG
h
9
MC
ice, ch
+
Reef crest
Alacranes in the northern Campeche bank (Fig. 1) is an exceptionally large bank-reef (Komicker et al. 1959; Bonet 1967) with an atoll shape that covers an area greater than 650 km z (Fig. 2). In contrast with all other Campeche bank reefs, it has a deep lagoon (~ -20 m, Fig. 3) which is segmented by a complex network of inner reefs (Bonet 1967). A core boring recovered 33.5 rn of Acropora cervicornis facies on this reef, which indicates one of the fastest rates of Holocene reef accretion yet recorded: 14 m per 1000 year (Macintyre et al. 1977).
139
The Atlantic coral reefs of Mexico
Caribbean
G u l f of M~xico SW
NE
w
E
10m [ I
i
I
5 km
j
Alacranes W
'
5km Chinchorro
E
w
Cayos Arcas
E
Puerto Morelos W
E
lOre [ I
,
i
2km
Veracruz
I
0.1km
|
Majahual
Fig. 3. Profiles of selected reefs in the Gulf of Mexico and Caribbean (see Figs. 1 and 2). Puerto Morelos reef profile corresponds to the northern Caribbean sector and Majahual reef profile to the southern Caribbean sector. Profiles are drawn approximatelyat mid reef section. 3.1.3. C a r i b b e a n reefs. Fringing-like reefs border most of the continental and insular shores of the Mexican Caribbean (Jordfin-Dahlgren 1993a)(Fig. 1; Table 2). However, strictly fringing reefs (growing directly from shore) are found infrequently. Commonly a wide (typically hundreds of meters, range from hundreds to thousands of meters), shallow (typically-3 to -4 m, range -1 to -8 m) lagoon separates the reefs from the shoreline (Fig. 4). Thus perhaps these reefs are more aptly referred to as extended fringing reefs, as these Caribbean reefs do not form a classical barrier reef (James and Ginsburg 1979)
140
Jordrn-Dahlgren & Rodriguez-Martinez
(m the Caribbean region only the southem Belizean barrier reef may qualify as such); nor do they correspond to the bank-barrier reef concept of Davies (1928). The lagoon floor is usually sandy, harboring extensive beds of the marine phanerogam Thalassia testudinum, and sporadically coral knolls. We have arbitrarily divided the Caribbean margin into northern, central and southem sectors (Figs. 3 and 5). Northern sector. The dominant reef types are extended fringing reefs (Jord~inDahlgren 1988; Jord~n-Dahlgren 1993a, b) (Figs. 3, 4 and 5). There is a relatively high coral cover on the crest and rear reef zones, while the fore reef zone is mostly of low relief, gentle slope and is colonized by coral grounds (hard grounds colonized by multispecies assemblages with many small scleracfinian colonies, abundant sponges and hydroids, and where gorgonians may be highly conspicuous; Table 3) (Jord~n-Dahlgren et al. 1981; Jord~n-Dahlgren 1993a). Therefore, modem reef accretion has been minimal and features of ancient structures, more likely of late Pleistocene origin (Ward et al. 1985), determine present reef morphology. Commonly these reefs have an Acropora palmata cover on the shallow fore reef, reef crest and protected environments, while Montastraea annularis dominates the rear reef zone. In the coastal margin, leeward of Cozumel Island, reefs are mostly absent and instead, the near shore zone is sand floored. This condition may result from a "wave shadow" effect, induced by the windward setting of the island in relation to the mainland coast (Burke 1982). However, even in these mostly reef-less area, isolated but well-developed local reefs may appear, as in the Ahmaal area. On the windward side of Cozumel Island there are no extended fringing reefs, as in the continental margin. Here the island windward slope tends to descend gradually from the shore and thus coral grounds predominate. In a couple of sites along this margin there is a strong change in bottom relief, and here large scleractinian colonies generate a distinct reef wall, lacking spur and grooves (Jord~in-Dahlgren 1989). Also, on the NE of the island, highly porous but strong coralline-algae microatolls, up to five meters high, form a shallow arc against the shore (Ward et al. 1985). The most highly developed reefs of Cozumel island are found along the edge of the SW insular shelf (Fenner 1988; Muckelbauer 1990), topping an almost 400 m high underwater cliff. These reefs are on the lee of the island, but the very clear waters of the north-flowing Yucatan current (a branch of the Gulf Stream) continuously wash them, a fact that allows for a very diverse and abundant coral community to depths in excess of 50 m. Together the physiography of the area and the rich biotic assemblages make a very spectacular reef setting. Central sector. Reef morphology in this sector follows the same trends observed in the northern sector (Figs. 3 and 5) as these reefs arise also from a submerged crest that may correspond to an ancient shoreline (Jord~in-Dahlgren 1988; Jord~n-Dahlgren et al. 1994). The main characteristic of this area is a chain of shallow A. palmata reefs that border the two large shallow bays in the Sian Ka'an Biosphere Reserve area, which tend to be better developed than on the northern sector (Jord~in-Dahlgren 1993a; Jord~mDahlgren et al. 1994). Although the shelf widens in this area and the fore reef has a low angle slope, there is a high bottom relief of the bottom at several sites. This relief arises from varied features, from series of consolidated shallow crests or risen platforms poorly coral-colonized, to extensive dendritic projections of A. palmata into the shallow fore reef (Jord~in-Dahlgren 1988). Commonly, stands of A. palmata skeletons in growing position are found, indicating a high, although patchy mortality of this species in the area, by 1994 (Jord~n-Dahlgren et al. 1994).
The Atlantic coral reefs of Mexico
141
Fig. 4. Morphology of a typical extended fringing reef in the northern Caribbean sector. The relativelywide reef lagoon allows active water circulation thus generating an adequate environment for coral growth on the back-reef zone.
Southern sector. The extension of the continental shelf is reduced and reefs are better developed than in the northern sectors (Jord~n-Dahlgren 1988). Continental reefs are mostly extended fringing reefs with similar lagoon characteristics to the reefs in the north (Fig. 5), but the fore reef typically shows a higher bottom relief. Not uncommonly, spur and groove morphology dominate the fore reef both at shallow (1-12 m) and deeper depths (10-40 m) (Jord~m-Dahlgren 1993a). Shallow spurs have a variable height from
142
Jord{m-Dahlgren&Rodriguez-Martinez
3 to 7 m, rounded side walls separated by irregular groves 3 to 6 m wide. Deeper water spurs are commonly very long and thin, 5 to 12 m high, with steep and non-porous walls, separated by narrow channels 1 to 6 m wide. Below forty meters usually isolated coral patches in a mostly bare rocky pavement dominate (Jordfin-Dahlgren 1988). In some sites there is no spur morphology, but impressive and extensive sets of shallow water (5-10 m) Montastraea annularis and Colpophyllia natans pinnacles, topped with A. palmata. On the reef crest A. palmata usually dominates, but in several instances Millepora complanata also colonize the breaker zone. The major reef formation of the southem sector is Chinchorro bank (Figs. 1, 2, 3), the largest atoll-like reef found in the Caribbean region (Jord~in and Martin 1987) (Table 3). The windward fore-reef of Chinchorro consists of a complex set of 2 to 3 series of spur and grooves f r o m - 2 to -18 m (Jord~in and Martin 1987), not unlike the shallow depth spurs previously described. Below the spur sets, a relatively gentle slope is colonized by coral grounds, and below -40 m by isolated coral patches. The windward reef crest is almost continuous and the breaker zone tends to be colonized by coralline algae (Jord~in and Martin 1987), in contrast with the Millepora-Acropora assemblage that dominates northern reefs crest. A chain of small banks and islets make-up the leeward margin, which descends to a narrow terrace (300-700 m wide, depth 12-30 m), beyond which an almost vertical cliff descends to depths in excess of 400 m, as off Cozumel island (Jord~in and Martin 1987) (Fig. 3). Chinchorro's lagoon is relatively shallow increasing from a couple of meters in the northern area, down to -8 to -10 m in the south, where a
Fig. 5. Reefs of the Caribbean coast of Mexico. Shallowreefs indicated by the dark bands, deeper reefs and coral groundsby light graybands. Referto figure 1 for relative geographicalposition of the three sectors.
The Atlantic coralreefs of Mexico
143
network of shallow reefs is found. Chinchorro is likely related to Belizean atolls whose development was strongly influenced by subsidence (Jordfin and Martin 1987).
3.2. Coral communities Coral reefs in the Caribbean and Gulf of Mexico have a similar coral biota to reefs farther south due to their downstream position in the major circulation patterns of the Caribbean (L6pez and Polanco 1991). Nevertheless, there is a reduction in the number of common scleractinian coral species from the Caribbean to the reefs of the SW Gulf (Fig. 6; Table 3). Coral species richness however, does not seem to decrease drastically as it does with gorgonians (Jordfin-Dahlgren 1992). 3.2.1. Reef crest (breaker zone). All reef crests are dominated by Acropora palmata. However, there is a decrease in subdominant components such as coralline algae and Millepora complanata toward the Gulf and an increase in zoanthids, mainly Palythoa caribaeorum and Zoanthus sociatus, both of which can be extremely abundant locally (Fig. 7). 3.2.2. Protected reef areas. Other common corals such as Diploria clivosa, Porites astreoides and Siderastrea siderea tend to be more abundant in the protected areas of the back reef and shallow lagoons of the Gulf reefs, than in similar environments in Caribbean reefs. Where the protected areas are deeper than a few meters, composition is similar in all the Mexican Atlantic reef area with large coral heads and pinnacles of Montastraea annularis and M. faveolata, usually topped by A. palmata.
Fig. 6. Live coral cover and number of common species in shallow reef areas (rear reef to fore reef ~ -10m) of differentreefs in the Atlantic margin of Mexico.Acroporapalmatastands composedmostlyby dead skeletons in growing position in the Gulf of Mexico reefs. M. annularis refers to the Montastraea annularis species complex. AL: Ant6n Lizardo.
144
Jord6n-Dahlgren &Rodriguez-Martinez
Fig. 7. Dominant biota in the reef crest on selected reefs along the Atlantic margin of Mexico. AL: Ant6n Lizardo. 3.2.3. Exposed reef areas. The shallow windward margin is usually fringed by a well developed belt of A. palmata although by the early 1990's most acroporid colonies in the SW Gulf reefs were dead (Jord/m-Dahlgren and Rodriguez-Martinez 1998). A similar condition was observed in Tri/mgulos and Cayos Arcas reefs by 1997, and Cayos Arenas in 1999 (per. obs.), whereas in Alacranes the species was scarce by 1992. The windward fore reef, between 5 m and 20 m, in most of northern and central Caribbean reefs as well as in the Campeche Bank reefs have coral grounds (Table 3) (Cochrane 1972). In the SW Gulf reefs in contrast, massive scleractinians such as M. annularis, D. strigosa and D. clivosa, predominate in this environment. In the Gulf reefs the deep fore reef, and in many cases the leeward reefs, have massive heads of the M. annularis complex, D. strigosa, P. porites and Colpophyllia natans, and coral cover can be close to 100%. In many instances the highest species richness is found at mid-depths close to the reef edges on the leeward margins. In some of the SW Gulf and Campeche Bank reefs extensive and thick beds of A. cervicornis predominate on the leeward and shallow areas but nowadays they are mostly dead. In the southern Caribbean reefs well colonized terraces and complex spur and groove systems contrast strongly with the northern Caribbean reefs. Also, there is a large coral cover on shallow spurs, mainly of Agaricia agaricites f carinata, and A. palmata on the upper parts. While coral cover is mostly restricted to the upper parts of the deeper spurs, basically by a rich assemblage of species dominated by Montastraea species, and where sponges and fleshy algae are also an important component. 4. NATURAL CONDITIONS AND STRESSES
4.1. Physical Environment The main oceanographic influence on the Atlantic reefs of Mexico comes from the Caribbean current system, as one of its branches is northwardly deflected by the Yucatfin peninsula into the Yucatfin channel, where all other Caribbean currents merge into the Gulf Stream. From here, Caribbean waters enter the Gulf of Mexico by two main paths:
The Atlantic coral reefs of Mexico
145
a) a shelf flow, over the Campeche Bank down to Trifingulos reefs, and periodically down to Cayos Arcas reef (Fig. 1), before turning Westward into the central Gulf basin as suggested by drift observations (Rezak et al. 1985); and b) by way of the loop-current (Cochrane 1972), as very large gyres of Caribbean waters detach from the main current and drift westward, eventually reaching the eastern shores of the Gulf of Mexico. For most of the year west-directed trade winds prevail. From September to April, polar continental air masses flow into the Gulf of Mexico and the Caribbean generating strong south to southwest-directed winds with speeds up to 120 km/h, although common speeds are half of that (Tulmell 1988). The main effect of these "nortes" is to reduce atmospheric and seawater temperatures, and increase turbidity, wave energy and ocean surf. They majority affect the southwest Gulf reefs, where sudden temperature drops of as much as 7~ have been recorded. The winter "nortes" also reach the Mexican Caribbean reefs, causing rapid drops in surface water temperatures of about 3~ (F. Ruiz per. com.). However this change does not seem to stress the coral community as evidenced by the healthy presence of the temperature-sensitive A. palmata. 4.1.1. Terrestrial runoff. Land influence upon reefs is restricted to the nearshore reefs of the SW Gulf. Which are affected by the discharge of large rivers during the rainy season. Although coral communities have being able to resist this freshwater input (Freeland-Lockwood 1971) (Fig. 1, Table 4), the lower coral and gorgonian diversity on these reefs may result from the combined effect of terrestrial runoff and winter storms, as well as from a relatively low oceanic circulation (Jordfin-Dahlgren 1993a). Such a situation has existed since at least the 16th century when the Spaniards introduced extensive farming and deforestation. The progressive expansion of agriculture has dramatically increased soil erosion of the extensive coastal plain, and mountain slopes, TABLE 4 Occurrence and relative intensity of natural perturbations (some may be indirectly enhanced by anthropogenic activities) on the coral reefs of the Atlantic coast of Mexico. H = high; M = medium; L = low; N = nil; X = unknown.
Southwestern Gulf
Campeche-Yucatfin
Caribbean
Climatological Storms
H
H
H
Strong storms
M-H
H
H
Cold spells
L-M
X
N
Water warming
X
X
L
Biological Diadema die-off Acropora mortality
H
H
H
H
H
M
Coral diseases
X
L
L
Algal overgrowth
M
M
L
Fish mortality
X
X
L
Bleaching
X
L?
L
146
Jorddn-Dahlgren & Rodriguez-Martinez
which constitute the watersheds of these large rivers. Nowadays, the threats to these reefs may come from sedimentation and additional anthropogenic effects, as discussed below. In the Caribbean sector, the karstic nature of the land and the lack of soils cause rapid rainwater percolation down to the water table, and no surface rivers are formed (Ward et al. 1985). Fresh water circulation is therefore underground and there is a net flux from land to ocean, therefore underwater springs may occur in reef areas. However, the water from these springs does not carry sediments, and it is not likely able to affect the coral community in this context. 4.1.2. Tropical storms and hurricanes. Hurricanes and tropical storms more likely affect all reefs in the Mexican Atlantic, but with different intensity and frequency. The hurricane season extends from June to November, peaking between August and September. Between 1886 and 2000, 162 storms (112 tropical storms and 50 hurricanes) have passed through the reef regions. Fifteen of these storms crossed all three reef regions (SW Gulf, Campeche Bank and Caribbean), twenty-three passed through the Campeche Bank and the Caribbean, and the remaining ones affected only one region (Fig. 8). The Campeche Bank and the Caribbean reefs are affected more often and by more severe hurricanes than those in the SW Gulf (Fig. 8). The highest hurricane frequency occurs in the Campeche Bank, because there is two storm sources: the ones coming from
Fig. 8. Number of tropical storms (white bars) and hurricanes (categories 1-2 in gray; categories 3-5 in black) between 1886-2000 that passed close to the three regions that include coral reefs in the Atlantic margin of Mexico (tracks between 17.5~ and 22.5~ latitude and 85~ and 98~ longitude). Hurricane categorybased on the SAFFIR-SIMPSON scale. Source: National Hurricane Center; NOAA and Colorado State University/Tropical Prediction Center.
The Atlantic coral reefs of Mexico
147
the Caribbean, and those generated in the Gulf itself. For the 111 years of available data the return period of major hurricanes (categories 3-5 in the SAFFIR-SIMPSON scale) was 37 years on the SW Gulf of Mexico, 18.5 years in the Caribbean, and 12.3 years in the Campeche Bank. In spite of this high storm frequency, the effect on reefs and on coral communities has only been documented for the northem Caribbean sector (Hurricane Gilbert in 1988: Jord/m-Dahlgren and Rodriguez-Martinez 1998). Observations of the effect of Hurricane Roxanne in 1996 on Cayos Arcas and Trifingulos reefs are in preparation to be published.
4.2. Biological Perturbations The effects of biological perturbations in the coral community, if somewhat discrete and of short duration are difficult to properly assess unless there is a permanent facility at a reef site. In Mexico, the only such facilities are in the northern Caribbean sector at Puerto Morelos, and thus more is known about this area. The occurrence, intensity, and after effects of biological perturbations in other reef regions of Mexico are largely unknown, but it is likely that widespread events such as the mortality of Diadema (Lessios et al. 1984), have impacted all reefs of the region (Table 4). 4.2.1. Diadema die off. During 1982, Diadema antillarum, a very abundant sea urchin on the northern Caribbean reefs was wiped out possibly by a water-borne pathogen (Lessios et aL 1984) (Table 4). However, the effect of this widespread mortality did not result in massive algal overgrowths in the Mexican Atlantic. This was probably because the herbivore fish population was not as depleted to the extent it was, in Jamaica, for example (Hughes 1994). Presently, there is a slow recovery of this formerly abundant species in the Mexican Caribbean as well as in the Campeche Bank (per. obs.), and in the SW Gulf reefs (G. Horta per. corn.) 4.2.2. Acropora mortality. Massive mortalities of Acropora palmata and A. cervicornis occurred during the 1970s in the SW Gulf reefs killing practically all the colonies (Jordhn-Dahlgren 1993a) (Table 4). As the mortality seemeded to have occurred gradually during several consecutive years (Jord~n-Dahlgren 1993a), and skeletons of the dead colonies remain intact and in growth position, the more likely killing agent could have been white band disease (Antonius 1981; Gladfelter 1982). The sudden mortality of acroporids due to cold spells during winter storms (Tunnell 1988) has been recorded, and that may have been an additional source of lethal stress. Cover of A. cervicornis in the shallow waters at Enmedio Reef decreased from up to 100% in 1971 to less than 5% in 19871991 (Tunnell 1992). Recovery is now proceeding slowly (Jordfin and Martin 1987). In the Campeche Bank at Cayos Arcas, and at Trifingulos reefs (Fig. 1), a similar situation was observed in 1997, and in Cayos Arenas in 1999. Most, if not all, colonies of A. palmata were dead, and most skeletons remained in the growth position; the effect was evident in both exposed and protected areas. Also, dead thickets of A. cervicornis, both intact and heavily disturbed (presumably by storms), were observed, from a few meters down to 25 m. Recolonization of A. palmata is occurring on reefs of the Campeche Bank and at Alacranes reef where many small colonies are growing on stumps of former large colonies, on the windward reef margin but not on the inner patch reefs (per. obs.). We have recently observed (1999) an ample number of live A. palmata
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colonies in many places at Cayos Arenas (unpublished results) suggesting an initial phase of recovery for this species. In the northern Caribbean reefs, A. palmata stands seem to have been less affected by the mortality events, and although white band disease had always been present, it has only affected isolated colonies. In this sector, physical destruction by hurricane Gilbert in 1988 was the main cause of massive acroporid mortalities (Jord/m-Dahlgren and Rodriguez-Martinez 1998). However, although A. cervicornis cover (Jord~n-Dahlgren et al. 1981) was scarce by 1979, a marked decrease has been observed in the last fifteen years (per. obs.), to the extent that the species is now rare. In the central and southern Caribbean sectors, large areas of living A. palmata reefs alternate with large areas where the species has been killed. Because skeletons remain in growth position, it seems more likely that the cause of mortality is biological, rather than physical-such as that derived from storm effects. 4.2.3. Coral diseases. Little is known of the extent of coral diseases in the Mexican Atlantic reefs (Table 4), although we have observed black band (Secretaria del Medio Ambiente, Recursos Naturales y Pesca 1996) and white band (Gladfelter 1982) in all reef areas. What appears to be white band (Richardson et al. 1998) on Dichochoenia stokesii has been observed on colonies off Cozumel. However, we have not seen a widespread epidemic of any of these coral diseases, nor of diseases of gorgonians (Nagelkerken et al. 1997). Changes in coral coloration are observed routinely, but rarely on more than a few colonies of a given reef in the northern Caribbean sector; if these correspond to some disease stage, or are something else, is unknown. 4.2.4. Algal overgrowth. Algae' overgrowing corals and the surrounding reef substrates, resulting in the death of corals and/or inhibiting the settlement of new coral larvae, seems to be restricted to a few sites, which are heavily influenced by human activities (Table 4). Reefs off Veracruz in the SW Gulf (Fig. 1) lying close to the shore, constitute one example. Point algal-overgrowth events are seen in places of heavy human influence. One such point is found in the Cayos Arcas reef (Campeche Bank), in a restricted area where supply and maintenance ships for the oil take shelter. In the Caribbean sector the most dramatic example is that of the small Garraf6n reef in Isla Mujeres, where in the past people were allowed to walk and stand over the reef. No other extensive algal overgrowths are seen in this sector. Periodically, after hurricanes and strong storms, when mechanical damage is severe and plenty of new substrate becomes available, fleshy algae like Padina spp. and Lobophora spp., take hold for a few months, and dominate the hard grounds. However this gradually decline to reduced, pre-storm abundances (per. obs). 4.2.5. Fish mortality. In 1980, extensive mortality was observed in the northern sector of the Mexican Caribbean. This event mainly involved herbivorous fish, and seems to have been widespread throughout the Caribbean at this time (Landsberg 1981). The cause of death was not determined, although plankton tows at the same time showed large and unusual numbers of copepods, suggesting a previous phytoplankton bloom. Since then, no other massive mortality of the kind has been observed (Table 4).
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4.2.6. Bleaching. Bleaching of corals in the northern sector of the Mexican Caribbean was observed in 1995, 1997 and 1998, but not before. The major bleaching events of 1982-83 and 1989-90, observed in other Caribbean regions (Glynn 1991) did not extend to this area, and apparently were not witnessed in the rest of the Mexican Caribbean as far as Belize. During the 1990s bleaching of corals, gorgonians and sponges occurred, most pronounced on species of the Montastraea annularis complex, Millepora complanata and Agaricia tennuifolia. Although the bleaching was extensive, it did not seem to cause extensive coral mortality and recovery proceeded rapidly (per. obs.). It is not known if there were bleaching events in the Campeche Bank and SW Gulf reefs, although isolated pale colonies were observed on several occasions (Table 4). 5. ANTHROPOGENIC IMPACTS Anthropogenic impacts on coral reefs in the Mexican Atlantic are here grouped into two major types: fisheries, and those associated with coastal developments. In the past, the SW Gulf reefs have been the most exploited, followed by the Campeche Bank reefs It is only quite recently, from the 1980s onward, that anthropogenic pressure on the Caribbean reefs has been building up to now significant levels. 5.1. Fisheries As in most other countries, fishing has been the primary use of coral reefs in the Mexican Atlantic (Table 5). There is no proper documentation of reef fisheries, as fishery information is normally based on catch landings, not on the specific location of the catches. As the fishing is carried out on the inner shelf, near reefs and in the reefs themselves as well as on the open shelf, it is not possible to know whether the catch is coming from reefs or not. Also, since most of the fishing is done in small boats, much of this catch may go unrecorded. Mexico's commercial fishing fleet consisted of 76,974 vessels in 1996, 95.7% of which were small boats (Secretaria del Medio Ambiente, Recursos Naturales y Pesca 1996).
5.1.1. SW G u l l The SW Gulf reefs are close to the shore and to near large urban centers, with the exception of the Isla Lobos reefs. In Veracruz, the largest city on the coast of the Mexican Gulf, the nearby reefs had been the object of commercial, recreational and self-sustainable fishing activities for several hundred years. The main fishing produce include octopus, snail, grouper, snapper, grunts, sharks and lobster (Secretaria del Medio Ambiente, Recursos Naturales y Pesca 1996). Some areas of seagrass beds on the shallow lagoon of the Veracruz reefs have been destroyed by clam fishing (Ch~vez and Tunnell 1993). Use of these reefs is now regulated, but enforcement seems to be difficult, mostly by lack of resources. In the other SW Gulf reefs of Tuxpan and Isla Lobos, fishing still goes on very much unchecked, and the situation seems to be similar to that known from the Veracruz reefs. 5.1.2. Campeche Bank. Fishermen from many settlements bordering the Southem Gulf of Mexico, from Veracruz to Yucat~in, exploit the Campeche Bank reefs. Fishermen will travel up to 300 km of open ocean, in 24 feet-long open boats with outboard motors and
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TABLE 5 Human use of coral reefs and its effects. H = high; M = medium; L = low; N = nil; X = not known. Issues
SW Gulf of Mexico
Campeche Bank
Caribbean
Over fishing
H
H
H
Destructive fishing methods
N
N
N
Collection of specimens
H
X
L
Coral mining (in past times)
H
N
N
Channel dredging
H
N
L
Ship grounding
H
M
M
Anchor damage
M
L
M
Eutrophication
H
N
X
Chemical pollution
H
L
X
Oil spilling
M
M
N
Agricultural runoff
H
N
N
Discharge of sewage effluents
H
N
L
Coastal strip development
H
N
H
Deforestation
H
N
L
Unrestricted tourism
M
L
M
a small ice-chest, to fish in the reefs area. Common fishing procedures are line, long-line and net fishing in and around the reefs. In the last 10 years spear and hook fishing with homemade hookas had have a very severe impact on the lobster populations in the shallow reefs. Although not technically sophisticated, the main practice is to actually comb the reef with small boats that are able to cross all over it. The day's catch is concentrated in larger vessels which carry ice-chambers and which also serve as moving platforms. The owners of small boats will usually trade fish with the crew of the larger vessels for ice or gas. 5.1.3. C a r i b b e a n . In the Caribbean reefs, the fishing effort has been intensive over the last twenty years. But is mostly directed to high quality species like spiny lobster (Panulirus argus and P. guttatus), conch (Strombus gigas), and of several species o f groupers and snappers. The Caribbean coast of Mexico was formerly an isolated and completely undeveloped area, with the exception of Cozumel and the Mujeres islands. The expansion o f the resort area of Cancfn has opened this territory to the pressures of m o d e m development. Nowadays, most commercial fin-fisheries have suffered a reduction in mean fish size and catches. An ongoing shift from fishing to guiding tourists to reefs coincides with harvesting smaller fishes of a wide array of species to fill the demand of local restaurants. Spiny lobster fishery subsists with some oscillations (Bri6nes and Lozano 1994), but conch (S. gigas) fishery is practically depleted along the mainland coast, although commercial fishing continues on Chinchorro Bank.
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5.2. Coastal developments Urban, tourism, industrial and port developments in or nearby coastal and reef zones occur in all three reef regions, although with quite different magnitudes (Table 5). 5.2.1. SW Gulf. The large city of Veracruz exerts the heaviest anthropogenic impacts on any reefs in Mexico, which results from its large size and proximity to the reefs. In addition to intense fishery, these reefs receive the outflow of major fiver systems carrying agricultural and industrial wastes both from the urban discharges of the city and port of Veracruz as well as from the wide area around it. The Anton Lizardo reefs, a few kilometers southeast of Veracruz, fare better, as they are not so close to the city, but they still suffer some riverine influence. Direct impacts are mainly those caused by ship grounding, and, by recreational divers and snorkelers which are becoming common in certain popular reefs (Chfivez and Tunnell 1993). Only one reef, Isla de Sacrificios, has been closed to recreational activities by government authorities (since 1982). Although a widespread mortality of acroporids might have affected these reefs (Jordfin-Dahlgren 1993a), they are surprisingly in a much better condition that may be suspected from all these anthropogenic influences. The reefs of Tuxpan are supposed to be affected only occasionally by contaminated river discharges, and recently, by recreational diving and snorkeling which is a great success. The Isla Lobos reefs are farther from urban settlements, but on Isla Lobos island there is an oil pumping station, and spills are known to occur. Although is not known whether these have affected the reefs. 5.2.2. Campeche Bank. It seems unlikely that the reefs of the Campeche Bank, lying far from shore, suffer any effects from coastal urban developments, nor they are currently affected by massive tourist activities. Nevertheless, a large deep-water oil terminal has been operating in the neighborhood of the Cayos Arcas reef since 1982. This terminal is able to fill up three very large tankers simultaneously in less than 48 hours and the waiting line of ships is clearly visible on the horizon (per. obs.), and the closest filling buoy is about 1.4 km WSW from the reef, in a downstream position. However, the maintenance and supply ships anchor in the open lagoon of Cayos Arcas (Fig. 2) where they have caused localized impact on the coral community below the anchoring buoys, because of the practice of dumping solid waste overboard, and possibly organic wastes as well. No other extensive, negative effects of this oil facility on the health of these reefs are documented. But chronic spills exist in the area (Gladfelter 1982) (per. obs.), and more likely the oil-tankers pump out oil-contaminated water ballast, prior to being filled. 5.2.3. Caribbean. The Mexican Caribbean is bordered by Quintana Roo state, the least populated one in the country, and an estimated annual growth rate of 6.48% between 1990 and 1995 (Instituto Nacional de Estadistica, Geografia e Informfitica 1997). This coast has become a very successful resort area and is nowadays the main destination of tourists within Mexico, with almost 4 million visitors in 1997. Because the coast was formerly undeveloped, there is a tremendous boom of resorts of all kinds to service the increasing tourist demand. Because coastal development in the area is quite recent, reef health is still good (per. obs.), but the proximity of reefs to shore and the accelerated expansion of the urban and tourism infrastructure in the coastal strip, is cause for concern.
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Aside from the threats to reefs by coastal landscape modification, which affect both the natural drainage system and shore sediment dynamics, pollution and direct physical impacts appear of paramount importance. As the mainland terrain is karstic, with little or no soil and most of the reefs are fringing the shore, urban and resort untreated discharges are the major threats, because all discharges eventually seep into the underground water system which flows from land to sea. There are no general sewage treatment systems. The only proper treatment of discharge waters is in the large resorts, while towns and small settlements have no sewage treatment. There is no effort to remove excess nutrients (as by plant uptake), beyond a few very small-scale experiments. All the impacts associated with recreational activities on coral reefs, from boating to swimmers and divers, occur in the northern reef sector. In some instances, impacts are serious enough to cause rapid reef degradation as observed locally at Garraf6n reef off Isla Mujeres and at Punta Nizuc in Cancfin. On the other hand, in Cozumel where the reefs setting is more conducive to protection and there is more ecological awareness in the users population, the National Park regulations approach adequate protection levels. Large development projects have up to now been concentrated around Cancfin. However, modem coastal development is rapidly expanding toward the south, and the government plans are to build up a huge, high density, tourist resort complex all along the Caribbean coastal strip, extending down to the Belizean border. This tourist complex will be only partially interrupted by the existing Sian Ka'an biosphere reserve area, where only low-density developments are allowed. It is hoped that proper regulations and opportune enforcement may lessen these threats, especially when the status of National Park is being granted to many reef areas, but there is still a long way to go in this respect. 6. CORAL R E E F P R O T E C T I O N Reef refuges, and marine protected regions, were established by decree for certain regions many years ago, but no formal regulation or enforcement was devised for them. Recently, after a slowly emerging national public concern and international pressures, the federal government has implemented activities to better protect natural resources of the country. For coral reefs, protection has been focused on the creation of specific protected marine areas. The current law governing protected areas is the General Law for Ecological Equilibrium and Environmental Protection, last modified in 1996. This law regulates natural protected areas, defines criteria for the use of flora and fauna, and includes guidelines for environmental impact assessment. It transfers responsibilities to state agencies and municipalities, although marine affairs are still of federal concern. There is no question that these actions are a major improvement over past government and social attitudes, and there is reasonable expectation that the protection efforts will expand. What remains to be seen is whether these actions to protect the reefs are implemented rapidly enough to buffer the effects of ever-expanding massive coastal development. In practice, lack of proper management programs, and of government funds for independent administration and surveillance hinder the proper implementation of these actions. In addition, difficult social conditions in the country, together with the poor
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quality of law enforcement, constantly challenge the strict adherence to the existing protection laws, many of which also need constant revisions as experience on the complexity of regulation accumulates. This situation is further complicated by low ecological public awareness, and as Mexican society is primarily land-based, the contact with the sea environment has been minor. A major flaw of the protection programs is lack of support for widespread educational programs at all levels (Rodriguez-Martinez and Ortiz 1999). In addition quality scientific research is not well supported, nor monitoring programs in the proper scale. 6.1. Marine protected areas reef in Mexico
Coral reefs are protected either as biosphere reserves or national parks. The second category is usually reserved for coastal and tourist development areas. Nine protected natural areas that include coral reefs exist in the Atlantic margin of Mexico, two of them are biosphere reserves and seven are national parks (Fig. 9). 6.1.2. S W Gulf of Mexico Parque Nacional Sistema Arrecifal Veracruzano. Created in 1992, this park includes
all the coral reefs in the Veracruz Reef System. It has been estimated that 1,000 divers per month visit the park between May and September and less than 200 per month the rest of the year (G. Horta per. com.). The management program is under review, but surveillance is generally insufficient. Only one reef, Isla de Sacrificios (Fig. 2), has been closed since 1982 to recreational activities by local government authorities, apparently with good results. Scientific knowledge of these reefs is limited. The main threats are: chemical pollution, oil spills (local), over-fishing, channel dredging, coastal development, and recreational impacts.
Fig. 9. Marine protected areas that include coral reefs on the Atlantic margin of Mexico. Barrier/fringing reefs along the Caribbean coastline are not evident at this scale, see figure 3. * Reefs incorporated to the protected area in 1998 are not considered in the managementprogram.
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6.1.3. Campeche Bank Parque Nacional Arrecife Alacranes. Created in 1994, but because it is relatively far from land tourism demand is still small, although ecotourism is being planned for the area with the building of dormitories on one of the islands. A management program is being developed. Although one of the more studied reefs in M6xico, scientific knowledge of this reef is still limited. The main threats are presently over-fishing, and in the near future the effects of tourism. 6.1.4. Caribbean There are seven marine protected areas in the Caribbean, four National Parks and two Biosphere Reserves (Fig. 9): Parque Nacional Costa Occidental de Isla Mujeres, Punta Canctin y Punta Nizuc. Reefs between Isla Mujeres and Cancfin were declared a Flora and Fauna Reserve in 1973, and became a National Park in 1996. Almost 2,500 tourists visit these reefs every day (Direcci6n del Parque Nacional per. com.). Serious conflicts exist among owners of marinas and fishermen. The management program was published in 1998, although scientific knowledge of these reefs is scarce. The main threats are effects of tourism, eutrophication, and pollution from untreated sewage. Parque Nacional Arrecife de Puerto Morelos. The park was created in 1998 by request of the local community. Perhaps the best known reefs in M6xico are included in this park as two marine laboratories have operated in this area since the 1970's. Scientific knowledge of these reefs can still be improved. Tourism use is low with less than 300 people per month, and fishing is allowed in the area. The coral reefs are in good condition, although undergoing recovery from damage caused by hurricane Gilbert in 1988. The management program was published in 2000. The main threats are effects of fishing on reefs, tourism, risk of increased nutrients due to the input of raw sewage. Parque Nacional Arrecifes de CozumeL SE Cozumel reefs were declared as a Refuge for the Protection of Flora and Fauna in 1980. In 1996 the area was declared a National Park, after great popular concern regarding the construction of a pier within the limits of the refuge area. Although this is one of the most visited diving sites in the world, with almost 1500 divers per day (E. Carvajal per. com.), it also has a series of ways to achieve effective reef protection. The management program was published in 1998. Scientific knowledge of these reefs is limited. The main threats are damage by careless divers, shore development, and potentially pollution from untreated sewage. Reserva de la Biosfera Banco Chinchorro. Created in 1996, it has been estimated that fewer than 100 divers visit the reef each month (A. Aguilar per. com.). Scientific knowledge of this reef is limited and the management program is being developed. The main threats are over-fishing and tourist development. Reserva de la Biosfera de Sian Ka'an. Originally a land-coastal reserve created in 1986, an additional area of coral reefs was included in 1998 (Fig. 9). Over 42,000 tourists visited the Reserve in 2000 and it is estimated than 40% of them make use of the reefs (Direcci6n de la Reserva de la Biosfera Sian Ka'an per. com.). There are approximately 120 authorized boats, most of them offering their services for sport fishing in the lagoons and bays and for the observation of the wildlife around the reserve. It has been estimated that 60% of these boats operate on the reefs. The only management program is for the decree of 1986; but the area added in 1998 is managed
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under the same criteria. Scientific knowledge of these reefs is limited. The main threats are over-fishing of commercial species (lobster, queen conch, and fish), tourist development and expanded private housing on the coast of the reserve. Parque Nacional Isla Contoy. Not a reef reserve per se, Isla Contoy was declared a Natural Reserve and Fauna Refuge in 1961, because is a nesting ground for many avian species. In 1998 it was declared a National Park, including the marine portion around it, where some reefs are found. In 2001 the average number of visitors was 1,000 per month and it is estimated than 10% make use of the reefs (Direcci6n del Parque Nacional Isla Contoy per. com.). Scientific knowledge of the few reefs is limited and the main threats are over-fishing and pollution. Parque Nacional Arvecifes de Xcalak. The park was created in 2000 by request of the local community. A management program is under development. Tourism use is low, with less than 100 visitors per month to the reefs. Main treats include over-fishing, shore development and tourist-related activities. ACKNOWLEDGMENTS
Many thanks to R. Ginsburg for a careful review of this work, and also to H. Reyes, A. Banaszak, and two anonymous reviewers for their helpful comments to this manuscript. Also we wish to thank all our colleagues who kindly share with us their knowledge of coral reefs in Mexico, particularly J.P. Carricart, G. Horta-Puga, E. Carvajal, A. Arellano and A. Aguilar. REFERENCES
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Jordan, E. 1988. Arrecifes profundos en la Isla de Cozumel, M6xico. Anal. Inst. Cienc. Mar Limnol., UNAM. 15:195-208. Jordan-Dahlgren, E. 1988. Arrecifes coralinos del Caribe Mexicano: Su potencial de uso. Informe final del convenio PCCBBNA-021928 CONACyT- UNAM, M6xico. 192 p. Jord~in-Dahlgren, E. 1989. Efecto de la morfologia del sustrato en el desarrollo de la comunidad coralina. Anal. Inst. Cienc. Mar Limnol., UNAM. 16:105-118. Jordan-Dahlgren, E. 1992. Recolonization patterns of Acropora palmata in a marginal environment. Bull. Mar. Sci. 51: 104-117. Jord~n-Dahlgren, E. 1993a. E1 ecosistema arrecifal coralino del Atlantico Mexicano. Rev. Soc. Mex. Hist. Nat. 44: 157-175. Jord~n-Dahlgren, E. 1993b. Atlas de los Arrecifes Coralinos del Caribe Mexicano. In." E1 sistema continental, Vol. 1. ICMyL-UNAM/CIQRO, M6xico, DF. 110 p. Jordan, E. & E. Martin. 1987. Chinchorro: Morphology and composition of a Caribbean atoll. Atoll Res. Bull. 310: 1-33. Jordan-Dahlgren, E. & R.E. Rodriguez-Martinez. 1998. Post-hurricane initial recovery of Acropora palmata in two reefs of the Yucatan Peninsula, Mexico. Bull. Mar. Sci. 63: 213-228. Jordan-Dahlgren, E., M. Merino, O. Moreno & E. Martin. 1981. Community structure of coral reefs in the Mexican Caribbean. Proc. 4th Int. Coral Reef Symp., Manila 2: 303-308. Jordan-Dahlgren, E., E. Martinez-Chavez, M. Sanchez-Segura & A. Gonzalez de la Parra. 1994. The Sian Ka'an Biosphere Reserve Coral Reef System, Yucatan Peninsula, Mexico. Atoll Res. Bull. 423: 1-19. Komicker, L.S., F. Bonet, R. Cann & C.M. Hoskin. 1959. Alacran Reef, Campeche Bank, Mexico. Inst. Mar. Sci. Publ., Univ. Texas. 6: 1-22. Landsberg, J.H. 1981. Unusual mass fish mortalities in the Caribbean and Gulf of Mexico. Dis. Aquat. Org. 22: 83-100. Lessios, H.A., J.D. Cubit, D.R. Robertson, M.J. Shulman, M.R. Parker, S.D. Garrity & S.C. Levings. 1984. Mass mortality of Diadema antillarum on the Caribbean coast of Panama. Coral Reefs 3:173-182. Logan, B.W. 1969. Coral reefs and banks, Yucatan shelf, Mexico. Amer. Assoc. Petrol. Geol. Mem. 11: 129-198. L6pez, L. & O.J. Polanco. 1991. La fauna de la ofrenda H del templo mayor: 199-163. In: O.J. Polanco (ed.), La fauna en el templo mayor. Inst. Nac. Antrop. Hist., Mexico. Macintyre, I.G., R.B. Burke & R. Stuckenrath. 1977. Thickest recorded Holocene reef section, Isla P6rez core hole, Alacran Reef, Mexico. Geology 5" 749-754. Moore, D.R. 1958. Notes on Blanquilla Reef. Inst. Mar. Sci. Publ., Univ. Texas 5: 151155. Morelock, J. & J. Koening. 1967. Terrigenous sedimentation in a shallow water coral reef environment. J. Sedim. Petrol. 37: 1001-1005. Muckelbauer, G. 1990. The shelf of Cozumel, Mexico: Topography and organisms. FACIES 23: 185-240. Nagelkerken, I., K. Buchan, G.W. Smith, K. Bonair, P. Bush, J. Garz6n-Ferreira, L. Botero, P. Gayle, C. Heberer, C. Petrovich, L. Pors & P. Yoshioka. 1997. Widespread disease in Caribbean sea fans: I. Spreading and general characteristics. Proc. 8th Int. Coral Reef Symp., Panama 1: 679-682.
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Rezak, R., T.J. Bright & D.W. McGrail 1985. Reefs and Banks of the Northwestem Gulf of Mexico. John Wiley & Sons, U.S.A. 259 p. Richardson, L.L., W.M. Goldberg, K.G. Kuta, R.B. Aronson, G.W. Smith, K.B. Ritchie, J.C. Halas, J.S. Feingold & S.L. Miller. 1998. Florida's mystery coral-killer identified. Nature 392: 557-558. Rigby, J.K. & W.G. MacIntyre. 1966. The Isla de Lobos and associated reefs, Veracruz, Mexico. Brigham Young Univ. Geol. Stud. 13: 3-46. Roberts, C.M. 1997. Connectivity and management of Caribbean coral reefs. Science 278: 1454-1457. Rodriguez-Martinez, R.E. & L.M. Ortiz. 1999. Coral reef education in schools of Quintana Roo, Mexico. Ocean Coast. Manag. 42: 1061-1068. Secretaria del Medio Ambiente, Recursos Naturales y Pesca. 1996. Anuario estadistico de pesca, M6xico. www.semamap.gob.mx/sspesca/annario96.htm Spaw, R.H. 1978. Late Pleistocene carbonate bank deposition; Cozumel Island, Quintana Roo, Mexico. Gulf Coast Assoc. Geol. Soc. Trans. 28: 601-619. Tunnell, J.W., Jr. 1988. Regional comparison of Southwestem Gulf of Mexico to Caribbean Sea coral reefs. Proc. 6th Int. Coral Reef Symp., Australia 3: 303-308. Tunnell, J.W., Jr. 1992. Natural versus human impacts to Southem Gulf of Mexico coral reef resources. Proc. 7th Int. Coral Reef Symp., Guam 1: 300-306. Villalobos, A.F. 1971. Estudios ecol6gicos en un arrecife coralino en Veracruz, M6xico" 531-545. In." Symp. Investig. Res. Carib. Sea Adjac. Reg., Willemstad, Curaqao. Ward, W.C., A.E. Weidie & W. Back. 1985. Geology and Hydrogeology of the Yucatan and Quatemary Geology of Northeastern Yucatan Peninsula. New Orleans Geol. Soc. 160 p.
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Coral reefs of Guatemala Ana C. Fonseca E. 1 and Alejandro Arrivillaga 2 1Centro de Investigaci6n en Ciencias del Mar y Limnologia (CIMAR), Universidad de Costa Rica. San Pedro, San Jos6 2060, Costa Rica 2johnson Controls World Services. USGS National Wetlands Research Center, 700 Cajundome Blvd. Lafayette, Louisiana 70506, USA
ABSTRACT: Coral reef research in Guatemala has a very short history. Hard-bottom biotopes are sparse along both Guatemala's coasts; however, there is no evidence of coral reefs presence on its Pacific coast. Reef development exists on the Caribbean coast, mainly around Punta de Manabique, and most reefs are protected by the Refugio de Vida Silvestre de Punta de Manabique (Punta de Manabique Wildlife Refuge). This is the sole marine park in Guatemala. Coral reefs at Punta de Manabique consist of a series of continental carbonated banks. Currently they are highly deteriorated, live coral cover is low (8.75%) and non-coralline macroalgae cover is high (65%). There are 29 species of scleractinian corals. The main impact to coral reefs at Punta de Manabique is terrestrial sedimentation coming from deforested lands, mainly from the Motagua river basin. High sediment loads are causing coral death and algae overgrowth. Apparently, current herbivorous populations are not able to control the macroalgae. Coral composition is atypical to most Caribbean reefs, which are dominated by Montastraea annularis: Guatemalan reefs are dominated by macroalgae and coral species resistant to sediments, such as Siderastrea siderea. In addition, natural events such as hurricanes, temperature increases and the massive mortality of Diadema in 1983, may have contributed to the deterioration of Guatemalan reefs. Coral reefs at Punta de Manabique constitute one of the most important resources of the coastal-marine territory of Guatemala. The economic activity in Punta de Manabique is focused on artisanal fisheries around these reefs and developing tourism. Promotion of environmental education and research, reinforcement of fishing and tourism regulations, and an adequate management plan for the Refuge and the regional fiver basins are recommended.
1. I N T R O D U C T I O N
Guatemala is located in the northern part of Central America and has borders with Mexico to the north and west, and Belize, Honduras, and E1 Salvador to the east (Fig. 1). Its territory occupies 108,780 km 2. The total littoral length is 405 km (Foer and Olsen 1992). The largest coastal zone is located on the Pacific side (255 km), in the southern portion of the country, and it consists of black volcanic sand beaches. Several small-tomedium sized rivers discharge on this side of the country and there are a series of coastal lagoons and mangrove forests. The Caribbean coast of Guatemala extends for 150 km and is located on the Gulf of Honduras; despite its small size, it supports important commercial and artisanal fisheries. Latin American Coral Reefs, Edited by Jorge Cortrs 9 2003 Elsevier Science B.V. All rights reserved.
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Fig. 2. Location of known reefs and hard bottom biotopes on the Atlantic coast of Guatemala.
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Punta de Manabique occupies a large section of this coast which is generally low with forested areas overlooking the coast, dissected with rivers. Most sea beds bottoms at the rivers mouths and bays consist of silty sands (PROARCA 1996). Three main rivers discharge their water into the Caribbean: Sarstoon, Motagua and Dulce (Fig. 1). The primary freshwater influence in the region is from Rio Motagua located on the eastern side of Punta de Manabique (Gulf of Honduras). An artificial channel, Canal de los Ingleses, connects Graciosa Bay to the eastern shore of Punta de Manabique (Y~fiez-Arancibia et al. 1999).
1.1. Reef research history Coral-reef research in Guatemala is scarce and recent. Coral reefs of the Caribbean coast have been incidentally mentioned in studies conducted with other objectives in mind. One of the earliest written reports was that of Bortone et al. (1988), who studied fish communities in an artificial reef established in 1982 in the Amatique Bay, about 15 km NW of Puerto Barrios (Fig. 1). Similarly, the presence of reef formations was indicated by Cazali (1988) in her study of bivalves and Prado (1990) in her study of gastropods. Near-shore coral reef and hard-bottom biotopes are sparse along both Guatemala's coasts, but there is reef development on the Caribbean coast of Guatemala, mainly around Punta de Manabique (Fonseca 2000) and on Heredia Shoal, 15 km west of Punta Moreno (Cazali 1988). Hard bottoms and coralline algae are present at Punta Cocoly, Punta Herreria and La Guaira, and on the littoral from Punta Herreria to Tapon Creek (Cazali 1988). Other rocky and reef beds are present near the Sarstoon River mouth and at Palo Blanco Shoal. Other reef formations know to local fishermen are Chatarra, Hamilton and Satuye (Fig. 2). There is no evidence of the existence of coral reefs on the Pacific coast maybe only isolated corals on the few hard bottoms (Cort6s and Hatziolos 1998; Kramer et al. 2000). Fonseca (2000) made a rapid reef assessment on those Caribbean carbonated banks known by fishermen around Punta de Manabique in order to describe reef structure and the composition of benthic organisms. The Point Intercept Transects Method was used to determine the relative substrate cover; using a 10 m long linear transect and recording what was located at each point every 50 cm. Chain transects were used to calculate the spatial relief (Rogers et al. 1994). A collection of corals, other invertebrates, algae and seagrass samples were deposited at the Natural History Museum of the University of Guatemala. There were no previous descriptions or evaluations of these reefs. The results of this report (Fonseca 2000) are published in this chapter. Further research must be undertaken to determine the history of formation, extension, and diversity of these reefs. Other coastal ecosystems have been studied, including mud flats (Salaverria and Rosales 1993) and seagrass beds (Arrivillaga and Baltz 1999; Y~ifiez-Arancibia et al. 1999; Arrivillaga 2000). Specifically, seagrass beds of La Graciosa Bay in Punta de Manabique have been the object of recent extensive studies (Arrivillaga 2000). In addition, the utilization of seagrass meadows by fishes and decapod crustaceans has been described for exposed (beach) and protected (bay) estuaries near the mouth and inside of La Graciosa Bay (Arrivillaga and Baltz 1999; Arrivillaga 2000). 1.2. Description of Punta de Manabique shoreline Punta de Manabique is located southwest of the Gulf of Honduras on the northeast side of Amatique Bay (Fig. 1). This peninsula is 23 km long, and is separated from the
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continent at its base by the Canal de los Ingleses. The coast of Punta de Manabique consists of a series of sandy bars and peat swamps. Sandy bars are old carbonated banks, and the swampy sections between these banks have been filled with sand and organic matter. Rain forest is the dominant vegetation (Centro de Estudios Conservacionistas 1995). The northeastern section of Punta de Manabique, facing the Gulf of Honduras, has on the windward side narrow, free gray sandy beaches exposed to high surges for most of the year. There is a large accumulation of thinks, branches, Sargassum, Thalassia, Syringodium. and garbage. These materials mainly come from the mouth of the Motagua river transported by the northwest current. The southwest section facing Amatique Bay, consists of leeward narrow, and f'me gray sandy beaches with low surge. On the southeast, Punta de Manabique has sandy beaches, with good nesting sites for the marine turtles Dermochelys coriaceae, Eretmochelys imbricata, Caretta caretta and Chelonia mydas. Graciosa Bay is a shallow coastal lagoon located on the east side of Amatique Bay. Graciosa Bay is surrounded by red mangrove forests although large sections of these mangroves were destroyed by Hurricane Mitch in 1998. It also has extensive seagrass meadows of Thalassia testudinum, Syringodium filiforme and Halodule beaudettei (Arrivillaga 2000). At La Graciosa and Amatique bays, the manatee Trichechus manatus, an endangered species worldwide, is frequently observed (Centro de Estudios Conservacionistas 1995; Fonseca 2000). 2. CORAL REEFS OF PUNTA DE MANABIQUE
2.1. Reef descriptions The reefs at Punta de Manabique are low carbonated banks (Fig. 3), with moderate coral richness, low coral cover, high noncoralline algae cover (Fig. 4), and small coral colonies (diameter and height < 1 m). A list of species found in these reefs, 29 corals, 44 other invertebrates, 24 algae and 4 seagrasses is given in Tables 1, 2 and 3. Visibility is low (7 m) and the mean temperature is 29~ A general description of four of the main banks (Graciosa, Manglar, Guinea, and Cabo Tres Puntas banks) (Fig. 2) is presented below. Graciosa bank is located 3 km west from La Graciosa Bay mouth (Fig. 1). It is 6 to 8 m deep, with an area of 25 x 50 m, and a low complexity index (i=1.37 • 0.2; Fig. 3). Mean live coral cover is 10.1 + 4.6%, and algae cover is 73.7 + 7.6% (Fig. 4). Mean density of corals is 4.0 • 1.0 colonies m -2 (Fig. 5) and 8 species were found. The most common coral species were Siderastrea siderea, Porites astreoides and Montastraea cavernosa. Suspended sediment concentrations are high and coral colonies are covered by layers of mucous. The sediment seen at this bank may come from the Canal de los Ingleses. Manglar bank is located southwest of Ptmta de Manabique and 1.5 km of shore (Fig. 2). It is 14 to 17 m deep, has an area of 25 x 25 m, and has a low complexity index (i=1.25 + 0.1; Fig. 3). Mean live coral cover is 13.6 + 6.4%, and algae cover is 33.4 + 4.3% (Fig. 4). Mean coral density is 4.0 + 1.4 colonies m "2 (Fig. 5), and 8 species were found. The most common coral species were Siderastrea siderea, Siderastrea radians, Porites astreoides, Montastraea cavernosa, Madracis decactis, Stephanocoenia micheliniL Agaricia tenuifolia, Meandrina meandrites and Helioseris cucullata. Guinea bank is composed of many reef patches of low relief (i=l .2 + 0.0; Fig. 3), with a mean depth of 24 m and located northeast of Guinea creek in San Francisco del Mar (Fig. 2). Mean live coral cover is 1.5 + 2.1%, and algae cover is 81.8 + 8.6% (Fig. 4). Mean
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1.35
i 1.25
1.15
1.1
Graciosa
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Fig. 3. Complexity index (i) by site, Punta de Manabique, Guatemala.
80
[] Graciosa bank
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.-.
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, !
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Fig. 4. Substrate cover by site, Punta de Manabique, Guatemala.
•'E1.5 "5 u
1
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~Graciosa
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Fig. 5. Coral colonies density by site, Punta de Manabique, Guatemala.
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TABLE 1 Stony corals (Class Hydrozoa and Anthozoa) found in reefs around Punta de Manabique.
Millepora complanata Porites astreoides Porites porites forma divaricata Siderastrea siderea Siderastrea radians Leptoseris cucullata Agaricia tenuifolia Agaricia agaricites Agaricia grahamae Oculina difusa
Montastraea annularis Montastraea franksi Montastraea faveolata Montastraea cavernosa Solenastrea hyades Diploria strigosa Meandrina meandrites Manicina areolata Colpophyllia natans Mycetophyllia ferox
Mycetophyllia aliciae Mycetophyllia danaana Scolymia cubensis Mussa angulosa Eusmilia fastigiata Madracis decactis Madracis mirabilis Stephanocoenia michelinii Phyllangia americana
TABLE 2 Other marine invertebrates of Punta de Manabique (*Included in CITES list). Phylum Porifera Class Demospongiae Callyspongia plicifera Callyspongia vaginalis Cibrochalina vasculum Verongula gigantea Xetospongia muta Niphates erecta Niphates digitalis Amphimedon compressa Cinachyra sp. Cliona delitrix Phylum Cnidaria Class Hydrozoa Order Hydroida Dentitheca dentritica Order Stylasterina Stylaster roseus * Class Anthozoa Subclass Octocorallia Order Gorgonacea Erythropodium caribaeorum Pseudoplexaura sp. Eunicea sp. Plexaurella sp. Muricea gpendula? Pseudopterogorgia sp. Pterogorgia guadalupensis Gorgonia ventalina Order Alcyonacea Carijoa riisei Subclass Hexacorallia Order Antipatharia Cirrhipathes (Stichopathes) leutkeni Order Zoanthidea Palythoa caribaeorum Order Actinaria Condylactis gigantea Bartholomea annulata
Phylum Ctenophora Class Tentaculata Mnemiopsis mccradyi Phylum Annelida Class Polychaeta Bispira brunnea Bispira variegata Phylum Molusca Class Gastropoda Strombus raninus Cassis madagascariensis Class Bivalvia Spondylus americanus Pinna carnea Phylum Arthropoda Class Crustacea Order Decapoda Periclimenes pedersoni Stenorhynchus seticornis Phylum Ectoprocta Class Gymnolaemata Order Cheilostomata Trematooecia aviculifera Phylum Echinodermata Class Asteroidea Oreaster reticulatus Class Holothuroidea Actinopygia agassizii Eostichopus amesoni Holothuria mexicana Class Echinoidea Lytechinus variegatus Diadema antillarum Echinometra virides Eucidaris tribuloides Phylum Chordata Class Ascidiacea Ascidia sydneiensis
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TABLE 3
Marine algae and seagrasses of Punta de Manabique. MARINE ALGAE
Phylum Phaeophyta Sargassum fluitans Sargassum sp. Dictyota ciliolata Dictyota sp. Lobophora variegata Turbinaria turbinata Phylum Chlorophyta Halimeda incrassata Halimeda discoidea Penicillus pyriformis Penicillus dumetosus Caulerpa sertularoides Caulerpa racemosa Caulerpa mexicana Codium isthmocladum Ventricaria ventricosa
Valonia utricularis Udotea sp. Acetabularia sp. Phylum Rhodophyta Galaxaura sp. Jania adherens Amphiroa tribulus Porolithon pachydermum Peyssonnelia sp. Phylum Cyanophyta Schizotrix sp. SEAGRASSES
Class Angiosperma Thalassia testudinum Syringodium filiforme Halodule beaudettei Halophila baillonis
density of corals is 0.5 a: 0.7 colonies m "2 (Fig. 5), and 9 species were found. The most common coral species were Siderastrea siderea, S. radians, Porites astreoides, Montastraea cavernosa, Madracis decactis, Stephanocoenia michelinii and Leptoseris cucullata. Several vase sponges (Niphates digitalis and Callyspongia plicifera) have been found in this site. Northeast of Cabo Tres Puntas ("Three Point Cape"), between the second and the third points, 1 to 5 km from the coast, a number of patch reefs can be found, which are well known to fishermen (Fig. 2). The bottom is sandy except for the nearest section to the first point where there is a large accumulation of mud, apparently coming from the Motagua River and other small effluents such as the San Francisco and Canal de los Ingleses. At 9 to 12 m depths, there are dense octocoral gardens (11.1 octocorals m2). From 12 to 18 m deep, there are several reef patches of low relief (i=1.19 + 0.2; Fig. 3), of around 15 x 15 m, which are separated from 50 to 100 m. There are many fleshy macroalgae attached to the substrate over the reef patches and floating over the surrounding sandy plains. Some algae reach heights of up to 1 m. Mean live coral cover is 9.1 + 3.0%, and algae cover is 55.6 + 21.5% (Fig. 4). Mean density of corals is 2.0 + 1.0 colonies rn"2 (Fig. 5), and 8 species were found. The most common coral species were Montastraea faveolata, 34. franksi, Siderastrea siderea, Stephanocoenia micheliniL Agaricia agaricites, Agaricia tenuifolia, Porites astreoides and Eusmilia fastigiata. Offshore from the sandy bank where these reef patches are located, there is a deep channel parallel to the shoreline and is used by large ships. Behind this channel, 12 km offshore, there is another sandy bank with reef patches that have never been evaluated. The substrate is mostly covered by non-coralline macroalgae, especially on Guinea and Graciosa banks (Fig. 3). Macroalgae on these banks are known to be harmful to corals. The most common species are: Caulerpa sp. and Dictyota sp., Lobophora variegata, Ventricaria ventricosa, Valonia utricularis, Codium isthmocladium, Sargassum sp. and the blue-green algae Schizotrix sp. Frequently encountered coral species on these banks
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are Siderastrea radians, S. siderea, Madracis decactis, Montastraea cavernosa, Stephanocoenia michelini and Porites astreoides. This is not the typical coral composition of most Caribbean reefs, which are usually dominated by Montastraea annularis (CARICOMP Data Base 1999). Particularly, Siderastrea siderea, Siderastrea radians and Porites astreoides are known to be very resistant to sediments and are relatively abundant in sites with a high sedimentation (Cortrs and Risk 1985). The density of coral colonies is higher on the southwestern banks of Punta de Manabique (La Graciosa and Manglar) than on the northeastern banks (Guinea and Cabo Tres Puntas) (Fig. 5). The sea urchin Diadema has not been found (Fonseca 2000). 2.2. Present condition
Reef banks within Punta de Manabique show fleshy macroalgae typical of sandy plains where herbivory is low. Apparently, the herbivorous are not able to control macroalgae abundance as on other Caribbean reefs (Hay 1984). The Manglar bank could be considered the area in best condition, as it shows the highest levels of live coral and sponge cover (Fig. 4). However, the Cabo Tres Puntas bank has the largest reef area and coral richness (Fonseca 2000). Reefs in Guatemala have degraded mainly as the result of siltation stress. Since information on these reefs is scarce, it is hard to determine changes that have occurred over time. However, live coral cover is similar to what is found on other reefs on the Central American Caribbean coast that are also affected by terrestrial sediments (e.g. 13% in Cahuita, Costa Rica) and Belize (10-16%) (CARICOMP Data Base 1999). In addition, as on other Caribbean reefs, algae cover is greater than coral cover (CARICOMP Data Base 1999). 3. NATURAL DISTURBANCES Some natural events that have affected the entire Caribbean region could have contributed to the deterioration of Guatemalan reefs. Several hurricanes that affected the Guatemalan coast (e.g. hurricanes between 1945 and 1949, Hurricane Fifi in 1972, and Hurricane Mitch in 1998) could have caused some reef destruction. Local fishermen and diving instructors have observed several bleaching events in 1983 and 1998, possibly due to temperature increases, and the Diadema massive mortality (1983) that resulted in widespread non-coralline algae overgrowth (Hughes et al. 1987). There was also an earthquake on February 4, 1976 that extended east and west from the Motagua fault (Young et al. 1989). The effects of this event on the coral reefs of Punta de Manabique were not quantified, but reefs could have been affected by sediment increase and substrate fracture, as observed in Costa Rica (Cortrs et al. 1992). 4. ANTHROPOGENIC IMPACTS It could be inferred from high-water turbidity that the biggest problem at Punta de Manabique is the chronic influx of terrestrial sediments coming from upstream rivers. This is a major long-term threat for reefs at Puma de Manabique and for continental reefs elsewhere (Wilkinson 1992). Sediments are transported by the main current that flows northwest, causing corals death and algae overgrowth. On the northeastem section
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of Puma de Manabique, the influence of the Motagua river, and other small effluents, which flow over deforested and eroded watersheds is evident. Amatique Bay also receives terrestrial sediments from the Dulce, Machacas and Sarstoon rivers and Canal de los Ingleses (Centro de Estudios Conservacionistas 1995). Human population is relatively low (850 inhabitants) on Punta de Manabique. A narrow coastal band has been used mostly for small house construction, subsistence agriculture, and cattle ranching. Artisanal fishing is the main economic activity, primarily along the eastern section of Amatique Bay and the Gulf of Honduras (Echeverria de Le6n 1994). Fishermen like to fish and dive over coralline banks where fishes, lobsters (Panulirus spp.) and snails (Strombus spp.) are concentrated. Some of the common fishing techniques (e.g. netting) are not recommended since they are neither size nor species selective. Capture levels of commercially important species from Puma de Manabique are unknown. Moreover, inhabitants from Puma de Manabique prefer to dive and extract marine resources from nearby Belizean Cays. Turtle nesting is common on the beaches of Puma de Manabique; but, eggs extraction is occasional and for domestic consumption (Centro de Estudios Conservacionistas 1995). Tourist visitation to Puma de Manabique is sporadic, and although it has increased in the last decade and the region has a high potential for greater increase (Centro de Estudios Conservacionistas 1995). Recently, a dive store was established at Amatique Bay, and it is promoting tourism. This could be positive if a good regulation plan is implemented. 5. PROTECTION AND MANAGEMENT Reef banks on the Caribbean coast of Guatemala are within the Punta de Manabique Wildlife Refuge (15~176 88013'- 88~ This refuge protects an area of 1393 kmz (449 terrestrial and 944 marine). It comprises the peninsula, 27 km east to the Motagua river, 12 km offshore in the Honduras Gulf, and the Amatique and Graciosa Bays (Centro de Estudios Conservacionistas 1995). This is the only marine park in Guatemala. However, for protection a management plan for the refuge and regional river basins must be implemented. Particularly, fishing and tourism must be regulated. Guardianship at the refuge needs to be reinforced and the environmental consciousness of the population should be promoted. Reefs from the Caribbean coast of Guatemala are within the Mesoamerican Reef System ("Sistema Arrecifal Mesoamericano", SAM) which is considered a priority for conservation worldwide. This reef system extends from the northern end of the Yucat~in Peninsula in Mexico, to the Bay Islands in Honduras, including the Barrier Reef of Belize and the Caribbean coast of Guatemala. It has been recognized by national governments at the meeting of Tulum in 1997, where they committed their countries to support its management and conservation (Marin 2000). From the species found on Punta de Manabique reefs (Tables 1, 2 and 3), all hard corals, the lace coral Stylaster roseus, and the fire coral Millepora alcicornis are included in the second category of the CITES list. This means that these species cannot be extracted from their natural environments. At present they are not in the Red List of the IUCN. Today, the most pressing research need for Guatemala's coastal ecosystems is to determine the distribution, abundance, and status of the main coral species. The location,
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composition and extent of these coastal ecosystems may be a crucial indicator of water quality and overall health of coastal resources. Unless these resources are identified and research is begun on their ecosystems, there will be few objective criteria for the formulation of management policies to foster scientifically based resource conservation. ACKNOWLEDGMENTS Mario Yon, Luisa Paredes and Eddy helped dm2ng the exploration to the reefs of Punta de Manabique. PANADIVERS store provided logistical support and valuable information. Mario Dary Foundation (FUNDARY) and The Nature Conservancy (TNC) provided coordination and funding. REFERENCES ArriviUaga, A. 2000. Ecology of seagrass fishes and macroinvertebrates on Guatemala's Atlantic coast. Ph.D. dissert., Louisiana State Univ., Baton Rouge, Louisiana. 163 p. Arrivillaga, A. & D.M. Baltz. 1999. Comparison of fishes and macroinvertebrates on seagrass and bare-sand sites on Guatemala's Atlantic coast. Bull. Mar. Sci. 65:301-319. Bortone, S.A., R.L. Shipp, W.P. Davis & R.D. Nester. 1988. Artificial reef development along the Atlantic coast of Guatemala. Northeast Gulf Sci. 10: 45-48. Cazali, G.M. 1988. Inventario de pelecipodos de la costa Atl~intica de Guatemala con enfasis en especies comestibles. Thesis, Universidad de San Carlos, Ciudad de Guatemala. 134 p. Centro de Estudios Conservacionistas. 1995. Estudio t6cnico del firea de protecci6n especial "Punta de Manabique". Propuesto Biotopo Protegido. Facultad de Ciencias Quimicas y Farmacia, Universidad de San Carlos de Guatemala, Ciudad de Guatemala. 82 p. Cort6s, J. & M.E. Hatziolos. 1998. Status of coral reefs of Central America: Pacific and Caribbean coasts. 32-37. In: C. Wilkinson (ed.), Status of Coral Reefs of the World: 1998. GCRMN, Australian Institute of Marine Science. Cort6s, J. & M.J. Risk. 1985. A reef under siltation stress: Cahuita, Costa Rica. Bull. Mar. Sci. 36: 339-356. Cort6s, J., R. Soto, C. Jim6nez & A. Astorga. 1992. Earthquake associated mortality of intertidal and coral reef organisms (Caribbean of Costa Rica). Proc. 7th Int. Coral Reef Symp., Guam 1: 235-240. Echeverria de Le6n, A.G. 1994. Caracterizaci6n de la actividad pesquera artesanal en la Peninsula de Manabique, Puerto Barrios, Izabal. Facultad de Agronomia, Instituto de Investigaciones Agron6micas, Universidad de San Carlos de Guatemala, Ciudad de Guatemala. 89 p. Foer, G. & S. Olsen. 1992. Las costas de Centro Am6rica: diagn6sticos y agenda para la acci6n. ROCAP-USAID-University of Rhode Island. 290 p. Fonseca E., A.C. 2000. Evaluaci6n ecol6gica rfipida de los arrecifes coralinos de Punta de Manabique, costa Caribe de Guatemala. Report for The Nature Conservancy (TNC), Washington D.C. 23 p. Hay, M.E. 1984. Patterns of fish and urchin grazing on Caribbean coral reefs; are previous results typical? Ecology 65: 446-454.
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Hughes, T.P., D.C. Reed & M.-J. Boyle. 1987. Herbivory on coral reefs: community structure following mass mortalities of sea urchins. J. Exp. Mar. Biol. Ecol. 113: 3959. Kramer, P., P.R. Kramer, E. Arias-Gonz~ilez & M. McField. 2000. Status of coral reefs of northern Central America: M6xico, Belize, Guatemala, Honduras, Nicaragua and E1 Salvador. 287-313. In: C. Wilkinson (ed.), Status of Coral Reefs of the World: 2000. GCRMN and Australian Institute of Marine Science. Marin, S. 2000. Unidos por un tesoro mundial en Mesoam6rica. WWF, Centroam6rica, 3 (2): 7-12. Prado, L.M. 1990. Colecta, clasificacidn y distribucidn de las especies de gaster6podos en la costa Athintica de Guatemala. Thesis, Universidad de San Carlos, Ciudad de Guatemala. 120 p. PROARCA 1996. Gulf of Honduras: preliminary site overview. PROARCA/Costas, TNC, WWF and University of Rhode Island. 22 p. Rogers, C.S., G. Garrison, R. Grober, Z.M. Hillis & M.A. Franke. 1994. Coral reef monitoring manual for the Caribbean and Western Atlantic. Natl. Park Serv., Virgin Islands. Salaverria, A. & F. Rosales. 1993. Ecologia pesquera de la costa Atl~intica de Guatemala: evaluaci6n inicial, Bahia de Amatique, Izabal. Informe de Avance. Universidad de San Carlos, Ciudad de Guatemala. 105 p. Wilkinson, C.R. 1992. Coral reefs of the world are facing widespread devastation: can we prevent this through sustainable management practices? Proc. 7th Int. Coral Reef Symp., Guam 1:11-21. Ygfiez-Arancibia, A., D.J Zarate-Lomeli, M. Gomez Cruz, R. Godinez Orantes & V. Santiago Fandino. 1999. The ecosystem framework for planning and management the Atlantic coast of Guatemala. Ocean Coastal Manag. 42:283-317. Young, C.J., T. Lay & C.S. Lynnes. 1989. Rupture of the 4 February 1976 Guatemalan earthquake. Bull. Seism. Soc. Amer. 79: 670-689.
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The reefs of Belize J. G i b s o n a and J. Carter b aCoastal Zone Management Authority and Institute, P.O. Box 1884, Belize City, Belize. bUniversity of New England, Department of Life Sciences, Biddeford, Maine 04005, U.S.A. ABSTRACT: The Belizean Barrier Reef complex includes the largest continuous reef system in the western Atlantic and includes three offshore atolls, numerous patch reefs, unique faro formations, and fringing reefs. It ranges from 10 km to 32 km in width and extends for a distance of 220 km parallel to the mainland coast. The present-day patterns of reef development along the barrier reef and within the shelf lagoon are related to the southern dip of underlying fault blocks that support the modem reef topography, regional differences in wave-energy conditions, and terrestrial runoff, particularly in the south. At its northern limit, it begins as a fringing and bank-barrier reef just offshore of the Pleistocene Ambergris Cay peninsula. Further south, it forms long sinewy stretches of barrier reef intermingled with deeper broken patches and shallow pavements dotted with various coral colonies. Interconnected coastal areas are characterized by extensive strips of mangrove forests, river deltas and estuaries, and coastal lagoons. First noted for their magnificence by Charles Darwin, these reefs have been well researched, beginning with detailed scientific studies in the late 1950s. In the early 1960s several geological and biological studies and baseline surveys were carried out by the international scientific community. In the early 1970s the Smithsonian Institution established a marine research station at Carrie Bow Cay in the central province of the Belize barrier reef, and has since completed a large number of seminal reef studies. More recently, additional research stations have been established by other agencies and organizations to foster conservation objectives as well as to conduct basic research, adding further to the quantity and quality of reef research in Belize. Despite this comprehensive research work, however, it is only recently that studies have started to document the actual health or status of Belize's coral reefs. Several monitoring initiatives are revealing that signifycant changes are occurring, such as a general decrease in percentage of coral cover in several locations and a change in coral communities. Hurricanes, coral disease, bleaching, siltation, nutrient enrichment and over fishing are the primary causes of disturbances to the reefs. Management strategies to address these impacts are a major part of the national integrated coastal zone management program, with the network of marine protected areas forming the backbone of reef protection efforts. Other significant activities of this program include land use planning, environmental impact assessments, and a mooring buoy system. This integrated approach, in coordination with a proposed regional initiative, is considered the best hope for the future conservation of the reefs of Belize.
I. H I S T O R Y
OF RESEARCH
A l t h o u g h C h a r l e s D a r w i n d e s c r i b e d the reefs o f f the coast o f B e l i z e "as the m o s t m a g n i f i c e n t .... " in his b o o k o f 1842 entitled The Structure and Distribution of Coral Reefs, r e s e a r c h on these reefs started only about four d e c a d e s ago. T h e first investigations b e g a n in 1959 and w e r e carried out by the C a m b r i d g e E x p e d i t i o n to British H o n Latin American Coral Reefs, Edited by Jorge Cort6s 9 2003 Elsevier Science B.V. All rights reserved.
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duras (Thorpe and Stoddart 1962). Their research focused on the coral species found around Rendezvous Cay. One of the expedition members, David Stoddart, later surveyed the country's three atolls: Turneffe Islands, Lighthouse Reef and Glover's Reef (Stoddart 1962). Stoddart also published a series of reports on the effects of hurricanes on the Belize reefs and their subsequent recovery (Stoddart 1963, 1969, 1974). During the 1960s, several geological studies of the reef were carried out, led by E.G. Purdy of Rice University (Purdy 1974). Other geological studies were undertaken by Robert Ginsburg and Noel James and focused on the morphology, sediments and organisms of the deep barrier reef (James and Ginsburg 1979). General reef descriptions were provided by Wantland and Pusey (1971) who described the patch reefs of Southern Belize, and by Miller and Macintyre (1977) who published a guidebook to the Belize reefs. Detailed studies of shallow barrier reefs were conducted by James et al. (1976) and on the patch reefs of Glovers Atoll by Wallace and Schafersman (1977). Since 1972, the Smithsonian Institution has run a marine research station on Carrie Bow Cay located in the central portion of the barrier reef. This station is the site of the Institution's Investigations of Marine Shallow-Water Ecosystems (IMSWE) and Caribbean Coral Ecosystems (CCRE) programs. Through these Program a large number of reef research projects and publications have been produced (Riitzler and Macintyre 1982), with scientists studying in great detail the ecology and geology of the Carrie Bow Cay reef system. More recently, scientists based on Carrie Bow Cay have studied the reefs of the Pelican Cays area (Goodbody 1995, 1996; Littler et al. 1995). Two additional research stations have been established over the past five years. These are the Wildlife Conservation Society's station on Middle Cay, Glovers Reef, and the University of Belize's marine research centre on Calabash Cay, Turne-ffe Islands. Investigations carried out by these field stations will add significantly to the volume of reef research in Belize.
2. DESCRIPTION OF REEF AREAS All the typical reef zones are present in Belize, as well as almost the entire suite of Caribbean coral species (Rtitzler and Macintyre 1982). Recent studies have led to new observations in Belize, with 61 species of stony corals (Scleractinia, Milleporidae, and Stylasteridae) now recorded (Fenner 1999). The variety of reef types includes barrier reef, atolls, patch reefs, fringing reefs and faros (Fig. 1). 2.1. Barrier reef The Belize Barrier Reef is the longest reef in the Atlantic, stretching for approximately 220 kin along the entire coast of the country, from the border with Mexico in the north to the Gulf of Honduras in the south. Its structure is determined to a large extent by the submarine geology of the area. Belize is located on the Yucatan continental block, which is separated from the Nicaraguan-Honduras block to the south by an eastwest fracture zone that forms the Cayman Trench (Perkins 1983). Along the eastern edge of the Yucatan block, a series of five parallel, north-northeast trending submarine ridges and scarps were formed (Fig. 2), and the Belize Barrier Reef is situated on the inner three of these ridges (Dillon and Vedder 1973). The ridges are on a southerly dipping
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Fig. 1. Map showingthe Belizebarrierreef and the three outeratolls (fromGarciaand Holterman 1998). platform, and during the Holocene sea level rise they were inundated at different rates due to their different elevations (Burke 1993). Between the mainland and the barrier reef lies a lagoon that is 20 to 40 km wide, and only a few meters deep in the north, deepening to 50 m towards the south.
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Fig. 2: Map showing the parallel submarine ridges along the Yucatan Block (after Dillon and Vedder 1973). The barrier reef complex is comprised of a reef crest several meters in width, a series of spurs and grooves extending seaward for about 100 meters, and a wide barrier reef platform. The reef complex varies in width from several kilometers in the north, to less than 100 meters in the south (Burke 1979). Burke (1982) has distinguished three provinces of the barrier reef system, each having distinct communities and geomorphological characteristics, a reflection primarily of the different wave energy reaching them as a result of the sheltering influence of the atolls. The northern province runs for 46 km of shallow-water reefs, extending as far as the northern tip of Gallows Point Reef. Although this province has an elevation conducive to good reef development, the factors of poor water quality and exposure to high energy waves have resulted in these being for the most part discontinuous "ribbon reefs", except for those along Ambergris Cay. The reef in the Bacalar Chico region in the north, along the border with Mexico, has the unusual formation of a double reef crest (Gill et al. 1996). Just south of the border with Mexico, the reef actually runs onto the shore at Rocky Point (McField et al. 1996). The passes in the reef in this province are typically wide and shallow.
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The central province, extending for 91 km from Gallows Poim Reef to Gladden Spit, is the best developed due to its elevation, good water quality and moderate wave action (Burke 1993). The reefs are wide and continuous, with a high-relief fore-reef and the greatest abundance of coral species. This province is the most protected from ocean waves, which has contributed to the development of the most luxuriant and extensive reefs, particularly those near Columbus and Tobacco Cays. A unique double high spur and groove system occurs in this central section of reef, extending for approximately 16 km. The southern province, running for only 10 km from Gladden Spit to the Sapodilla Cays, is characterized by discontinuous reefs, mainly adjacent to islands. Burke (1993) explains that this province is less developed due to its deeper elevation and more open exposure. The channels in the reef are narrow and deep. In this province the barrier reef ends in a J-shaped hook in the Gulf of Honduras, some 40 km from the mainland. Purdy (1998) discusses the origins of this peculiar hook-shaped configuration, proposing that the eroded limbs of an underlying syncline dictate its shape. These three provinces of shallow-water reef communities extend for a total of 147 km, with the remaining shelf edge consisting of channels, carbonate shoals, algalcovered pavement, and deeper reef communities (Macintyre and Aronson 1997). A typical cross-section of the reef can be seen in Fig. 3 as described in Rtitzler and Macintyre (1982), with the reef divided into four major zones: back reef, reef crest, inner fore reef, and outer fore reef. Burke (1979) gives a detailed description of the reef zonation through a series of transect analyses across the barrier reef. In summary, the barrier reef is composed of the common Caribbean reef communities, with varying degrees of development. Along the central barrier reef, Agaricia sp., Millepora complanata and Porites porites dominate the spurs. The spurs of the northern and southern sections, however, are comprised of coralline algae, Millepora complanata, Porites astreoides, and Diploria sp. A ridge of Acropora cervicornis characterizes the central section. (However, this has changed in recent years, due to the loss of A. cervicornis to whiteband disease, as described in section 4.2). In contrast, the northern and southern provinces have a high diversity coral community comprised primarily of Agaricia sp., Montastraea spp., Mycetophyllia spp. and Colpophyllia spp. 2.2 Atolls Three atolls lie east of the barrier reef: Tumeffe Islands, Lighthouse Reef and Glover's Reef. These are separated from the barrier reef by water 360 to 1100 m deep (Perkins 1983). 2.2.1 Turneffe Islands atoll. The Turneffe Islands atoll lies about 9 to 23 km from the barrier reef on the second submarine ridge. It is the largest atoll with an area of 531 km 2, a length of 48 km, and up to 16 km wide. It consists primarily of mangrove islands surrounding a shallow lagoon with few coral patches. It has a Segmented reef rim with 23 cuts or channels, most of which are narrow and shallow (Stoddart 1962). The windward reef is narrow and well-defined. Stoddart (1962) describes its zonation near Calabash Cay as having a Cervicornis zone, followed by an Annularis zone, a reef crest comprised of Agaricia, and an outer slope with Montastraea, Porites and Siderastrea. In contrast, the atoll's leeward reef is wider, the reef crest is not defined, and the reef is submerged. The zonation is described by Stoddart (1962) as first a sandy area with
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Fig. 3. Reef transect at Carrie Bow Cay showing zonation (from RUtzler and Macintyre 1982).
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gorgonians, then the main reef at about 3 - 5 m with Montastraea annularis, Diploria spp., Porites porites and Agaricia agaricites. The rubble-covered bottom then slopes steeply into deep water. Tumeffe Islands Atoll does not have a deep central lagoon, its reefs do not form an entire margin, and there is no reef flat, all of which are features of a true atoll. Stoddart (1962) proposes that "bank reef' would be a more appropriate term for describing this structure. 2.2.2. Lighthouse Reef atoll Lighthouse Reef is the easternmost of the atolls and, along with Glover's Reef, lies on the third submarine ridge. Extensive pavements of encrusting Lithothamnion, a feature that does not occur on the other reefs, characterize the windward reefs of both atolls. With an area of 203 km 2, Lighthouse Reef is the smallest atoll. It has a well-developed rim broken by three channels. Stoddart (1962) described the zonation of the eastern or windward reefs as first a Lithothamnion pavement, followed by a Palmata zone, a mixed reef zone with A. palmata, P. astreoides, P. porites and A. agaricites, an elevated reef-rock zone comprised of dead, eroded reef rock with Millepora, and an outer slope which falls steeply from about 1 m to over 7 m, and which then levels off to a platform with large, massive A. palmata. The western reefs are characterized by a cominuous rim of coral, with only a couple of channels, that falls steeply from the reef crest to deep water. The zonation is as follows (Stoddart 1962): a gorgonian zone, a Cervicornis zone, the reef crest dominated by M. annularis, with A. palmata, Millepora spp., A. agaricites, P. porites and Dendrogyra cylindrus, and finally a vertical wall of Montastraea. Many patch reefs are located in the fairly shallow central lagoon. However, these patches are small and without pronounced zonation (Stoddart 1962). The southeast side of the atoll has a large bight, which may have resulted from submarine slumping, resulting in the great depths off Half Moon Cay (Stoddart 1962; Meyer 1992). Meyer (1992) also suggests that additional support for this theory is provided by the narrowness of the living reef on this crescent-shaped rim. The eastern reefs of this atoll have a very wide back reef apron with an equally wide zone of living reef fronting the back-reef zone. In contrast, the reef along the Half Moon Cay bight is much narrower and the structure is compressed. This possibly represents a stage in the recovery of the windward reef following a collapse of the atoll margin. The famous "Blue Hole" is located on this atoll. This is a large circular sinkhole with a diameter of approximately 318 m and a maximum depth of 125 m (Dill 1971). Cave systems formed on offshore limestone platforms and atolls during the Pleistocene lowering of sea the level. The Blue Hole formed when the ceiling of a large cavern collapsed. The upper rim of the Blue Hole has lush coral growth, with narrow passages of only 50 meters on the northem and eastem sides. Many large stalactites extend from an overhanging ceiling, some of which tilt at an angle of 10 to 13 degrees. This indicates that during their formation, there was regional tilting by tectonic movements. Following this event, the sea levels rose and the cave was submerged. 2.2.3. Glover's Reef atoll. Glover's Reef atoll, with an area of 212 km z, has been described as a prototypic atoll: it possesses the best-developed reef growth and the greatest variety of reef types in the Caribbean (Dahl et aL 1974). Stoddart (1962) describes it as
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"a splendid example of a true atoll, comparable to anything in the Pacific or Indian oceans". The southernmost of the atolls, Glover's Reef has an almost completely emergent peripheral reef broken by only three channels (Perkins 1983). The windward reef's zonation is characterized by first a Porites zone, followed by an Annularis zone, a Porites-Lithothamnion zone, then the reef crest of dead reef-rock encrusted with A. agaricites, P. porites, Millepora, and finally a well-defined groove-and buttress zone mainly of massive A. palmata colonies on the outer slope (Stoddart 1962; Perkins 1983). (This composition has changed as a result of Hurricane Mitch in 1998; see section 4.1.). The leeward reef is also continuous with only a few openings. The zonation, as described by Stoddart (1962), is comprised of a mixed Cervicornis zone, a mixed Palmata zone, followed by an Annularis zone to depths of 5 m that continues down to 10 m with taller and massive colonies in deeper water, and then long buttresses of M. annularis and pillars of D. cylindrus. The deep central lagoon is studded with over 700 patch reefs. James and Ginsburg (1979) noted the deepest known living hermatypic corals in Belize occur off the eastern side of Glover's Reef at a depth of 103 rrL They also recorded live specimens of Halimeda commonly growing as deep as 80 m, with one observed at 110 m. This species of algae generally grows to depths of 67 to 73 m. 2.3. Patch reefs Patch reefs vary in size from small clumps of coral heads to patches 80 m wide. They are virtually absent in the northern shelf lagoon, except for areas off Ambergris Cay and near discontinuous segments of the barrier reef. However, patch reefs and "sand bores" are plentiful in the central and southern shelf lagoon and in the central lagoons of Lighthouse Reef and Glover's Reef atolls (Perkins 1983). The patch reefs of the southem lagoon have formed on Pleistocene topographic highs (Halley et al. 1977). Most patch reefs have the following zonation (Perkins 1983): seaward slopes of M. annularis and A. palmata, and a leeward slope covered with A. cervicornis and P. porites. They are often surrounded by an apron of Halimeda, sand and coral rubble. The patch reefs off Ambergris Cay, however, are dominated by M. annularis (Macintyre and Aronson 1997). Yorke (1971) conducted a comprehensive study of the southem patch reefs and noted nine types of zonations which can be grouped into three major reef zones: the coastal, inner and barrier reefs. The coastal zone patch reefs have low relief and are speciespoor, forming in brackish and often turbid water; the inner or shallow zone patch reefs form in clear water and have low relief but are species-rich; and the barrier reef zone patches have high relief with varying coral composition depending on factors such as surface currents and wave action. Halley et al. (1977) studied the structure of the Boo Bee patch reef, providing a sketch of the generalized zonation. The study also included drilling a core through the patch reef, reaching Pleistocene limestone, and providing a cross section of the reef with a sample of the sediment types at various depths. They estimated the underlying patch reef was submerged 8000 year BP. Wallace and Schafersman (1977) described the structure of patch reefs on Glover's Reef, and Wallace (1975) gives an account of the coral assemblages of three zones of patch reefs within this atoll's central lagoon. However, McClanahan and Muthiga (1998)
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show that these patch reefs have undergone a major ecological change over the past 25 years, exhibiting a 75% reduction in hard coral cover. An interesting feature is the "Spires" located on the southwest side of Glover's Reef. These are patch reefs/coral heads with a diameter of 30 to 50 m starting at a depth of 50 m, tapering off to a diameter of 3 to 8 m as they rise to the surface. They occur in a chain, running parallel with the southwest reef wall (Moore 1992). Recent research has also been conducted on the patch reefs of Mexico Rocks, off Ambergris Cay. In this region there are hundreds of patch reefs ranging in size from a meter to more than 10 m. They lie in the barrier reef lagoon, opposite a break in the reef, and along a linear high ridge of Pleistocene bedrock (Mazzullo et al. 1992). These patch reefs are considered unique because they are virtually monospecific, composed of 83% M. annularis (McHenry 1996). These reefs are younger than those found in the southern shelf lagoon, the latter area being inundated earlier during the Holocene. 2.4. Faros Faros, or rhomboidal-shaped atolls within the lagoon, are unusual reef types. They are rims of reef growing on strike-slip fault features, with steep sides enclosing a deep central lagoon, and lying in a parallel pattern reflecting the influence of faulting (Perkins 1983; Macintyre and Aronson 1997). In Belize, they are located in the widest section of the southem shelf lagoon between two deep channels, the Inner Channel and the Victoria Channel. Examples of faros include the Pelican Cays and the Laughing Bird Cay faro, which has a dramatically pinnacled lagoon. WestphaU (1986) describes three distinct units of these rhomboid reefs: the outer rims, intra-lagoons, and the inner reefs. The outer rims are generally narrow and steep-sided. The intra-lagoons can vary from small shallow areas, only a few meters across, to large deep lagoons. The inner reefs are located within the outer rim and are often linear in pattern, dissecting the intra-lagoons. The coral zonation of the faros is similar to that of other lagoon reefs. Macintyre and Aronson (1997) provide a description of the coral zonation of one of these low wave-energy patch reefs in the Pelican Cays. Westphall (1986) gives a detailed description of the Channel Cay reef complex, one of the smaller rhomboid reefs. Scientists operating from the Smithsonian's base at Carrie Bow Cay have been conducting extensive taxonomic and ecological surveys on the Pelican Cays, a faro which has experienced very little human disturbance and which has an exceptionally rich biodiversity. Goodbody (1995, 1996) has described the rich and unique ascidian communities that occur in this reef system. Littler et al. (1995) noted the very high plant diversity in the small geographic area of the Pelican Cays, stating that the main factor for this is the juxtaposition of "complex mangrove, coral, seagrass and algal biomes under stable pristine seawater conditions." This faro represents a lowenergy environment dominated by photosynthetic and filter-feeding populations.
2.5. Fringing reefs Fringing reefs occur close to the mainland in an area between Placencia and Punta Ycacos, at the northern entrance to Port Honduras (Perkins 1983). This reef community has a low diversity, dominated mainly by the hardy species of Siderastrea and Porites. These corals can tolerate variations in salinity and turbidity, which are experienced in these inshore waters.
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3. PRESENT STATE The coral reefs of the Caribbean are among those under greatest threat, possibly as a result of the Caribbean Sea being small and enclosed, its interconnection via ocean currents, and the high density of coastal human populations (Wilkinson 1993). On the other hand, Belize's relatively small population and low level of industrial development have resulted in corresponding low levels of impact on its reefs. Wells (1988) noted that the major threat was from hurricane damage, but warned that new threats may arise from runoff from agriculture and coastal tourism development. This predicted situation is materializing as a result of a population growth rate of 2.8% (NHDAC 1998), and the rapid pace of coastal development related to tourism, agriculture and aquaculture. Ian G. Macintyre of the Smithsonian Institution, who has a long history of reef research in Belize, is quoted in The State of the Coastal Zone Report: Belize 1995 (McField et al. 1996) as saying that the barrier reef can no longer be considered pristine, but it is still the best in the Caribbean. Due to the relatively good condition of its reefs, Belize is considered one of the region's most important source areas of larvae and juveniles of corals and other reef species (Cort6s 1997). 3.1. Past data
Although there has been extensive work on the geology and morphology of Belize's reefs as described above, there is a lack of consistent data which reflects the general state and health of the country's coral reef ecosystems. Results from preliminary monitoring efforts, however, illustrate some changes. For example, some sites studied show a decrease in coral cover or a change in coral composition. At Carrie Bow Cay, cover has decreased from 30-35% in the 1970s to 12-20% in 1995 at the 10-13 m depth range, due primarily to loss of A.cervicornis (Koltes et al. 1998). Macintyre and Aronson (1997) noted that, following the loss of Acropora cervicornis due to white-band disease (WBD) similar to the mass destruction of this species throughout the Caribbean, staghom rubble is now covered with brown algae, primarily Lobophora variegata in the forereef zone. In the backreef area, the loss of A. cervicornis has been replaced by Porites porites. In the area of Carrie Bow Cay the algal cover has increased, with fleshy macroalgae comprising 63% of cover in surveys carried out in 1991 (Aronson et al. 1994). In their studies conducted on the Channel Cay faro, Aronson and Precht (1997) documented a reduction in total coral cover of 30%, from 85% in 1986 to 60% in 1995. McClanahan et al. (1999) report that this macroalgal dominance is evident along the barrier reef, from Ambergris Cay in the north to the Sapodilla Cays in the south, regardless of the increasing distance of these areas from the mainland and thus from human influence. Similarly, the replacement of staghorn coral by fleshy algae has been the case at Glover's Reef atoll, where McClanahan and Muthiga (1998) have documented a decline in coral cover from 80% to 20% on the patch reefs, with the greatest change being a 99% reduction of Acropora spp. When Wallace (1975) studied the patch reefs of this atoll in 1970-1971, he reported a cover of 80% hard coral and 20% algae. The cover composition has therefore been reversed. Such high algal cover is often associated with high nutrients, but Glover's is an oceanic atoll, a long distance away from land-based influences. McClanahan and Muthiga (1998) suggest that the cause for this radical change over the past 25 years may be a combination of white-band disease and low
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herbivory, rather than nutrients, sedimentation or pollution. It is important to note, however, that the Acropora on the fore-reef was abundant and the changes only occurred on the patch reefs (McClanahan and Muthiga 1998). The fore-reef obviously has been more resilient to those factors that have resulted in the mortality of Acropora and the growth of algae on the patch reefs in the atoll's lagoon. Preliminary results of a recent investigation of the level of nutrients on the atoll, however, show that levels are high (Mumby 1998). It is proposed that these nutrients are due to upwelling on the fore-reef, and the decomposition of organic matter within the lagoon. Recent observations from satellite imagery also indicate that the run-off of nutrients from watersheds in northern Honduras can extend as far north as the Glover's Reef atoll, and could possibly be a cause of the high nutrient levels being measured (M. McField, per. com.). Further studies on the interplay of herbivory, nutrients and wave exposure are therefore required to explain this phase shift from coral-dominated to algaldominated patch reefs within the Glover's Reef lagoon. Aronson et al. (1998) describe a change in the southern lagoon reefs in which the dominant staghom coral Acropora cervicornis has been replaced by Agaricia tenuifolia. The A. cervicornis here was also decimated by an outbreak of white-band disease over the past decade. In most other places in the Caribbean, the mass mortality of staghom coral by white-band disease (WBD) has led to its replacement by fleshy macroalgae (Ginsburg 1994). On these Belize lagoon reefs, however, this is thought to have been averted by the abundance of the herbivorous sea urchin Echinometra viridis that has prevented algae from becoming established. 3.2. Current studies There are four major monitoring or rapid assessment studies which are ongoing and which should help to improve the knowledge of the health and general status of the Belize reefs. These are included in the nationwide coral reef monitoring program initiated by the Fisheries Department and the Coastal Zone Management Institute, CARICOMP, the CPACC monitoring program, and the AGRRA program. 3.2.1. National reef monitoring program. The National Coral Reef Monitoring Program, spearheaded by the Coastal Zone Management Program of the Fisheries Department, began in 1992 with the collection of data from four sites on the barrier reef using the chain transect method. Data were subsequently collected from an additional two sites located on one of the atolls. Preliminary results from these studies showed a hard coral cover ranging from 17% to 30% (Young et al. 1993; Young 1994). Young (1994) also noted a macro-algae percent cover ranging from 22% to 40% at the barrier reef sites. As the chain transect method proved to be very time-consuming and labor-intensive, the general monitoring technique was changed to the video-transect method as described by Aronson et al. (1994). Since 1995 this method has been used, in collaboration with the studies of a doctoral student, and the program has been extended to 17 sites located on the barrier reef (including northern, central and southern regions), the atolls, and a faro. Preliminary results have been recorded on species richness, number of corals bleached and diseased, reef complexity index, benthic cover, and fish abundance (McField 2001). A Coral Reef Monitoring Working Group, with representatives from government, NGOs
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and the university, has been established to coordinate the Program and to encourage additional efforts throughout the country. 3.2.2. CARICOMP. Caribbean Coastal Marine Productivity (CARICOMP) is a regional program to study land-sea interactions, which focuses primarily on productivity. In view of the mounting evidence that Caribbean coastal ecosystems are degrading because of increasing anthropogenic stresses, as well as natural and global impacts, it was recognized that a long-term monitoring program such as CARICOMP was required to document changes (CARICOMP 1997a). For the monitoring of coral reefs, CARICOMP employs the chain transect method at permanently marked sites. In Belize there are three official CARICOMP sites: one at Carrie Bow Cay monitored by the Smithsonian Institution, one at the Hol Chan Marine Reserve monitored by reserve staff, and most recently, one at Calabash Cay, Tumeffe Islands monitored by staff of the Marine Research Centre, University of Belize. CARICOMP is the first Caribbean-wide review of coral reefs that is yielding quantitative data (CARICOMP 1997a). Preliminary results for the Carrie Bow Cay site in 1995 show a mean percent cover (for 10 transects) of 59.2% for algae, and 16.6% for hard corals (CARICOMP 1997a). Comparing data for four successive years, up to 1995, very little change has occurred in community composition. This site is considered to be little influenced by the land, but experiences natural stresses of hurricanes, D i a d e m a mortality, bleaching and white-band disease, and the human impact of overfishing (CARICOMP 1997a). 3.223. CPACC program. CPACC (Caribbean Planning for Adaptation to Climate Change) is a regional project with the objective of supporting Caribbean countries in preparing to cope with the adverse effects of global climate change in coastal marine areas. It has a coral reef monitoring component that focuses primarily on the impacts of climate change on coral reefs, and which is based in the three countries of Belize, Jamaica and the Bahamas. In a workshop held in Belize in early 1998, the appropriate monitoring methodology was determined, including the criteria for site selection. It was agreed generally that Belize will monitor at least four sites, representative patch reefs located in the northern and central sections of the barrier reef lagoon and on two of the three atolls, using the video-transect technique (Walling 1998). Following another workshop held in the Bahamas in early 1999, the protocols were refined further and training was received in data analysis. Belize has subsequently started collecting data from three sites: the Glover's Reef, Hol Chan, and South Water Cay marine reserves. The results of this program should add to the knowledge base of the general status of Belize's reefs. 3.2.4. AGRRA program. AGRRA, or the Atlantic and Gulf Rapid Reef Assessment, program arose from an expressed need to develop a rapid assessment protocol to determine the status of the many reefs in this region for which there is little or no data available. This group has completed a revised protocol that uses both line transect and quadrat methods (Ginsburg et al. 1998). Belize is currently using this technique to assess several sites along its reef. It is expected that results from the data collected can contribute to the distinction between anthropogenic and natural impacts, and also identify reefs that require special protection (Ginsburg et al. 1998).
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4. NATURAL DISTURBANCES It is often difficult to determine whether disturbances are entirely natural or humaninduced, or a combination of both. For example, hurricanes are generally classified as natural disturbances. However, as a result of global warming, which is considered to be human-induced to a large extent, the intensity and frequency of hurricanes could increase (Mitchell 1990). Nevertheless, the following influences have been included as natural disturbances: hurricanes, coral diseases, bleaching, Diadema mortality and sea level rise. 4.1. Hurricanes Hurricanes have been the most powerful factor affecting the reefs of Belize (Perkins 1983; Wells 1988). Given the country's location in the hurricane belt, they will no doubt remain as possibly the greatest threat to the reefs in terms of magnitude and rate of destruction (McField et al. 1996). Major hurricanes of this century in Belize have occurred in 1931, 1955 and 1961. Stoddart (1963) documented in detail the effects of Hurricane Hattie in 1961, which had winds of 300 km/hr and high tides of 3 to 5 m. Between Rendezvous and English Cays, up to 80% of the corals were destroyed, with a belt of heavy damage extending for 5065 km, north to St. George's Cay and south to Cay Glory. No extensive colonies of A. cervicornis remained over this tract of barrier reef. Moderate damage extended as far south as Curlew Cay, presently a shoal that lies south of Carrie Bow Cay. Tumeffe Islands atoll reefs suffered extensive damage, particularly from Pelican Cay north to Mauger Cay. Branching species of coral were more susceptible to hurricane damage than massive species. The most resistant species was Montastraea annularis, the least resistant were A. cervicornis, Porites spp., and small unattached corals such as Manicina areolata and Siderastrea radians (Stoddart 1963). Destruction of coral may also have continued after the passage of the storm, as movement of the coral rubble and debris created can damage a much larger area and also hamper recolonisation (Stoddart 1963). Stoddart (1969, 1974) subsequently resurveyed these reefs, three and ten years after the passage of Hattie. By 1963 near Carrie Bow Cay, living coral in shallower spurs approached pre-hurricane luxuriance, but deeper ones were still bare. By 1972, there was no obvious evidence of storm damage (Stoddart 1974). In contrast, by 1965 at Tumeffe, living corals were still almost nonexistent. Ten years later the tract of severely damaged reef had not recovered. Based on these surveys, Stoddart (1974) concluded that it would take more than 25 to 30 years for a reef to recover to a mature stage after a catastrophic hurricane. Other hurricanes that have caused damage to the reefs include Laura in 1971, Fifi in 1974, and Greta in 1978. Near Carrie Bow Cay, Hurricane Fifi caused a proliferation of Acropora cervicornis in the back reef and lagoon, and Hurricane Greta also had a major impact on A. cervicornis, damaging the back reef and resulting in a great deal of coral debris (Wells 1988). More recently, Hurricane Mitch, which was the fourth strongest storm documented this century with winds of 290 km/hr, passed approximately 120 miles southeast of Glover's Reef during the last days of October 1998. Preliminary investigations showed that this storm caused substantial damage to the reefs. Reports received from Glover's Reef atoll (T. Bright, per. com.) note that the windward fore-reef
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was extensively damaged, with both branching and massive corals affected. Many of the corals remaining were severely abraded, with little living tissue remaining. Using survey techniques adapted from AGRRA, Kramer et al. (1999) conducted a rapid assessment of Hurricane Mitch damage at 75 reef sites in Belize, and concluded that damage to shallow reefs was highest along northeast sides of the barrier reef and atolls. In contrast, damage to deep reefs was localized and minor. It must be noted that the occurrence of Hurricane Mitch followed a severe bleaching event. Thus, the damage to the reef resulted as a series of events, beginning with elevated sea-water temperatures and the bleaching event, followed by the storm damage from Hurricane Mitch, and ending with a prolonged period of turbid freshwater flowing over the reef. The heavy rainfall associated with hurricanes can lower seawater salinities enough to affect corals adversely, causing them to eject their zooxanthellae (Stoddart 1969).
4.2. Coral diseases As mentioned earlier, WBD has been the cause of a large die-off of Acropora on many reefs in Belize. This has led to either an increase in algal cover or a change in coral species (Ginsburg 1994; Macintyre and Aronson 1997; McClanahan and Muthiga 1998; Aronson et al. 1998). Black band disease (BBD) has been recorded at sites on the barrier reef and the three atolls. It has been very prevalent in the highly used Hol Chan Marine Reserve, where treatments have been attempted (McField et al. 1996). Treatments were discontinued, however, as they proved to be ineffective. Studies in Belize (Grosholz and Ruiz 1997) have shown that black-band disease commonly infects Montastraea annularis and Diploria strigosa. The occurrence of the disease was randomly distributed and the overall cover was low, with a prevalence of 4% at the study site. Other studies have shown that BBD seems to develop more in May and June, when the seas are calm (Perkins 1983). Although it is not known whether the frequency of this disease is increasing in Belize, studies in Jamaica have shown that it can contribute to the progressive elimination of massive corals on reefs (Bruckner and Bruckner 1997). A component of the National Reef Monitoring Program is also recording the frequency of coral diseases. Preliminary results show that in addition to WBD and BBD, there are also occurrences of white plague (mainly on M. annularis and A. agaricites), yellow band disease (primarily on M. annularis), and purple blotch (on Siderastrea siderea) (McField 2001). Kramer et al. (1999) also recorded extensive damage to massive corals (Montastraea annularis) from black band disease and white plague, possibly as a result of warmer sea temperatures and the passage of Hurricane Mitch. 4.3. Diadema mortality The mass mortality of the black sea urchin Diadema antillarum in 1983, which occurred throughout the Caribbean (Lessios et al. 1984), also affected the reefs of Belize. Prior to this die-off, densities recorded on the spur and groove zone of the barrier reef at Carrie Bow Cay were as high as 4.3 urchins rn2 (Lewis and Wainwright 1985). Very few urchins, which are important herbivores on the reef, now occur. Counts carried out at the CARICOMP site near Carrie Bow Cay in 1995 showed a few very small individuals at a density of 0.07 urchins rn"2 (CARICOMP 1997a). McClanahan and Muthiga (1998) report a very low density from Glover's Reef of less than 1 per 1000 m E.
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4.4. Bleaching Coral bleaching, or the process in which corals expel their symbiotic algae, is a recent phenomenon in Belize. Low levels of "background" bleaching have been recorded in the past. For example, in 1992 reports were received of bleaching in the Laughing Bird Cay faro (Clark 1992). The species most affected was Sidereastrea siderea, with other species affected including Agaricia agaricites, Montastraea annularis, Siderastrea radians, Acropora cervicornis and M. cavernosa. Nevertheless, prior to 1995, other bleaching events reported in many areas of the Caribbean had not significantly affected Belize. 4.4.1. Mass bleaching. Widespread bleaching took place for the first time in Belize in September 1995, a time that coincided with high water temperature, calm weather and increased solar radiation. At this time, bleaching occurred throughout the Caribbean (CARICOMP 1997b). During this event 7 sites were surveyed and 59 hard corals tagged (CARJCOMP 1997b). Results showed that within 6 months partial mortality had taken place in some species, and partial to full recovery in others. In back-reef locations along the barrier reef, Montastraea annularis and Agaricia agaricites were the species most affected; on the fore-reef on the atolls, M. annularis and Siderastrea siderea were most affected. Near Carrie Bow Cay, the most severely affected species were Agaricia lamarcki and A. grahamae. McField (1999) recorded that 52% of corals surveyed in November 1995 were affected by bleaching. This survey was carried out as part of the National Reef Monitoring Program, and used a new technique, the "weighted-bar swimming transect method" (McField 1999), to rapidly and quantitatively assess the extent of bleaching. Results of this study showed that the most affected species was M. annularis, followed by S. siderea and A. tenuifolia. The extent of bleaching varied by depth for some species. S. siderea and M. annularis were more bleached in fore-reef sites, with P. porites, A. tenuifolia and other species of Agaricia more bleached in back-reef sites. By May 1996, only 7% of corals surveyed were bleached, with 25% of the tagged bleached corals showing at least partial mortality. Agaricia tenuifolia had the highest rate of partial mortality of 43%, followed by Montastraea annularis with 26%. In contrast, all the Acropora spp. had fully recovered. As previously mentioned, many reefs are now dominated by A. tenuifolia (Aronson and Precht 1997). The susceptibility of this species to bleaching and its subsequent mortality is therefore a matter of concern (McField 1999). Similarly, the significant effect of bleaching on M. annularis, a dominant coral in the Caribbean, is also a grave concern.
Burke et al. (1997) recorded the effects of bleaching on the patch reefs at Mexico Rocks, Ambergris Cay, during the 1995 bleaching event. This area also experienced 50% bleaching. Prior to the event, the patch reefs had a 35% cover of dead coral. Six months after the bleaching, this area had increased to 49%. Many of the degraded surfaces were covered with fleshy macro-algae, for example, Turbinaria spp., Padina spp., and Caulerpa racemosa. By 1997, however, a survey showed that these surfaces were free of algae. In early September 1997, reports were received of a bleaching event on the reefs of Port Honduras (W. Heyman, per. com.). Surveys showed sea temperatures as high as 34~ and salinities of 17 - 24. Down to a depth of 8 m, bleached species were recorded and included M. annularis, M. cavernosa, S. radians, S. siderea, P. astreoides, Diploria spp.,
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M. areolata, and Solenastrea bournoni. The high temperatures, coupled with the low
salinity, are thought to have triggered this bleaching. In early September 1998, first reports of bleaching were recorded for the reefs off Ambergris Cay (G. Smith, per. com.). By mid-September, the bleaching was reported to be widespread, including areas on the barrier reef, lagoonal reefs and atolls (T. Bright, per. com.). This bleaching event coincided with a time of high sea temperatures (up to 32~ and calm weather, and preliminary investigations report that it was comparable in severity to the event in 1995 (M. McField, per. com.). Kramer et al. (1999) describe the mortality from this bleaching event as extensive for shallow water reefs, with the main species affected being Agaricia tenuifolia and Millepora complanata. On deep reefs, the recovery from bleaching has been slow, with massive corals still pale and partially bleached 8 months after the event. Agaricia tenuifolia, the main species that colonized the former A. cervicornis flanks on the shoals in the south-central lagoon, experienced almost 100% mortality during this bleaching event (R. Aronson, per. com.). This change may provide the opportunity for invasion by pathogens and algae, eventually leading to a long-term decline in the reefs (McField, 1999). In summary, given the apparent increasing frequency of these events and the predicted increase in global temperature and UV radiation associated with global climate change, the longterm effects of coral bleaching could be severe and generally undermine the reef framework (Burke et al. 1997; McField, 1999). As a result of the impacts of bleaching and Hurricane Mitch, the shallow-water reefs of Belize have sustained "catastrophic losses" (Kramer et al. 1999). 4.5. Sea-level rise The impact of rising sea levels on low-lying countries fringed by coral reefs, such as Belize, is obviously of great importance. Rising sea levels bring to mind the inundation of vast expanses of coastal regions with subsequent erosion. But there is consensus among the scientific community that the threat is not immediate (Houghton et al. 1990). Controversy exists concerning the significance of the present rate of global sea-level rise, and how it may relate to the greenhouse effect (Chui 1991). Although the present rate of sea level rise and its interpretation are subject to disagreement among experts, it is a fact that sea level is rising in Belize, as it is in most coastal regions, with the potential to cause major problems just at the time when rapid coastal development is taking place. If global warming and associated sea-level rise continue to occur in the next century, these problems will be exacerbated. Recent analysis indicates that global sea level has risen about 2 mm per year for at least the last century (Trupin 1990; Douglas 1991), and probably at a much smaller rate for the previous several millennia (Keamey and Stevenson 1991; Varekamp et al. 1992). In contrast many scientists argue that global sea level will rise at a faster rate than at present because of global warming. The Intergovernmental Panel of Climate Change (IPCC) (Houghton et al. 1990) reports continued global warming and additional sealevel change of 18 cm by 2030 and 44 cm by 2070. In a separate study Church et al. (1991) calculate a rise of 35 cm by 2050. Presently the effect of rising sea level in Belize is minimal. However, should the rate of rise in sea level in future years exceed the ability of coral growth to keep pace, Belize could experience major structural damage to its unprotected coast line as well as catastrophic faunal extinction in the
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marine coastal environment. Observing and interpreting this small but highly significant acceleration of global sea level in a timely manner is a critical aspect of any climatemonitoring program. Various agencies within and outside of Belize are involved in large-scale intergovernmental efforts to monitor sea-level changes in the coming years. 5. ANTHROPOGENIC IMPACTS 5.1. Nutrient enrichment
Nutrification is one of the main anthropogenic threats to reefs in the Caribbean region (Ginsburg 1994; Szmant 1997). The two major sources of nutrients entering coastal waters in Belize are the run-off of fertilizers and the discharge of domestic sewage. Large amounts of fertilizers are used on the banana plantations located in the central and southern parts of the country and cover approximately 5,000 acres (McField et al. 1996). In 1994, the amount of fertilizers applied to banana farms totaled 3,685 tons (Usher and Pulver 1994). All the banana plantations are located near rivers and in areas of high rainfall, factors which may increase the rate of runoff (McField et al. 1996). Several studies have shown that high amounts of these chemicals enter the sea. Another area of concern is the citrus plantations in the Stann Creek Valley and the coastal plains to the south. It is believed that the run-off from the valley region could be high enough to cause eutrophication of coastal patch reefs (Hall 1994). The coastal plains, which are less fertile, require higher levels of fertilizer and lime, and drainage systems. This increases the risk of pollution of nearby coastal waters. In the case of domestic sewage, the major areas of concern are discharges from treatment facilities, septic tanks, and direct outfalls. These are concentrated in the areas of Belize City, Dangriga and populated Cays (McField et al. 1996). The only treatment facilities are located in Belize City and San Pedro, both of which provide secondary treatment. Inadequate sewage treatment and disposal, such as faulty septic tanks and direct discharge into rivers and the sea, have resulted in high nutrient levels in coastal waters in the following areas: Chetumal Bay, Belize River and Haulover Creek estuaries, Belize City area, North Stann Creek, Placencia, Punta Gorda, San Pedro, Cay Caulker and several other Cays (Archer 1994). Other important sources of nutrients include runoff from aquaculture farms and deforestation activities (McField et al. 1996). Although no studies have documented a link between nutrient enrichment and an effect on the reefs of Belize, measurements at sites along the barrier reef indicate levels ranging from undetectable to 3 ~tM of nitrates, and from undetectable to 0.6 ~tM of phosphates (Belize CZM Institute Report 1999). Studies conducted by LaPointe et al. (1992) have shown that the availability of P is the limiting factor controlling productivity and dominance of macroalgae along the Belize Barrier Reef. The threshold level concentrations for dissolved inorganic N (DIN) and soluble reactive phosphorus (SRP) that will result in enhanced macro-algae growth are >0.10 ~tM and >1.0 ~tM, respectively. The study also suggests the removal of P from wastewaters and land-based runoff as a good strategy to control eutrophication. 5.2. Siltation
Siltation of coastal waters is increased by soil erosion arising from agricultural practices in the Stann Creek and Toledo Districts, deforestation, particularly along river
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banks, destruction of mangroves and seagrass beds, and marine dredging (McField et al. 1996). Citrus plantations often include the riparian riverbanks, causing increased erosion. Milpa farming, or shifting cultivation, in the Toledo district often takes place on steep slopes, also increasing the risk of soil erosion. Several agrochemicals are sedimentbinding, and thus their transport out to coastal waters is enhanced by increased soil erosion and siltation of the rivers. The loss of mangroves along the coast can also lead to increased siltation of coastal waters. Mangroves act as a buffer, filtering runoff from the land and trapping sediments. In the Belize City area, the rate of mangrove clearance was estimated at 3.6% per year (McShane 1991), and clearance rates may have increased nationally over recent years. Marine dredging activity has been increasing in recent years with most operations carried out to fill low-lying areas for tourism or real estate development (McField et al. 1996). There is concern that many of the sites are in sensitive areas near coral reefs, and also are inadequately managed in terms of mitigating measures such as use of silt curtains. More than half the quarry or mining permits issued in 1995-1997 were for sites located near the Cays, mainly Ambergris Cay, Cay Caulker, and Cay Chapel. For example, a mining permit was issued in 1999 for the area around Cay Chapel for the extraction of 150,000 m 3. Many dredge sites have damaged seagrass beds which are important natural sediment traps, preventing silt from reaching the reef (Birkeland 1985). In general, conditions dealing with the equipment, methods, and other requirements for environmental protection are included as a term of the license issued. Regular monitoring, however, to ensure these conditions are implemented, is lacking. A study is currently underway to assess the movement of sediments from three southern watersheds into the coastal waters and the impact of these sediments on the reef (WRISCS 1998). The pattern of land use differs in each of the watersheds under investigation. This research should provide information on the links between sediment dynamics and land use patterns. 5.3. Overfishing Evidence for the effects of fishing on populations and communities of coral reef fishes in Belize and elsewhere throughout the tropics is available from a growing number of studies (Ralston and Polovina 1982; Alcala 1988; Carter et al. 1990; McClanahan and Muthiga 1994, 1997; Roberts 1995). Although these and other studies provide general information about overfishing coral reefs, there is an increasing number of studies in recent years showing that overfishing reduces the size and fecundity of fish species compared to non-fished areas (Murray et aI. 1999). For example, no-take reserves were shown to be effective at protecting exploitable species from fishery depletion and provided fish to support surrounding fisheries by increasing the abundance and larger size classes of exploitable species in reserve areas (Johnson et al. 1999). Less published evidence exists to suggest fishing on coral reefs has been directly harmful to recruitment except for a few studies on sharks and large predatory fishes. Unlike most temperate fisheries, many families of commercially important coral reef fishes (e.g. groupers) are sequential hermaphrodites and as such are theoretically highly vulnerable to overfishing (Bannerot et al. 1990). A few studies have reported direct evidence of the effects of fishing on the sex ratios of populations of sequential
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hermaphrodites (Moe 1969; Shapiro and Lubbock 1980; Colin 1992). A study of commercial catches in Belize comparing a heavily fished vs. lightly fished grouper spawning aggregation showed that the population structure of these fishes shifted toward smallersized fishes and a higher female/male sex ratio as fishing pressure increased (Carter et al. 1990). There is more evidence available that intensive fishing can alter community structure of coral reef fishes over short (Russ and Alcala 1989) and long (Koslow et al. 1994) periods of time. Two years after fishing ceased along targeted sections of the Belize barrier reef, Sedberry et al. (1992) reported higher relative abundance values and higher species diversity values for protected areas of the reef in contrast to heavily fished habitats. In a later study of similar sites, investigators again reported significant differences in fish abundance and diversity between habitat types and depths for many coral reef dependent species (Polunin and Roberts 1992). Of the commercially important coral reef fish exploited in Belize, grouper and snapper comprise the bulk of the catch. Fish are captured by hook and line seasonally at traditional spawning banks scattered throughout the reef complex (Craig 1966; Carter et al. 1990). Data from studies in Belize and elsewhere indicate that sustained and tmmanaged fishing pressure on these banks may result in changes to population structure, leading to a collapse of the fishery (Shapiro 1986; Carter et al. 1990; Colin 1992). In general, these and similar studies suggest coral reef fisheries in Belize and elsewhere are highly vulnerable to exploitation (Carter and Sedberry. 1996; Jennings and Polunin 1996; McField et al. 1996), and that marine fisheries yields on coral reefs are near or beyond their estimated maximum economic yields (Ngoile et al. 1988; Sanders et al. 1988; McClanahan and Kaunda-Arara 1996). This vulnerability to overexploitation, in contrast to fishes commonly caught in higher latitudes, is believed due in part to their peculiar life history traits (Bohnsack 1990). Unlike most temperate water fishes, reef fishes are usually restricted to the hard substrate, are often territorial, many species exhibit sex reversals, and most have limited ranges of habitat and depth (Munro and Williams 1985) and exist in "nutrient deserts" (Odum and Odum 1955; Marshall 1980). Stocks of many commercially important reef fish in Belize are faced with increasing fishing pressures and their populations are at risk of collapse or show serious signs of stress. In addition, the reductions in fish grazers attributed to overfishing (Hay 1984), particularly in combination with mass mortality of Diadema, are often cited as a cause of a switch in the dominant cover of the substratum from stony corals to fleshy algae (Levitan 1988; Shulman and Robertson 1996). Overfishing may also be responsible in part for a major change in the ecology of one of the largest and most remote reef atolls just offshore of Belize (McClanahan and Muthiga 1998). In the absence of effective conservation measures, it is likely genetic diversity will diminish in reef-dependent fishes over time, and important species will become permanently scarce or diminutive in size with reduced fecundity (Cuellar et al. 1993). In the past, conservation and management of the Belize coral reef fishes has been based on the biology of target species using conventional management techniques such as catch quotas, gear restrictions, size limits, limited entry and temporary area closures. Unfortunately these methods in Belize, as elsewhere in the Caribbean have been largely ineffective (Roberts 1997). More recently, the Belize Fisheries Department has adopted a strategy based on recommendations whereby selected habitats are set aside as fisheries
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reserves while the remaining area is managed by conventional options (Carter et al. 1992; Carter and Sedberry 1996). Strict no-take zones replicated within this broader string of protected areas are promising management tools because of their potential to 1) protect all living resources regardless of taxa; 2) enhance or maintain sustainable fisheries by preventing stock collapse and enhancing larval production by protecting brood stock (Bohnsack and Ault 1996; Roberts 1997). A high priority for Belize at the present time is the rigorous evaluation of the short and long-term effectiveness of existing marine reserves throughout the Barrier Reef Ecosystem. Strong scientific evaluation of marine reserve effectiveness is necessary to provide the empirical evidence to support theoretical assumptions. And it is equally important to disseminate the results of these evaluations to the public at large. By doing so the goals, economic and social benefits of marine reserves will be better understood to fishers and other user groups.
5.4. Direct damage Direct damage to corals has been reported from areas with intensive boat and diving activity. This includes anchor damage, boat groundings, and direct impact from divers. A large percentage of the 134,289 tourists visiting Belize in 1997 (Belize Tourist Board, 1998), went diving or snorkeling during their stay. For example, a study conducted in 1995 showed that of 305 tourists surveyed, 51% went diving and 72% participated in snorkeling (CZMP 1995). A more recent survey of 5,974 visitors showed that 31.1% went diving and 59.4% went snorkeling (Belize Tourist Board 1998). The Hol Chan Marine Reserve received 41,380 visitors during the year 1997/1998; in contrast, the number of visitors in 1991/1992 was 33,669 (Belize Tourist Board 1998). There is a clear need for these activities to be carefully managed in order to maintain a healthy reef ecosystem. Anchor damage is also a growing concern. There have been a couple of instances of severe damage from small cruise boats anchoring on the reef at Lighthouse Reef and at Glover's Reef atolls. Although the number of visitors on cruise ships had declined from a high of 13,661 in 1994, to only 2,678 in 1997 (Belize Tourist Board 1998), the industry has revived, and 1999 has so far witnessed a 28% increase in cruise-ship visitors. 5.5. Oil spills The threat of an oil spill is a potential major threat to the coral reefs of Belize. The long-term impacts of oil on reefs are well documented as the result of a major spill in Panan~ in 1986 (Jackson et al. 1989). International fuel tankers enter Belizean waters once a month, and local fuel barges transport fuel to the Cays and atolls on a weekly basis. To date, however, there have been only a few very minor spills. Risks of oil spills also occur during offshore drilling operations, and the southern section of the reef is believed to have substantial oil reserves (McField et al. 1996). Fourteen offshore wells have been drilled, the most recent one being in early 1997 at a site located between the barrier reef at Gladden Spit and the Glover's Reef atoll. No active offshore drilling, however, is presently taking place. Environmental impact assessments are required for all oil exploration projects through the provisions of the Environmental Protection Act 1992. In addition, an oilspill contingency plan is in the process of being prepared by the Department of the Environment.
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6. PROTECTION AND MANAGEMENT The protection and management of the reefs of Belize are reviewed in detail by Gibson and McField (2001). As the impacts caused by anthropogenic threats to reefs and other coastal habitats in Belize increased, the need for adopting an integrated approach to management became apparent. Early legislation in Belize targeted management of particular species, such as lobster and conch, which are important commercial fisheries species. This was followed more recently by broader legislation governing the management of habitats, such as the establishment of marine reserves and provision for the protection of mangroves. It has been recognized, however, that the integrity of protected areas may be threatened by lack of appropriate policies and legislation addressing issues that may be far removed from the boundaries of reserves, such as the impacts of landbased activities. Thus, the approach of integrated coastal zone management, which takes an even broader ecosystems approach to management, was initiated in 1990. Some of the ICZM activities undertaken which specifically relate to coral reefs include the following: (1) Expanding the network of marine protected areas; (2) Introducing land-use planning and zoning; (3) Formulating of policies, guidelines and regulations; (4) Establishing a mooring buoy system; (5) Creating a data base to provide information aimed at improving management; (6) Conducting basic monitoring and research (discussed above). 6.1. Network of Marine Protected Areas
The system of marine protected areas in Belize forms the backbone of the coastal management Program, and is one of the main strategies aimed at conserving coral reefs and their biodiversity (Bohnsack 1996). Presently there are 10 marine protected areas (MPAs), listed in Table 1 and shown in Fig. 4. All existing sites include reef habitat, with exception of the Corozal Bay Wildlife Sanctuary. Three sites are located on the offshore atolls: Glover's Reef Marine Reserve, which encompasses the entire atoll, and the Half Moon Cay and Blue Hole Natural Monuments, which are located on Lighthouse Reef. Four sites include reef tracts on the northern, central and southern provinces of the barrier reef: Bacalar Chico Marine Reserve, Cay Caulker Marine Reserve (northern province), South Water Cay Marine Reserve (central province) and Sapodilla Cays Marine Reserve (southern province). The Laughing Bird Cay National Park protects one of the faro-reef formations of the central lagoon. The Port Honduras Marine Reserve provides protection to some inshore reefs. Seven of these MPAs (Bacalar Chico Marine Reserve and National Park, Blue Hole Natural Monument, Half Moon Cay Natural Monument, South Water Cay Marine Reserve, Glover's Reef Marine Reserve, Laughing Bird Cay National Park, and Sapodilla Cays Marine Reserve) have been designated a World Heritage Site, the Belize Barrier R e e f Reserve System. This protected-area network is attempting to include representative areas of the different types of marine habitats located within the territorial waters of Belize. To this end, marine habitats were mapped from Landsat TM imagery as part of the GEF/UNDPfimded CZM Project (Matus 1997). The habitat classification scheme for this mapping
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TABLE 1 Marine-Protected Areas in Belize (adapted from Gibson et al. 1998).
Existing protected areas Hol Chan Marine Reserve Glover's Reef Marine Reserve Half Moon Cay Natural Monument Bacalar Chico National Park and Marine Reserve Laughing Bird Cay National Park South Water Cay Marine Reserve Sapodilla Cays Marine Reserve Blue Hole Natural Monument Corozal Bay Wildlife Sanctuary Cay Caulker Forest Reserve and Marine Reserve Port Honduras Marine Reserve Total
Total area (ha)
Marine area (ha)
1 116 30 784 3 925 11 303 4 286 29 789 12 742 410 71 939 4 362 40 521
1 024 30 735 3 907 6 118 4 261 29 153 12 722 410 71 939 4 299 39 848
211 177
168 867
u u u
u u u
Proposed Protected Areas Tumeffe Atoll Mexico Rocks Belize River mouth and cays u = not yet defined
exercise was developed by Mumby et al. (1998), and includes both geomorphological and benthic categories. It is expected that this marine habitat map will be analyzed in view of the existing and proposed protected area sites to determine where the gaps are and to make recommendations for additional representative areas to be added to the protected- area system. The marine-protected areas are managed either by the Fisheries Department or the Forest Department, but in some instances a joint approach to management is being taken, such as for the Bacalar Chico National Park and Marine Reserve. In some cases collaborative management with NGOs is taking place as for example, between the Forest Department and the Belize Audubon Society for the Half Moon Cay Natural Monument. This integrated approach to management, which involves more direct management by the communities involved, is also under negotiation for the management of the Laughing Bird Cay National Park and the Cay Caulker Marine Reserve. The marine-protected areas are a means for providing protection to coral reefs, particularly in relation to tourism and exploitation. Many of the MPAs have zoning schemes that provide for multiple use, such as traditional fishing and recreational activities, but with a core or "no-take" zone. Several of the reserves include within their boundaries important spawning grounds, e.g., for the Nassau grouper. More research needs to be carried out to determine the "source and sink" areas in order that marine reserves are located in the most optimum areas in terms of replenishing marine populations. However, as this is a very difficult process, the recommended action to achieve fishery and conservation goals is to establish dense networks of reserves that encompass a significant area and variety of habitats (Roberts 1998). More emphasis needs to be placed on tourism management and it is expected that this need will be addressed when the current management plans are revised or updated.
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Fig. 4, Map of existing and proposedmarine-protectedareas.
6.2. Land-use planning As many of the threats to the reef are caused by activities on land, land-use planning is a focal point of the ICZM program. Existing planning powers are being used whereby
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development plans are being prepared for many coastal areas. Two pieces of legislation allow for land-use planning in Belize: the Land Utilization Act, and the Housing and Town Planning Act (McField et al. 1996). The former provides for a type of strategic planning in which the land is zoned for the most appropriate use (rural, urban, residential, reserve, etc.) and also governs the density for subdivisions (Gibson et al. 1998). Several of the areas zoned, known as Special Development Areas, are located along the coast. In the case of subdivisions, many are also located on the coast and Cays. Under the Central Housing and Planning Authority, Ambergris Cay and Cay Caulker have been declared as special planning areas. A master plan has been developed for Ambergris Cay, and through the CZM Program a development plan is currently being prepared for Cay Caulker. Also, through the CZM Program, development guidelines have also been prepared for the Cays of the Turneffe Islands atoll and for the Cays near Belize City. These guidelines recommend specific types of development, population density, and methods for waste management, and identify particularly sensitive areas that should remain as reserve land. There are plans to zone the marine waters for particular uses under the CZM program. Apart from the zones within the MPA area system, the only existing zones are for shipping channels, no-anchoring areas, and slow-speed or no-wake areas (Gibson et al. 1998).
6.3. Policies, guidelines, and legislation The CZM Program has been active in developing policies, guidelines and legislation aimed at protecting coastal resources, particularly the reefs of Belize. Through the CZM Advisory Council, a multi-disciplinary committee, the views of the all the relevant agencies are represented. This Council is actively involved in drafting policies and guidelines to improve management of the country's coastal resources. A major issue identified was the development of the Cays or small islands, formed from either sand or mangroves, and which total over 1,000. To address the various concerns, a Cays Development Policy was prepared and will be submitted to the Cabinet for consideration. This policy document includes aspects such as land use, clearance and extraction, infrastructure, waste disposal, recreation and tourism, all of which have direct bearing on the health of the nearby coral reefs. Other policy documents prepared under the CZM Program that relate to coral reefs include those on Marine Dredging, Cruise Ships, and Small Recreational Vessels. The CZM Program has also been instrumental in contributing to the development of various guidelines, including the detailed guidelines for the development of Cays on the Turneffe Island atoll and the Cays adjacent to Belize City (see Section 6.2 above). Unfortunately, however, these guidelines and policies have not yet been formally adopted and are implemented on an a d hoc basis. Important legislation that controls development on the coast and Cays is the requirement for environmental impact assessment. Such assessments are required for large-scale developments or those that are in fragile environments, such as the Cays. As a result of the impact assessment process, mitigation measures are included which minimize any detrimental effects on coastal ecosystems. The CZM Program has also developed a CZM Act that was passed in April 1998. This Act provides for the establishment of a CZM Authority that is charged with the responsibility of coordinating all activities in the coastal zone and preparing and over-
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seeing the implementation of a comprehensive management plan for the coast. This plan should ensure the sustainable use and protection of the coastal resources of Belize. 6.4. Mooring buoy system It has been long recognized that the anchoring of boats on or near corals can cause considerable amount of damage to reefs. Anchor damage has been on the increase in Belize with the growth in marine tourism, and a national mooring buoy program was initiated to address this problem. The first "John Halas" type buoys were installed in the Hol Chan Marine Reserve in 1988. They proved to be very successful, and in 1990 the San Pedro Town Board installed a series of mooring buoys off Ambergris Cay (Azueta 1998). This was followed by installation of buoys off Cay Caulker in 1993. In collaboration with the Belize Tourist Board, the Fisheries Department installed 52 mooring buoys countrywide, starting in late 1997 (Azueta 1998). These buoys are colorcoded and mapped in a GIS data base, which includes information on buoy type, depth, GPS position, and installation date. Azueta (1998) notes that the Fisheries Department intends to conduct an educational program on the use of these buoys, holding special meetings with the dive tour guides. 6.5. Coastal resources data base The CZM Program recognized from an early stage the value of mapping data on coastal resources, their use and conservation (McField et al. 1996). Emphasis has been placed on developing a data center with geographical information system (GIS) capabilities. The CZM Institute has information available on many topics, which is used in planning, to address management issues, and to guide management decision-making. Data gathering and mapping is an ongoing process and will continue to be a central component of the CZM program. In specific relation to coral reefs, a marine habitat map for the country was developed in 1997 from Landsat TM satellite imagery.
7. CONCLUSION The health of Belize's coral reefs will depend to a large extent on the success of the integrated approach to management that is being undertaken by the Coastal Zone Management Authority and Institute, along with the implementation of the national CZM Plan. This will need to involve strengthening the management of the marine protected areas, including the implementation of on-the-ground management for those areas that are "paper parks", improving the level of reef monitoring that is directly related to management, and increasing the emphasis on surveillance and enforcement. This is recognizably an enormous challenge for Belize, to develop the capability of managing its marine resources in an effective manner that keeps pace with the country's rapid development. The success of management measures will also depend on collaboration with the adjacent countries, as the coral reef is affected by land-based activities from throughout the region. Management of the marine system should therefore also take place at the regional level. With the introduction of the Mesoamerican Barrier Reef Initiative which includes Mexico, Belize, Guatemala and Honduras, this regional approach is being addressed, and provides hope for the future of Belize's coral reefs.
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ACKNOWLEDGMENTS
We are very grateful to UNDP/GEF for financial assistance to the CZM program in Belize. REFERENCES
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Ralston, S. & J.J. Polovina. 1982. A multispecies analysis of the commercial deep sea handline fishery in Hawaii. Fish. Bull. 80: 435-448. Roberts, C.M. 1995. Rapid build-up of fish biomass in a Caribbean marine reserve. Conserv. Biol. 9:815-826. Roberts, C.M. 1997. Ecological advice for the global fisheries crisis. Trends Ecol. Evol. 12: 35-39. Roberts, C.M. 1998. Sources, sinks and the design of marine reserve networks. Fisheries 5:16-19. Russ, G.R. & A.C. Alcala. 1989. Effects of intense fishing pressure on an assemblage of coral reef fishes. Mar. Ecol. Prog. Ser. 56: 13-27. Riitzler, K. & I.G. Macintyre (Eds.) 1982. The Atlantic Barrier Reef Ecosystem at Carrie Bow Cay, Belize I: Structure and Communities. Smithson. Contr. Mar. Sci. 12:539 p. Sanders, M.J., P. Sparre & S.C. Venema. 1988. Proceedings of the workshop on the assessment of the fishery resources in the Southwest Indian Ocean. FAO NTIS RAF/79/065/WP/41/88/E: 277 p. Sedberry, G.R., J. Carter & P.A. Barrick. 1992. A comparison of fish communities between protected and unprotected areas of the Belize reef ecosystem: implications for conservation and management. Proc. Gulf Carib. Fish. Inst. 45: 95-127. Shapiro, D.Y. & R. Lubbock. 1980. Group sex ratio and sex reversal. J. Theor. Biol. 82: 411-426. Shapiro, D.Y. 1986. Reproduction in groupers: 295-327. In: J.J. Polovina & S. Ralston (eds.), Tropical Snappers and Groupers. Biology and Fisheries Management. Westview Press Inc., Boulder, Colorado. Shulman, M.J. & D.R. Robertson. 1996. Changes in the coral reef of San Bias, Caribbean PanamA: 1983 to 1990. Coral Reefs 15: 231-236. Stodddart, D.R. 1962. Three Caribbean atolls: Tumeffe Islands, Lighthouse Reef and Glovers Reef, British Honduras. Atoll Res. Bull. 87:1-151. Stoddart, D.R. 1963. Effects of Hurricane Hattie on the British Honduras reefs and cays, October 30-31, 1961. Atoll Res. Bull. 95: 1-142. Stoddart, D.R. 1969. Post hurricane changes on the British Honduras reefs: re-survey, 1965. Atoll Res. Bull. 131: 1-31. Stoddart, D.R. 1974. Post hurricane changes on the British Honduras reefs: re-survey, 1972. Proc. 2"d Int. Coral Reef Symp., Brisbane 2: 473-483. Szmant, A.M. 1997. Nutrient effects on coral reefs: a hypothesis on the importance of topographic and trophic complexity to reef nutrient dynamics. Proc. 8th Int. Coral ReefSymp., PanalT~ 2: 1527-1532. Thorpe, J.E. & D.R. Stoddart. 1962. Cambridge Expedition to British Honduras. Geogr. J. 128: 158-171. Trupin, A.W. 1990. Spectroscopic analysis of global tide gauge sea level data. Geophys. J. Int. 100: 453-551. Usher, W. & E. Pulver. 1994. Evaluation of pesticide and fertilizer usage in bananas and potential risks to the environment. NARMAP/Banana Growers Association, Winrock Intemational Institute for Agricultural Development, Belize City. 92 p. Varekamp, V.C., E. Thomas & T.E. Van de Plasche. 1992. Relative sea level rise and climate change over the last 1500 years. Terra Nova 4: 293-304.
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Wallace, R.J. 1975. A reconnaissance of the sedimentology and ecology of Glover's Reef Atoll, Belize (British Honduras). Ph.D. dissert., Princeton Univ., Princeton. 140p. Wallace, R.J. & S.D. Schafersman. 1977. Patch reef ecology and sedimentology of Glover's Reef Atoll, Belize. In: Reefs and Related Carbonates: Ecology and Sedimentology. Amer. Asso. Petrol. Geol., Studies in Geology 4: 37-53. Walling, L.J. 1998. The Proceedings of the Technical Workshop for the Implementation of Component 5: Coral Reef Monitoring for Climate Change, March 10-12, 1998, Belize City, Belize. CPACC/RPU, Barbados. 21 p. Wantland, K.F. & W.C. Pusey III. 1971. A guidebook for the field to the southern shelf of British Honduras. Gulf-Coast Asso. Geol. Soc., 21st Ann. Mtg.: 1-87. Wells, S.M. 1988. Coral Reefs of the World. Vol 1: Atlantic and Eastern Pacific. UNEP, Nairobi, IUCN, Gland. 373 p. Westphall, M.J. 1986. Anatomy and history of a tinged-reef complex, Belize, Central America. M.Sc. thesis, Univ. Miami, Coral Gables, Florida. 135 p. Wilkinson, C.R. 1993. Coral reefs of the world are facing widespread devastation: can we prevent this through sustainable management practices? Proc. 7th Int. Coral Reef Symp., Guam 1:11-21. WR/SCS. 1998. Watershed-Reef Interconnectivity Scientific Study Newsletter No. 1, May 1998. WRISCS, Raleigh International, Belize. 2 p. Yorke, M.E. 1971. Patch reef communities of southern British Honduras and illustrated catalogue of common British Honduras corals. In: K.F. Wantland & W.C. Pusey (eds.), A guidebook for the field trip to the southern shelf of British Honduras. 21st Ann. Meet. Gulf Coast Ass. Geol. Soc., Appendix 1:1-41. Young, E.R. 1994. Community descriptors for four sites along the barrier reef of Belize. Fisheries Dept., Ministry of Agriculture and Fisheries, Belize, TR-93-004, in collaboration with Caribbean Environmental Health Institute, St. Lucia. 14 p. Young, E.R., H. Mora, E. Castillo, M. Dotherow & S. Auil. 1993. An analysis of coral cover and lobster and conch population densities at Glover's Reef. Fisheries Dept., Ministry of Agriculture and Fisheries, Belize TR-93-003.20 p.
203
Nicaragua's coral reefs: status, health and management strategies Joe R y a n ~'b and Y a m i l Z a p a t a r
aUniversity of Maryland, Center for Environmental Science - AEL, 301 Bradock Rd., Frostburg, Md 21532-2307, USA. bCentre for Tropical Ecosystems Research, University of Arhus, Dept. of Ecology & Genetics, Bldg. 540, DK 8000 Arhus C., Denmark. CDANIDA Programa de Transporte, Puerto Cabezas, Nicaragua. ABSTRACT: Although corals are found on both of Nicaragua's coasts, reef-building corals have only been reported to occur on the extensive Nicaragua Shelf on the Caribbean coast. This is presumably due to differences in average nutrient concentrations, water depth and temperature on the two continental shelves. Given that coral reef formations are uncommon on the Pacific continental shelf, this chapter focuses almost entirely on the country's Caribbean reef formations, which occur in three zones on the Nicaraguan shelf- the nearshore shelf, the central shelf and the shelf edge. While the nearshore reefs were once well-developed, many of the reefs have been hit hard during the past two decades by increasingly greater volumes of fresh water and suspended sediments from 13 major rivers that drain 90% of the country's entire surface water drainage. The best-studied reefs are those on the central shelf, around the Corn Islands, where live coral cover was found to range between 5 and 55%. Average live coral cover averaged 30% at the five permanent transects at the CARICOMP site on Big Corn Island since the reef-monitoring program began in 1993. No information is available for the shelf slope. While increasing suspended sediment loads appear to be the greatest human threat to Nicaragua's nearshore reefs, fishing activities have also damaged corals in the nearshore and central zones. Direct fishing impacts include chemicals (e.g., chlorine) used by lobster divers, lobster traps dropped onto the reefs and anchor damage, whereas indirect impacts include the capture of reef herbivore and juvenile species as by-catch in Jamaican fish traps and shrimp trawlers, as well as physical destruction of seagrass nursery habitats by shrimp trawlers. Despite these multiple threats to the country's coral reefs, Nicaragua still lacks a coherent strategy for managing these ecologically important habitats. While there are many reasons for this shortcoming, much of it is related to a general lack of awareness at high political levels about the important role that coral reefs play in supporting fishery resources and biodiversity. Another reason is due to inadequate legislation for protecting corals, serious institutional gaps and overlaps in managing marine resources and biodiversity, as well as the lack of human capacity to conduct monitoring, research and integrated reef management.
1. I N T R O D U C T I O N N i c a r a g u a is one o f s e v e n Latin A m e r i c a n countries h a v i n g Pacific and C a r i b b e a n territorial waters (Fig. 1). As with the other countries, the extent o f coral r e e f d e v e l o p m e n t Latin American Coral Reefs, Edited by Jorge Cort6s 9 2003 Elsevier Science B.V. All rights reserved.
204
s Ryan & Y. Zapata MEXICO
Caribbean S e a
BELIZE
./
GUATEMALA HONDURAS
~
TmilMnm
g l l gllfftm
Nicaragua
Shelf
Pacific
Shelf
Pacific Ocean
COLOMBIA
Fig. 1: Map showingthe relative location, size and shape of Nicaragua and its two continental shelves. varies greatly between these two physiographically distinct coastal zones. Based on the limited available information, large coral reef formations have only been found on the extensive Nicaragua Shelf on the Caribbean coast. Only small patches of solitary pocilloporid and octocorals have been reported on the considerably smaller Pacific shelf, near the Costa Rican border. Although there are insufficient data for completely explaining the observed differences in coral reef growth on the two shelves, factors such as the size and morphology of the two continental shelves offer some explanation. Average water depths on the smaller Pacific continental shelf are deeper and waters are cooler as a result of seasonal upwelling and deep currents that rise to cover the shelf, thereby limiting coral reef formations. Conversely, the larger Nicaragua Shelf (25,277 km 2) is relatively shallow (average depth is 30 m). The size and depth of the shelf create conditions that enhance the warming of overlying shelf waters (Ryan 1992a), which are conducive to coral reef growth across the shelf. Available data on nutrients for Nicaragua's Pacific and Caribbean waters are sparse, but several inferences could be made regarding the differences in nutrient concentrations from the different life history strategies of the fish fauna (S/mchez 1996) on the two coasts. In general, Birkeland (1990) suggests that the response of the Pacific fish fauna to seasonally induced upwelling of nutrients has been to develop short-life cycles, with high annual species turnover rates and high population densities for most species. Alternatively, most Caribbean species tend to be long-lived species having low species turnover rates and high diversity, but they are characterized by low species population
Nicaraguas "s coral reefs
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densities (S/mchez 1996). Such characteristics are common in nutrient-poor waters where coral reefs are found (Birkeland 1990). Given that coral reef formations appear to be uncommon on the Pacific continental shelf, the remainder of this chapter will focus on the reef building corals on the Nicaraguan Shelf located on the Caribbean coast. 2. HISTORY OF CORAL REEF RESEARCH The first global attention on Nicaragua's coral reefs began in the early 1970s, when Nietschman (1973) made qualitative observations of the reefs used by turtle fishermen from Tasbapaunie on the Caribbean coast. Several years later, Geister (1983) carried out qualitative surveys and mapping of reef formations on the northern part of Big Corn Island, while several other investigators followed with studies of physical processes on the shelf. Roberts and Suhayda (1983) examined the wave energy diffraction patterns caused by the fore-reef at Big Corn Island, while Roberts and his colleagues conducted qualitative surveys ofhermatypic corals in the Pearl Cays (Roberts and Murray 1983) and bathymetfic surveys of the middle shelf (Murray et al. 1982) at the same time. Ironically, this period leading up to us backed war produced some of the best work describing coral reefs, bathymetry and physical processes since the British Admiralty Commanders Owen and Barnett surveyed the shelf (British Admiralty charts between 1836-1843). The 1980s marked a quiet period for coral reef investigations in Nicaragua, even though this was a time when coral reef research, monitoring and advanced academic training in marine science were blossoming in other Latin American countries (Cort6s 1997). During this time, Nicaragua was engaged in a major civil war and a crippling economic embargo in Nicaragua, in which security concerns made marine research difficult, funds for sampling and equipment were lacking, and there was no institutional capacity for studying or managing the country's reefs. However, Ryan and his colleagues carried out several rapid surveys in the late 1980's on the Corn Islands (Ryan et al. 1990) and Pearl Cays (Ryan 1992b) to assess the coral damage inflicted by Hurricane Joan 1990, as well as their subsequent recovery (Ryan 1992b, 1994a, b). This generated some interest by the Government and it eventually led to the development of an integrated reef management strategy for the two islands and the establishment of the permanent CARICOMP reef site and monitoring between 1992 and 1997 at Big Corn Island. After the war ended, a US-supported five-year project was launched within the Ministry of Natural Resources and the Environment (MARENA) to develop a management strategy for the marine and coastal resources in the northern part of the shelf within an area later designated as the Cayos Miskitos Reserve. However, the project paid surprisingly little attention to the abundant coral reef habitats scattered throughout the Miskito Cays, nor to the benefits of linking the fishery and coral reef management program to help protect one of the most critical habitats for what is one of the most economically important fish and lobster populations in Central America (Ryan et al. 1993, Ryan 1995). When USAID's lavish project terminated, it had only succeeded in making only a few qualitative reef surveys (Alevizon 1992; Jameson 1996; Marshall 1996) and in establishing a small reference collection of relatively common Caribbean corals at the Smithsonian (Jameson 1996). Today, the ecological relationships and the physical conditions within the Reserve are poorly understood and it remains a "paper park".
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3. ENVIRONMENTAL CONDITIONS AND ECOLOGICAL RELATIONSHIPS It is helpful to conceptualize coral reef formations as occurring in 3 geographic zones that extend across the shelf (Fig. 2), which differ with respect to the influence of rivers draining through Nicaragua's Caribbean coastal lowlands and the composition of shelf bottom sediments. They include the following: beginning from the Mean High Water Level on the mainland, extending seaward to 15 k m - shelf bottoms are a mixture of terrigenous sediments of which silt is abundant in those areas that are influenced by rivers; here bottom sediments contain less than 40% CaCO3 (Murray et al. 1982); 9 Central S h e l f - extending from a point 15 km offshore, to the edge of the continental shelf, which is composed of hard calcareous bottoms whose flat profile is interrupted by several large reef formations; bottom sediments contain between 40% and 80% CaCO3 (Murray et al. 1982); 9 Shelf Edge and S h e l f Slope - the point where the shelf drops steeply into the Caribbean; little is known about the composition of the biodiversity of this area, but it appears to be composed of Halimeda banks with some coral formations; bottom sediments are dominated by more than 80% CaCO3 (Murray et al. 1982). 9Inner S h e l f -
Some of the major coral formations found in each geographic zone, as well as available information on the physical, chemical and ecological processes on the shelf are briefly described below.
3.1. Physico-chemical processes Morphological features such as the shelf's size, shape and depth are responsible for controlling physical events such as wave energy, rainfall patterns, water temperatures and current patterns throughout much of Nicaragua's Caribbean coast (Roberts and Murray 1983). The shelf is roughly triangular in shape, extending seaward to 250 km in the north while narrowing to approximately 20 km near the Costa Rican border (Fig. 2). Water depths drop rapidly within the first few kilometers of the coastline and thereafter, they average approximately 30 meters (Roberts and Murray 1983) until reaching the edge of the shelf, where the continental slope plunges almost vertically into the deep Caribbean. The Tradewinds, which are the dominant forces responsible for surface waves on the Shelf most of the year (Fig. 2), become most intense between December and March. Data for the Corn Islands indicate that winds blow steadily from the ENE at 7-10 m s~, with a steadiness factor of 90% (Roberts and Suhayda 1983) for most of the year. As with most of the Caribbean, the strongest occur between December and late February (exceeding 30 m s~), while the calmest months are between March and May, when winds averaging less than 1 m s"l. Currents circulating on the shelf fall into three categories - the strong Caribbean Current directed toward the coast, several local currents and the Coastal Boundary Layer (CBL) running parallel to the coast. Local currents and the CBL are largely influenced by winds, but deeper currents are part of the general circulation patterns in the Caribbean (Roberts and Murray 1983).
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Fig. 2. Map of the Nicaragua's Miskito coast and the Nicaragua Shelf showing the three different zones of coral reef formations.
The Caribbean Current originates from the deeper portions of the Caribbean Sea and flows westward toward the nearshore shelf. As it encounters the shallow, warm waters of the shelf, it also warms as it spreads across the shelf. Local currents have been measured in shallow areas above the continental shelf, and they vary seasonally in both their direction and velocity (Robinson 1999; Ryan 1999). In general, local currents on the shelf run from north to south, or southeast at approximately 1-2 knots (CIP 1980; Roberts 1997). The Coastal Boundary Layer (CBL) is one of the most conspicuous currents in the nearshore zone and today it appears to be an important factor in controlling reef growth within 25 km from the coast. Visually, it appears as a sharp boundary separating turbid nearshore waters and the blue Caribbean. The CBL is established during the rainy
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season each year (see Ryan 1992a), when thirteen major rivers discharge their suspended sediment loads onto the shelf at different locations. Roberts and Murray (1983) reported that the cumulative annual water discharge (260 x 1 0 9 m 3 y-l) of the major rivers flowing through the Caribbean coastal lowlands represented 90% of the entire freshwater drainage in Nicaragua. This includes three of the five largest rivers on the isthmus. Murray and Young (1985) reported that annual sediment loads from five of these rivers were approximately 25 x 1 0 6 metric tons. During the rainy season as these rivers carry large volumes of water and suspended sediments toward the nearshore shelf, they encounter resistance from the combined forces of the Trade winds and the Caribbean Current. These counter-forces push the out-flowing river water against the coast. This produces a turbid, brackish water body with differences in water density (e.g., salinity and turbidity) relative to seawater, which results in the establishment of a weak (0.5-1.0 m/sec) coastal boundary current running southward and parallel to the coast during much of the wet season (Crout and Murray 1978; Murray et al. 1982; Murray and Young 1985; Roberts and Murray 1983; Ryan video documentation). The direction of current movement of the CBL is variable (north-south in the wet season and south north in the dry season), as are other currents on the shelf (Ryan pers. obs.; Robinson 1991, 1999). The seasonal variability of current direction on the Nicaraguan Shelf contradicts the broad generalizations made by others (CIP 1980; Roberts 1997), who assumed that current flows on the shelf are southerly. Other anecdotal information from fishermen and observations by the authors suggests that currents also flow northward during the spring, carrying turbid waters from the Rio San Juan to the Corn Islands (Ryan per. obs.) Continuous water transparency data for the Nicaragua shelf are lacking, but horizontal secchi disk measurements taken at the Corn Islands during the CARICOMP surveys between 1993 and 1997 (Ryan unpubl, data) suggested that water transparency consistently ranged between 3 m (July and November) and 25 m (March and April). While long-term, continuous salinity data are also lacking for the shelf, continuous measurements at nearby San Andrrs Island showed reported that average concentrations there were reported to be between 34 and 36 psu (Diaz and Garz6n-Ferreira 1993). Ryan et al. (1998) reported similar salinity values at the Corn Islands between July-August and March. Data on nutrient concentrations are also lacking for the Nicaraguan Shelf, although Diaz and Garz6n Ferreira (1993) have observed that seawater in the Western Caribbean is characterized by low biological productivity (<100 milligrams Carbon m 2 dl) relative to continental coastline of South America (>500 mg C m 2 dl). Hine et al. (1988) and Hallock et al. (1988) suggest that nutrients in the Western Caribbean are heterogeneously distributed and that nutrients are found in areas ofupwelling and in the plumes of large rivers that penetrate the Caribbean for great distances. Although there are no continuous air temperature, rainfall records or seawater temperatures for the Shelf, some limited temperature data were collected for the Corn Islands using Hobo-Temp probe measurements between 1994-1995 (Ryan et al. 1998). However, continuous readings were impossible because underwater Hobo-Temp probes were repeatedly stolen by lobster divers. For the available data, temperature ranged between 26 ~ and 29.5~ which were consistent with data reported by Triffelman et al. (1992) and longterm data collected between 1959-1981 for nearby San Andrrs Island reported by Diaz and Garz6n Ferreira (1993). The latter authors also reported that the annual mean air
Nicaraguas's coral reefs
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temperature for San Andr6s was 27.4~ and the relative humidity was 81% (Diaz and Garz6n-Ferreira 1993). Water temperatures during the coolest months on the Caribbean coast were from December to March, with an average of 26~ or lower, whereas average water temperatures of 28~ occur during the warmest months between May-September (Ryan et al. 1998). Average monthly rainfall is 50 nma, although rainfall varies greatly between the northern and southern part of the shelf and highest rainfall rates occur between July-November (Ryan 1992a, 1994a). 3.2. The ecological setting and environmental conditions of reefs The Nicaragua shelf contains a mosaic of corals, seagrasses and mangroves. Seagrass meadows (Thalassia testudinum) on the shelf are believed to be among the most extensive beds in the Caribbean, if not the world (Zieman per. com.). Given their widespread occurrence on the shelf, it is likely that the ecological relationships between seagrasses and coral reef complexes warrant further investigation. Reef residents such as lobster, juvenile parrotfishes and grunts are commonly observed either during the day or night within seagrasses adjacent to reefs on the central shelf (Ryan unpubl, data). Seagrasses also represent an important habitat for other reef inhabitants such as green turtles (Chelonia mydas), which may comprise the largest populations in the entire Atlantic basin (Cart et al. 1978; Mortimer 1983). Turtle fishermen frequently set their nets for green turtles around the "rocks" (corals) of the Pearl, Tara and King's Cays (Nietschman 1973; Ryan unpubl, data) and the Miskito Cays (Nietschman, per. com.). Although coral reefs, seagrasses and mangroves are believed to be closely linked through having close ecological relationships in much of the Caribbean, such a generalization is not possible for the Nicaragua shelf. These three habitats co-ocurre only in the Miskito Cays, and to a limited extent, on the middle portion of the nearshore shelf at the Pearl Cays (Ogden and Zieman 1977; Fry et al. 1982; Ogden and Galdfelter 1983). While the development of the three habitats is greatest at the Miskito Cays, only a few of the Pearl Cays contain mangroves, and seagrasses, and there is poor coral reef development (Ryan unpubl, data). On the Com islands, mangrove coverage is less than 1% of the total area of each island, but there are healthy reefs and seagrasses found on both islands. Algal flats are another ecologically important habitat associated with Nicaragua's coral reefs. Halimeda is one of the most abundant vegetative covers of shelf bottoms (Phillips et al. 1982) and on the adjacent Nicaragua Rise (Hine et al. 1988). Phillips et al. (1982) and Vadas et al. (1982) identified 77 algal species that are associated with shallow coral reefs and ridges on the northern shelf, whereas Ryan (1993) reported a total of 102 reef-associated algal species for the Miskito Cays, Corn Islands and Pearl Cays. 4. NATURAL EVENTS, HUMAN IMPACTS AND REEF CONDITIONS Until recently, the primary threat to corals on the Nicaraguan Shelf has been periodic tropical storms and seawater warming events. Hurricanes that have hit the shelf for millennia, but there have been several that have been especially strong during the past thirty-five years, including Hattie (1961), Irene (1971), Joan (1988), C6sar (1996) and Mitch (1998). Hurricane Joan hit Big Com Island directly and caused considerable damage the shallow reefs (<6 m depth) at Big Corn Island and in the Pearl Cays. Recent bleaching
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TABLE 1 Summary of information on ecological conditions of some of Nicaragua's Caribbean coral reefs (NOTE: CBL is the Coastal Boundary Layer). Station numbers are shown for the reefs surveyed at the Corn Islands. Location Pearl 9 9 9 9 9 9
Estimated Area
Cays Kalinbila a South W a t & Clark a Maroon b Askill b Seal b
A. palmata A. palmata A. palmata A. palmata A. cervicornis A. palmate 100 km 2
Big 9 9 9 9 9 9 9 9 9 9
35 km 2
9 9 9 9 9 9
BCI- 17 d BCI-18 d
Damage (Natural & Anthropogenic) Siltation;, fishery wastes C B L siltation,algae Hurricane; recovering C B L siltation C B L siltation; Hurricane Joan Hurricane Joan
20 20
CBL siltation C B L siltation
M. annularis M. annularis P. astreoides M. annularis D. clivosa D. clivosa P. astroides M. annularis A. palmata M. annularis P.astreoides A. palmata P. astroides A. palmata M.annularis M.annularis D. clivosa M.annularis M. annualris
27 <20 40 10 15 5 15 15 30 55 >20 25 20 25 30 30 5 5 5
M.annularis A. palmata M. annularis D. strigosa No Information
65 15 15 10 No Information
None Storms Storms Unknown No Information
800 km 2
M. annularis
No information
Eutrophication; siltation
<20 km 2
No information
No information
No information
None Storm; eutrophication None Eutrophication Hurricane Joan Hurricane Joan Hurricane Joan Hurricane Joan None None Storms; Hurricane Joan Storms Storms; Hurricane Joan Hurricane Joan None None Storms; Hurricane Joan Storms; eutrophication Storms; eutrophication
35 km 2
Little Corn Island 9 LCI-1 d 9 LCI-2 d 9 LCI-3 d 9 LCI-4 d 9
< 10 10 11 <5
A. palmata A. palmata
Corn Island CARICOMP reef: BCI-1 d BCI-2 d BCI-3 d BCI-4 d BCI-5 d BCI-6 d BCI-7 d BCI-8 a BCI-9 a BCI-11 d BCI-12 d BCI-13 d BCI-14 d BCI-15 a BCI- 16 d
9
Average Coral Cover (%)
690 km 2
Tara & King's Cays b 9 Little Tyra 9 Little King
9
Dominant Coral Species
Old Wife Bank
Miskito Bank 9 Morisson Dennis e San Juan River 9
Morris Shoal
9P. Christie, unpublished data; b j. Ryan, unpublished data; r J. Ryan et al. (1998); d Ryan (1994a); o W. Alevizon (1992) summarizes some of the available information on the environ-mental health of some of the reefs for which data are available, while existing information on reefs in the three zones is summarized in the remainder of this section.
events
that
have
plagued
the
Caribbean
appear
m o r t a l i t i e s i n t h e M i s k i t o C a y s (J. C o r t 6 s p e r . corn.) .
to
have
caused
considerable
coral
Nicaraguas's coral reefs
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In terms of human influences, it appears that sedimentation and nutrients from coastal rivers, and unsustainable fishing practices are the most likely factors contributing to the unusual number of dead reefs on the nearshore shelf. Unsuitable fishing gear produces physical and chemical damage, as well as direct alterations of some of the ecological relationships on many reefs. Physical damage comes diverse sources, including boat anchors and dropping wooden lobster traps on top of reefs. Chemical impacts result mainly from the use of chlorine by some lobster divers (there is no good information about how widespread this practice actually is). Ecological alterations are even more difficult to quantify, but some anecdotal information suggests that shrimp trawlers operating in the nearshore areas are catching high percentages (up to 90%) of by-catch, which includes both adult and juvenile coral reef fishes. Jamaican fish traps are also a problem due to their non-selectivity (see Ryan 1994b) and taking many reefs herbivores. For the middle part of the nearshore shelf zone, there appear to have been widespread coral mortalities between 1970 and 1993 (P. Wells per. com.; lobster fishermen per. com.) and increased sediment loads from the Rio Grande de Matagalpa (Fig. 2) appears to one of the causes. It is the third largest river (by flow volume and discharge rate) and is one of the sources of the CBL, which occasionally extends its turbid waters into the cays during the rainy season (Ryan 1992a; photo documentation). 4.1. The Nearshore Shelf
Coral reefs are found adjacent to several cays such as the Pearl, Man O'War, King and Tara Cays on the nearshore shelf. However, reef development is relatively poor in waters located less than 10 km from Nicaragua's Caribbean coastline, mainly due to the Rio San Juan, the Rio Escondido, Rio Grande de Matagalpa and Rio Coco (Fig. 2), which discharge high volumes of freshwater and sediment that empty onto the nearshore shelf during the rainy season. It has been hypothesized that the increased suspended sediment loads resulting from widespread deforestation associated with the advancing agricultural frontier (Ryan 1992a, 1994b, 1995) are one of the major causes of coral mortalities in many of the nearshore reefs (Ryan 1992a, 1994a, b; Ryan video documentation). While some reefs are reported to occur between the Rio Escondido and the Rio San Juan (P. Wells per. com.), no surveys have been made of these reefs. The following subsections present some of the available information for reefs on the nearshore shelf. 4.1.1. The Pearl Cays. The Pearl Cays (Fig. 2) comprise an archipelago of 18 cays located between 5 and 15 km east of Pearl Lagoon. They cover an area of approximately 600 km2 and are found in depths ranging between 1 and 20 rn. Most of the cays are composed of reef rubble and many of the adjacent reefs have been covered with sand or silt from coastal rivers and the CBL. The tops of many of the shallow reefs surrounding the cays can be seen during mean low water. According to fishermen, the reefs in the areas pro-vide an important lobster habitat and fishing grounds. While there is neither freshwater nor a permanent population living on the cays, transient turtle fishermen spend several weeks while setting their nets on the reefs trying to capture green and hawksbill turtles. Although a seafood company has recently set up a facility to buy lobsters from divers at one of the cays, no environmental management conditions were stipulated as of 1997.
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The available information about the health and distribution of corals in the cays is limited to just a few studies and observations that span 3 decades. Those reefs that are within 5 km from the Caribbean coastal beaches (specifically Maroon Cay) appear to have been completely dead since the late 1970s (Roberts and Murray 1983; Ryan 1992b; Christie unpubl, data). However, reefs located beyond this area seem to have undergone some major changes over the past thirty years. Nietschman (per. com.) mentioned that coral growth in the cays was "luxuriant and well-developed", especially in the northern reefs around Askill Cay in the early 1970s. Several years later, qualitative reef surveys carried out in several Pearl Cays (Roberts and Murray 1983) noted the presence of large, healthy coral reef formations and that the cays supported a thriving coral community (primarily Acropora palmata) on their windward and eastem sides. Within the last decade Ryan (1992b) found that over 70% of the corals at the four cays visited by Roberts and Murray (1983) were now comprised of dead reefs that were covered by filamentous algae and silt. In the northernmost cays, less than 20 percent live coral was observed at 20 m depths surrounding Askill Cay, which were described as being "luxurious" two decades earlier. However, patches of Acropora were well developed in some areas and new recruits of up to 12/m~-were observed at several of these northern reefs (Ryan video documentation). Massive corals (e.g., Montastraea and Siderastrea) were heavily covered with silt and algae and they did not show the same signs of regeneration. Live coral cover in all of the outer cays that were examined exceeded 10%. Christie (unpublished data) made similar observations in his survey of the same reefs 5 years later, but noted that acroporids were regenerating in some areas (Table 3), although recovery rates appeared to be slow. Most of this damage appears to be related to increasing sediment loads that are delivered by the Rio Grande de Matagalpa (Fig. 2). 4.1.2. Man O'War, Tara and King's Cays. The Man O'War, Tara and King's Cays are located less than 20 km SE of the Rio Grande de Matagalpa (Fig. 2). The area of coral growth covers approximately 100 km2. A qualitative reconnaissance of the reefs was made in May 1991, with branching (Acropora) and boulder corals (Montastraea and Siderastrea) being the most abundant of the 22 coral species observed (Ryan, unpublished data). Live coral coverage was estimated to be between 20 and 30%. Corals did not seem to have been affected by suspended sediments delivered by the Rio Grande de Matagalpa at the time. 4.2. The Central Shelf The "central shelf' commences east of the Pearl Cays and extends to the edge of the continental shelf (Fig. 2). It includes the largest reef formations on the shelf, which are located in the Miskito Cays and the Corn Islands. Coral formations on the central shelf are scattered between depths of 1 and 20 m, and reefs are well developed relative to those on the nearshore shelf, with live coral cover as high as 55%. Most of the available information for the Miskito Cays and the Corn Islands is presented in the following sub-sections.
4.2.1. The Misldto Cays. The Miskito Cays (Fig. 2) rise from one of the largest shallow platforms in the western Caribbean (Ryan 1992a). It is dotted with numerous mangrove cays and coral reefs (locally known as the Cayos Miskitos), which are located approximately 50 km due east of the mainland and form the largest group of patch reefs on the
Nicaraguas "scoral reefs
213
Nicaraguan shelf. They are important fishing grounds for local communities who have fished lobster, shrimp, turtles and finfish at subsistence levels for centuries. In 1991 the Nicaraguan Government declared the Cayos Miskitos Marine Reserve (MCMR) as the country's first marine reserve. Alevizon (1992) suggested that the northern part of the Nicaraguan shelf is divided into 2 ecologically distinct regions by a system of bank reefs, which line the continental shelf. A shallow lagoon-like area is located inshore from these banks, and is believed to restrict water movement between the two regions. Terrigenous sedimentation in this northern area appears to be high, even though seagrass meadows and patch reef formations are extensive. In his limited survey of the Miskito Cays, Alevizon found that patch reefs were broadly distributed in shallow waters around Morisson Dennis Cays seaward to a distance of approximately 15 km. Patch reefs were covered with dense filamentous mats of green algae, primarily Chaetomorpha and Debesia, which are usually associated with high nutrient inputs. Alevizon (1992) suggested that nutrient production in the extensive mangrove forests that cover most of the cays may stimulate algal growth. In an area known as Miskitnata near the Morisson Dennis Cays, he also found large Montastraea annularis colonies rising 4-5 rn above the sea floor. In a 3-day coral survey, Jameson (1996) identified 25 species of hard corals. However, he only described the reefs and adjacent marine habitats in qualitative terms (e.g., high or low quality). Suspended sediments appeared to be affecting the corals, since most flat coral forms (no values given) "showed an unusually large amount of sediment on their surface". Bottom sediments consisted of fine material that was easily stirred up. He also indicated that satellite images from the US National Oceanic and Atmospheric Administration (NOAA) showed that most of the sedimentation and eutrophication affecting the MCMR comes from rivers on the Honduran coast. Corals were overgrown by fleshy micro-algae on the northwest reefs by the Honduran border. Although the survey reported that coral recruitment was "high", no values were given. Marhsall (1996) conducted fish surveys on 9 reefs (between 1-5 m depths) in the MCMR. Although he did not identify any coral species in the area, he reported that all reefs were surrounded by Thalassia and that carpet algae (no species mentioned) was abundant in the survey areas. Of the 35 fish reef species identified, one third were herbivores (no data on fish abundance were reported). 4.2.2. The Corn Islands. The Corn Islands rise above the central Nicaraguan Shelf to form the only inhabited islands along the Caribbean coast of Nicaragua (Figs. 2 and 3). Great Corn Island lies between latitudes 12008'40'' and 12~ and longitudes 83004'24 '' and 83~ and has an area of approximately 10.3 km2. It is inhabited by around 5,000 people, making it one of the most densely populated areas in Nicaragua. Little Corn Island, located 15 km to the northeast, is approximately half the size and has a population of about 500. A lobster and scale fish fishery, and two seafood processing plants producing over 40% of Nicaragua's total seafood exports, provide the primary sources of income for the two islands (Ryan et al. 1993; Ryan 1994a, b, 1995). Divers and lobster boats are the primary visitors to the reefs. The physical shape of the fringing reef systems surrounding the two islands differ with respect to their configuration and orientation to the incoming waves. The fringing reef on Big Corn runs from the northem shore, and arcs for approximately 2 km toward the south.
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J. Ryan & Y. Zapata
The drop-off on the seaward edge of the reef is gradual and begins at around 10 rn water depth on the top of the reef, down to 15 m where the reef gives way to extensive sand fiats and hard limestone bottoms with numerous patch reefs. The fringing reef on Little Corn Island runs in the opposite direction (south to north) on Little Com. On both islands, the extent of coral development appears to be related to water depth, and to the type of underlying substrate within the different reef zones. General descriptions are available for the physiographic features (Conzemius 1929; McBirney and Williams 1965) and underwater environments (Geister 1983; Roberts and Suhayda 1983; Ryan 1992b, 1994a, b; Ryan et al. 1998) of Big Corn Island. The underlying geology and hydrological forces in operation on the island are summarized by Ruden (1993), who calculated that approximately one-half of the island lies beneath the 2 m contour line, and a sea level rise of only 0.5 m would inundate about one-third of the island. He noted that the island is composed of Tertiary (Miocene-Pliocene) basalts protruding through late Tertiary carbonates. These basalt formations extend offshore, covering an area of approximately 10 km2 and are probably the foundation of the first reef building corals. It has been hypothesized (Broegaard 1995) that the island's dynamic aquifer is geologically connected to the nearshore reefs (<1 km from the island) through small fissures and that freshwater and sewage from the island may be seeping over these reefs. Ryan (1992b) and Broegaard (1995) have hypothesized one of the primary causes to be nutrients from Big Corn Island entering the sea from both surface runoff and through sub-terraneous connections. Characterization o f the reefs on Big Corn Island. The reef "system" surrounding Big Corn Island (Fig. 3) is actually composed of four different formations - inner patch reefs in the back:reef lagoon, the nearshore Cana fringing reef, outer patch reefs greater than 1 km from shore, and the rock reefs on the south side of the island. The first two formations protect the big island from storm surge by dissipating up to 80% of the wave energy directed toward the island (Roberts and Suhayda 1983). One of us (Ryan) conducted several visual surveys of the reef system one week prior to the hurricane, and 6 months after the hurricane. Extensive areas of the reefs were covered or scoured by shifting sands due to Hurricane Joan, while 3 m tall colonies of Acropora palmata were knocked over (Ryan et al. 1990; Ryan 1992b, 1994a). While acroporids regenerated in many of the damaged areas, massive corals were badly damaged in shallow (<4 m) waters. The effects of the recent Hurricane Mitch on the northern portion of the shelf are unlaaown. Using the standard quadrat method, Ryan and his colleagues subsequently carried out quadrat surveys of 18 stations at Big Corn Island and they identified 15 species that comprise 90% of the live coral coverage on the Corn Island reefs (Ryan 1994a). However, they found no statistically significant differences in coral species diversity between the nearshore and outer reefs at Big Corn Island, although differences in living coral cover between the two areas was significant. Coral coverage around the island ranges from less than 5% in the reefs less than 1 km from the shore to 55% on some of the deeper patch reefs along the fringing reef (Ryan 1992b; 1994a). Many of the nearshore reefs located within 1 km from Big Corn Island were found to be in a state of decline in 1993. Coral abundance, species diversity, and species richness in the reefs within this area are lower than the offshore patch reefs. Algae and encrusting sponges have colonized damaged corals in these shallow areas.
Nicaraguas "s coral reefs
215
Other quantitative surveys of a portion of the Corn Island reefs were carried out at a permanently marked reef as part of the CARICOMP Program, which Nicaragua joined in 1992 (see Smith et al. 1994; CARICOMP 1997 a, b, c). Five permanent transects were established and monitored using a combination of chain, quadrat and video measurements. The methodology and results for a three year period are described elsewhere (Ryan et al. 1998). During 1994, the quadrat method was used to compare results from the line transects at the CARICOMP site. Figure 3 shows the relative location of these sites.
Caribbean Sea
BCl-7 (CARICOMP)
Cana Reef oeo 9
9
9
9
Rocky Pt.
Brig Bay
.
- :. .... ,,,.. ........ ,:.,,.-7
"
Brad Bay
Inllil
hnl'
/ ...."~ Mangroves
,t111 Nearshorereefs 9
CoralReef survey sites
I Note: Map not scale; Big Corn Island area is 10 km2
. . . . . .
ii
Fig. 3. Map of the Big Corn Island showing the permanent CARICOMP monitoring site and the reef locations that have been surveyed.
Table 2 lists some of the species that were found in the two different studies and illustrates the observed differences between the chain transect and meter square methods that were used in the two studies. The data represent average values for at least up to 10 replicate samples per quadrat at 15 different locations and five transects at the CARICOMP site. Table 3 summarizes the results for mean coral cover for five transects at the CARICOMP site between 1993 and 1995.
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J. Ryan & E Zapata
Little Corn Island. Little Corn Island has a total area of approximately 5 km2 and a population of roughly 500. The windward side of the island is protected by a long fringing reef, which suffered major storm damage combined with some other impact (possibly from a diesel trawler that ran aground in the middle of the reef). Coral growth is sparse (Ryan 1992b, 1994a) and the reef was largely dead in 1993. The reef skeleton originates at the eastern shore and curves to the northeast along the entire eastern side of the island. Five survey sites were examined at Little Corn Island, and two were measured quantitatively by the meter square transect method. LCI-1 was located at a large patch reef in the TABLE 2 Coral species composition comparing meter-square quadrats and chain transects, August 1994. Quadrat Coral Species
Percent Abundance
Chain
Rank
Percent Abundance
Rank
Montastraea annularis
48.5
1
49.3
1
Agaricia sp.
21.1
2
8.3
3
Porites astreoides
6.9
3
11.6
2
Agaricia agaracites
6.6
4
8.3
4
Pseudopterogorgia spp.
5.6
5
2.8
7
Millepora alcicornis
3.2
6
0.2
17
Porites porites furcata
1.6
7
1.5
Muriceopsis flavida
1.2
8
0
Porties porites
1.0
9
6.2
Montastraea cavernosa
1.0
10
0
Porites colonensis
0.9
11
0.9
Agaricia humilis
0.4
12
0
9 m 5 12
Mycetophyllia spp.
0.4
13
0.6
16
Pseudopterogorgia bipinnata
0.3
14
2.8
8
Pseudopterogorgia americana
0.3
15
0
Siderastrea siderea
O.1
16
0
Porites porites divarcata
O.1
17
1.0
Gorgonia mariae
O.1
18
0
Eunicea spp.
0.1
19
0
Colpophyllia natans
0.1
20
0.7
Manicina areolata
O.1
21
0
Dichocenia stokesii
0.1
22
11
14
0
Agaricia agarites dania
0
~
1.7
6
Leptoseris cucullata
0
~
1.1
10
Meandrina meandrites
0
~
0.9
13
Mycetophylia aliciae
0
~
0.5
15
Scolymia sp.
0
~
0.1
18
Acropora cervicornis
0
~
O.1
19
Species Number by Method
-
-
S = 19
Total coral species found in the two surveys = 28
S = 22
Nicaraguas "s coral reefs
217
TABLE 3 Mean percent cover and standard deviation (in italics) of cover by different benthic categories, by transect and overall mean values between 1993-1995. CARICOMP Site Transect-Number
Overall
Benthic Category
#1
#2
#3
#4
#5
Mean
Algae
mean
0.71
0.73
2.40
2.90
1.70
49.30
sd
0.41
0.52
3.50
2.50
1.50
5.30
Stony Corals Soft Corals Sponges Non-Living
mean
18.90
30.70
20.20
24.40
32.00
25.20
sd
4.00
5.40
3.90
1.10
5.60
6.00
mean
0.70
0.72
6.40
2.90
1.70
1.70
sd
0.41
0.52
2.40
2.50
1.50
1.00
mean
1.80
1.30
3.10
0.81
1.90
1.80
sd
0.65
1.30
1.30
0.91
2.30
0.86
mean
34.40
22.20
23.80
32.10
25.20
27.50
sd
11.00
4.60
18.40
7.20
7.40
5.40
backreef lagoon while LCI-2 was set up on the north side of the outer fringing reef. Additionally, divertowed observations were made over the area located 200 rn seaward of the flinging reef. In general, the patch reefs that were surveyed are in excellent condition, well developed, and exhibited the highest live coral cover around the Com Islands (Ryan 1992b). Fish' populations are rich and large predators, are abundant, as are lobsters. This appears to be due to the low population density and small number of commercial fishermen, as well as the lack of Jamaican fish traps being used by islanders. Coral reef damage caused by Hurricane Joan on the little island was minimal, relative to the extensive damage it caused on Big Corn Island. Large volumes of sandy beach on the west side of the island were washed away, and there was some damage to large branching corals (Ryan et al. 1990). One of the greatest threats to the healthy patch reefs in the backreef lagoon is the impending construction of a tourist hotel hoping to attract divers to these small reefs. Unless an integrated management plan is developed, these magnificent reefs will likely be destroyed. 4.3. The Outer Shelf There is little information regarding coral distribution pattems on the outer cont:mental shelf and its slope, and most is anecdotal. Although remote bathymetric profiles carried out by Murray et al. (1982) showed hard formations rising above the shelf to a depth of approximately 25-30 m, these could be Halimeda bioherms described by several studies (Hallock et aL 1988; Hine et al. 1988; Triffelman et al. 1992). However, lobster divers have indicated that the shelf slope has many "beautiful rocks" (a common term for corals) and an abundance of large fish swimming in the currents. There is no information available on the human impacts of reefs on the outer shelf.
5. CORAL REEF PROTECTION AND MANAGEMENT STRATEGIES After almost 30 years since Nietschrnan (1973) first brought attention to Nicaragua's coral reefs and their importance to subsistence fishing communities on the Caribbean
218
J. Ryan & Y. Zapata
coast, there is still no coherent coral reef management strategy in Nicaragua. While there are many reasons for this situation, one of the most fundamental is the lack of awareness at the highest levels about the important ecological role that coral reefs play in supporting the country's Caribbean fisheries (e.g., scalefish, lobsters) and marine biodiversity. Another reason is due to the fragmented mandates and regulations of the two primary government institutions (PAANIC, 1993), which today are the Ministry of Natural Resources and Environment (MARENA) and the Department of Fisheries (ADPESCA), which is placed within the Ministry of Commercial Development and Industry (MIFIC). MARENA is charged with the conservation and management of natural resources whereas ADPESCA's role is to administer aquatic resources sales. Traditionally, MARENA's responsibilities stopped at the high water line and the Department of Fisheries assumed the role of protecting harvestable marine resources. This institutional imbalance has resulted in unsustainable fisheries practices and to some extent, the loss of coral reefs on the Nicaragua shelf. With the exception of one brief period between 1989 and 1994, Nicaraguan governments have not had the tools to understand the relationships between marine biodiversity, fishery resources, and healthy marine habitats. Instead there has been a focus on classical fishery management strategies, which tend to ignore the importance of habitats and the ecological aspects. There is also little reef management capacity and scant funding available to expand the existing knowledge about the country's Caribbean reefs. Unless MARENA and MIFIC can incorporate the protection of coral reefs and other ecologically important habitats into an integrated management framework, there is little reason for optimism. However, MARENA has taken an important first step by establishing a management program for the Miskito Cays Reserve. Nonetheless, there are many complications with managing such a large area with limited resources and management of corals is weak because of funding limitations and a lack of trained staff. Although they are understaffed, MARENA's Department of Management of Coastal Areas (DEMAC) is also an important player and they most recently embarked on f'mding ways to implement the community-based reef management strategy for the Corn Islands that was developed in the early 1990s (Ryan 1993). Figure 4 shows a conceptualized approach to managing some of the reefs surrounding Big Corn Island, which has been considered by DEMAC. Community based reef management initiatives are limited. Ryan (1994a, 1995) and Christie (1999) have coupled their research results with popular environmental education and participatory action planning, but only to a limited extent and at the local level. The work by Christie (1999) with CAMP (Community Area Management Program) Lab in the Pearl Cays reefs has been by far the most successful approach in bringing about active and sustainable community involvement in reef management. However, the fact that this work has largely been directed at creating awareness among local communities, they appear to have failed to get the attention of a wider, and more influential group of policy and decision-makers, who remain elusive targets. The question of how to manage Nicaragua's Caribbean reefs is an interesting one, since Roberts (1997) has suggested that Nicaragua's reefs are primarily "downstream" reefs. This would suggest that the reefs should be less dependent on local management to maintain biodiversity. While this is an interesting field of future study, further data are required to test Roberts' hypothesis over a long time period. However, time is of the
Nicaraguas "s coral reefs
219
Fig. 4. Diagram showing one of the proposed strategies for protecting reefs and marine resources at Big Corn Island (fromRyan 1994a). essence in halting the degradation of Nicaragua's reefs and in the opinion of the authors, urgent action is required to develop preliminary policies, legislation, management strategies and constituencies to implement management plans at the lowest possible level and with the help of the private sector (e.g., seafood and tourism companies). Priority actions should include developing strategies for: 9 9
9
9
9
creating greater coral reef environmental awareness at the highest political levels, among the private sector and at the community level; seeking small, but carefully targeted financial support from donors to carry out training and institutional development in all aspects of reef research and management; developing partnerships be formed between the Government, the private sector (fisheries and tourism companies), local coastal communities and universities on the Caribbean coast; continued support for the CARICOMP program at Corn Island and exploring the possibilities to expand the program to the Cayos Miskitos and Pearl Cays on different parts fo the extensive Nicaragua Shelf; creating additional Marine Reserves for protecting critical reef habitats on the shelf.
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J. Ryan & Y. Zapata
ACKNOWLEDGMENTS The work on Com Island which helped produce this article, has largely been possible through the involvement of a special group of highly dedicated people, who have generously contributed their time to the primary author. We especially thank Learme Rut-ten, who provided invaluable technical expertise, logistical and moral support; the Bluefields Marine Conservation Project (BMC) from the United Kingdom (particularly Kevin Hawney and Pete Smith) who dedicated their time for diver training, in assisting with the CARICOMP work at Corn Island monitoring and with providing funds to help purchase essential equipment. We are tremendously grateful for the early help from Janet Klenma, Walter Jaap and Jorge Cort6s, and the later assistance from Rodolfo Chan, Liza Gonzfilez and especially Desire6 Elizondo, who first brought attention to MARENA. The continuous support and encouragement from Patrick Christie and Rikke Broegaard will never be forgotten. The Norwegian Development Assistance Program (NORAD), provided a grant that initiated the first quantitative surveys at Corn Island. Dr. Jeanne Mortimer and the Caribbean Conservation Corporation provided an invaluable stipend for training Nicaraguan divers. Without the untiring patience and support from Ken McKaye, the University of Maryland/AEL and Fr. Adolfo L6pez de la Fuente, the Corn Island work would never have succeeded. Finally special thanks go to Erica Rosenthal who helped start the whole thing in 1989 with funding for the original hurricane damage survey and to the commitment of the late Dennis Castro to marine conservation in Nicaragua. REFERENCES
Alevizon, W. 1992. Report on visit to the Miskito Cays. Drait Report to the Caribbean Conservation Corporation and USAID, Managua, 14 pp. Birkeland, C. 1990 Caribbean and Pacific coastal marine systems: Similarities and differences. Nature Res. 26:3-21. Broegaard, R. 1995. Aguas oseuros bajo el paraiso. WANI 18: 45-49. CARICOMP. 1997a. Physiography and setting of CARICOMP sites: a pattern analysis. Proc. 8th Int. Coral Reef Syn-tp., Panamfi 1: 647:-650. CARICOMP. 1997b. Caribbean coastal productivity (CARICOMP): A research and monitoring network of marine laboratories, parks and reserves. Proc. 8th Int. Coral Reef Syrup, Panand 1" 641-646. CARICOMP. 1997c. CARICOMP monitoring of coral reefs. Proc. 8~ Int. Coral Reef Symp., Panamfi 1" 651-656. Carr, A., M. Carr & A. Meylan. 1978. The ecology and migrations of sea turtles: 7. The West Caribbean green turtle colony. Am. Mus. Nat. Hist. 162: 1-42. Christie, P. 1999. Participatory action research and its role in coastal area management in Pearl Lagoon, Nicaragua. Ph.D. dissert., Univ. Michigan. 245 p. Conzemius, E. 1929. Les ties Corn du Nicaragua. La Geografie, Paris 52: 346-352. Cort6s, J. 1997. Status of the Caribbean coral reefs of Central America. Proc. 8~ Intl. Coral Reef Syn-~., Panamfi 1" 335-340. CIP. 1980. Descripci6n pesquera del Atlfintico Nicaragiiense: Parte II. Report by the Centro de Investigaciones Pesqueras. 24 p.
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Crout, R.L. & S.P. Murray 1978. Shelf and coastal boundary layer currents, Miskito Bank of Nicaragua. Proc. 16th Coastal Eng. Conf., ASCE/Hamburg, West Germany: 38-57. Diaz, J.M. & J. Garzrn-Ferreira 1993. Los arrecifes coralinos de la Isla de San Andrrs, Colombia: Estado actual y perspectivas para su conservacion. I N V E ~ Report. 135 p. Fry, B., R.Lutes, M. Northarn & P. Parker 1982. A laC/14Ccomparison of food webs in Caribbean seagrass meadows and coral reefs. Aquat. Bot. 14: 389-398. Geister, J. 1983. Holocene West Indian coral reefs: geomorphology, ecology and facies. FACIES 9: 173-284. Hallock, P., H.B.N. Hine, A.C. Vargo, G.A. Elrod & W. Japp. 1988. Platforms on the Nicaraguan rise: example of sensitivity to carbonate sedimentation to excess trophic resources. Geology 16:1104-1107. Hine, A.C., P. Hallock, M. Harris, D. Belknap & W. Jaap. 1988. Halimeda bioherms along an open seaway: Miskito channel, Nicaraguan rise, SW Caribbean Sea. Coral Reefs 6: 173-178. Jameson, S. 1996. Coral reef ecosystems of the Miskito Coast Marine Reserve: Surveys and management recommendations. In: Environmental Initiative of the Americas Fisheries Project (USAID), USAID publication. 4 p. Marshall, M. 1996. Reef fish surveys of the Miskito Cays, within the Miskito Cays Protected Area, Nicaragua. In: Environmental Initiative of the Americas Fisheries Project (USAID), USAID publication. 9 p. McBimey, A. & H. Williams 1965. Volcanic history of Nicaragua. Publ. Geol. Sci., Univ, California 55:1 -75. Mortimer, J. 1983. The feeding ecology of the West Caribbean green turtle (Chelonia mydas) in Nicaragua. Biotropica 13: 49-58. Murray, S.P. & M. Young 1985. The nearshore current along a high rainfall, tradewind coast of Nicaragua. Est. Coast. Shelf Sci. 21: 687-699. Murray, S.P., A.S. Hsu, H.H. Roberts, E.H. Owens & R.L. Crout 1982. Physical processes and sedimentation on a broad, shallow bank. Est. Coast. Shelf Sci. 14: 135-157. Nietschman, B. 1973. Between the land and water: The subsistence ecology of Miskito Indians. Seminar Press, Berkley, California. Ogden, J.C. & E.H. Gladfelter 1983. Coral reefs, seagrass beds and mangroves: Their interaction in coastal zones of the Caribbean. UNESCO Reports in Marine Science #23. Ogden, J.C. & J. Zieman 1977. Ecological aspects of coral-reef seagrass bed contacts in the Caribbean. Proc. 3rd Int. Coral Reef Symp., Miami 2: 377-382. PAANIC 1993. Plan de acci6n para el medio ambiente nicaraguense. Final report to ASDI, DANIDA and the World Bank, Managua, 76 pp. Phillips, R.C., R.L. Vadas & J.C. Ogden 1982. The marine algae and seagrasses of the Miskito Bank, Nicaragua. Aquat. Bot. 13:187-195. Roberts, C. 1997. Connectivity and management of Caribbean coral reefs. Science 278: 1454-1457. Roberts, H.H. & S.P. Murray 1983. Controls on reef development and the terrigenouscarbonate interface on a shallow shelf, Nicaragua (Central America). Coral Reefs 2: 7180.
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Roberts, H.H. & J.N. Suhayda 1983. Wave-current interactions on a shallow reef (Nicaragua, Central America). Coral Reefs 1:209-214. Robinson, S. 1991. Diagn6stico preliminar de la situaci6n actual de medio ambiente en la Region Aut6noma Athintica Sur: Parte I, Volume VI-A. Report by E1 Instituto Nicaraguense de las Regiones Auton6mas (INDERA), Managua.76 p. Robinson, S. 1999. Final report on the ecology and phsyiography of Nicaragua's coastal zone. OAS and the Rio San Juan Global Environmental Facility Project. 22 p. Ruden, F. 1993. The hydrological environment of an oceanic basalt island. Mew_ XXIV Congr. Int. Assoc. Hydrogeol.: 1166-1182. Ryan, J.D. 1992a. Medioambientes marinos de la costra Caribe de Nicargua. WANI 12: 35-47. Ryan, J.D. 1992b. Los arrecifes coralinos del Caribe nicaraguense. WANI 13: 35-52. Ryan, J. 1993. Las plantas submarinas del Caribe nicaraguense. WANI 14: 67-75, Ryan, J. 1994a. The Corn Island reef survey: Coral degradation patterns and recommended actions. Report to NORAD and IRENA, Managua. 42 p. Ryan, J. 1994b. The need for diversification and management of Nicaragua? Caribbean Fisheries. Studies in Environmental Economics and Development (Special publication series), University of Gottenburg, Sweden. 14 p. Ryan, J.D. 1994c Ecosistemas marinas y el manejo sostenible en la costa central del Caribe Nicaraguense. WANI 16:5-21. Ryan, J. 1995. Recursos pesqueros y su uso sostenible en la costa Caribe de Nicaragua. WANI 16: 1-13. Ryan, J. 1999. The status of coastal environments within the Rio San Juan watershed. Annex to Final Report submitted to OAS and the Rio San Juan San Global Environmental Facility Project. 16 p. Ryan, J., A. Rudloe & J. Rudloe. 1990. Preliminary assessment of coral damage inflicted by Hurricane Joan. Unpublished report, Greenpeace and the Earth Island Institute. 26 p. Ryan, J., L. GonzAlez & E. Parra. 1993. Plan de acci6n del medio ambiente Nicaraguense: Diagn6stico y Propuesta para los Recursos acu~ticos. Report prepared for DANIDA, ASDI and the World Bank, 242 pp. Ryan, J., L. Miller, Y. Zapata & O. Downs. 1998. Great Corn Island, Nicaragua: 95-105. In: B. Kjerfve (ed.), CARICOMP-Caribbean Coral Reefs, Seagrass and Mangrove Sites. UNESCO, Paris, 95-105. S~inchez, C. 1996. Listado taxon6mico de las especies identificadas en los ocranos Pacifico y AtlLntico (Mar Caribe) de Nicaragua. MEDE-PESCA Tech. Rept. 36, 14 p. Smith, S. & 14 authors. 1994. The status and recent history of coral reefs at the CARICOMP network of Caribbean marine laboratories: 73-79. In: R.N. Ginsbttrg (compiler), Proc. Colloq. Global Aspects of Coral Reefs. Univ. Miami, Florida. Triffelman, N.J.,P. Hallock & A.C. Hine 1992. Morphology, sediments and depositional environments of a small carbonate platform: Seranilla Bank, Nicaraguan Rise, southwest Caribbean. J. Sedim. Petrol. 62:591-606. Vadas, R.L., T. Fenchel & J. Ogden 1982. Ecological studies on the sea urchin, Lytechinus variegatus, and the algal- seagrass communities of the Miskito Cays, Nicaragua. Aquat. Bot. 14:109-125.
Past, present and future of the coral reefs of the Caribbean coast of Costa Rica Jorge
Cortes a
and Carlos Jimrnez
a, b
aCentro de Investigaci6nen Ciencias del Mar y Limnologia (CIMAR), and Escuela de Biologia, Universidadde Costa Rica, San Pedro, San Jos6 2060, Costa Rica. bZentrum for Marine TropenOkologie,Universit/itBremen, Farenheitstr. 6, D-28359 Bremen, Deutschland.
ABSTRACT: Coral reefs are present on the southern section of the Caribbean coast of Costa Rica. Three areas of reef development are recognized: 1) fringing and patch reefs between Moin and Lim6n, 2) fringing reefs, patch reefs, and carbonatebanks at Cahuita National Park, and 3) fringing reefs, patch reefs, carbonate banks, and algal ridges between Puerto Viejo and Punta Mona. Reef structure and coral species composition is similar to other Caribbean reefs, with some exceptions, for example the presence of a well-developedalgal ridge. Forty-one species of scleractinian corals, 3 of hydrocorals and 26 octocorals have been reported. Even though most coral reefs are within Protected Areas they are being degraded by human activities on nearby areas. Live corals coverage have been declining while dead coral and algal coverage have increased. The main cause of damage to coral reefs is the excess terrigenous sediments present, produced by deforestation, coastal alteration, and inappropriate agricultural practices. 1. I N T R O D U C T I O N
1.1. The Caribbean coast of Costa Rica The Caribbean coast of Costa Rica consists mainly of high energy sandy beaches, which in the southern section are interrupted by carbonate promontories (Fig. 1), consisting of fossil reefs (Pleistocene, Holocene), and beachrock in some sections. Extant reefs grow on top of these rocky outcrops (Cort6s and Guzmfin 1985a). Some of the fossil reef tracts extend along the coast, while others are found inland. Preliminary measurements of these fossil reefs indicate that they are pinching out, i.e. the extension of extant reefs is smaller than their fossil counterparts. This is probably due mainly to increased sediment input by rivers, which is expanding the sandy beach areas. This trend, combined with the degradation of the extant reefs, will eventually result in a continuous, sandy beach coastline, with fossil reefs inland. The climate of the Caribbean coast of Costa Rica is humid and hot, with year-round rains. Precipitation decreases along the coast from the northwest to the southeast (Herrera 1986). Tides are diurnal, with a range of less than 50 crn, and are greatly affected by wind direction and force. The main current runs from the northwest to the southeast, Latin American Coral Reefs, Edited by Jorge Cortfs 9 2003 Elsevier Science B.V. All rights reserved.
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with strong eddies in the opposite direction along the coast. The main NW-SE current and the SE-NW countercurrents transport sediments from the rivers to the reef areas (Cortrs and Risk 1985; Cortrs et aL 1998). Waves are normally from the northeast, although they may come from other directions during hurricanes in the Caribbean, and can be strong, breaking corals and lifting sediments from the reef (Cortrs 1981). No hurricane has hit the coast directly in historical time. Three coral reef areas on the Caribbean coast of Costa Rica are recognized: 1) fringing and patch reefs between Moin and Lim6n, 2) fringing reefs, patch reefs, and carbonate banks at Cahuita National Park, and 3) fringing reefs, patch reefs, carbonate banks, and algal ridges between Puerto Viejo and Punta Mona (Fig. 1). In this chapter we present the history of research on the Caribbean coral reefs of Costa Rica, describe the extant reefs, comment on natural and anthropogenic impacts affecting the reefs, and end with a discussion about their protection and management.
1.2. Research history Dawson (1962) published the first papers on marine organisms (algae) from the Caribbean coast of Costa Rica. Houbrick (1968) described the litoral mollusc fauna of the Portete area (Fig. 1), including the reefs. Based on a collection done in 1969 at Portete, Banta and Carson (1977) published a paper on the Bryozoa of Costa Rica. The first complete study of a coral reef on the Caribbean coast of Costa Rica was conducted by Wellington (1974a). He described the reef and associated organisms at Cahuita, and that information was used to declare it a National Park, the first in Costa Rica that protected an important marine ecosystem_ Risk et al. (1980) presented further descriptions of the reef at Cahuita and published the first list of coral-boring sponges from Costa Rica. Wellington (1974a) and Risk et al. (1980) indicated that terrigenous sedimentation was negatively affecting the coral reef at Cahuita. This lead Cortrs (1981) to study the siltation problem in detail, identifying the banana plantations and deforested uplands of Valle de La Estrella, north of the reef (Figs. 1, 3), as the sources of the sediments. Sediment accumulation in the coral skeletons coincided with the alteration of the watershed (Cortrs 1981; Cortrs and Risk 1985). Siltation has continued, and combined with other anthropogenic and natural disturbances, continue to degrade the coral reef at Cahuita (Cortrs 1994). For an alternative hypothesis on the origin of the sediments at Cahuita see Hands et al. (1993): They proposed that the sediments originated from erosion of the shoreline adjacent to the reef at Cahuita. Cortrs and Guzrrmn (1985a) presented the first paper that described all the main coral reef areas on the Caribbean coast of Costa Rica. The largest coral reef is at Parque Nacional Cahuita, followed by the reefs at Refugio Nacional de Vida Silvestre GandocaManzanillo (Fig. 1), which were described by Cortrs (1992a). Lists and/or descriptions of several groups of organisms from the Caribbean coast of Costa Rica have been published: algae, more than 270 species (Dawson 1962; Wellington 1974b; Soto and Ballantine 1986), sponges, 38 spp. (Loaiza Coronado 1991; Cortrs 1996), hydrocorals, 3 spp. (Cortrs 1992b), octocorals, 26 spp. (Guzrr~n and Cortrs 1985; Guzm,~n and Jimrnez 1989), scleractinian corals, 41 spp. (Cortrs and Guzrrfin 1985b; Cortrs 1992a, c), other cnidarians, 18 spp. (Cortrs 1996-1997), mollusks, more than 400 spp. (Houbrick 1968; Robinson and Montoya 1987; Rodriguez et al. in press), bryozoans, 11 spp. (Banta and Carson 1977), isopods, 7 spp. (Breedy
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Fig. 1. The Caribbean coast of Costa Rica, with indication of the protected areas. The points on the southern part of the coast are carbonate promontories made up fossil reefs and beachrock, on which the extant reefs grow. and Murillo 1995), stomatopods, 5 spp. (Vargas and Cort6s 1997), zooplankton, 16 taxa (Morales and Murillo 1996) and decapods, 30 spp. (Vargas and Cort6s 1999). Other publications on reef invertebrates include descriptions of a barnacle that lives in corals (Young 1989), two species of benthic copepods (Mielke 1994), and a new species of isopod (Wetzer & Bruce 1999). Other papers have been published on the density and compressive strength of the coral Siderastrea siderea (Jim6nez and Cort6s 1993), the distribution and density of black sea urchin Diadema antillarum (Valdez and Villalobos 1978), mortality of Diadema in 1983 (Murillo and Cort6s 1984), mass mortality of the sea fan Gorgoniaflabellum in the mid 1980's (Guzrn~n and Cort6s 1984), coral mortality due to high water temperatures (Cort6s et al. 1984; Jim6nez 2001), and death of coastal and reef organisms due to a magnitude 7.5 (Richter Scale) earthquake (Cort6s et al. 1992, 1994). In addition, five papers have been published conceming pollution on the Caribbean coast, including two on fecal con-
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tamination of coastal waters (Mora et al. 1987, Mora 1991), one on oil pollution (Mata et al. 1987), one on heavy metals in sediments and corals (Gtmmhn and Jim6nez 1992), and one on metals in the sea cucumber Holothuria (Halodeima) mexicana. (Rojas et al. 1998). Finally, eight theses have been written based on research on the Caribbean coast, mainly at Parque Nacional Cahuita. Research subjects have included: seasonal variation on the chemical composition of five species of algae (Charpentier 1980), impact of sediments on corals and reef degradation (Cort6s 1981), benthic microcrustaceans (Breedy 1986), phytoplankton primary productivity (Silva Benavides 1986), abundance and distribution of zooplankton (Morales 1987), sponge diversity from Isla Uvita and Cahuita (Loaiza Coronado 1989), trace metal pollution in a sea cucumber (Rojas 1990), and trace metals in the water column (Sandi 1990). 2. DESCRIPTION OF THE REEFS 2.1. Corals
Forty-one species of scleractinian corals and three hydrocorals have been reported from the Caribbean coast of Costa Rica (Cort6s and Guzmfin 1985a; Cort6s 1992a, b, c, 1996-1997, in prep.). Of these, 35 species are zooxanthellate reef-building corals, while the rest are shallow-water azooxanthellate corals. The main reef-building species are: Siderastrea siderea, Agaricia agaricites, Porites astreoides and Diploria strigosa. Important reef-builders of the Caribbean like Montastraea annularis and Acropora cervicornis, are not abundant on the Caribbean coast of Costa Rica (Cort6s and GuzroAn 1985a). In addition, there are no reports of deep-water corals from the Caribbean of Costa Rica (Cort6s in prep.), although the systematic study and exploration of deep offshore reefal environments, such as the ones encountered off Gandoca-Manzanillo (see below), will undoubtedly change this. 2.2. Coral reefs
2.2.1. Moin - Lim6n. Fringing and patch reefs, as well as coastal carbonate substrates, can be found between Moin and Lim6n, including Isla Uvita (Figs. 1, 2). In this area, three Hydrocorals (Cort6s 1992b), 18 hermatypic corals (Cort6s and Guzmfin 1985b; Cort6s 1998), three azooxanthellate corals (Cort6s in prep.), and 21 octocorals (Guzm,Sn and Cort6s 1985; Cort6s 1998) have been found. This section of the coast is subject to heavy wave action, and the largest reefs grow on the protected sides of islands (Fig. 2). This area is also exposed to freshwater runoff, terrigenous sediments, sewage, dredging, petroleum pollution and solid wastes from the main ports on the Caribbean of Costa Rica (Mata et al. 1987; Guzmfin and Jim6nez 1992; CIMAR 1998). The coast between Moin and the Port of Lim6n (Fig. 2) is bordered by carbonate substrates that extend from above the upper tidal zone down to a depth of 15 m. The shallow areas have seagrasses, isolated colonies of S. siderea and P. astreoides, and extended sections dominated almost exclusively by Millepora complanata and calcareous algae (Halimeda spp.). The front sections of the intertidal ledges are constructed by the barnacle Megabalanus antillensis and by crustose coraUine algae, and are eroded by Echinometra lucunter; colonies of Astrangia solitaria are also found there (Cort6s and Guzrnfin 1985a). The submerged platform is covered with algae, hydroids, sponges and
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Fig. 2. Coralcommunitiesand coral reef areas between Moin and Lim6n,including the islands. isolated corals; the most abundant corals being: P. astreoides and A. agaricites forma purpurea (Cort6s and Guzrnfin 1985a). Below 15 m in depth the bottom consists of soft mud (Cort6s 1998). Isla P/Ljaros (Fig. 2) has a small reef (about 100 m2) built mainly by colonies of S. siderea, 1 to 1.5 m in diameter (Cort6s and Guzmfin 1985a). The exposed northern side of the island has a carbonate substrate similar to the one described above. In 1996, the island's reefs were exploited as a source of corals for the curio trade at Puerto Lim6n. Portete (Fig. 2) had a one-hectare coral reef on the eastern side of the bay entrance that was uplifted by the 1991 Lim6n Earthquake (Cort6s et al. 1992 and see below under Natural Disturbances). It was built by A. palmata on the crest and S. siderea, A. agaricites and Porites astreoides on the reef front and back. The lagoon was covered with the seagrass Thalassia testudinum (Cort6s and Guzrrfin 1985a). Between Portete and Playa Bonita (Fig. 2), there is an extensive carbonate platform similar to the one described above. It has been eroded by small fresh water creeks, creating a system of channels and grooves in the platform. Groups of Porites astreoides, S. siderea and Diploria spp. were very common in small coves with relatively calm waters; areas also popular among tourist for swimming. These corals were severely affected by the construction of a small causeway that altered water circulation in the coves. All carbonate outcrops between Moin and Lim6n are covered mainly by algae, hydroids and in some cases octocorals, milleporids and scleractinian corals (Cort6s 1998). Colonies of S. siderea at Portete, had lower skeletal density when compared with more turbulent and silted reefs such as Cahuita (Jim6nez and Cort6s 1993), possibly due to the presence of freshwater and pollutants.
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Isla Uvita (Fig. 2) is less than 1 km off the Port of Lim6n, but a strong current separates it from the port and its pollution. So, it is possible to observe well-developed reefs on the island. The north and northwest sections are exposed to heavy wave action so coral development is meager. The east side has an extensive carbonate platform, with microatolls of Siderastrea siderea and Montastraea cavernosa in the lagoon. Two ridges, up to 5 rn long, built by vermetids have also been observed (nothing similar has been observed in Costa Rica). The intertidal platform is large and extends on the east side of the island, and it is now exposed due to the uplift during the 1991 earthquake. Before, it had a rich intertidal fauna, with the coral Siderastraea siderea in deeper sections. The south side has a coral reef covering an area of about 2 hectares. The dominant species are S. siderea, M. annularis, M. franksL M. cavernosa and P. astreoides (Cortrs and Guzrnfin 1985a; Cortrs 1998). The north side of Isla Uvita has a very diverse benthic community consisting mainly of hydroids, sponges, algae, and several unidentified species of bryozoans; scleractinian species are limited to Astrangia solitaria and Phylangia americana. 2.2.2. Cahuita. The largest fringing reef of the Caribbean of Costa Rica, and one of the most studied reefs in the country, is located at Parque Nacional Cahuita (Figs. 1, 3). Three species of hydrocorals (Cortrs 1992b), 31 species of hermatypic scleractinians (Cortrs and GuzmAn 1985b), six species of azooxanthellate corals (Cortrs in prep.) and 19 species of octocorals (Guzmfin and Cortrs 1985), have been reported from Parque Nacional Cahuita, making it the most speciose reef of the Caribbean of Costa Rica. This reef has been degrading during the last 30 years due mainly to siltation, as well as other anthropogenic and natural causes. Live coral coverage decreased from 40% in the early 1980's to 10% in the mid 1990's (Cortrs 1994). Even so, Blair et al. (1996) found that the primary reason tourists visit the area is the National Park and its reef. They attributed an overall revenue at approximately $1.2 million per year to the and indicated that if the park was not there, Cahuita could expect to lose that amount of annual tourist revenue. The coral reef at Cahuita consists of three barriers (Fig. 3): The outer barrier, stretching about 5 km from the western to eastern side of Punta Cahuita, is separated from the coast 100 m to 2 km. Between this barrier and the coast there is a small fringing reef, about 500 m long and within 100 m of the shore, called the inner crest. Finally, a barrier, 100 m long, is located at the westem end of the reef (Cortrs and Risk 1984, 1985; Cortrs and GuzmAn 1985a). The outer barrier has well-developed spurs and grooves made up mainly of dead corals and calcareous algae. The spurs crest at a depth of 0.5 m, with a sandy base at around 15 m in depth. Intricate complexes of crevices and caves are found at several sections of the spurs (per. obs.). Silicious sponges, bryozoans and solitary corals are common in the walls. Live corals from the shallow sections include M. complanata, S. radians, F. fragum and A. agaricites. The deeper sections have D. stn'gosa and P. astreoides (Risk et al. 1980; Cortrs and Risk 1984). A shallow lagoon (<1.5 m) is located behind the outer barrier. The seagrasses Thalassia testudinum and Syringodiumfiliformis predominate in the most protected areas, and Sargassum just behind the crest where water movement is greater. Patches of Porites spp. have been found in some sections of the lagoon at Punta Cahuita. Patch reefs of one to 25 m in diameter are found in the larger lagoon. The main species there were A. palmata and D. strigosa (Risk et al. 1980; Cortrs and Risk 1984). A. palmata suffered massive death in 1983 (Cortrs et al. 1984), and extensive colony fragmentation
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Fig. 3. Coral communities and coral reefs around the Cahuita town and at Parque Nacional Cahuita. due to the 1991 earthquake (Cort6s et al. 1992); the few surviving colonies have been growing new branches since then. The inner crest has the highest coral diversity, with A. palmata predominating in the shallow sections. Due to the A. palmata die-off in 1983, only small live patches remain. The reef front is covered by A. agaricites and P. astreoides, and the reef base by 10 to 12 species, mainly, S. siderea, D. strigosa, M. cavernosa, M. annularis and M. franksi (Risk et al. 1980; Cort6s 1981; Cort6s and Risk 1984, 1985). Live coral coverage has dropped from around 40% in the early 1980's to less than 10%. Most of the A. palmata populations is dead, but the populations of the other main species are about same as in the 1980's (Cort6s 1994), although some rare species, e.g. Oculina diffusa and Madrasis mirabilis, have not been seen again. The reef on the western side (Fig. 3), called Arrecife don David (Cort6s and Guzmfin 1985a), has large colonies ofA. palmata, C. breviserialis, D. strigosa, M. cavernosa and D. clivosa. Here, corals are overgrowing cannons from a colonial period shipwreck and gaps in the reef structure that were made by divers extracting objects from the wreck. The lagoon has T. testudinum and S. filiformis, and the corals P. porites and Manicina areolata (Cort6s and G u z l ~ n 1985a). Offshore carbonate banks have been found off Cahuita, and four have been explored (Jim6nez and Cort6s unpubl, data): They range in size from 180 to 2,400 m 2 and from 4 to more than 30 m in depth. These carbonate banks have between 6 and 14 species of scleractinian corals. Live coral cover is low to moderate (13.4 to 33.6%) and corals are
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generally restricted to the upper parts of the banks, while black corals (mostly Cirrhipathes spp.), octocorals (mostly Ellisella spp.) and sponges dominate the flanks and deep sections of the banks. Algae and sponges are generally dominant in the shallow and fiat sections of the banks. The most abundant corals, in decreasing order, are Diploria spp., Agaricia spp., Colpophyllia spp., S. siderea and P. astreoides. Because some of the banks are fight on the predominant SE current, strong currents are common and sediments accumulate on the leeward flanks. Bank morphology is oriented parallel to the coast, with the steepest flanks opposing the incoming waves. Percent cover of dead corals, sand and fragments was higher (39.3 + 5.9%) on the banks most exposed to the current. There, buried under free silt layers, are numerous standing Acropora palmata skeletons. 2.2.3. P u e r t o V i e j o - P u n t a M o n a . There are coral communities and coral reefs between Puerto Viejo and Punta Mona (Figs. I, 4), and the following species have been identified from the area: three hydrocorals (Cortrs 1992b), 27 hermatypic corals (Cortrs and Guzrnfin 1985b; Cortrs 1992a, c), two azooxanthellate corals (Cortrs in prep.), and 18 octocorals (Guzrnfin and Cortrs 1985; Guzmfin and Jimrnez 1989; Cortrs 1992a). Around Puerto Viejo (Fig. 4), the reefs are mostly dead due to siltation, coral extraction, and pollution by sewage and solid wastes. Even so, the following live corals have been found: D. clivosa, S. siderea, P. astreoides, M. complanata, P. porites and F. fragum (Cortrs and Guzmfin 1985a). In 1988, coral cover was low (11.6 + 4.3%) and was mainly D. clivosa (4.3%). Other important components at the time were calcareous algae including Halimeda (33.3%), and Millepora complanata (11.8%). Five years later, coral cover was lower (6.9 + 2.2%), and consisted mainly of P. astreoides (2.5%). M. complanata had also declined (6.8%), and there was an increase in algae (37.8%), dead coral (22.1%) and solid wastes (Jimrnez and Cortrs unpubl, data). At Playa Chiquita (Fig. 4), there is a small narrow fringing reef with small buttresses, covered by large fiat colonies ofM. cavernosa, M. franksi and M. annularis. Coral cover at this site did not changed much from 1988 (12.7 + 5%) to 1995 (13.2 _+3.6%), even though calcareous algae increased considerably from 16.5 to 37.5% (Jimrnez and Cortrs unpubl. data). D. clivosa had the highest percent cover in both years (3.8 and 4.8%, respectively). The reef at Punta Cocles (Fig. 4) is about 1,000 m 2 and has incipient buttresses on the front with tops at 2 m deep and bases at 6 m deep (Cortrs and Guzrnfin 1985a). The walls of the spurs were covered with A. agaricites forma purpurea and A. humilis, in addition to nine coral species. Cortrs and GuzmAn (1985a) also reported live coral coverage at 5%, with S. siderea as the most abundant species. From Punta Uva to Punta Mona, the coral reefs are within the Refugio Nacional de Vida Silvestre Gandoca-Manzanillo (Fig. 1), and although live coral cover here is low (less than 10%), reef conditions, in terms of species diversity and health, are good. D. clivosa, P. astreoides and M. complanata predominate in shallow waters, while in deeper waters D. strigosa, S. siderea, D. stellaris and M. cavernosa predominate (Cortrs 1992a). D. strigosa covers the greatest area, while S. siderea has the most colonies. These two species constitute more than 50% of the live coral, the rest being made up by 24 other species (Cortrs 1992a). Fringing reefs are located around the main rocky points, such as Punta Uva (Fig. 4), while patch reefs are found in the lagoons and protected areas (Cortrs 1992a). The reefs off the town of Manzanillo (Fig. 4) consist of an algal ridge dominated by Neogoniolithon
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Fig. 4. Coral communities and coral reefs between Puerto Viejo and Punta Mona.
strictum. This ridge is similar to the one described by Steneck et al. (1997) from the Bahamas, but the one off Manzanillo is larger and exposed to more energy. Calcareous algae dominate the front of the platform (76.1 + 10.9%), where coral cover is very low (1.1 + 1%), consisting mainly of fiat colonies of D. clivosa (Jim6nez and Cort6s unpubl. data). Coral cover is higher in other sections of the reef (3.4 to 9%), with the most abundant species, in decreasing order, being D. clivosa, D. strigosa and Agaricia spp. Offshore carbonate banks consist of hard substrate surrounded by sand. Most are 50 to 100 mlong by 25 to 40 m wide, with tops at depths between 8 and 15 m (Cort6s 1992a). The deep offshore fronts of the carbonate platform (25 m deep and 1-2.5 km from the coast), run parallel to the shore from Punta Uva to Punta Manzanillo, and are dominated by Cirrhipathes sp., Ellisetla spp. and Leptoseris cucullata (Jim6nez and Cort6s unpubl. data). Other abundant corals in the vertical walls are Mycetophyllia spp., Isophyllastrea rigida, Agaricia spp. and Scolymia cubensis. At the base of the platforms (25-40 m deep), barrel sponges of the genus Xestospongia, with diameters of 1.5 m, are common. Pipe sponges (Aplysina spp.) 1.8 m long have also been observed. Farther offshore, isolated small carbonate banks, similar in shape to those described above, are abundant at a depth of 40 m (Jim6nez and Cort6s unpubl, data). They have few coral species, the most common ones being M. cavernosa, L. cuculata and Agaricia spp., but have many sponges and Cirrhipathes sp. Two sedimentary environments, defined by marine currents and the source of sediments, have been recognized at Refugio Nacional de Vida Silvestre Gandoca-Manzanillo (Cort6s et al. 1998). One, located between Punta Uva and the north side of Punta Mona (Fig. 4), is characterized by sediments derived from the coral reefs and local geological formations. The other lies between Punta Mona and Rio Sixaola (Fig. 4), where sediments come primarily from outside the area. Reefs on the south side of Punta Mona (Fig. 4) have been affected by sediments from Rio Sixaola (Cort6s 1992a).
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3. NATURAL DISTURBANCES
3.1. Warming events In June 1983, water temperatures along the Caribbean coast of Costa Rica were between 29 and 35~ causing bleaching and death of reef organisms (Cort6s et al. 1984). One of the most affected species was Acropora palmata. Most of the colonies of this coral died and recovery have been slow, especially at Refugio Nacional GandocaManzanillo (Cortes et al. 1984; Cort6s 1992a). In 1995, during doldrums weather, water temperatures at Cahuita and Manzanillo were 29-32~ and bleaching was observed down to a depth of 20 m at Cahuita, and 15 m at Manzanillo (Jim6nez 2001). In Cahuita, 62% of the coral colonies bleached but mortality was only around 7%. Montastraea cavernosa (13.3%) and Millepora complanata (16.3%) had the highest mortalities. Coral species with more than 65% of their colonies bleached were F. fragum, M. cavernosa, A. agaricites, P. porites, P. astreoides and Montastraea spp. At Manzanillo, bleaching was less intense (24.2%) than in Cahuita, but mortality was higher (8%). Porites furcata and P. porites had the highest mortalities (17.1 and 11% respectively). The most commonly bleached corals (>65% of the colonies) were A. agaricites, P. astreoides, S. radians, S. siderea and F. fragum. Minor bleaching events were also observed in 1992 and 1998, both coincident with high water temperature. 3.2. Mass mortality Mass mortality events involving two reef organisms of the Caribbean coast of Costa Rica have been reported. First, beginning in 1982 and culminating in 1983, the sea fan Gorgonia flabellum died all along the coast (Guzm~n and Cort6s 1984). This was the first of several reports of mass mortality of Gorgonia spp. in the Caribbean. Since 1995, both G. flabellum and G. ventalina have been dying in several locations around the Caribbean due to the fungus Aspergillus sp. (Nagelkerken et al. 1997), but appear to be recovering in Costa Rica. In 1983, and again in 1992, the black sea urchin Diadema antillarum suffered massive mortality. Populations were reduced from 4 to 33 ind m "2 t o 1 ind 100m"2 (MuriUo and Cort6s 1984; Cort6s 1994). The 1983 die-offwas associated with the spread of a pathogen by currents (Lessios et al. 1984).
3.3. The 1991 Lim6n earthquake In April 1991, a magnitude 7.5 earthquake (The Lim6n Earthquake) uplifted the coastal zone between Moin and the border with Panarrfi. Near Lim6n, uplift was on the order of 1.9 m, while in other areas it was around 50 cm. In total, 2.5 km2 were added to the coastal area. This uplift caused the death of many intertidal and reef organisms (Cort6s et al. 1992, 1994). About 40% of all seagrass, or about 37,000 m 2, was lost, in addition to 5,000 m 2 of the coral reef at Cahuita. There was slumping of the reef front at Cahuita, and all Acropora palmata colonies were broken, as were some massive corals (Cort6s et al. 1992). This process of punctuated uplift of the Caribbean coast of Costa Rica is evident since the Pliocene (Cort6s et al. 1992; Denyer et al. 1994; Denyer 1998). The exposed areas were rapidly covered by vegetation and altered by human activity (Jim6nez and Cort6s 1994).
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4. ANTHROPOGENIC IMPACTS 4.1. Siltation
The most important anthropogenic impact on Caribbean coral reefs of Costa Pica has been, and continues to be, increased terrigenous sediment influx (Cort6s 1981, 1992a, 1994; Cort6s and Risk 1984, 1985; Cort6s and Guzrrfin 1985a; Cort6s et al. 1998), as in other Central American reefs (Cort6s 1997). At Cahuita, live coral coverage is low and average colony size is large. The amounts of suspended and resuspended sediments are very high, and sediments are trapped in the massive coral skeletons. Coral growth rates are low, and are significantly inversely correlated with sediment resuspension rates. The increase in terrigenous sediments in this reef was caused by deforestation and banana plantations in Valle de la Estrella (Fig. 3) (Cort6s 1981; Cort6s and Risk 1984, 1985). Sediment concentrations have continued to increase and live coral coverage to drop at Cahuita (Cort6s 1994). Other reefs on the Caribbean coast of Costa Rica are also impacted by terrigenous sediments, for example those at Puerto Viejo and Punta Mona (Fig. 4) (Cort6s and Guzlrmn 1985a; Cort6s 1992a; Cort6s et al. 1998). 4.2. Pollution
Analyses between 1981-1985 for petroleum pollution indicated that the levels were low, with sporadic events of high concentrations. The highest concentrations were found in the port areas of Lim6n (Fig. 2). Toward the end of the study there was a gradual increase in tar balls at Puerto Vargas (Mata et al. 1987). Hydrocarbon concentrations between Moin and Lim6n were higher in 1997-1998 than in previous surveys in the 1980's (CIMAR 1998). The coastal zone between Portete and Lim6n (Fig. 1) is polluted with fecal wastes. Some areas have concentrations as high as 240,000 NMP 100ml ~, and 5 of the 8 sites studied have levels higher than the accepted maximum (Mora et al. 1987). Other areas must be monitored for possible increases of fecal contamination, with dire health consequences (Mora 1991). High levels of heavy metal pollution in coral skeletons and sediments, even in "pristine" reefs, were found by Guzrn~n and Jim6nez (1992) on the Caribbean coast of Costa Rica and PanarnL The sources of the heavy metals may be natural, but they are mainly of anthropogenic origin, including sewage discharges, oil spills (from refineries and tankers), the misuse of agricultural chemicals and fertilizers, and topsoil erosion. The concentrations and in-tissue distributions of six metals, were determined in the sea cucumber Holothuria (Halodeima) mexicana by the atomic absorption. The samples ranged in size from 17 to 25 cm in length and weighed between 280 and 600 g. The metal concentration ranges (mg kgt dry weight) were: Cd 0.1-2.5; Pb 0.2-26; Mn 4.146; Cu 1.3-69; Zn 14-174; Fe 20-1044. In general, the respiratory tree was the structure that showed higher levels of metals, except for Cu and Pb, which were higher in the muscles and the body wall, respectively. Nevertheless, pollution levels were intermediate to low (Rojas et al. 1998). Sandi (1990) reported on trace metal concentrations in surface water and sediments. Concentrations were always lower than in the sea cucumber, except for copper and zinc (Rojas et al. 1998). Solid wastes are present on all beaches and in some reefs of the Caribbean coast (Cort6s and Guzn~n 1985a, per. obs.). A significant amount of the garbage found in reefs come from the banana plantations, the rest is from the coastal towns (Cort6s unpubl, data).
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4.3. Tourism
Tourist visitation to the Caribbean coast of Costa Rica, as well as coastal development has increased enormously in the last two decades. The number of visitors to Cahuita National Park increased dramatically between 1982 and 1991 (latest data available) (Bermddez 1992). This increased visitation has had an impact on the coral reefs of the region (Cortrs 1994). There is evidence of damage by reef-walkers on the small population of Manicina areolata at Cahuita. Nearly all colonies in the path through the lagoon that the walkers used to reach the reef crest were damaged or overturned. M. areolata colonies in other areas not utilized by the visitors had significantly lower incidences of damage. The impact on the Manicina population was exacerbated by boaters who pulled their boats in these shallow waters increasing the damage by crushing the reef (Jimrnez and Cortrs unpubl, data). The impact of reef walkers and snorklers was measured recently in the lagoon at Punta Cahuita. On average a person breaks 3.18 colonies of Porites porites and overturns 0.26 masses of the coralline algae Amphiroa fragilissima per day (Gove and Cortrs unpubl, data). An average of 1.48 kicks to corals per person with f'ms was significantly higher than 0.31 kicks without fins (Gove and Cortrs unpubl, data). Both of these studies reveal strong tourist pressure at Cahuita. An increase in the number of boats that take snorklers and swimmers to the reef at Cahuita has increased the impact on two particular patch reefs favored by tour operators (shallow waters and good coral condition). One of these patch reefs, known as E1 Jardin, has been depleted of its octocoral population, which gave the place its name. Large colonies of D. clivosa, M. annularis, C. natans and M. cavernosa are dead on top due to abrasion caused by swimmers, who ot~en rested upon them. This behavior was at times encouraged by the boater who brought them to the reef. Additionally, anchors were dragged along the bottom, uprooting octocorals and ovemmfing small massive corals. Coral fragments were, on average, 12.4 times more abundant at E1 Jardin than in three nearby patch reefs without visitors (Jimrnez and Cortrs unpubl, data). Millepora accounted for 52.7% of the fragments, followed by Agaricia spp. (32.6%), Porites spp. (13.1%) and A. palmata (0.6%). In 1994 and 1995, tourist were also observed collecting corals and reef organisms, increasing the destruction of the area. At Punta Mona, we have recorded coral damage due to anchoring by tourism related boats. In a small cove at the lee side of Isla Mona, large stands ofL. cucullata and Agaricia spp. (25 m 2 aprox.) were marked in 1994 for a growth study. In 1995, 63% of the area was destroyed by anchors from boats that take snorklers and swimmers to the area. Also, dozens of beverage cans were found in the bottom. Finally, there is one report of black coral extraction at Punta Uva by recreational divers (S. Larkimstnmz, per. com. 1997). One of the colonies was approximately 2 m high by 2.3 m wide, and was considered the attraction of the deep dives there. 5. PROTECTION AND MANAGEMENT Two protected areas with coral reefs are located on the Caribbean coast of Costa Rica, Parque Nacional Cahuita and Refugio Nacional de Vida Silvestre Gandoca-Manzanillo (Fig. 1). Collection of corals is not permitted within these protected areas, which has greatly reduced this problem. However, commercial and artisanal fishing is still permit-
Coral reefs of the Caribbean coast of Costa Rica
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ted within the protected areas. This has resulted in overexploitation of some resources, e.g., lobsters, red snappers and groupers. In addition, uncontrolled tourist activity in the region, and associated coastal development, has increased significantly in recent years (Bermfidez 1992; Cortrs 1994), with its associated damage (see above). The amount of people diving on the reefs has also increased enormously, so it is necessary that areas be designated for diving activities. These spots must be marked by buoys that can also be used as mooring for boats, as has been done at a few sites in Cahuita. There in 1996 and 1998, a group of local divers, fishers, and tour operators from the town of Cahuita participated in coral reefs courses (coordinated by one of us, CJ). Following the course they placed mooring buoys in the three patch reefs that were visited the must by tourist, and they discouraged the extraction of corals or any other reef organism, as well as physical contact with the corals by visitors. These education programs, which offer training in marine science, coral reef ecology, and dive ethics, have had positive results. Another management strategy, an experiment in co-management, was initiated at Cahuita National Park in the early 1990's. One section of the park is managed by the local community, while the rest, including the reefs, is managed by the Ministry of the Envkonment and Energy. Results to date (2001) have been very encouraging, and mutually beneficial for the government and the local community. All impacts to the reefs of the Caribbean coast of Costa Rica are dwarfed by the siltation problem. Increased terrigenous sediment loads are the main cause of degradation and death of coral reefs in Costa Rica and most tropical areas (Ginsburg 1993). This is a problem that originates outside the reef areas, and its control must be sought in the watersheds that drain to the reef areas. An integrated approach that includes the watersheds and the marine environments must be taken in order to save the coral reefs. ACKNOWLEDGMENTS
Research on coral reefs of the Caribbean coast of Costa Rica has been possible through grants from the Vicerrectoria de Investigaci6n, Universidad de Costa Rica, and from CONICIT (Project 90-326-BID), and with support of the National Conservation Area System. M.M. Kandler, M.J. Risk, M.M. Murillo, H.M. Guzrrfin, P.O. Baumgartner, C. Mora, A.C. Fonseca, O. Breedy, A. Le6n, S. Ramirez, E. Ruiz, C. Gamboa, A. Segura, and M. Saborio helped at different times in the field and laboratory. The manuscript was greatly benefited by the reviews ofK. Qualtrough, R. Soto, A.I. Dittel and C. Lotion. REFERENCES
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Caribbean coral reefs of Panama: present status and future perspectives H6ctor M. Guzm~n Smithsonian Tropical Research Institute, P.O. Box 2072, Balboa, Republic of Panama ABSTRACT: One of the goals of this work is to review the conservation status of the Panamanian Caribbean coral reefs and to demonstrate that there is sufficient and adequate information to support new legislation for their protection. Panama has 1,295 km of coastline in the Caribbean with coral reefs along almost all its coast, from Punta Cabo Tibur6n on the border with Colombia to Punta Boca del Drago, 27 km from the border with Costa Rica. The total coral reef surface area is estimated at 754 km 2, mostly fringing reefs. Of these reefs, 81% are located in the eastern region and form part of the indigenous reservation of Kuna-Yala. In this region, there is also the highest diversity of corals, octocorals and sponges, with 97%, 100% and 93%, respectively, of the total number for the country. Live coral cover has changed dramatically in the last 20 years, with a reduction as high as 50-70% in several areas along the coast. At present the highest average cover ranges between 25% and 30%, to be found in the eastern and western regions. The reefs have been affected by natural disturbances such as seawater warming, associated with E1 Niflo events, and by diseases. However, from a historical point of view, anthropogenic disturbances have gone beyond our general comprehension. They started with massive coral mining more than 500 years ago, at the time of the Spanish conquest, and have continued up to the present day, during the construction of the Panama Canal and with the traditional coral mining and landfilling practices used by the Kuna people. Five marine-terrestrial protected areas along the Caribbean coast do not include the best reefs of Panama or protection is inadequately enforced. Reefs are at high risk due to coastal development particularly that associated with tourism; 48.5% of the country's tourist attractions are located along the coastal zone. This creates a pressing and unavoidable need to protect coral reefs as part of an integrated national coastal management and conservation plan.
1. INTRODUCTION
Recently, the global destruction of coral reefs has been observed with concern by scientists and authorities in charge of the management of natural resources. Among the main causes of degradation are overfishing, sedimentation and enrichment by nutrients (eutrophication) (Roberts 1993). The consequences Of these activities affect not only the structure and function of reef ecosystems, but also have a socio-economic impact on many countries of the Caribbean region. Coral reefs are highly productive and diverse ecosystems that play an important role in the maintenance of the coastal zone, bringing direct benefits to the surrounding human settlements and the economies of several nations (Hatcher 1988, 1990; Spurgeon 1992). Among these benefits are the protection of the coastal zone against erosion, food production, drug production and recreational tourism. The appraisal of each of these Latin American Coral Reefs, Edited by Jorge Cort6s 9 2003 Elsevier Science B.V. All rights reserved.
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benefits is a very difficult task, but it is generally agreed that suitable protection will result in an overall healthier economy that will benefit the inhabitants of the coastal zone (Spurgeon 1992). At present, the lack of protection of these ecosystems is the main indirect cause of their degradation in the Republic of Panama. Inadequate management of the coastal zone and deforestation of surrounding areas have accelerated the destruction of most reefs locally at a time when the country is gearing up for an increase in tourism development that, among other plans, contemplates the recreational use of these habitats. Virtually all Panamanian coast containing reefs has been incorporated into the national master plan for tourism development (IPAT/OEA 1993) and one would expect that before its implementation, a general land-use plan for the country would be in place to guide the long-term management of these resources, with due concern given to the coastal communities. Nevertheless, the trend of accelerated degradation of both reefs and local economies implies quite the contrary. This work provides, for the first time, a general review of our knowledge of the Caribbean coral reefs of Panama and an assessment of their conservation status. It aims also to demonstrate that there is sufficient and adequate baseline information about these reefs and related resources for use by local authorities to support the new and sound legislation that is urgently required for the long-term sustainable conservation of this ecosystem. An integrated conservation and management plan for the coastal zone is a pressing and unavoidable need. 1.1. Hydrography and meteorology of Panama's Caribbean coast Panama has 1,295 km of coastline on the Caribbean side, characterized by a narrow continental shelf with a variable width that ranges from 5.5 km to a maximum of 39 km and an approximate surface area of 6,000 klTl2 (IGNTM 1988). Caribbean tides in Panama are semidiurnal or diurnal (mixed), not clearly predictable and with an amplitude below 0.5 m. Tides are higher than usual during the dry season due to the influence of northeasterly winds (Glynn 1972). North and northeast winds have a strong influence along the coastal zone throughout the year, mostly from January to April (DMA 1988; Cubit et al. 1989). The central coast is particularly affected by wind-driven waves and tides during the dry season, while they have a lesser impact on the leeward side of the eastern (Kuna-Yala) and western (Bocas del Toro) archipelagos where the largest reef tracts occur. The main coastal current, coming from northern Nicaragua and Costa Rica and nmning eastbound, affects Panama throughout the year with possibly a greater influence between the months of June and August when it rtms closer to the coast (DMA 1988; Greb et al. 1996). The Caribbean is not subject to seasonal upwelling but it is affected by strong runoff from several rivers and by high rainfall (Cubit et al. 1989). Temperature remains relatively stable throughout the year (< 3~ variation) with the highest temperature recorded during the rainy season (April-December) (Cubit et al. 1989). Nutrients, plankton, turbidity and chlorophyll are less abundant in the eastern region of the country where the oceanographic conditions are typically oligotrophir (D'Croz and Robertson 1997; D'Croz et al. 1999). Nevertheless, this pattern does not seem to hold along the western region, around Bocas del Toro, where the fiver runoff and rainfall are higher (Guzmfin and Guevara 1998a; L. D'Croz per. com.).
The Caribbean coral reefs of Panama
243
1.2. Research history The Panamanian reefs have been the subject of several studies over more than a century. However, it is difficult to establish when research started, because the records of several expeditions carried out during the 19th century, many of them associated with the search for a shorter route for the building of the Panama Canal, are not easily available or well documented. Nevertheless, it is true that research in Caribbean Panama from that period onwards, and possibly up to the mid 20 th century, paid special attention to hydrographic and oceanographic descriptions and included massive collection campaigns and the description of new species of corals and reef-related organisms. For example, in 1874 Thomas Selfridge remarks in his book "Reports and Explorations and Surveys of the Isthmus of Darien" that during his San Blas (Kuna-Yala) explorations he used navigation charts prepared by Commander Lull with detailed localization of coral reefs (Heckadon-Moreno 2002). The U.S. Fish Commission steamer Albatross dredged the coast off Col6n in 1884; one of the collected octocoral species, Nicella schmitti, was described later (Bayer 1961). During the zoological explorations of the Italian naturalist Enrico Festa in 1895, reef flats close to the city of Col6n were briefly described following an all but unsuccessful attempt to dredge the bottom but which ended up with the collection of organisms during the extreme low tide (Heckadon-Moreno 2001). Many such collections took place in shallow areas or by dredging and among some interesting records are those of Meek and Hildebrand (1923) who collected and identified some 237 fish species along the "extensive reefs" from Col6n to Portobelo between 1911 and 1912. Taylor (1929), collected and made observations on the macroalgae of reef and rocky areas and deLaubenfels (1936) collected sponges manually and by raking the intertidal zone. He reported 21 species of which 33% were hitherto unknown to science. Likewise, Rubinoff and Rubinoff (1962) produced new fish records for the Caribbean central coast. However, it was only shortly after the mid-20th century, and with the support of the Smithsonian Tropical Research Institute, established in the old Canal Zone, that the more detailed studies of the coral reefs along Caribbean Panama began. The first research work took place at Galeta Island, about 15 km east of the entrance of the Panama Canal and at Kuna-Yala (San Blas), in the eastern region of the country, where, in the early 1970s, the first two marine laboratories, or field stations, in Caribbean Panama, and possibly in all Central America, were built. In 1974, the Smithsonian Institution Environmental Sciences Program was established in Galeta, with the purpose of monitoring long-term climatic and hydrological changes (Meyer and Birkeland 1974); this work is still in progress today (Cubit et al. 1989) and it has been expanded to other regions of the country. About 350 contributions have been published from the marine and coastal environments nearby or from around the central region. There, research has focused on population dynamic studies and the behavior of plants and animals from reef flats and subtidal reef areas (Caldwell 1985; Cubit et al. 1986; Sebens 1982; Lasker 1979, 1980). Herbivory processes in reefs (Hay 1981, 1984) and the impact of petroleum on coral reproduction, reef structure and subsequent reef recovery have also been studied (Burns and Knap 1989; Jackson et al. 1989; Guzrrfin et al. 1991, 1994; Guzmfin and Holst 1994). Meanwhile, at the Kuna-Yala field station several research projects were initiated, with 150 scientific reports published up to its closure in 1997. These projects brought an enormous contribution to the knowledge of the reproductive and evolutionary biology of octocorals (Brazeau and Lasker 1988, 1990, 1992; Coffroth et al.
244
H.M. Guzmdn
1992; Coma and Lasker 1997; Lasker 1985, 1990; Lasker et al. 1996, 1999), echinoderms (Lessios 1981, 1987, 1991, 1998; Lessios et al. 1984b)and reef fish (Cole 1988; Hoffman and Robertson 1983; Robertson 1984, 1992; Robertson et al. 1976, 1988, 1993, 1999; Warner 1975, 1984, 1990; Warner and Hoffman 1980), to mention but a few. Among some of the pioneering work, stands out the concern about the imminent migration of marine organisms throughout the Panama Canal (Chickering 1930; Rubinoff 1965, 1968; Rubinoff and Rubinoff 1968), the impact of petroleum on the Col6n coastal reefs (Rtitzler and Sterrer 1970; Birkeland et al. 1976), coral mining in Kuna-Yala (Porter and Porter 1973), as well as the comparisons of the biota on both sides of the isthmus (Glynn 1972; Porter 1972a, b, 1974). These authors described for the first time the structure, diversity and distribution of coral reefs off the eastern and central regions of Caribbean Panama, from the mouth of the Chagres River to the Diablo River in Nargana, Kuna-Yala. It is worth mentioning some classical contributions, amongst which are a few controversial ones, which have set guidelines for further basic research in the Caribbean region. Included amongst these are: biological changes in marine ecosystems associated with the Panama Canal and the possible construction of a sea-level canal (Rubinoff 1968, 1970; Topp 1969), sexual selection and sex change in reef fishes (Warner et al. 1975), tests on the molecular clock in sea urchins (Lessios 1979), massive mortality of the long-spined sea urchin Diadema antillarum (Lessios et al. 1984a), settlement of coral larvae due to chemical stimuli from coralline algae (Morse et al. 1988), long-term population changes in reef fishes as a consequence of the Diadema die-off (Robertson 1987, 1988, 1991), the impact of petroleum upon reefs and other coastal communities (Jackson et al. 1989) and the controversial definition of the Montastraea annularis sibling species complex (Knowlton et al. 1992).
2. DESCRIPTION OF THE REEFS 2.1. Geological origin Panama's origin is reflected mostly in the formation of the Central American isthmus, the closure of which affected the circulation patterns of the oceans and the climate worldwide, with changes in the distribution of plants and animals (Coates 1997). In geological terms, the Central American region is of recent origin, starting with the formation of islands in what is currently eastern Panama and the subsequent formation of the southern half of the isthmus in the mid-Miocene, about 11 million years ago. In the following million years (Ma), the region became an archipelago and the circulation between the Caribbean and the Pacific Ocean was restricted, with the creation of new coastal-marine habitats (Coates 1997). At the end of the Miocene (7-6 Ma), the depth of the oceans surrounding Panama was about 150 m and by the end of the Pliocene (ca. 4 Ma) they had become shallower, with depths less than 50 m. The isthmus was probably closed about a million years later. It is presumed that towards the end of the Pliocene there were still marine corridors that connected the two oceans until their final closure (Coates et al. 1992; Coates and Obando 1996; Coates 1997). The definitive separation of the two oceans took place in the southern region of Central America with the Isthmus of Panama being the last land to emerge (Coates et al. 1992; Collins and Coates 1999). After the closure of the isthmian barrier, a temporary breach may have occurred during
The Caribbeancoralreefs of Panama
245
the Ice Age glaciation and associated interglacial warming and changes in sea level (Coates and Obando 1996; Coates 1997). It is estimated that over the past 20,000 years the sea level may have risen up to 135 m as modem glaciers have been melted (Coates 1997). Although small patch reefs appeared in Panama's Caribbean by the mid-Miocene, large-scale coral reefs and the associated coralline sediments started to appear mainly in the upper Pliocene to the Pleistocene, occurring at relatively deep levels of 80-100 m during this latter period (Collins et al. 1999). During the formation of the isthmus and particularly during the Pliocene and Pleistocene turnover periods (4-1 Ma), there were speciation and extinction episodes that dramatically transformed the Caribbean's coralline fauna; approximately 80% of the more than 100 coral species of the MiocenePleistocene disappeared and 60% of the current species were originated. The diversity of corals in the Caribbean zone off Costa Rica and Panama during this period was greater than that in other sites in the Caribbean region, although the change off Panama started more recently (3-2.2 Ma), completing itself by about 1.6-1.2 Ma (Budd et al. 1999). According to Budd et al. (1999), the diversity of coral species found in the fossil record is higher off Costa Rica (82 species) than off Panama (35 species) (Budd et al. 1999). This is dissimilar to the record of present day species which shows that Panama almost doubles (>65 species) the diversity of Costa Rica (Guzmfin and Guevara 1998b, 2001). Regarding fossil azooxanthellate corals, the highest diversity of the wider Caribbean appears off the Dominican Republic and Panama, with 20 and 15 species respectively, although this possibly reflects a greater collection effort in these regions (Cairns 1999). Even though not all the reef structures of the country have been dated in order to determine their origin, it is considered that recent reefs (Holocene) started to develop in Caribbean Panama about 7,000 years ago with the formation of fringing reefs typical of the Caribbean and dominated by Acropora palmata (see Macintyre and Glynn 1976). This species built reefs mainly in exposed areas and allowed the development of other massive coral species such as Diploria strigosa, Stephanocoenia michelinii, Porites astreoides and Montastraea annularis along back reef areas and upper and intermediate slopes about 5,000 years ago. At the same time, a lagoon environment developed and species such as P. furcata and A. cervicornis appeared (Macintyre and Glynn 1976). A. palmata kept pace with the rising and changing sea level that occurred at the end of the Holocene transgression when rapid reef growth took place. The accretion rate of these reefs, based mainly on this dominant species, fluctuated between 10.8 and 1.3 m/1000 years, with an average of 3.9 m/1000 years (Macintyre and Glynn 1976). Within the 3,000 to 2,000 year B.P. period, the dominance of A. palmata started to decrease. Vertical development of these reefs was subsequently limited by changes in the sea level and possible sedimentation during the last 2,000 years; corals reduced their active contribution to the construction of new reef framework, particularly in habitats exposed to high energy (Macintyre and Glynn 1976; Macintyre et al. 2001). 2.2. Reef distribution and changes in coral cover
Panama has coral reefs along almost all its Caribbean coast, from Punta Cabo Tibur6n on the border with Colombia (08~ - 77~ to Punta Boca del Drago (09~ 82~ 27 km from the border with Costa Rica (Fig. 1). The development and structure of these reefs varies dramatically with the degree of wave and wind exposure and their proximity to the mainland, being better developed on the
246
H.M. Guzmrn
Fig. 1. Map of the Republic of Panama showing the four political provinces on the Caribbean side (KunaYala, Colrn, Veraguas and Bocas del Toro) and the three arbitrarilydefined regions where the main reef structures have been described until now (eastern, central, western; indicated between diamond symbols). From east to west, the eastern region is divided into three sub-regions and limits are indicated (cross symbols); Tubuala, Ailigandi, Nargana. Details for the Bocas del Toro archipelago are shown in Figure 7. leeward side of side of insular systems. In particular, the best reef growth and development takes place in the Bocas del Toro and Kuna-Yala archipelagos, where there are hundreds of cays, islands and islets surrounded by fringing coral reefs. These islands are of calcareous or volcanic origin and their surfaces range between a few m 2 and 61 km 2 (Isla Colrn, Bocas del Toro). In order to simplify the presentation of this work in the following sections, the Caribbean coast has been arbitrarily divided into three large regions (Fig. 1), partly because the greatest reef development was found in them, but also because these were the areas where most reefs have been described to date and information is available. These areas, in turn, have been subdivided into smaller subregions, sometimes based on political units, which are suggested as potential areas of conservation or management. Likewise, this section shows existing trends in coral cover for the intervening regions, based on historical records and current monitoring programs. 2.2.1. Eastern region. If we analyze the distribution of reefs by political unit or at provincial level, we fred that the most extensive and best-developed reefs off Panama are located at Kuna-Yala (San Bias), with approximately 610 km 2. So far, reef surface area has been estimated using only satellite images and aerial photographs for this region. These reefs are part of the indigenous reservation or "Comarca" of Kuna-Yala, an area entirely under the custody and management of the Kuna autonomous people and without interference from the government of Panama since 1938 (Tice 1995; Ventocilla et al. 1995; Howe 1998). The archipelago is made up of about 365 coral islands (Ventocilla et al. 1995). Along its length, hundreds of shallow reef patches cover more than 26 km2; most of them close to the mainland. Fringing coral reefs run along the
247
The Caribbean coral reefs of Panama
continental coast forming extensive reef flats bordered by gentle slopes down to 10-15 m. About 2-5 km offshore and around the islands and cays, large reef complexes develop with several habitats including internal enclosed lagoons with coral-dominated slopes, external barriers and deep reefs. Seaward reef fiats that are part of the external barriers are vast, dominated by spurs and grooves up to 15 m deep, and covered mainly by crustose coralline algae and several coral species that are resistant to wave action, e.g. Agaricia agaricites, Porites astreoides, Diploria spp. and Siderastrea siderea, among others. It is important to point out that these reef fiats were described at first as algal ridges, especially those of the Cayos Holand6s (Glynn 1973). Recently it was discovered that these structures had been formed about 2,000-2,800 years ago and were built with extensively lithified Agaricia and Millepora rubble, which is characteristic of storm deposits coated by cmstose coralline algae (Macintyre et al. 2001). Therefore, they may not be considered as true algal ridges (sensu Adey 1978). , Within this province or eastern region (Fig. 1), the largest reef tracts occur in the 'corregimiento" (jurisdiction) of Nargana (ca. 365 km2), followed by Ailigandi (ca. 152 km 2) and Tubuala (ca. 93 km2). Active vertical reef development can be observed to more than 45 m deep in the Nargana sub-region, particularly in areas that are farther away from the mainland, such as Cayos Holand6s and Limones. The reefs of Punta San Blas, Nargana, have been surveyed and monitored for more than 30 years (see Porter 1974). Changes in live coral cover show a gradual decrease from ca. 40% in 1983 (see Shulman and Robertson 1996) to ca. 15% in 1997, with a slight recovery of ca. 5% for 2001 (Fig. 2).
40-
Qx Kuna-Yala Bocas del Toro
o~ 3 0 Isla Grande
L_
> O
-- 2 0 0 >
n9 1 0 - Bahia Mina,,
....
I
83
"
I
I
....
85 86
I
I
88
90
I
"
I
"
I
'1
92 93 97 98 Year Survey
'
I'
99
'
'1
'"
00
I'
01
I .......
02
Fig. 2. Long-term changes in live coral cover in four reef areas along the Caribbean coast of Panama. Analyses based on published (Guzmhn et al. 1991" Shulman and Robertson 1996) and unpublished (Smithsonian Institution Marine Environmental Science Program) data sets.
248
H.M. Guzm6n
2.2.2. Central region. This region includes the Province of Col6n, with an estimated reef surface area of 48 km 2, from the Kuna-Yala border to the Bel6n River, the western provincial border. The most extensively studied reefs in this region are located between Isla Grande and the mouth of the Chagres River, including Portobelo and Bahia Las Minas (Guzrn,hn et al. 1991; Guzrn~n and Hoist 1994). All these fringing reefs follow the mainland coastline throughout their extension with little vertical development - not more than 15 m deep. This is due mainly to the effect of the northeast trade winds and ocean waves that have a direct influence on this coastal region throughout the year. The best development occurs in the areas of Isla Grande and Bahia Las Minas (Fig. 1). In both regions, macroalgae cover comprises 80% in most reefs (Guzmhn et al. 1991; Guzmhn and Hoist 1994). Live coral cover has changed remarkably in the reefs of Isla Grande-Portobelo since 1985, where there were reefs with an average cover of approximately 25% that, following natural and anthropogenic disturbances (see Sections 3 and 4), gradually decreased to levels close to 10% in 1992 (Fig. 2). As in the eastern region, a slight recovery of about 7% (Fig. 2) was observed in the late 1990's. The reefs of this region are composed mainly of Diploria clivosa, Agaricia tenuifolia, A. danai and Millepora complanata coral species in shallow areas of up to 2 rn deep, bordered by a relatively short slope dominated by D. strigosa, Colpophyllia spp. and Siderastrea siderea. Currently, small and isolated patches of Acropora palmata are found between Isla Grande and near Portobelo where they formerly made up vast fringing reefs parallel to the coast. The reefs of this subregion have shorter reef fiats and a greater number of shallow and deep reef patches. Towards the Bahia Las Minas area, live cover accounted for 22% in 1985 but decreased in 1986 due to a major oil spill (Jackson et al. 1989; Guzrn~n et al. 1991), reaching about 5% by the end of 1992 with a very slight recovery of ca. 5% towards 1998 (Fig. 2). The composition of species and zonation is similar to those previously mentioned, but with a greater abundance and development of Siderastrea siderea colonies. This subregion has large reef fiats with a surface area of 4 to 24 ha (Guzrn~n and Hoist 1994) constantly exposed to high wave energy and quite short reef slopes of less than 10 m. The three largest and most representative reefs of this subregion, Isla Payardi, Isla Largo Remo and Isla Galeta, have areas of 48 ha, 44 ha and 35 ha, respectively (Guzrnhn and Hoist 1994). The reefs located west of the Panama Canal entrance were studied only in the early 90s (Guzn~n and Hoist 1994). In general, they are not highly developed and have a quite homogeneous relief from the reef fiat towards the base. Siderastrea siderea, Diploria clivosa and Millepora complanata dominate the reef environments of this sector (Guzmhn and Hoist 1994). A total of seven reefs have been described west of Bahia Las Minas (Punta Galeta) as far as the mouth of the Chagres River, most of which are formed by vast reef fiats of up to 23 ha. The largest of these reefs located in Isla Media Palma has reef fiats of 16 ha and subtidal reefs of 18 ha (Guzrr~n and Hoist 1994). The combined coral cover for this sector is low, ranging between 3% and 11% by 1992 (Guzmhn and Hoist 1994). It is important to point out that vast reefs existed within the Bahia Lim6n, the entrance to the Panama Canal. However, they were completely destroyed (see section 4) and, currently, there are only small patches of up to 4 m deep dominated by Millepora and Siderastrea corals located on the western margin of the bay and parallel to the old Fort Sherman.
The Caribbeancoral reefs of Panama
249
2.2.3. Western region. There are reefs all along the coast from the Chagres River to the Calov6vora River where the western region begins (see Fig. 1). These reefs, which cover the western part of the Province of Col6n and the coast of Veraguas, have been visited but not documented to date. They might be described as extensive low relief reefs or subtidal reef platforms, composed mainly of macroalgae and the corals Siderastrea siderea and Diploria clivosa. Their vertical development is limited by the direct impact of waves and winds that may not allow the formation of intertidal reef fiats either. At the base of these reefs, small patches of Agaricia spp. and sponges are often found. The area defined here as the western region comprises the whole Bocas del Toro archipelago (ca. 3,500 km2), formed by 6 large forested islands and hundreds of small mangrove cays (Fig. 1). Surrounding all these islands and along a large part of the mainland coast, fringing coral reefs up to 20 m deep and dozens of shallow reef patches have developed. The archipelago has an estimated reef surface area of 87 km2, the second largest of the Caribbean of Panama. The reefs of the archipelago have been evaluated in detail since 1997 and live coral cover of up to 50% has been reported, depending on the depth, reaching up to 90% in shallow areas (Guzrmin and Guevara 1998a, b, 1999, 2001). Leeward reefs are generally more developed than those off the exposed northern shore of the islands (Guznfin and Guevara 1998b), with a somewhat characteristic zonation with shallow areas built mainly by Porites furcata, bordered by Agaricia danae or A. tenuifolia on the upper slope. From the intermediate slope area towards the reef base, the reefs are composed of massive corals, mainly Colpophyllia spp., Montastraea franksi, M. cavernosa, Siderastrea siderea and Stephanocoenia intercepta. Typical deeper habitat coral species, Agaricia undata and A. lamarcki, are observed at 15-20 rn deep. In Bahia Almirante and parallel to the coast from Puerto Almirante to the northern side of Isla Crist6bal, there is an almost continuous fringing reef more than 30 km long, composed exclusively of Porites furcata in the shallower areas (Guzrrfin and Guevara 1998a, b). It is important to note that within the archipelago there are healthy and vast populations of Acropora palmata and A. cervicornis corals (Guzrmin and Guevara 1998a, 1999, 2001), now considered endangered throughout the Caribbean (Precht et al. 2002). Over the past four years, unlike the rest of the country, a gradual decrease of up to 10% in the live coral cover has been observed (Fig. 2). 2.3. Reef conservation status Caribbean reefs have been visited relatively recently and information about live coral cover includes data from 1998 to date. Almost all the reefs along Caribbean Panama have been affected by natural or man-made disturbances in one way or another (see sections 3 and 4), and in some locations these temporal changes have been recorded as part of monitoring programs in combination with historical records (Ogden and Ogden 1994; Shulman and Roberson 1996; Guzrrfin et al. 2003) (Fig. 2). Figure 3 summarizes our current conservation status for most Caribbean reef areas in Panama. We observe that none of the subregions has an average live coral cover higher than 30%; the reefs of the Nargana sector in Kuna-Yala are those in the best condition but under high risk (Guzn~n et al. 2003). The worst conserved reefs are those located in the central region of the country, from the Chagres River to Isla Grande, with live coral cover lower than 15% (Fig. 3). It is important to point out that these cover values represent a wide spatial scale and that they are the result of a combination of observations from several reefs described individually within each subregion, with a minority of
250
H.M. Guzm6n
14
30 L_
o 20 0 0
0
6 .----
29
42
15
10
~
_.1
0
Tubuala Ailigandi Nargana
Isla Grande
Bahia Minas
Bocas Bocas Mainland Islands
Fig. 3. Summary of most recently updated percentage live coral cover in seven sub-regions along the Caribbean coast of Panama. Survey years are 2001 for Tubuala-Nargana, 1998 for Isla Grande-Bahia Las Minas and 1998-2000 for Bocas del Toro. Number of reefs is indicated at the top of each bar.
reefs showing cover reaching 50%. Nevertheless, we believe that the statistical data from the more than 100 reefs quantitatively described, truly represent the spatial scale that is necessary to update the country's status because both highly degraded and relatively pristine reefs have been included in the analysis.
2.4. Diversity
The diversity of hermatypic scleractinian corals in Caribbean Panama was estimated at 49 species in the early 1970s, excluding four species of Millepora (Porter 1972a). This diversity, all found in the Kuna-Yala region, seemed impressive and was similar to the diversity observed for other reefs across the Caribbean, such as those off Jamaica (Porter 1972a). The absence of the species Dendrogyra cylindrus was considered curious because this coral was abundant off all the Caribbean islands. Likewise, the author questioned the presence of Solenastrea off Panama. Almost two decades later, the presence of 61 species of hermatypic corals is reported off Panama, including three species of Millepora (Hoist and GuzmAn 1993). This list includes for the first time, the presence of D. cylindrus off the central region of the country, confrere the presence of two species of Solenastrea, includes a new, recentlydescribed species, Porites colonensis, off Col6n and includes separately the three sibling species of the now controversial Montastraea complex (sensu Knowlton et al. 1992). In this chapter, the list of species for Caribbean Panama is updated, including the distribution of coral species at sub-regional level, in addition to octocorals and sponges. The diversity of corals increased to a total number of 70 species, including four species of Millepora (Table 1). Among the new records is the species Goreaugyra memoriales, which has only been found in Kuna-Yala, the country's highest diversity area (97%). The status of this species has been recently questioned (see Veron 2000). The central and western regions contain 77% and 87%, respectively, of the country's diversity. A lower number of species is found in the Bahia Las Minas area, with 51 species, while the highest diversity is found in Nargana, with 66 species (Table 1).
251
The Caribbean coral reefs of Panama
TABLE 1 List of scleractinian and hydrocoral (Millepora) coral species from the Caribben coast of Panama by study regions. 1, Tubuala; 2, Ailigandi; 3, Nargana; 4, Portobelo-Isla Grande; 5, Rio Chagres-Bahia Las Minas; 6, continental areas; and 7, insular areas. Species 1 A cropora cervicornis A cropora palmata Acropora prolifera Agaricia agaricites Agaricia carinata
Eastern Region 2 3
Western Region 6 7
X X
X X
X
X
Agaricia crassa Agaricia danai
X
X X
X X
X
X
X
X
Agaricia fragilis Agaricia grahamae Agaricia humilis Agaricia lamarcki Agaricia purpurea
X X X X X
X X X X X
X X X X X
X
X
X
X X X
X X X
X X X
X X X X X
Agaricia pusilla
X X X X
X X X
X
X
X
X
X
X X
X
X
X X
X X
X
X
Colpophyllia breviserialis
X
X
X
X
X
X
X
Colpophyllia natans
X
X
X
X
X
X
X
Agaricia sp. Agaricia tenuifolia Agaricia undata Colpophyllia amaranthus
Goreaugyra memorialis Dendrogyra cylindrus Dichocoenia stellaris Dichocoenia stokesi Diploria clivosa
X X X X X
Central Region 4 5 X X
X X
X X
X X
X X
X
X X X X X
X
X
X X
X X X
X X X
X X X X
X X X
X X X
X X
Diploria labyrinthiformis Diploria strigosa Eusmilia fastigiata
X X X
X X X
X X X
X X X
X X X
X X X
X X X
Favia fragum Isophyllastrea rigida
X X
X X
X X
X X
X X
X X
X X
Isophyllia sinuosa
X
X
X
X
X
X
X
Leptoseris cucullata
X
X
X
X
X
X
X
Madracis decactis
X
X
X
X
X
X
X
Madracis formosa Madracis luciphila Madracis mirabilis Madracis pharensis Madracis senaria
X X X
X X X X
X X X X X
X X
X
X
X
X X X
X X
Manicina areolata Manicina mayori Meandrina brasiliensis
X X X
X X X
X X X
X
X
X X X
X X X
252
H.M. Guzm6n
Table 1 cont.
Species
Eastern Region 1
Central Region
2
3
Western Region
4
5
6
7
Meandrina danae
X
X
X
Meandrina meandrites
X
X
X
X
X
X
X
Millepora alcicornis
X
X
X
X
X
X
X
Millepora complanata
X
X
X
X
X
X
X
Millepora squarrosa
X
Millepora striata
X
X
X
X
X
X
X
X
X
X
X
X
X
Montastraea annularis Montastraea cavernosa
X
X
X
X
X
X
X
Montastraea faveolata
X
X
X
X
X
X
X
Montastraea franksi
X
X
X
X
X
X
X
Mussa angulosa
X
X
X
X
X
X
X
Mycetophyllia aliciae Mycetophyllia danaana Mycetophyllia ferox Mycetophyllia lamarckiana Mycetophyllia reesi Oculina difusa Porites astreoides
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Porites branneri
X
X
X
X
X
X
X
X
X
X
X
X
Porites colonensis
X
X
X
X
X
X
X
Porites divaricata
X
X
X
X
X
X
X
Porites furcata
X
X
X
X
X
X
X
Porites porites
X
X
X
X
X
X
X
Scolymia cubensis
X
X
X
X
X
X
X
Scolymia lacera
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X 9 X
Siderastrea radians Siderastrea siderea
X
X
X
Solenastrea bournoni
X
X
X
Solenastrea hyades
X
X
X
X
X
X
Stephanocoenia intersepta
X
X
X
X
X
X
X
Total
56
61
66
54
51
57
59
70
Soft corals or octocorals represent 38 species, with the highest diversity in KunaYala (Table 2). The only previous list containing this information concerned Kuna-Yala (Clifton et al. 1997). It reported 26 species without including the genera Iciligorgia and Nicella. N. schmitti was previously described for Panama (Bayer 1961) and, according to the report, was widely distributed in all the regions. Two possible new species for Kuna-Yala are included in the current list (Table 2). One hundred percent of the country's species are present in the eastern region, whereas only 60.5% and 82% are found in the central and western regions, respectively. It is worth mentioning that only 24 species were known for the eastern coast of Mexico and Central America (Bayer 1961).
The Caribbean coral reefs of Panama
253
TABLE 2 List of octocorals species from the Caribben coast of Panama by study regions. 1, Tubuala; 2, Ailigandi; 3, Nargana; 4, Portobelo-Isla Grande; 5, Rio Chagres-Bahia Las Minas; 6, continental areas; and 7, insular areas. Species
Eastern Region 1
Briareum asbestinum Erythropodium caribaeorum Ellisella barbadensis Ellisella elongata Ellisella sp. Eunicea calyculata Eunicea fusca Eunicea laxispica Eunicea mammosa Eunicea succinea Eunicea tourneforti Gorgonia flabellum Gorgonia mariae Gorgonia ventalina Iciligorgia schrammi Muriceopsis flavida Muriceopsis sulphurea Muricea elongata Muricea laxa Muricea muricata Muricea atlantica Muricea pinnata Nicella schmitti Nicella sp. 1 MiralIn
~n =
X X X X X X X X X X X X X X X X X X X X
9
Plexaura kuna Plexaura flexuosa Plexaura homomalla Plexaurella nutans Plexaurella sp. Pseudoplexaura porosa Pseudopterogorgia acerosa Pseudopterogorgia americana Pseudopterogorgia bipinnata Pseudopterogorgia kallos Pterogorgia anceps Pterogorgia citrina Pterogorgia guadalupensis Total 38
2
X X X X X X X X X X X X X X X X X X X X X X X
Central Region
Western Region
3
4
5
6
7
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
~)(
X X X X X
X X X X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X X
X
X
X
X
X
X
X
X
23
23
25
29
X
X X X X X 30
X X X X X 34
X X
X 33
X
254
H.M. Guzmdn
TABLE 3 List of sponges from the Caribben coast of Panama by study regions. 1, Tubuala; 2, Ailigandi; 3, Nargana; 4, Portobelo-Isla Grande; 5, Rio Chagres-Bahia Las Minas; 6, continental areas; and 7, insular areas. Central Region
Easto'n Region 1
2
3
4
5
Acarnus souriei
X
Adocia implexiformis Agelas clathrodes
X X X X
X X X X
X X X
X
Agelas confiera Agelas dispar
X X X X X
X
Agelas flabelliformis Agelas sceptrum
X X
X
X X
X
X
Agelas schmidti Agelas wiedenmyeri
Western Region 6
7
X
X
X X
X X X
X
Amphimedon compressa Amphimedon erina Amphimedon rubens
X X
X
X X
X
X
X
X
X
X
X
X
X
X
Anthosigmella varians
X
X
X X
X
X
X
X
X
X
X
X X
X
X
Artemisina melana Apysilla gracilis Aplysina archeri Aplysina aurea
X X X
X
X X
X
X
X
Aplysina cauliformis
X
X
X
X
X
X
X
Aplysina fistularis
X
X
X
X
X
X
X
Aplysina fulva Aplysina lacunosa
X
X
X
X
X
X
X
X
X
X
X
X
Callyspongia armigera Callyspongia longissima Callyspongia vaginalis Calyx podatypa
X
X
X
X
X X
X
X
X
X
X
Ceratoporella nicholsoni Chelonaplysilla erecta
X
X X
X
X
X
X X
X X
X X
X
X
X
X
X
X
X X X
X X X
X X
X
X
X
X
X
X X
X X
X
X
X
X
Cliona delitrix
Dictyodendrilla nux Diplastrella megastellata Diplastrella ministrella
X
X
Cliona aprica Cliona lampa Cliona langae Cribrochalina vasculum Desmapsamma anchorata
X
X
X
Chondrilla nucula Cinachyra alloclada Cinachyra sp. Clathria aspera
X
X X X X X
X X
X X
X X
X X
X X
X
X
X
X
X X
X X
The Caribbean coral reefs of Panama
255
Table 3 cont.
Eastern Region 2 3
1 Discodermia dissoluta Ectyoplasia ferox
X
X
Central Region 4 5
X
Western Region 6 7
X
X
X X
X
Geodia neptuni Haliclona hogarthi Halisarca sp.
X X X
X X
X
X X
X X
X X
X X
Hyattella intestinales Iotrochota birotulata Ircinia campana
X X
X X
X X
X X
X X
X X X
X X
Ircinia felix Ircinia strobilina
X X
X X
X X
X X
X X
X X
X X
Ircinia variabilis Leucandra aspera Monanchora barbadensis
X X X
X X X
X X X
X X
X X
X X
X
Monanchora unguifera
X
X
X
X
X
X
X
Mycale americana Mycale arndti
X X
X X
X X
X X
X
X
X
Mycale laevis
X
X
X
X
X
X
X
Mycale laxissima
X
X
X
X
X
X
X
X
X
X
X X
X
X
Neofibularia nolitangere Niphates amorpha
X
X
X X
Niphates digitalis Niphates erecta
X X
X
X
Niphates ramosa
X
Oceanapia bartschi
X
X
Pachypellina podatypa
X
Petrosia pellasarca
X
X
X
X
X
X
X
X X X
Phorbas amaranthus Plakortis angulospiculatus
X X
X X
X X
X X
X X
X
X
Plakortis haHchondroides
X
X
X
X
X
X
X
Pseudoceratina crassa Pseudaxinella lunaecharta
X X
X X
X X
X X
X X
X X
X X
Ptilocaulis walpersi
X
X
X
X
X
X
X
Sigmadocia caerulea
X
X
X
Sigmadocia piscaderaensis Siphonodictyon coralliphagum
X
X
Spheciospongia vesparium Spirastrella coccinea
X X
Spirastrella mollis Tedania ignis Teichaxinella burtoni
X
X
X
X
X X
X X X
Tethya crypta Topsentia amorpha Ulosa ruetzteri
X
X
X X
X X
X
X X
X
X
X
X
256
H.M. Guzmrn
Table 3 cont. 1
Eastern Region 2 3
Central Region 4 5
Western Region 6 7
Verongula reiswigi Verongula rigida
X
X
X X
X
X
X
X
Xetospongia muta
X
X
X
X
X
X
X
Xetospongia proxima Xetospongia rosariensis Total 88
X 54
X X 63
X 73
X 52
X 47
X 54
X X 56
Sponges are an important sessile group in reefs, of which we recognize 88 species for the Caribbean coast (Table 3). Of these species, 93% are found in Kuna-Yala, followed by 72% for Bocas del Toro (63 species) and about 59% and 53% for the areas of Isla Grande and Bahia Las Minas, respectively. Previously, 58 species of sponges were reported for Kuna-Yala, including species that inhabit seagrass meadows and mangrove roots (Clifton et al. 1997). I agree with these authors that the diversity of sponges off Panama has been underestimated and that more efforts are needed to identify those that occur. More than 640 sponges have been reported for the wider Caribbean (van Soest 1984). Figure 4 summarizes the diversity of the three groups of sessile organisms previously presented and includes figures for each region along Caribbean Panama. Generally, we may say that the country's highest diversity is found off Kuna-Yala.
Fig. 4. Total number of species for major sessile taxa (scleractinian corals, octocorals, sponges), in three regions of the Caribbean coast of Panama.
3. NATURAL DISTURBANCES Panama has been affected mainly by sea warming and diseases in corals and other reef-related organisms (Ogden and Ogden 1994; Shulman and Robertson 1996). In the early 1980s, the massive mortality of Diadema antillarum, which apparently began near Panama, started to have a negative impact on reefs all over the Caribbean because of the
The Caribbeancoralreefs of Panama
257
loss of an important herbivore that controlled macroalgae growth (Lessios et al. 1984a; Hughes 1994; Lessios 1998; Hughes and Tanner 2000). Sea urchin densities, although they show some recovery in Jamaica's reefs (Edmunds and Carpenter 2001), have not reached levels comparable to those reported off Panama before the die-off, especially in Kuna-Yala (Guzrnfin et al. 2003), and similar to those in other regions such as Florida (Chiappone et al. 2002). During the 1982/83 E1 Nifio, Kuna-Yala reefs were affected by the anomalous sea warming, with bleaching of 32% of the live coral cover that affected mainly species such as Agaricia spp. and Montastraea annularis, and caused a mortality of 53% in the Agaricia cover (Lasker et al. 1984). Reef bleaching was also observed in several regions of the country during 1995 and 1997/8, apparently related to the same phenomenon but without further implications (Clifton et al. 1997; Guzrnfin pers. obs.). The Kuna-Yala time-series showed remarkable changes in the coral cover during the 1980s, which gradually extended during the 1990s (Fig. 2). Nevertheless, it must be pointed out that during 1987, coral mortality was reported in the central region, especially in the Isla Grande-Portobelo area (Fig. 2), the cause of which was not determined. It is suspected that the mortality may have been related to the brief warming that took place during that year or to white-band disease (sensu Gladfelter 1982) as the population of Acropora palmata was the most seriously affected (Guzrnfin et al. 1991). Regarding coral diseases, the massive mortality that virtually destroyed the entire population of Gorgonia flabellum octocoral off Costa Rica in the mid-1980s (Guzmfin and Cort6s 1984) and affected the whole of Panama (J. Cubit per. com.; H.M. GuzmAn per. obs.) must be mentioned. From the start, it was suggested that some kind of disease was involved and the probable agent was subsequently found to be a fungus, Aspergillus (Smith et al. 1996). Likewise, since the end of the 80s, white-band and black-band diseases (sensu Antonius 1981) as well as other recently-described diseases (Richardson 1998) have been regularly observed in reefs all along the Caribbean coast, although never in epidemic proportions or causing generalized mortality. One report from 1996-97 suggested a major outbreak of yellow-blotch/yellow-band disease off Panama at Kuna-Yala, affecting mostly Montastraeafaveolata (McCarty and Peters 2000). Finally, Panama is generally included in the area of the Caribbean region not affected by hurricanes (Cubit et al. 1989). Nevertheless, Hurricane Joan, the last hurricane to pass near this region in the last 100 years, had a devastating effect on the shallow-water sponge populations in Kuna-Yala (Wulff 1995). 4. ANTHROPOGENIC IMPACT Without doubt, the reefs of the central region of Panama have been the most affected by man-made adventures. The impact of civilization, as it is now known, on these reefs goes back to the times of the Spanish conquest. The history is quite similar for most Caribbean countries, as coral, for many centuries, was the main raw material used in the construction of fortresses and settlements in the whole region. With regard to Panama, it is worth mentioning the construction of the City of Portobelo, located in the central region of the country. By the late 16th century the first massive extraction of coral from nearby reefs had been carried out and continued for about 200 years (Fig. 5). In the Archivo General de Indias (AGI) coral mining activities are relatively well reported and provide great details on the periods of construction, demolitions due to redesign and the
258
H.M. Guzmdn
Fig. 5. Historical coral mining in Caribbean Panama. Seventeenthcentury Spanish fortification built with Montastraea, Colpophyllia and Siderastrea coral species in Portobelo, Panama (A); and detail of a coral wall (B).
reconstruction of several military fortresses and public and religious buildings that protected and made up Portobelo (Webster 1970; Castillero 1990). Corals or "sea stones" were extracted inside and around Portobelo cove and in pits located 45 km (8 leagues) west of the city, between Bahia Las Minas and Bahia Lim6n (formerly Puerto Naos)
The Caribbean coral reefs of Panama
259
(AGI 1595 in Castillero 1990). By the mid-18 th century, coral was still being mined from these sites, which seemed "inexhaustible" (AGI 1756 in Castillero 1990). Based on several documents from the AGI, where the quantity of materials used for several constructions is described in detail, over 70,000 m e of coral was mined in a short period of time (Castillero 1990). The buildings and structures or ruins of Portobelo, which have been included in the UNESCO World Heritage since 1980, were measured on site (Table 4), yielding a total volume of 15,387 m 3, of which coral accounted for some 12,923 m 3 (Jim6nez and Guzn~n in prep.).
TABLE 4 Estimated volume of existing Spaniard ruins constructed from the late 1500's to mid 1700's in Portobelo, Panama. Volume was measured in situ for each of the standing walls and coral volume was based on a 90 • 3.6% mean coral cover obtained from transects ran across the walls (Jim6nez and Guzm~in in prep.). Name of Building
Construction Period
Building Volume
Fort Santiago de la Gloria
1600-1760
7,420
6,554
Town
1596-1744
191
I42
1629-?
238
144
--1630-1638
1,944
1,749
Fort San Jer6nimo
1659-1758
1,320
1,188
Fort San Pedro (San Carlos)
1682-1686
981
588
Iglesia San Felipe
1600-1814
1,072
643
Iglesia San Juan de Dios Aduana
Convento Las Mercedes Fort San Fernando Estimated Total Volumes
(~)
Coral Volume
?-1736
51
33
1753-1758
2,170
1,882
15,387
12,923
(m3)
By the end of the 19th century, the French had initiated the first excavations for the construction of the Panama Canal, which the Americans would continue after 1904 (McCullough 1977). The entrance to the Canal from the Caribbean was located at Bahia Lim6n, where the extraction and dredging of all the coastal reefs started in order to fill the mangrove swamps over which military bases, airports and the City of Crist6bal were to be built (Comber 1916; Castillero 1962). Some records conform the extraction of approximately 20 million m 3 of reef coral and other material by the French Company from 1882 to 1885 and 33 million m s by the American Company from 1904 to 1907 (Comber 1916; Rousseau 1916; Noriega 1986). Moreover, the American Company built two 3.3 km-long breakwaters at the entrance of Bahia Lim6n between 1910 and 1916. These were destroyed a number of times by storms and rebuilt every time using new material dredged from the reefs off Coco Solo island, located at the eastern edge of the Bay. According to the records, about 1.5 million m 3 of reef-excavated material was needed to build the western breakwater and about 400,000 m 3 (part of the record lost) for the eastern one (Rousseau 1916). Concurrent to the construction of the Panama Canal and especially after 191 I, numerous American military bases (e.g. Fort Sherman,
260
H.M. Guzmim
Fort DeLesseps and Fort Randolph) were built around the coastal area of the Canal, from the mouth of the Chagres River to the Isla de Largo Remo in Bahia Las Minas. The same pattem of filling the mangrove swamps with reef coral was always followed and continued through the two World Wars until 1944. During this period, new US Navy and Air Force military bases were build or enlarged on the islands of Margarita, Coco Solo, Largo Remo and Galeta that became peninsulas by means of landfill (Copeland 1964; Gardner and Carpenter 1965). In recent times, between 1958 and 1974, more than 5 million m s of reefs were dredged to fill 80 ha of mangrove swamps and marshes in Bahia Las Minas during the construction of a refinery (see publicity leaflet of Refmeda Panamfi, S.A.). From the day the refinery started operating (1961-62) and continuing to this day, the area has been consistently polluted by hydrocarbons (Guzmfin and Jarvis 1996). Several oil spills have also affected and destroyed coral reefs in this area, particularly in 1968 and 1986 (Jackson et al. 1989; Guzmfin et al. 1991, 1994). To this, we must add the generalized pollution of coral reefs with different metals from multiple activities that take place both near to and at a distance from the coastal zone. These include port, industrial and fam3ing activities (Guzmfin and Jim6nez 1992), which are responsible for the emission of high levels of extremely toxic elements such as mercury (Guzrr~n and Garcia 2002). Equally important is the destruction of reefs due to the traditional coral mining and landfilling practices of the Kuna people in Kuna-Yala. The Kuna modify and expand their populated islands from the shores to the edges of the shallow reef flats, marking the perimeter with coral walls for landfill (Fig. 6a-b). This activity started 150 years ago when the Kuna living in the forests between Colombia and Panama decided to settle along the archipelago on the coastal zone (Tice 1995; Ventocilla et al. 1995; Howe 1998). The activity was first acknowledged in the early 1970s and the impact on reef habitats was brought to the attention of the authorities (Porter and Porter 1973). Recently, the impact of coral mining and landfilling was quantitatively assessed by means of direct measurement of the coral volume in the walls as well as the changes in the island surfaces, comparing photographic records from the 1960s with those of 2001 (Guzmfin et al. 2003). While the authors assessed only 50% of the inhabited islands, 20 km of walls with a coral volume estimated at 16,000 m 3 were measured in addition to an increased surface area of 6.23 ha due to coral landfilling. The growing tourist industry has further encouraged the Kuna to extract corals and other reef-related organisms for their sale as souvenirs (Fig. 6c). It is important to mention the impact of sedimentation on the reefs off the central and western regions of the country, a process that has resulted from indiscriminate deforestation along the coastal zone and fiver basins. This has contributed in part to the generalized degradation of the landscape observed throughout the country for decades. This problem has worsened during the last decade in the Isla Grande-Portobelo sector and in the last 5 years in Bocas del Toro (GuzmAn and Guevara 1999, 2001), both associated with tourist development and the mismanagement of forests in the river basins which has increased the runoff into the Caribbean. It has been observed, moreover, that a substantial portion of the vegetation and tree trunks produced during the process of deforestation is carried by the rivers down to the sea, where, with unexpected frequency, physically destroy the reef shallow habitats (Kilar and Norris 1988).
The Caribbean coral reefs of Panama
261
Fig. 6. Traditional coral mining in Kuna-Yala, Panama. Coral Cay enlarged by coral landfilling (A); coral wall at the edge of island (B); and souvenirs made of small coral colonies (notice fresh coral tissue), conchs, etc. to be sold by Kuna people to tourists (C). Photos by M. Guerra (A), and C.E. Jim6nez (C).
262
H.M. Guzm6n
Finally, unregulated exploitation of reef-related fishing resources is decimating the natural populations and, consequently, is drastically reducing the income of coastal zone populations. Lobster exploitation has already resulted in a situation of overfishing in Kuna-Yala (Castillo and Lessios 2001) and in Bocas del Toro (GuzroAn and Guevara unpubl, data). Moreover, among other non-traditional resources, three species of sea cucumber have been briefly exploited in Caribbean Panama, reaching overfishing levels in at least two of the species, Isostichopus badionotus and Astichopus multifidus (Guzrnfin and Guevara 2002). It has been suggested that the existing low densities may not allow their reproduction and recovery in the mid-term (Guzmfin et al. 2003). 5. PROTECTION, LEGISLATION AND MANAGEMENT 5.1 Protected Areas
Panama has four protected areas with reefs on the Caribbean side and under different management categories. The creation of a new protected area along the old Fort Sherman, from the mouth of the Panama Canal to the Chagres River, is at present under revision. Most areas have a rather weak legal definition as they were established by Directive Board Resolutions (Resoluciones de Junta Directiva; R.J.D.) or Ministry Decrees (Decretos de Gabinete) and not by national laws (see Navarro 1998). Moreover, at present there is a management plan only for Parque Nacional Portobelo, though plans are apparently being prepared for other areas and are expected by the year 2003. The protected areas are distributed throughout the three Caribbean reef regions previously defmed (Fig. 1), namely: (1) In the eastern region (Kuna-Yala), the Area Silvestre de Nargana with circa 99,000 ha managed by the Kuna people and established in 1994 (R.J.D. 22-94). The extent of the maritime-coastal zone under protection is not clear, but it is indeed within the "corregimiento" and includes the best reefs in the country. Most reefs close to the mainland and near settlements have been undeniably altered by traditional coral mining (see Fig. 6 and Guzrnfin et al. 2003). These authors have suggested eight priority conservation areas and the need for the creation of a network of protected areas to serve as a marine corridor within the indigenous reservation, a proposal that is now under consideration by the local authorities. (2) In the central region, there are two existing protected areas and one being created. The Parque Nacional Portobelo, with 13,226 ha, was created in 1976 (Decree 91) and includes the reef areas from Portobelo to Isla Grande in a strip bounded by about 70 km of coast and extending 2,000 m seaward. Most of these reefs are affected by sedimentation and runoff associated with coastal tourist development. The second area, Area Silvestre Protegida of Isla Galeta established in 1997 (Act 21), includes a coastal area of no more than 25 km and reefs in an advanced state of deterioration, directly as a result of the 1986 oil spill (Guzmfin et al. 1991). The third (possibly) protected area of San Lorenzo includes underdeveloped, low-diversity reefs (GuzmAn and Hoist 1994). This area is in fact designated for the conservation of one of the few pristine forest areas in the country's central region, a move that would indirectly benefit the reefs. (3) In the western region, the Parque Nacional Marino Isla Bastimento was established in 1988 (R.J.D. 22-88) with 13,226 ha, of which 11,596 ha includes protected marine environments. Recently, it was reported that the highest diversity or reefassociated organisms and best reef development occur outside the protected area
The Caribbean coral reefs of Panama
263
(Guzrrfin and Guevara 1998b, 1999). This park is under enormous pressure due to the high level of sedimentation caused by deforestation on the neighboring islands and increasing tourism. At present, a management plan is being elaborated for this park.
5.2. Legislation and Management In the previous sections, we have identified the present conservation status of many coral reefs on the Caribbean coast of Panama. We can confidently state that the diversity of scleractinian corals and other sessile organisms found here is representative of the wider Caribbean. On the one hand, we have observed that the percentage of live coral cover indicates that the reefs' health is not excellent. They have been gradually affected over the past 30 years by natural or anthropogenic disturbances. In some cases, the agent causing this deterioration has not been easy to identify, but in others, as in Bahia Las Minas where coral mortality above 80% has been reported, the problem can be clearly attributed to human disturbances (GuzmAn et al. 1991). On the other hand, it is important to point out that in most reefs where changes in coral cover, composition and diversity are monitored at present, a small recovery has been observed. Even though this improvement is lower than 10% and is not particularly significant, it indicates that the system has self-restorative capabilities. Both processes, the deterioration and the potential recovery, force us to recognize the inexorable need of exemplary legislation and better scientific management of the resources for the conservation of the country's reefs. The first reef conservation and environmental policy efforts started in 1977 when Panama became a signatory of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora). Legislation developed fin'ther during the early 1990s when two resolutions (R.J.D.) prohibited the extraction of corals (INRENARE R.J.D. N ~ 033-93, September 28, 1993) and reef fishes (Executive Decree N ~ 29, June 24, 1994) throughout the country. Nevertheless, because these two initiatives are mere "resolutions" and not national laws, in practice they have been documents that have never fulfilled their goal. The extraction of scleractinian corals, octocorals, anemones, sponges and reef fishes continues indiscriminately in several sectors of the country, and even worse, within protected areas. Moreover, Panama has signed Act 2 from 1995, which approves the Convention on Biological Diversity, and Act 9 of the same year, which regulates the Protection of Priority Protected Areas of Central America. More importantly for Panama, the Ley General del Ambiente N ~ 41 (Environment General Law) was established in 1998, which, up to now (October 2002) has not been clearly regulated, creating thus a legal vacuum that does not allow the adequate protection and management of coral reefs and their related resources. The following three examples elaborate the above statements and highlight the lack of legal attention bestowed upon reefs. At the same time, they reveal how the available scientific information has not been used appropriately in the implementation of protection measures for these ecosystems. Firstly, we have pointed out before that the best reef development and the largest reef extension in Panama is in Kuna-Yala under the autonomous political regime of the Kuna people. Since the early 1970s, there has been scientific information that, although not quantitative, has reported the traditional practices of coral mining and landfiUing, rather than the building of new communities on mainland, in order to keep pace with population growth (Porter and Porter 1973). Both researchers made repeated calls to the Kuna authorities and the central government,
264
H.M. Guzmfn
suggesting that coral extraction be controlled, and that the reef be sustainably managed, for the benefit of the Kuna people. Both parties have ignored the warnings and consequently reef destruction has reached unprecedented levels. What is worse, there is now an increase in the extraction of materials from other shallow habitats such as seagrass meadows and beaches (Guzmfin et al. 2003). Until 2001 reef deterioration as a result of this practice was monitored and was found to be limited to the western region or Punta San Bias (Shulman and Robertson 1996) while very little was known about the general state of reefs in the remaining area. However, the state of the reefs and some aspects of their diversity throughout the entire indigenous reservation are now well-known (Guzrnfin et al. 2003). Secondly, in the early 1990s the government gave permission to Spanish architects to extract coral from the Portobelo area reefs to be used as raw material in the restoration of some buildings erected by the Spaniards 500 years ago (see Fig. 5). Their intention, unconceivable to scientists now, was mainly to restore the Customs House (Aduana) using the same material with which it was originally built, which was coral. Some of the Portobelo National Park reefs had been monitored since 1985 (Guzmfin et al. 1991) and in 1992 it was reported that live coral cover within this area was lower than 10% (Fig. 2). Both the authorities and the Spanish technicians that in 1992 elaborated the first management plan for the protected area were fully aware of the existing scientific information. Years later, in 1997, which was declared International Year of the Reef, live coral extraction continued in order to complete the restoration work and, ironically, the local media reported that with this work "technical assistance was offered to train more than 30 Portobelo residents in restoration work with coral" (Santamaria-Loo 1997). Thirdly and f'mally, studies carried out in Bocas del Toro in the late 1990s identified sensitive and priority areas for conservation throughout the archipelago (Fig. 7), suggesting that the currently protected marine area did not include some of the important resources that needed to be preserved (GuzroAn and Guevara 1998b, 2000). These areas were selected on the basis of the presence of the greatest diversity ("hotspots") of corals and other sessile organisms within the archipelago (sensu Briggs 2002) and the existence of important populations of species considered to be endangered, such as Acropora palmata and A. cervicornis (Precht et al. 2002). In spite of public disclosure of the results and direct lobbying before the authorities as well as national and international non-governmental organizations since 1998, these areas remain unprotected to date, although we acknowledge that efforts are being made to change the current park limits. Time is important as a gradual deterioration of the reefs has been observed within these areas over the past three years (see histograms in Fig. 7). 6. CONCLUSION AND R E C O M M E N D A T I O N S The examples above refer to the best reef areas of Panama, which, without doubt, are the ones that should be protected. In short, analyzing the future prospects for the country's Caribbean reefs and rating them according to their current risk level due to environmental pressures (sensu Bryant et al. 1998), we can say that more than 80% of the coral reefs are at risk (Fig. 8). Indeed, 50% of the areas have a high-risk level. When we analyze in detail these levels for each Province, we observe that in Col6n 100% of the reefs are high-risk, followed by 75% and 50% for Bocas del Toro and Kuna-Yala, respectively (Table 5). These risk levels go hand in hand with the increase in the coastal population estimated at between 60% and 290% for the last 40 years (see Table 5; Stmglia and Winter 2002).
265
The Caribbean coral reefs of Panama
Fig. 7. Priority conservation area of Bocas del Toro, western Caribbean Panama, and changes in live coral cover from 1999 to 2002 at two reef-monitoring sites within the critical areas. Area containing the highest diversity of coral, octocorals and sponges or "hot spot" within the archipelago (light gray), and areas of relatively abundant endangered coral species Acropora spp. (dark gray). Notice the polygon that limits the existing marine protected area of PNMIB (modified from Guzm/m and Guevara 1999).
TABLE 5 Estimated reef area, percentage of reefs at risk, and demographic growth between 1960 and 2000, for geographical provinces along the Caribbean coast of Panama (see Fig. 1). Percent reef areas at risk (medium-high) were estimated combining four threat factors: coastal development, marine pollution, overexploitation, and inland pollution and erosion (Bryant et al. 1998). Population data include only those "Corregimientos" (smallest administrative political units) close to the coastal zone (CGR 2001). Province
Reef Area
High Risk
Population
Population
Change
(km2)
(%)
(1960)
(2000)
(%)
Kuna-Yala
610
50
19,509
31,619
62.1
Col6n
48
100
76,845
123,198
60.3
Veraguas
8.2
25
616
2,340
289.9
Bocas del Toro
87.4
75
27,238
103,307
279.3
266
H.M. Guzm6n
.~
6O
n,
50
t~ ~
O0
~
40
~ ao n,, = 20 r
L_
9
13.
10 0
m
Low
Medium
High
Threat Category
Fig. 8. Percentageof reefs at risk along the Caribbean coast of Panama, according to threat categories (sensu Bryant et al. 1998). One of the most important risk factors is the development of the coastal zone and the resultant overpopulation (Bryant et al. 1998). Tourism may be considered as the most important activity because 48.5% of the 1,398 tourist attractions included in the Tourist Development Master Plan (Plan Maestro de Desarrollo Turistico) of Panama (IPAT /OEA 1993) are in the coastal zone (JICA/IPAT 1995). Prospectively, 90.3%, 59%, 45.7% and 40.4% of these coastal tourist attractions, in comparison with non-coastal ones, are located in the Provinces of Kuna-Yala, Col6n, Veraguas and Bocas del Toro, respectively. Doubtlessly, reefs in these areas are an important tourist attraction but the reefs also fulfill a very important role in the productivity and functioning of a very complex coastal ecosystem. It is obvious that the maintenance of these high levels of tourist attraction will depend exclusively on the integral conservation of these coastal areas and their reefs and some kind of control on demographic growth (see Stmglia and Winter 2002). There is nothing new about all of the above. However, I would like to close this chapter with some personal comments on aspects that may be of help in the conservation of our reefs. It is well-established that in recent years coral reefs have become very popular on the environmental agenda of some governments and, especially non-governmental organizations (NGOs). On the one hand, I acknowledge the important work carried out by some of these NGOs in the diffusion of the magnitude of reef deterioration and status worldwide and of the long-term effect this degradation will have on the coastal zone in general if this trend is not reversed. On the other hand, it is to be noted that after all these multi-million dollar campaigns, very little change has been observed. Deterioration continues unchallenged in most countries, especially in the Neotropics. With a few localized exceptions that do not represent the spatial scale of the problem, it was possible to create protected areas that work, instead of the so-called "paper parks", and the problem has been halted. Considering the above and after participating personally in several planning workshops (technical and communal) for reef sustainable conservation, I can state with no doubt that something is amiss. Although scientists have taken the position of helping in the conservation process and are constantly supplying the information requested by the NGOs and resource managers, no
The Caribbean coral reefs of Panama
267
real solutions to the local and regional problems are emerging from this process. Part of the answer may lie in the lack of empowerment and organization of the civil society, but it is to be noted that the excessive financial resources available for conservation have been invested almost exclusively in planning workshops. We seem to have totally forgotten that, for the implementation and functioning of these plans, a very important ingredient is needed: the will of the political class. In short, we have common immediate conservation goals, but they must be better focused on the professional informing and lobbying of legislators and government officers who are the only ones that have the power to decide the future and management of resources in our countries. ACKNOWLEDGMENTS
I wish to thank the government of the Republic of Panama, the National Environmental Authority (ANAM), the Panama Maritime Authority (AMP) and the Congreso General Kuna for giving me collection permits and access to the reefs throughout the country for many years. I thank Carlos A. Guevara for all the support given to the acquisition of field information; without his help, it would have been impossible to describe the reefs of Panama. Thanks to I. Herngndez, for preparing the database, K. Kaufman for processing the data and L. Gonzhlez for photograph preparation. I wish to thank the Editor, J. Cort6s, for his constant support and patience. The information contained in this chapter has been obtained with the financial support of the Smithsonian Tropical Research Institute and the Smithsonian Institution Environmental Sciences Program, as well as with the partial support of The Nature Conservancy, Fundaci6n Natura de Panam,5, Fundaci6n PROMAR de Panamfi and AEK-PEMASKY. This chapter is dedicated to Irene, Adriana and Carolina, pillars of my existence. REFERENCES
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Porter, J.W. 1972a. Ecology and species diversity of coral reefs on opposite sides of the Isthmus of Panama. Bull. Biol. Soc. Wash. 2:89-116. Porter, J.W. 1972b. Patterns of species diversity in Caribbean reef corals. Ecology 53: 745-748. Porter, J.W. 1974. Community structure of coral reefs on opposite sides of the Isthmus of Panama. Science 186: 543-545. Porter, J.W. & K. Porter. 1973. The effects of Panama's Cuna Indians on coral reefs. Discovery 8: 65-70. Precht, W.F., A.W. Bruckner, R.B. Aronson & R.J. Bruckner. 2002. Endangered acroporid corals of the Caribbean. Coral Reefs 21:41-42. Richardson, L.L. 1998. Coral diseases: what is really known? TREE 13: 438-443. Roberts, C.M. 1993. Coral reefs: health, hazards and history. TREE 8: 425-427. Robertson, D.R. 1984. Cohabitation of competing territorial damselfishes on a Caribbean coral reef. Ecology 65:1121-1135. Robertson, D.R. 1987. Responses of two coral reef toadfishes (Batracoididae) to the demise of their primary prey, the sea urchin Diadema antillarum. Copeia 3: 637642. Robertson, D.R. 1988. Abundances of surgeonfishes on patch-reefs in Caribbean Panama. Mar. Biol. 97: 495-501. Robertson, D.R. 1991. Increases in surgeonfish populations after mass mortality of the sea urchin Diadema antillarum in Panan~ indicate food limitation. Mar. Biol. 111: 437-444. Robertson, D.R. 1992. Patterns of lunar settlement and early recruitment in Caribbean reef fishes at Panama. Mar. Biol. 114: 527-538. Robertson, D.R., H.P. Sweatman, E.A. Fletcher & M.G. Cleland. 1976. Schooling as a mechanism for circumventing the territoriality of competitors. Ecology 57: 12081220. Robertson, D.R., D.G. Green & B. Victor. 1988. Temporal coupling of production and recruitment of larvae of a Caribbean reef fish. Ecology 69:370-381. Robertson, D.R., U. Schober & J.D. Brawn. 1993. Comparative variation in spawning output and juvenile recruitment of some Caribbean reef fishes. Mar. Ecol. Prog. Ser. 94:105-113. Robertson, D.R., S.E. Swearer, K. Kaufmann & E.B. Brothers. 1999. Settlement vs. environmental dynamics in a pelagic-spawning reef fish at Caribbean Panama. Ecol. Monogr. 69:195-218. Rousseau, H.H. 1916. Terminal works, dry ports and wharves of the Panama Canal, p. 368-432. In The Panama Canal International Engineering Congress. Neal Publishing Co., San Francisco. Rubinoff, I. 1965. Mixing oceans and species. Nat. Hist. 74" 69-72. Rubinoff, I. 1968. Central American sea-level canal: Possible biological effects. Science 161: 857-861. Rubinoff, I. 1970. The sea-level Canal controversy. Biol. Cons. 3: 33-36. Rubinoff, R.W. & I. Rubinoff. 1968. Interoceanic colonization of a marine goby through the Panama Canal. Nature 217: 467-478. Rubinoff, I. and R.W. Rubinoff. 1962. New records on inshore fishes from the Atlantic coast of Panama. Brevoria 169: 1-7.
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Riitzler, L. & W. Sterrer. 1970. Oil pollution: Damage observed in tropical communities along the Atlantic seaboard of Panama. BioScience 20: 222-224. Santamaria-Loo, M. 1997. Los cuatrocientos afios de la historia de Portobelo. La Prensa Newspaper. March, 20 th. 1 p. Sebens, K.P. 1982. Intertidal distribution of zoanthids on the Caribbean coast of Panama: effects of predation and desiccation. Bull. Mar. Sci. 32:316-335. Shulman, M.J. & D.R. Robertson. 1996. Changes in the coral reefs of San Bias, Caribbean Panama: 1983-1990. Coral Reefs 15:231-236. Smith, G., L.D. Ives, I.A. Nagelkerken & K.B. Ritchie. 1996. AspergiUosis associated with Caribbean sea fan mortalities. Nature 382:487. Spurgeon, J.P.G. 1992. The economic valuation of coral reefs. Mar. Pollut. Bull. 11: 529-536. Struglia, R. & P.L. Winter. The role of population projections in environmental management. Environ. Management 30:13-23. Taylor, W.R. 1929. Notes on algae from the tropical Atlantic Ocean. Amer. J. Bot. 16: 620-630. Tice, K.E. 1995. Kuna Crafts, Gender, and the Global Economy. Univ. Texas Press, Austin. 232 p. Topp, R.W. 1969. Interoceanic sea-level canal: effects on the fish faunas. Science 165: 1324-1327. Veron, J.E.N. 2000. Corals of the World. Odyssey Publishing, Australia. 1382 p. Warner, R.R. 1975. The adaptive significance of sequential hermaphroditism in animals. Amer. Nat. 109:61-82. Warner, R.R. 1984. Mating behavior and hermaphroditism in coral reef fishes. Amer. Scient. 72: 128-136. Warner, R.R. 1990. Male versus female influences on mating-site determination in a coral reef fish. Animal Behaviour 39: 540-548. Warner, R.R. & S.G. Hoffman. 1980. Population density and the economics of territorial defense in a coral reef fish. Ecology 61: 772-780. Warner, R.R., D.R. Robertson & E.G. Leigh. 1975. Sex change and sexual selection. Science 190: 633-638. Webster, E.C. 1970. The Defense of Portobelo. The Florida State University, Campus Panama. 37 p. Wulff, J.L. 1995. Effects of a hurricane on survival and orientation of large erect coral reef sponges. Coral Reefs 14:55-61. Van Soest, R.W.M. 1984. Marine sponges from Curacao and other Caribbean localities. Part III. Poecilosclerida. Stud. Fauna CSara~ao Carib. Isl. 199: 1-167. Ventocilla, J., H. Herrera & V. Nufiez. 1995. Plants and Animals in the Life of the Kuna. Univ. Texas Press, Austin. 150 p.
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The Caribbean coral reefs of Colombia Jaime Garz6n-Ferreira and Juan Manuel Diaz Instituto de Investigaciones Marinas y Costeras "Jos6 Benito Vives De Andreis", INVEMAR. A.A. 1016, Santa Marta, Colombia
ABSTRACT: Research on Caribbean coral reefs of Colombia started during the 1960s with foreign scientists, and increased significantly in the last two decades with Colombian reef researchers. There are about 2800 km2 of coral reef areas within the Colombian Caribbean; more than two-thirds in the oceanic archipelago of San Andrrs and Providencia. This archipelago consists of oceanic islands, atolls and coral shoals. The reef complexes are of the bank-reef type and most have wide fore-reef terraces, almost continuous reefs on the windward side and poorly developed reef tracts on the leeward side. Corals have been observed below 50 m. Degradation of reefs has been documented in the populated island of San Andrrs and in the most remote and uninhabited atolls. Along the continental coast of Colombia there are few reef areas due principally to the scarcity of hard bottoms and the presence of large rivers. Less than 10% of the shelf has coral reefs, and in many cases they are only small fringes and patches in protected bays and inlets. There are also extensive offshore coral banks over antique diapiric domes (mud volcanoes). Incipient coral formations are found in the Guajira peninsula at the NE end of Colombia. The Santa Marta area is located near the central part of the coast; although coral communities are rich in species and diversely structured along this coast, reefs are rudimentary and usually restricted to narrow shore formations, in less than 30 m in depth. The archipelago of the Islas del Rosario is located off the central part of the coast. Including all associated submarine environments, the complex covers nearly 120 km 2, in which coral patches, fringing reefs, barrier reefs, shallow carbonate sand plains, seagrass meadows and mangroves shape an intricate mosaic. Corals in the Rosario islands have been observed below 50 m depth. The San Bernardo archipelago is located off the Golfo de Morrosquillo. It consists of islands and shallow shoals forming an extensive mosaic of coral patches, sand plains and seagrass meadows covering about 106 km2. The rocky coastal slopes of the Urabfi area have the westernmost reefs of the Colombian Caribbean. Coral communities grow to nearly 30 m depth, developing reef frameworks in sheltered settings. Other minor reef areas are Bajo Tortugas, Isla Fuerte, Bajo Bushnell, Isla Arena and I_as Animas bank. Natural disturbances include hurricanes, bleaching events, epidemic diseases of corals and other organisms, and algae proliferation. The principal anthropogenic disturbances are sedimentation, eutrophication, chemical pollution, overfishing, dynamite fishing, nautical activities and coral mining.
1. INTRODUCTION
The study of Colombian Caribbean coral reefs began during the 1960s, with the work of foreign researchers. Only seven reports were produced during that time, whereas 70 reports were written in the 1970s, 114 in the 1980s, and 138 in the 1990s until 1996 (Garz6n-Ferreira 1997). These data clearly indicate a steep increase in reef research through time in Colombia, which was triggered during the 1970s by the development of SCUBA and international cooperation. Participation of Colombian scientists in this Latin American Coral Reefs, Edited by Jorge Cortrs 9 2003 Elsevier Science B.V. All fights reserved.
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Fig. 1. Distribution of the coral reef areas of the Colombian Caribbean. 1. Puerto Lbpez; 2. Bahia Portete; 3. Cab0 de la Vela; 4. Manaure; 5. Santa ~ Tierra Bomba Marta and Parque Natural Tayona; 6. Banco de las Animas; 7. Isla Arena; 8. Bajo Salmedina; 9. Islas del Rosario; 10. B a and islands; 11. Bajo Tortugas; 12. Islas de San Bernardo; 13. Bajo Bushnell; 14. Isla Fuerte; 15. Isla Tortuguilla; 16. Urabi area; 17. Courtown cays; 18. Albuquerque cays; 19. San AndrCs island; 20. Providencia island; 21. Roncador bank; 22. Serrana bank; 23. Quitasueiiobank; 24. Serranilla bank; 25. Bajo Alicia; 26. Bajo Nuevo. The location in the Caribbean Sea of the two areas represented is shown in the inset map at the lower right
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research began to be important by the second half of the 1970s and increased thereafter. During the 8th International Coral Reef Symposium celebrated in Panarn~ in 1996, about 30 people from Colombia were present and founded the Colombian Society for Coral Reef Research and Conservation (SCCAR). In 1998, the Colombian research group was the largest among Latin American and Caribbean countries represented at the International Society for Reef Studies (ISRS). Of the several coral reef research groups in Colombia, the most stable and productive on the Caribbean coast is at the Instituto de Investigaciones Marinas y Costeras (INVEMAR), a national marine research institution located in Santa Marta. About 50% of the studies done on Colombian Caribbean coral reefs have been performed with the participation of INVEMAR (Garz6n-Ferreira 1996). Numerous descriptions of reef morphology, zonation and coral community composition were carried out by German researchers during the 1970s in the bays of the Santa Marta area, but also in other areas like the Rosario islands and San Andrrs (Prahl and Erhardt 1985). Quantitative studies on the structure of coral and other reef communities have been performed during the last two decades in several areas, whilst research about the dynamics, health and conservation of the reef environment have started to develop only in the last 10 years. In addition, great efforts have been made over the last decade to complete the baseline characterization (mapping, geomorphology, community composition, zonation) of all reef areas (Diaz 1990, 1999; Diaz et al. 1996a; Diaz et al. 2000) and to organize a national monitoring program (Garz6n-Ferreira 1999; Garz6n-Ferreira et al. 1999). About 40% of the research has been oriented towards systematics (taxonomic studies and inventories of species of diverse groups of reef organisms), and more than 50% of the studies have been devoted to fishes and corals (Garz6n-Ferreira 1996). Prahl and Erhardt (1985) reviewed the existing information until the middle of the 1980s, and wrote the first synoptic book on the Colombian reefs and corals. They listed 61 species of hard corals and recognized five major areas of coral growth in the Caribbean territories (Fig. 1): (1) the oceanic archipelago of San Andrrs and Providencia, located more than 700 km from the Colombian continental coast in the western Caribbean, which includes the islands of San Andrrs and Providencia and several atolls and banks (Courtown, Albuquerque, Serrana, Roncador, Quitasuefio, Serranilla and Bajo Nuevo); (2) the Guajira area at the eastem end of the continental coast, with poorly developed coral formations that are concentrated mainly in the bay of Portete; (3) the mountainous rocky shore of the Santa Marta area, near the central portion of the continental coast, with limited reef development but rich coral communities; (4) the Cartagena area, at the western half of the continental coast, which includes the extensive coral reefs of the Rosario and San Bernardo archipelagos, the islands of Tierra Bomba and Isla Fuerte, as well as several banks (Salmedina, Tortugas, Bushnell); (5) the Urab~i area, a small section at the western end of the Caribbean coast of Colombia near Panama, with rocky shores but only restricted reef development. Coral growth along the continental coast of Colombia is limited due to the scarcity of hard bottoms, the dominance of sedimentary environments, the presence of large rivers (Magdalena, Sinfi, Atrato, Rancheria), and the influence of upwelling waters in some areas (Guajira and Santa Marta) (Prahl and Erhardt 1985; Wells 1988; Garz6n-Ferreira 1997). Therefore, less than 10% of the shelf territories have coral reefs, and these are reduced in many cases to small fringes and patches at protected bays and inlets. At a distance from the shore in some areas, there are also extensive coral banks developed over antique diapiric domes (mud volcanoes), as is the case of the Rosario and San
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Bemardo archipelagos. The oceanic reef complexes of the San AndrOs archipelago have the best developed coral formations, including atolls, banks, barrier reefs, fringing reefs and patch reefs (Diaz et aL 1996a). There are about 2800 km2 of coral reef areas within Colombian waters in the Caribbean, most of which (about three quarters) belong to the San AndrOs archipelago (Diaz et aL 2000). 2. THE ARCHIPELAGO OF SAN ANDRES AND PROVIDENCIA The archipelago of San Andr6s and Providencia comprises a series of oceanic islands (San Andr6s, Providencia, Santa Catalina), atolls (Albuquerque Cays, Courtown Cays, Roncador Bank, Serrana Bank) and coral shoals (Quitasuefio Bank, Serranilla Bank) lined up in a NNE direction, along the lower Nicaragua Rise (Fig. 1). Only the three major islands are permanently inhabited, whereas the low lying sandy or shingle islets or cays of the atolls are only visited occasionally by fishermen and tourists or serve as military posts for the Colombian Navy. The archipelago includes nearly 75% of the total area occupied by coral reefs in the Colombian Caribbean, and represents one of the most extensive reef areas in the western Atlantic region. The Caribbean Current flows from E to W and, when it reaches the archipelago, it diverges into two branches; one continues to the W, crossing the Nicaragua Rise, and the other forms a large cotmterclock~se eddy to the SW and S. The sea surface temperature varies between 27 and 30~ and surface salinity is almost constant at about 36. Terrestrial runoff is limited to the immediate vicinity of the two high islands (Geister and Diaz 1997). The islands and atolls of the archipelago have a long geological history. Subsidence of the original volcanic basements and simultaneous capping of the seamounts by shallow water carbonates in late Tertiary to Quaternary times led to the formation of the present atolls and banks. The geology, geomorphology, composition and ecological features of these western Caribbean reef complexes are relatively well known. Several contributions, most of them published very recently (Milliman 1969; Geister 1975, 1992; Mfirquez 1987; Diaz et al. 1995, 1996a, 1996b, 1997; Geister and Diaz 1997; Sfinchez et al. 1997; Zea et al. 1998), give more detailed information on these and other topics. On the other hand, inventories of the marine biota include those by Werding et al. (1981) on various taxa from Providencia, G6mez and Victoria (1986) and Mejia et al. (1998) on the fish fauna, and Diaz-Pulido and Diaz (1997) and Diaz-Pulido and Bula-Meyer (1998) on the algae. The oceanic reef complexes of the archipelago are of the bank-reef type and most have several geomorphologic features in common (Figs. 2-4): the presence of wide forereef terraces, almost continuous peripheral reefs on the windward side and poorly developed reef tracts on the leeward side resulting in lagoons which are open to the ocean along their leeward (west) margin. The predominant factor controlling the distribution of the hermatypic biota in these reef complexes is the surf from high oceanic swells in the seaward eastern reefs, which affects both seaward and lagoonal reefs. The intensity of the swell is reflected in the predominant coral associations on the reef crests (Geister 1975). Hurricanes occur at irregular intervals (e.g. Hattie in 1961, Irene in 1971, Joan in 1988 and C6sar in 1996). The shallow peripheral reef, which is well developed and forms an almost emergent, continuous crest on the windward (east) side, rises to a conspicuous surf zone where the
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heavy oceanic swell breaks. A leeward reef tract is hardly ever developed, but short reef segments usually close the lagoons. The windward reef wall is dominated by Millepora complanata and Palythoa, with isolated patches of crustose coralline algae occurring where surf action is greatest. The windward reef is usually deeply penetrated by surge channels oriented perpendicular to the reef front, forming a typical spur-and-groove system_ Leeward peripheral reefs are usually isolated and composed mainly of large thickets of Acropora palmata, and massive Diploria spp. and Porites astreoides. Crustose coralline algae (Porolithon spp.), coating large areas of the reef framework, are also major constituents of these reefs (Diaz et al. 1996a). In front of the shallow peripheral reef, there is a broad fore-reef terrace up to several hundred meters wide, which slopes slightly seaward from 8 to 20-25 m. The sea floor then drops off steeply to the outer reef or atoll slope, with an occasional step at 35-45 m. The coral cover on the fore-reef terrace increases gradually with depth. Scattered thickets of A. palmata and encrusting Diploria spp. are usually the only scleractinians observable over the nude calcareous bottom down to a depth of nearly 10 m. Sheet-like, dark brown stained portions of the bottom are due to the encrusting sponge Cliona sp. Dense gardens of gorgonians (Pterogorgia, Pseudopterogorgia, Plexaura, among others) and scattered hemispheric colonies of Siderastrea spp., Montastraea spp. and Colpophyllia natans dominate the bottom community of the terrace to about 18 m. At 20-25 m, near the outer margin of the terrace, the diversity of scleractinians reaches a maximum. There, about 25-30 species of corals share the almost completely covered hard substratum with diverse algae, sponges and gorgonians. Deeper water associations of hermatypic scleractinians are found on the outer slope below 20 m of water depth. The lower limit of coral growth is not precisely known, but lies well below 50 m (Diaz et al. 1996a; Geister and Diaz 1997). The lagoon side of peripheral reefs is fringed by a shallow, wide lagoonal terrace, which is covered by sediments derived mainly from the erosion of the reef. At its lagoonward margin, this terrace drops steeply as a "sand cliff' to the bottom of the lagoon basins. The latter have depths ranging between 9 and 20 rrL Miniatolls, knoll reefs, ribbon reefs and anastomosing reefs develop within the lagoons. Anastomosing reefs form dense networks in some quiet-water settings (Diaz et al. 1997). Some of the deeper patch reefs thrive well below the wave base at depths between 5 and 18 rn, and are mostly made up by massive Montastraea faveolata, M. franksi and M. annularis. The pillar coral Dendrogyra cylindrus, Acropora cervicornis, Agaricia spp. and Porites spp. are also common. Other patch reefs reach the surface and emerge during spring low tides. Depending on the wave exposure of their setting within the lagoon, the upper parts of these reefs can be dominated either by Acropora palmata with Diploria spp. and Porites astreoides, by Acropora cervicornis with Montastraea spp., or even by Porites furcata and/or P. porites. Locally, lagoonal fringing reefs are present on the coasts of the islands and cays (Diaz et al. 1996a). Noticeable degradation of reefs has been documented for the Archipelago of San Andr6s and Providencia, not only in the populated island of San Andr6s (Diaz et al. 1995; Zea et aL 1998), but also in the most remote and uninhabited atolls (Garz6n et al. 1996). Overall, in San Andr6s live coral cover has declined more than 50% in recent years. Most affected, with up to 80% mortality, are the lagoonal patch reefs near the highly populated areas of the northern part of the island. From a total of 49 species of scleractinian corals so far recorded from San Andr6s, 19 were found to be affected to some extent by recent mortality. Among these, 14 species suffered maximum mortality
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levels of at least 50%, and some up to 80%, such as Acropora spp. and Porites furcata (Diaz et al. 1995; Zea et al. 1998). Mean values of recent mortality estimated during 1994-95 in the atolls of Courtown, Serrana and Roncador have been also around 50% (Diaz et al. 1996a). 2.1. San Andr(~s and Providencia islands San Andr6s island is the administrative and commercial center of the archipelago, with a booming tourist industry and a population of over 60,000. With a surface area of only 25 km2, San Andr6s is probably the most densely populated island in the Caribbean. The island and the surrounding reef-complex (16 km long and 8 km wide) is an ancient atoll that was uplifted and tilted to the east in Plio-Pleistocene times, rising today about 100 m above the sea (Geister, 1975). The windward barrier protects the northern and eastern lagoons from oceanic swell. Along the SE coast, the barrier approaches the shoreline and becomes a fringing reef. Shallow and deep patch reefs that dot the lagoon are mostly of the knoll reef or platform reef type (Fig. 2). Along the W coast of the island, no true coral reefs are developed, but a rich scleractinian fauna covers a great part of the submerged wave-cut terraces (separated by a step at -4 m) and the upper parts of the outer slope (Geister 1975; Diaz et al. 1995). Providencia and the nearby Santa Catalina islands are inhabited by about 4,500, mostly English-speaking people, who live predominantly by subsistence farming, fishing, and small-scale tourism. Providencia also originated as an early Tertiary atoll. However, reactivation of volcanism during Neogene times resulted in the formation of a highstanding volcanic island. The whole submarine platform is 33 by 8 km, with an overall NNE trend (Geister 1992). The 32 km long windward barrier reef of Providencia is one of the largest in the western hemisphere. Three major segments of the barrier are discontinuous and formed by a broad band of densely clustered patch reefs. Most of the patch reefs are pillar-shaped pinnacles with vertical walls, whose tops are covered by Millepora complanata. Shallow and deep patch reefs are abundant in the lagoon, the former being built principally by Acropora palmata and the latter by Montastraea spp. The lagoon is quite open to the W, and the leeward slope of the insular shelf deepens very steeply (Geister 1992). 2.2. Courtown, Albuquerque and Roncador atolls Courtown atoll lies 22 km ESE from San Andr6s. It is kidney-shaped and nearly 13 km long in a NW-SE direction. The lagoon is quite open to the leeward side. Two (formerly three) small sandy cays and a tiny sand spit are the only emergent portions of the atoll (Diaz et al. 1996a). Albuquerque Cays atoll, about 35 km SW of San Andr6s, is the only atoll in the area that has a roughly circular outline, with a diameter of about 8 krn (Figs. 3 and 4). It has two densely vegetated cays, which lie close together on the windward lagoonal terrace near the border of the lagoon basin. goncador Bank is an elongated atoll, 210 km NE of San Andr6s and 150 km E of Providencia. It is about 13 km by 6 km, with a NW-SE trend. The windward reef has a fish hook shape, with goncador Cay, a sparsely vegetated islet, at its NW end. The lagoon bears a high concentration of patch reefs mostly formed by Montastraea spp. In the southern half of the lagoon a dense mesh of anastomosing reefs covers nearly 70% of the lagoon floor (Diaz et al. 1996a, 1997).
The Caribbean coral reefs of Colombia
Fig. 2. Ecological units of the reef complex of San Andr6s island, Colombia, Southwestem Caribbean.
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Fig. 3. Ecological units of the reef complex of Albuquerque cays, Colombia, Southwestern Caribbean. Transect A is shown as a cross section in Fig. 4.
Fig. 4. E-W cross section of the reef complex of Albuquerque. BR: barrier reef; FT: fore-reef terrace; LE: leeward terrace; LG: lagoon; LT: lagoonal terrace; OS: outer slope; PR: peripheral reef. See Fig. 3 for the location of the transect.
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2.3. Serrana and Quitasuefio banks Serrana is an extensive reef complex, about 322 klTl2, with an approximately nearly triangular shape, about 150 km NE from Providencia. The windward reef wall is well developed on the NE, E and SE flanks of the atoll, attaining a total length of nearly 45 km; it is interrupted at three places by rather deep passes. To the W and NW, the atoll lagoon is completely open to the sea. The reef flat and the lagoon terrace are less distinct at Serrana than in the other atolls. Patch reefs (dominated by Montastraea spp.) are concentrated at the easternmost portion of the lagoon basin. Lying at the extreme SW end of the peripheral reef, Serrana Cay is about 500 m long and 200 m wide, with dunes over 10 m high, and densely covered by bushes and shrubs (Diaz et al. 1996a). Quitasuefio Bank lies about 70 km NNE of Providencia. With nearly 290 km2, it is one of the largest atoll-like structures of the area. It has no emerging cay, only a lighthouse built on the reef at its northern end. The windward reef wall extends over 40 kin, and parts of it emerge during low fide. In the lee of the reef wall, irregular patch reefs (dominated by Montastraea spp.) are abundant. Ribbon-like reefs and anastomosing reefs prevail in the eastern half of the lagoon, whereas patchy lagoonal reefs of the knoll-type are more abundant towards the W. Three very long and broad ribbon reefs rise almost to the water surface and enclose wide portions of the lagoon; these reefs are now mostly covered by rolling stones made up of crustose coralline algae (rodoliths). The bottom of the lagoon deepens gradually to the W. Here the lagoon is completely open, since a leeward reef tract is not developed.
3. THE GUAJIRA AREA Some incipient coral formations are found in the coastal zone of the Guajira peninsula located at the NW end of the Caribbean coast of Colombia. These occur mostly in small bays and inlets of the coastline between Cabo de La Vela and Punta Gallinas (Fig. 1). The most developed and best studied coral formations are in Bahia Portete (12~ and 72~ the largest bay in the area. Portete is a shallow closed bay, with a surface of about 80 kmz and a very small connection to the sea. Most of the coastline is fringed with red mangroves adjacent to a fiat desert. Although there are no river discharges to the bay, water is frequently very turbid due to wind induced resuspension of bottom sediments, which are predominantly muddy. Coastal upwelling is considerable in the Guajira area, and hence seawater temperature in the bay is reduced during the months of strong trade winds (monthly means below 26~ (INVEMAR 1988). Coral formations of Portete were described by Solano (1994), based on information collected during several environmental impact assessments carried out between 1981 and 1988. Although coral communities are widely distributed on the shallow bottoms of the southern and western portions of the bay, reef development in Portete is poor and restricted to less than 5 m in depth. Only 19 species of hard corals have been recorded, of which Millepora alcicornis is markedly widespread and abundant. Two types of coral formations can be identified in the bay. (1) Patch reefs: usually located at the outer margin of dense seagrass beds; these are topped with a shallow crest dominated by M. alcicornis with scattered small colonies of Porites spp., Favia fragum, other corals, and also abundant frondose algae. A short fore-reef slope supports mostly large heads of Diploria strigosa, Colpophyllia natans and Montastraea annularis, and usually ending at 3-4 m depth on a
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sott muddy bottom. (2) Sparse corals on seagrass beds: also dominated by colonies of M. alcicornis of variable size and density, usually growing radially and unattached; other corals that may be present include Diploria clivosa, D. stn'gosa, Porites spp. and C. natans. This type of coral assemblage is widespread and found principally on the extensive Thalassia testudinum beds of the bay in very shallow waters (0.5-2 m in depth). Recent quantitative data on structure of type 1 coral formations indicate that mean live coral cover is 31.4%, of which 19.5% is accounted by M. alcicornis, and that mean dead coral cover is 17% (INVEMAR 1992). This level of recent coral mortality can be explained by a strong bleaching event that occurred during 1987 in the bay (Solano 1994). The size and composition of some coral carpets occurring at depths from 10 to 15 m on the offshore continental shelf of the Guajira peninsula between Cabo de la Vela and Manaure are poorly known. Dense gardens of gorgonians and small encrusting colonies of Diploria spp. and Porites astreoides, upon which dense populations of pearl oysters occur, have been reported from these areas (Borrero et al. 1994). 4. THE SANTA MARTA AREA The Santa Marta area comprises about 80 km of a basically rocky shoreline located near the central part of the continental Colombian Caribbean, adjacent to the port city of Santa Marta (Fig. 1). Coastal topography is heterogeneous, with steep relief due to the proximity of the Sierra Nevada de Santa Marta, the highest mountain system of Colombia (5800 m above sea level). As a consequence, the shore is basically a cliff that is composed of several kinds of metamorphic rocks, with numerous rocky headlands, islets, bays and inlets. At the inner portions of the bays, it is possible to find sedimentary beaches, as well as a few mangroves, coastal lagoons and intermittent small rivers (Diaz 1990; Garz6nFerreira and Cano 1991; Garz6n-Ferreira 1998). Coral and other hard bottom communities are characteristic along the coast, while seagrass beds, mangroves and true coral reefs have developed to some extent only in sheltered settings within the bays. Shore communities of the area are affected seasonally by upwelling waters during the dry season, which can reduce sea surface temperatures to 21 ~ and increase nutrient concentrations, and by continental rim-off during the rainy season which reduces salinity (mean monthly data as low as 31 psu) and increases turbidity considerably. The city of Santa Marta, with about 400,000 inhabitants, is an important tourist and port center which discharges sewage directly into the shore without any treatment. Nevertheless, the city is located at the westem end of the area and the prevailing ocean current flows from the NE. Furthermore, most of the coral reefs in the area fall within a protected natural reserve (Parque Natural Tayrona). The first studies on the coral formations of the Santa Marta area were performed toward the end of the 1960s and during the 1970s by German researchers, who made inventories of species and qualitative descriptions of structure and zonation of benthic communities (Geyer 1969; Antonius 1972; Erhardt 1974; Erhardt and Werding 1975a, b). It was not until the second half of the 1980s that quantitative studies of coral communities (Solano 1987; Acosta 1994; Zea 1993, 1994), and some general mapping, oceanographic and geomorphologic characterizations (Diaz 1990; Garz6n-Ferreira and Cano 1991) were done. Exhaustive inventories of other groups of reef organisms in the area, such as sponges (Zea 1987), gorgonaceans (Botero 1987, 1990), mollusks (Diaz et al. 1990; Diaz 1994), echinoderms (Gallo 1988a, b) and fishes (Acero and Garz6n 1987a) were also carried out at that time.
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Coral growth in the Santa Marta area is usually restricted to narrow shore formations, which do not surpass 30 m in depth. Although coral communities are widely distributed along the rocky coastline, true coral reef structures have developed only on the sheltered sides of bays and inlets. On the outer wave exposed shores, high coral cover can be found below 10 m depth (80-90%), but only two species dominate (Montastraea cavernosa and Diploria strigosa) with small and entrusting colonies forming a thin coral layer over the rocks (Garz6n-Ferreira and Cano 1991). Two basic types of coral reefs can be identified in the area: narrow fringes growing over the coastal belt of metamorphic rocks, which are the most common, and extensive fringes growing away from shore on sedimentary flats in the inner portion of the bays (Garz6n-Ferreira and Cano 1991; Garz6n-Ferreira 1998). Although some Acropora palmata can be found in shallow water, rocky-shore fringes show a diverse coral fauna dominated by massive and encmsting species (mainly Diploria, Montastraea, and Colpophyllia), and have the form of a reef slope dipping 20-30 ~ down to 15-20 m in depth. In contrast, the inner fringes are characterized by extensive shallow reef flats dominated by one or two foliaceous and branching corals (mainly Acropora palmata, Agaricia tenuifolia, Porites porites and Millepora spp.), which become reef slopes covered with massive corals at about 6-8 m depth. In some cases (Chengue, Nenguange and Cinto bays), A. palmata has formed small barriers with very shallow back reef environments behind. Werding and S~nchez (1989) reviewed the information on the composition and distribution of coral formations of the Santa Marta area, indicating that reefs are rudimentary due to adverse growing conditions such as continental run-off, lack of adequate bottom structures for reef settlement and low water temperatures from the local upwelling. Nevertheless, coral communities are rich in species and diversely structured. Only a few coral species known to occur in other regions of the Caribbean Sea are absent in the Santa Marta area: Madracis formosa, Porites branneri, Dendrogyra cylindrus and Mycetophyllia reesi. Werding and S~nchez (1989) recognized eight different types of coral communities, each showing a specific species composition and form of colonies, and occurring in defined situations in the bays of the area. The most outstanding factor determining this variation are degree of exposure to predominant wave impacts and the gradually changing quality of water within the bays. Several other groups of reef organisms also show a high biodiversity in the Santa Marta area; Botero (1987, 1990) recorded 39 species of octocorals, Diaz (1994) listed 787 species of mollusks and Acero and Garz6n (1987a) reported 372 fish species. Recent studies on the structure of coral communities at Santa Marta show that algae is the dominant component in cover of the sessile benthic community (about 50-60%), while corals cover between 20 and 50% (mean around 30%) of the reef surface at depths between 9 and 22 m; the lowest value of coral cover is found in a station (Punta de Betin) adjacent to the city of Santa Marta (Acosta 1994; Zea 1994). Repeated surveys done at Chengue Bay within the CARICOMP monitoring program indicate that this situation has not changed during the last six years (Garz6n-Ferreira and Rodriguez in prep.). Coral communities in the Santa Marta area have suffered important changes in the last 30 years. This is mainly due to the massive mortality of several species of hard corals, which occurred during the 1980s, but is also due to slow chronic processes of coral mortality. The first indication of coral decline came from observations at Bahia Concha in the beginning of the 1970s by Antonius (1972), who reported total or partial
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mortality in about 80% of the colonies at one site. Werding and Sfinchez (1988) described a strong decline in cover by several hard corals at Punta de Betin between 1973 and 1988, including species that reached 100% mortality, such as Eusmilia fastigiata and Mussa angulosa, and others that lost about 50% of their live cover (Montastraea cavernosa and Stephanocoenia intersepta). Since Puma de Betin lies adjacent to the city of Santa Marta, these authors considered this decline to be a result of pollution both from the city sewage, and port activities, but also due to an increased runoff of sediments through rivers. Garz6n-Ferreira and Cano (1991) reported mass mortalities of branching and foliose species such as Acropora cervicornis (80%), A. palmata (60%), Agaricia tenuifolia (80%) and Porites porites (almost 100%), as well as numerous dead coral heads of S. intersepta, Montastraea annularis, Colpophyllia natans and Diploria strigosa in the reefs of the Parque Natural Tayrona. These authors considered increased sedimentation, reduction of light penetration, nutrient enrichment, diseases, and dynamite fishing to be the main factors causing coral decline in the area. 5. THE CARTAGENA AREA 5.1. The reef complex of Islas del Rosario The archipelago of the Islas del Rosario is located off the central part of the Caribbean mainland coast of Colombia about 25 km SW from Cartagena de Indias at 10~176 and 75~176 (Fig. 1). It comprises six small to medium sized islands or groups of islands, including the most western portion of the Bard Peninsula, and a series of shallow shoals. Including all associated submarine environments, the complex takes up an area of nearly 120 klT12 in which coral patches, fringing reefs, barrier reefs, shallow carbonate sand plains, seagrass meadows and mangroves create an intricate mosaic. Deeper basins and channels covered by fine sediments separate shallow areas. The islands have always been a favorite attraction for Colombian and foreign visitors and, with the exception of the most northern and western islands (Isla Tesoro and Isla Rosario), they are now densely built with hotels and private weekend houses. In the central part of the complex, a series of 17 islands, including the largest of the archipelago (Isla Grande), exhibit an overall E-W trend. Many studies done in Colombia on reefs and associated biota have been carried out in this complex. Early studies include those by Pfaff (1969), who first listed the scleractinian and milleporid species (60 species), and Werding and S~inchez (1979) describing the zonation of reefs in several locations of the complex. Ramirez (1986), Sarmiento et al. (1989) and Galvis (1989) analyzed the structure of the coral communities, whereas the works by Monsalve and Restrepo (1989), Penereiro et al. (1990), Shnchez (1995), Schonwald (1998) and Cendales (1999) represent more integrated efforts for characterizing and mapping the reef structures and other marine habitats. The islands and nearby shallow shoals lie on portions of the continental shelf that were apparently uplifted in late Tertiary time, due to the diapiric activity (mud volcanism) that was produced by compression and ejection of clay material from the deeper layers of the continental shelf toward the upper ones (Vernette 1985). The shallowest diapiric promontories were then capped with a limestone framework in the Pleistocene. During low sea-level stands of the Pleistocene glaciations and in early Holocene, the area was emerged. At that time, the limestone cap underwent erosion by rainwater, resulting in a karst topography characterized by numerous sinkholes. This topography was flooded
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towards the end of the Holocene transgression (about 3000 years B.P.), and new coral reefs became re-established according to the available submarine topography, i.e. predominantly on the topographic highs. The sinkholes of the ancient karst topography are at present very conspicuous in both terrestrial and submarine landscapes of the archipelago. The distribution and structure of the coral communities of the Recent reef complex are mainly controlled by both water depth and wave energy. At a rather short distance from the N and NW (windward) coasts of the islands and from the most western part of the Ban] peninsula, well-developed and almost emerging barrier reefs occur. The barrier reef in front of the main island group is about 4 km long. It is interrupted in some places by more or less deep and wide gaps, through which boats and small yachts usually enter the lagoon and reach the islands. Towards the windward side, the barrier reef slopes gradually to about 35 m and exhibits four well defined depth zones according to the dominant scleractinian species. The breaker zone of the barrier down to a depth of about 2 m is widely dominated by thickets of Acropora palmata, which are, however, mostly dead today. Millepora and massive and encrusting Diploria strigosa are also locally common. Until a few years ago, extensive thickets of Acropora cervicornis formed a characteristic zone between 6 and 10 m depth (Werding and Sfinchez 1979; Prahl and Erhardt 1985). Apparently, most of them were affected by white band disease and bleaching events in the last two decades. This zone is now occupied by macroalgae overgrowing the collapsed thickets and fragments of A. cervicornis. Scattered colonies of Porites astreoides and other massive corals may be observed as well (pers. obs.). The number of species and cover of massive corals increases rapidly with depth beyond 10 m. A distinct mixed zone, in which up to 20 massive and plate-like coral species may occur within a few square meters, occupies a broad zone extending to a depth of 25 m or more. Montastraea franksi becomes more and more dominant, and, in depths beyond 30 m, it forms bulky colonies of more than 2 m in height (Prahl and Erhardt 1985). The barrier reef in front of the windward coast of Isla del Tesoro exhibits a well developed wave-breaking crest with Acropora palmata. The reef very gradually deepens to the N, forming a terrace-like topography with scattered massive colonies of Diploria and Siderastrea to a depth of roughly 8 m, from where the outer reef slope suddenly begins to drop off. It is very steep, sometimes almost vertical, and is densely overgrown by massive and plate-like scleractinians, sponges and black corals (Sfinchez 1995). The northwestern coast of the Barfi peninsula is flanked by fringing reefs with massive colonies dominated by Montastraea faveolata, M. annularis and Colpophyllia natans. Acropora cervicornis was formerly an abundant component of the scleractinian association. Near the western end of the peninsula, the fringing reef disappears, but an almost continuous row of patch reefs paralleling the coast form a barrier-like structure. The shallow crest of these reefs was formerly made up of A. cervicornis, but nowadays crustose and fleshy algae with scattered Porites porites and P. astreoides grow instead. Algae mostly cover the front slope of these reefs, but deeper zones dominated by living Porites porites, Agaricia tenuifolia and Montastraea faveolata respectively can still be recognized at some sites. The shallow bottoms on the leeward and wave protected areas of the archipelago are mostly covered by sand and seagrass. However, coral carpets and patch reefs are well developed on their outer borders and slopes. Porites porites and P. astreoides are the dominant scleractinians in the shallowest patches to about 5 m water depth, but usually
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they are replaced by Agaricia tenuifolia at the upper portion of the slopes. A. tenuifolia is also the main constituent of the scleractinian assemblage bordering the steep slopes of the karstic sinkholes to a depth of roughly 12 m, where massive scleractinians such as Montastraea annularis, M. faveolata and Colpophyllia natans become abundant (Schonwald 1998; Cendales 1999). The floor of the sinkholes is mostly covered by carbonate sand. Although the coral reefs and associated marine environments of the archipelago are whitin to a Natural National Park since 1985, overfishing and the seasonal influence of turbid, nutrient-rich, and low salinity waters from the Cartagena Bay and the Canal del Dique have seriously affected the structure of the coral community (reduced cover of living coral, overgrowth of algae) (Alvarado and Corchuelo 1992; Garz6n-Ferreira and Kielman 1994). 5.2. The reef complex of Islas de San Bernardo The San Bernardo archipelago is located off the Golfo de Morrosquillo, about 100 km SW from Cartagena de Indias, at 9~176 and 75~176 It comprises eight small to medium-sized islands and a series of shallow shoals that form an extensive mosaic of coral carpets, sand plains and seagrass meadows that takes up a total area of about 106 km2. Two elongated basins oriented in a NE-SW direction, and reaching depths of about 40 m, are covered by fine sediments and divide the shallow areas of the complex into three more or less distinct sectors. The origin, gross morphology (including the karst topography with sinkholes) and most characteristics of the coral associations are features very similar to those akeady described from Islas del Rosario (Vernette 1985; L6pez-Victoria 1999). In contrast to the Islas del Rosario, only a few studies, some of them even unpublished, have been carried out on the marine environment of this archipelago. Early studies on the coral fauna and reefs of these islands include those by Erhardt and Meinel (1975), who listed the stony coral species around the Isla Ceyc6n, and Ramirez et al. (1994), who described quantitatively the structure of some coral assemblages in shallow water. A comprehensive study including thematic maps and characterization of the reef structures was carried out recently by INVEMAR, from which most of the information below has been taken (L6pez-Victoria 1999). The most eastern portion of the complex, close to the mainland coast, includes Isla Palma and a couple of small, shallow sandy shoals with scattered coral carpets dominated by Porites porites and massive Montastraea spp. The second, central sector of the complex is an approximately 12 km long by 1-3 km wide ribbon-shaped shoal that lies in a NE-SW direction. Three low islands (Mangle, Panda and Ceyc6n) emerge in the NE, middle, and SW portions of the shoal. The shallowest flat bottoms (2-6 m deep) of this area are mostly covered by seagrass with scattered colonies of Siderastrea siderea and vase-like sponges. Sediments mostly cover the NW and SE slopes of the shoal as well, although concentrations of bulky coral colonies (Montastraea faveolata and M. annularis) build notable but distinct reef structures along the northwestern margin. Scattered coral carpets widely dominated by Porites porites and some sinkholes with Agaricia tenuifolia occur around Isla Ceyc6n, near the SW end of this shoal. The outer, most extensive sector of the complex includes two major islands (Tintipfin and Mficura) and an artificial, densely populated islet (El Islote). The latter was built from coral rubble and great amounts of conch shells (Strombus gigas) by fishermen, in order to avoid the annoying mosquito plague on the other islands. The outermost part of
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the complex, facing NW to the open sea, is an extensive, half moon-shaped bank (Bajo Minalta). The upper parts of this bank show a characteristic karst topography in which occasional deep sinkholes alter the rather fiat or slightly undulating bottom relief. Numerous low-lying patch reefs are regularly distributed over the entire area, but those attaining larger sizes and developing true reef structures occur mainly in the northern part toward the outer edge of the bank. Here, the reefs develop a series of parallel buttresslike structures that are oriented from N to S and are separated by about 10-20 m. These reefs are composed of a diverse coral biota, but Montastraea faveolata, Siderastrea siderea, Agaricia tenuifolia and Porites porites are clearly dominant. Scattered thickets ofAcropora cervicornis thrive among massive heads ofM. faveolata in some places. A gently dipping slope to the seaward (N) side of Isla Tintip/m is characterized by numerous sinkholes, forming very heterogeneous bottom relief. Sediments mostly cover the deep bottoms within the holes, but scattered bulky, pagoda-shaped colonies of Montastraea faveolata and M. franksi thrive as well. The steep slopes and crests between contiguous holes are densely overgrown with Agaricia tenuifolia, A. agaricites, Porites porites, and plate-like colonies of Montastraea spp. and P. astreoides. However, large portions of the former coral cover are now overgrown by algae such as Halimeda spp. and Lobophora variegata. The shallow bottom surrounding the islands, as well as a tongueshaped shoal (Bajo Nuevo) that extends for nearly 7 km to the south of Isla Mficura, are mostly covered by sediments, but coral carpets formed by P. porites occur as well. Dense Thalassia meadows take up a great portion of the bottom on the leeward side of the islands. In contrast to the reef complex of Islas del Rosario, neither a barrier reef nor fringing reefs are developed at any location in the reef complex of the Islas de San Bemardo.
5.3. Bajo Tortugas With the exception of nautical charts and a few descriptive notes accompanying an inventory of the reef fishes of the area (Torres 1993), no published information is yet available about the Tortugas bank. The following description is based merely on personal observations and bathymetric profiles made by the authors during a recent visit to the area aboard a research vessel. Bajo Tortugas is an elongated topographic high lying on the central portion of the continental shelf. It extends for nearly 12 km in a southwest direction from the reef complex of Islas del Rosario. However, it is detached from the latter by a 2 km wide submarine valley with sandy bottom and depths of roughly 50 m. The bank has a snake tongue-like shape, with its "bifid" end pointing to the southwest, and is surrounded by muddy and sandy bottoms of more than 70 m in depth. The average depth of the upper part is about 16 m, but in several places the reef structures rise to about 7 m below the surface. The bottom relief and coral framework structures of the Tortugas Bank are greatly controlled by a characteristic karst topography with sinkholes and elongated small valleys. Numerous adjoining holes of varying diameter and shape over an extensive area of the central part of the bank give the area a distinctive pockmarked submarine appearance. Here, the sandy floors in the holes attains depths over 35 m, whereas the upper surfaces between the holes are usually shallower than 10 m. The latter portions are densely overgrown by Agaricia tenuifolia, Porites porites and calcareous green and red algae (Halimeda spp., Galaxaura sp.). The steep slopes of the sinkholes exhibit diverse scleractinian assemblages with pagoda and plate-like growth forms of Montastraea
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faveolata, as well as M. franksL Mycetophyllia spp., Agaricia agaricites, and other species. Gorgonacean octocorals (Gorgonia ventalina, Plexaura spp., Pseudopterogorgia spp., and others) and vase-like sponges (Xestospongia muta, X. rosariensis) are a distinctive feature of the reef community in the western seaward half of the bank. This is apparently due to a stronger influence of oceanic waves. 6. THE URABA AREA The Golfo de Urab~i, near the Colombia-Panarrfi border, represents the most southem portion of the Caribbean Sea (Fig. 1). The waters of the Golfo de Urab~i are highly affected by terrestrial runoff due to large amounts of sediment and freshwater discharged by the Rio Atrato into the southern part of the gulf. Although most of the coasts surrounding the gulf are dominated by low, alluvial plains with sandy and muddy beaches, swamps, and mangroves, its northwestern part, from near the small village of Acandi towards the Panan~ border and beyond, is mostly bordered by the foot hills of the Serrania del Darien. It forms steep rocky slopes that plunge to depths of 15 to 30 m before flattening out to form muddy sandy fiats. The cliffy coastline is interrupted by pocket beaches and coves. Coral communities have settled on the hard substrata along the submerged slope, developing reef framework in sheltered settings. The coral communities and other littoral habitats in this area were first briefly described in an unpublished report by Werding and Manjarrrs (1978), including preliminary lists of scleractinians and other invertebrates. Prahl and Erhardt (1985) and Wells (1988) later summarized some of the observations in that report. Inventories of the marine biota include those by Werding (1978) and Campos and Manjarrrs (1988) on the Crustacea, by Acero and Garz6n (1987b) on the fishes, and by Bula-Meyer and Schnetter (1988) on the algae. No further information was obtained on the coral reefs of this area until 1995, when a Colombian scientific expedition worked there intensively for six days, to asses the distribution, extent, geomorphology, composition and health of the coral communities (Diaz and Diaz-Pulido in prep.). A total of 31 scleractinian, two milleporinid and one stylasterinid coral species were recorded during this survey. The scleractinian-dominated community is one of the prevailing marine bottom habitats on the shallow, rocky areas along the northwestern shores of the Golfo de Urabfi. These communities fringe the coastline almost continuously from about latitude 8~ northwest to the Colombia-Panan~ border at Cabo Tibur6n (8~ and beyond, and from near low tide level down to depths of nearly 30 m in some locations. Such communities surround the small, rocky offshore islets (Isla Narza and Terr6n de Amicar) as well. Diaz and Diaz-Pulido (in prep.) differentiated four major coral communities or assemblages in the area. The 'stn'gosa_crustose algae' assemblage, which is notably dominated by scattered encrusting colonies of the scleractinian Diploria strigosa, many crustose red algae, algal turfs and various gorgonians (Plexaura, Plexaurella); the scleractinians Montastraea cavernosa and Porites astreoides also may be frequent in deeper, sheltered settings. According to their observations, this is the most widely distributed assemblage in the area; it is developed in depths between 2 and 7 m on the submarine terrace that fringes almost the entire coast facing the open sea, being exposed to heavy swells from the north. A second, well-defined assemblage, was called 'siderea' because of the conspicuous dominance of massive, semi-spherical colonies of Siderastrea siderea,
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which usually grow very close to one other covering nearly 50% of the bottom area; this assemblage occurs in very shallow, rather sheltered zones. An 'agaricites' assemblage, well represented at only one locality (between the mainland coast and the Terr6n de Amicar islet), is dominated by the lettuce coral Agaricia agaricites; the deeper slopes and bases (12-17 m in depth) of these reefs are covered predominantly by other platelike and massive scleractinians, such as Colpophyllia natans, Montastraea spp. and Mycetophyllia spp. The coral assemblage in settings deeper than 10 m is mostly characterized by a dense and diverse scleractinian cover. This 'mixed coral' assemblage is seemingly common in this area where deeper, slanting hard bottoms and relatively well illtm~ated waters occur. Massive and plate-like forms of the scleractinians Montastraea cavernosa, M. franksi, Colpophyllia natans and Solenastrea hyades are generally predominant. 7. OTHER REEF AREAS 7.1. Isla Fuerte
Isla Fuerte is a small highstanding island located about 12 km off the south-central Colombian coast (at about 9~176 'W), representing the emerged NE portion of a 13 km2 limestone shelf. The morphology and composition of reefs and other submarine habitats around the island have recently been described (Diaz et al. 1996c). The insular shelf rises from the surrounding muddy bottoms from depths between 20 and nearly 40 m. The island is surrounded by an almost flat, gently dipping terrace-like platform that extends for about 2 km to the W, SW and S, to depths of 6-8 m. Seagrass covers a great part of the shallow bottoms on the western and southern sides of the island. With the exception of scattered sandy patches, the western portion of the shelf exhibits a bare calcareous bottom sparsely overgrown by filamentous algae, macroalgae and encrusting scleractinians such as Diploria strigosa, Siderastrea siderea and Agaricia agaricites. On the northern, more wave-exposed bottoms, gorgonians and sponges become co-dominating elements. To the south, the shelf bottom is covered by free sand and mud, and is densely vegetated by seagrass. To the east, close to the island shores, some small coral carpets and low-lying patch reefs composed of Porites porites or bulky heads of Siderastrea radians grow. Thickets of Acropora cervicornis (mostly dead) may be observed among the Siderastrea heads or scattered on the sand bottom. The shelf edge and outer slope are mostly occupied by coral framework. This slope rises steeply and breaks the water surface only in the NE sector, where it forms a 1.5 km long, wave-breaking barrier close to the windward shore of the island, protecting it from erosion. This reef exhibits a crest mainly composed by Millepora complanata, encrusting Diploria clivosa and scattered patches of the zoanthid Palythoa caribbaeorum. Sparse thickets of Acropora palmata and small colonies of Porites astreoides thrive among large amounts of coral rubble (made up mostly by fragmented colonies of ,4. cervicornis and Agaricia tenuifolia) at a depth of 2-4 m. Below this zone, the slope dips steeply to a depth of nearly 10 m. Dead A. tenuifolia (overgrown by algae) and scattered heads of P. astreoides are here the only scleractinian elements covering the bottom. A scleractinian association constituted of bulky colonies of Montastraea faveolata, M. cavernosa, M. franksi, Colpophyllia natans, Diploria labyrinthiformis, and plate-like forms of Agaricia sp. and Mycetophyllia spp. become increasingly common toward the deep zones of the slope until the more level sandy bottom, at 25-28 m, occurs.
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The remaining coral formations along the outer shelf margin constitute a discontinuous belt of low-lying reefs rising only to 5 m below the water surface. Acropora cervicornis seems to have formerly been a major constituent of these reefs because of the abundant collapsed thickets and rubble of this species that can be observed in many places. The coral assemblage along the outer margin and slope of the shelf consists at present of massive colonies of Montastraea annularis, M. faveolata, M. cavernosa, Siderastrea siderea and Colpophyllia natans, among others. Many segments of this peripheral reef belt are interrupted at irregular intervals by sand aprons, descending at a low angle across the slope. A total of 25 scleractinian and 2 milleporinid coral species has been recorded from the reefs around Isla Fuerte (Diaz et al. 1996c). 7.2. Bajo Bushnell Bushnell bank is located about 30 km off the south central Caribbean coast, 18 km to the W from Isla Fuerte and not far from the outer edge of the continental shelf (Fig. 1). The bank is a dome-shaped topographic high on the continental shelf (1300 m in diameter) which rises from surrounding depths of about 60 m to nearly 12 m. Like other offshore reef areas of the central part of the continental shelf, its origin is probably also related to diapiric activity (mud volcanism) (cf. Vemette 1985). The bottom habitats and morphology of the bank were described recently for the first time (Diaz et al. 1996c). The upper part of the bank is a plateau with a low slanting angle to the east, its shallowest portion being close to the northern, seaward margin. The zone of highest coverage by living corals also corresponds to this portion of the plateau. Here, the coral framework has developed a series of elongated or meandering spurs (in a roughly NESW direction) rising up to 2 m from their bases. Wide valleys in which the bottom is mostly covered by coarse sediments and coral rubble separate them. The spurs are formed by a diverse scleractinian assemblage in which Agaricia tenuifolia, A. agaricites and the massive Montastraea faveolata, M. cavernosa and Colpophyllia natans are clearly dominant. Among them, several species of octocorals (Gorgonia ventalina, Pseudopterogorgia spp., Plexaurella spp. and others) and vase-like sponges (Agelas conifera) are well represented. Towards the E and the S, the bottom relief is reduced, the angle of the slope increases and the coral cover diminishes. The calcareous hard substrate is overgrown by crustose coralline algae, brown algae (Stypopodium zonale, Dictyota sp.), bulky vase-like sponges (Xestospongia muta) and gorgonians. These elements become gradually scarce below 25 m and the hard substrate becomes patchy, until the entire bottom is covered by sand beyond a depth of nearly 30 m. The northern slope of the bank margin begins at depths between 14 and 18 m as a subvertical drop-off. The bottom of the slope is densely covered by plate-like scleractinians (Montastraea franksL Mycetophyllia spp. and Agaricia sp.) in the upper settings, whereas azooxantellate elliselids, black corals and sponges are the predominating elements of the sessile community in deeper settings. A total of 29 hard coral species has been reported from Bushnell Bank (Diaz et al. 1996c). 7.3. Isla Arena Isla Arena is a small shingle cay located about 6 km off the coast, nearly 50 km NE from Cartagena and 100 km SW from the mouth of the Magdalena River, at 10~
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and 75~ 'W (Fig. 1). Due to its location, in an area greatly influenced by the sedimentloaded plume of the Magdalena River, the occurrence of such a coralline habitat in this part of the Caribbean was unexpected. Here, an assemblage of small but healthy corals was found recently along the NW and W seaward shores of the island (described in detail by Pinz6n et al. 1998). The development of reef corals is generally restricted to habitats shallower than 6-7 m. Living thickets of Acropora palmata with broad, fan-shaped branches thrive in the NE portion of the area forming a wave-breaking seaward reef. Behind this reef, there is a crest containing Millepora complanata and Palythoa caribbaeorum and a shallow fiat covered by coral rubble. The SW side of the island deepens gradually, forming a shallow terrace on which encrusting colonies of Diploria clivosa and algae grow. Between 2 and 5 m of water depth, massive colonies of Siderastrea siderea and Diploria strigosa and scattered thickets of A. palmata dominate the coral assemblage of the seaward side. Fringing the more sheltered NW shore, there is a healthy patch of Acropora cervicornis and A. prolifera around which the flat bottom is covered by a dense carpet of zoanthids and anemones. Since the waters surrounding Isla Arena are turbid and quite turbulent during most parts of the year, and substrate availability is low, only 9 scleractinians are found there. Despite this, these species (including Acropora palmata, A. cervicornis and A. prolifera) apparently thrive and are more healthy than in most Caribbean reefs of Colombia where environmental conditions appear to be more appropriate for coral growth. 7.4. Las Animas bank
This is a poorly known, submerged coral formation along the outer edge of the continental shelf off the Gulf of Salamanca (at about 10~176 about 30 km SW from Santa Marta (Fig. 1). The occurrence of this ribbon, made of corals, crustose algae and shell material, was only discovered in recent years (Blanco et al. 1994). The coral carpet has hardly altered the bottom topography, extending for nearly 7 km between depths of 24 and 32 m along the shelf edge just before the begining of the continental slope. The only scleractinians reported up to now from this area are Agaricia sp. and Porites astreoides. 8. NATURAL DISTURBANCES Modem natural disturbances of Colombian Caribbean reefs include hurricanes, bleaching events, epidemic diseases and algae proliferation, although some of these may also be the indirect result of human activities. Hurricanes have affected only the territories of the San Andr6s archipelago, but their impact on the coral reefs of this area has been poorly documented. Geister (1975) observed extensive destruction of Acropora cervicornis stands in San Andr6s island in 1973, and considered this to be a consequence of the impact of hurricane Irene in 1971. Other hurricanes that hit the archipelago during the last decades were Hattie in 1961 and Joan in 1988 (Diaz et al. 1995). These authors observed, during 1992, accumulations of detached octocoral skeletons and numerous overturned coral heads, as well as complete destruction of A. cervicornis reefs (100% dead and fragmented), on shallow reef bottoms around San Andr6s. Diseases have been implicated to be responsible for mortalities that affected several important invertebrates on Colombian reefs during the last two decades, as in most of
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the Caribbean Sea. These include the well documented mass mortalities of the black urchin Diadema antillarum in 1983 (Lessios et al. 1984; Diaz et al. 1995) and seafans of the genus Gorgonia spp. during the 1980s (Garz6n-Ferreira and Zea 1992; Diaz et al. 1995, 1996a; Zea et al. 1998). Several coral diseases also have been observed frequently in recent years (Garz6n-Ferreira and Cano 1991; Diaz et al. 1995; unpublished data of the authors). White Band Disease has since been recorded on Acropora palmata and A. cervicornis, and is considered to be responsible for a majority of the recent population decline of these coral species in all Colombian reefs. Black Band Disease and White Plague also are common diseases of massive corals, while Yellow Band Disease has been recorded only recently in Colombia from a strong event that occurred in 1998 at the San Bemardo islands. Nevertheless, the most common coral illness on Colombian reefs is the Dark Spots Disease, which is being studied in detail and affects mainly the massive corals Siderastrea siderea, Montastraea annularis and Stephanocoenia intersepta (Garz6n-Ferreira and Gil 1998; Gil-Agudelo 1998). The occurence of bleaching events of corals and other reef invertebrates have been documented in Colombian Caribbean reefs only for the last decade. Zea and Duque (1989) studied the 1987 Caribbean-wide event in the Santa Marta region, reporting that no more than 10% of the living coral tissue was found to be affected. Solano (1994) made some observations on the same event in Bahia Portete, indicating that about 26% of the coral colonies in shallow waters were bleached and that 80-90% of affected Millepora alcicornis colonies died. Solano et al. (1993) reported another bleaching event at Islas del Rosario during 1990, finding that less than 10% of the stony coral colonies were affected. A minor bleaching event was observed again in late 1995 at Chengue Bay in the Tayrona Natural Park (CARICOMP 1997). All these bleaching events have been coincident with elevated seawater temperatures, but to some degree also with increased water turbidity. As at many other Caribbean localities, algae have become the dominant component of the benthic biota on most Colombian coral reefs. Algal cover in San Andrrs Island was on average near 70% (26% of frondose species) in 1992 (Diaz et al. 1995), while in the Santa Marta area it has fluctuated between 50 and 60% during the last decade (Zea, 1993, 1994; Garz6n-Ferreira 1998). Frondose algae (especially the brown Dictyotaceae and the green calcareous Halimeda spp.) have been prolific in all Colombian reefs during the last years, particularly in areas protected from direct wave energy, where they partially cover live coral colonies and generate bleaching and mortality of coral tissues (Garz6n-Ferreira and Cano 1991; Diaz et al. 1996a; Zea et al. 1998). Algal invasion of live coral tissue was recorded in more than 50% of the examined colonies at the Courtown, Albuquerque, Serrana and Roncador atolls in 1994-1995 (Garz6n-Ferreira et al. 1996). 9. ANTHROPOGENIC DISTURBANCES AND MANAGEMENT Anthropogenic disturbances in Colombian reefs comprise sedimentation, eutrophication, chemical pollution, overfishing, dynamite fishing, nautical activities and coral mining. Sedimentation due to land clearing and erosional runoff is supposed to be one of the most important agents of stress for the reefs of the continental coast, especially because of the discharges of large rivers like the Magdalena, Shaft and Atrato which affect most of the coast. There is a lack of historical data to evaluate changes in turbidity and sedimentation rates on the reefs. Nevertheless, the presence of fine sediments over coarse deposits in
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some reefs (Garz6n-Ferreira and Cano 1991), the high levels of deforestation in the country, and the strong degradation of some reefs located near river mouths (Werding and Sfinchez 1988; Acosta 1994) suggest that increased sedimentation has to be considered as a source of impact in Colombian reefs. Another important source of stress to coastal ecosystems in Colombia is sewage pollution, since almost all coastal population centers (several of which support more than 200,000 inhabitants) discharge sewage directly into nearshore waters without any treatment (CORPES C.A. 1992). There is clear evidence of sewage related reef degradation at San Andrrs, one of the most densely populated islands in the Caribbean (Diaz et al. 1995), and some indication of this in the Santa Marta Bay (Werding and S~nchez 1988). Chemical pollution has been seen as another potential agent of reef degradation, due to the presence of large industrialized cities in the coastal zone (such as Barranquilla and Cartagena) and of large rivers that carry polluted discharges from inland cities. Changes in the morphology of river beds and in the location of river discharges for coastal development have generated considerable degradation of coral reefs in Colombia since Colonial times. During the XVII century Spaniards dug an artificial branch (the Canal del Dique) of the Magdalena River that discharged into the Bahia de Cartagena, which changed the environmental conditions of the bay to an estuarine system and eliminated extensive coral communities (INVEMAR 1997). Over the last two decades, additional discharges of the Canal del Dique have been opened into the Bahia de Barbacoas, creating turbid currents and eutrophication that have affected considerably the coral reefs of the nearby Islas del Rosario (Alvarado et al. 1986; Alvarado and Corchuelo 1992). Overfishing is another important human disturbance present in all coral reef areas of the Colombian Caribbean. Although there are no quantitative data to support this, recent qualitative observations on many reefs, including reefs remote from human settlements, indicate a quasi-absence of commercial species like spiny lobsters, queen conchs, snappers, groupers, grunts, triggerfishes, hogfish and the great barracuda. As a consequence, in recent years, formerly despised non-traditional catch fishes, such as parrotfishes, angelfishes and surgeonfishes, have become a major target for the local fishery (Garz6n-Ferreira and Cano 1991; Diaz et aL 1995, 1996a; Garz6n-Ferreira 1997; Zea et al. 1998). Fishing with explosives is an illegal practice that has generated localized destruction of the reef habitat in some areas of the Colombian Caribbean, such as the Santa Marta area, the Islas del Rosario and the Islas de San Bemardo. Some physical damage to reef structures has been produced locally also by ship groundings (San Andrrs archipelago) and other nautical activities (boat traffic, anchoring, diving), derived mostly from artisanal fisheries and tourism. Coral mining for construction is a minor disturbance on Colombian reefs, and has only been observed in the Rosario and San Bemardo archipelagos. Management for conservation of the Caribbean reef areas of Colombia was boosted through Law 99 of 1993, which created the National Environmental System (SINA) and the Ministry of the Environment. The SINA is integrated by the Ministry, 34 regional management corporations, five research institutions, and an administrative special unit for natural parks (UAESPNN), who work in coordination to provide management actions (based on scientific information) for the protection of natural resources. The Instituto de Investigaciones Marinas y Costeras (INVEMAR) was reorganized to become the national marine research institution, linked to the Ministry, that has to produce information and management recommendations for the conservation of the marine envi-
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ronment, especially regarding fragile and valuable ecosystems like coral reefs. Recently, INVEMAR completed the baseline characterization of coral reef areas of the Colombian Caribbean (Diaz 1999; Diaz et al. 2000) and is developing an appropriate system (the SIMAC) for monitoring these and other coralline areas in the Pacific coast (Garz6nFerreira 1999; Garz6n-Ferreira et al. 1999). In the Colombian Caribbean, there are three national parks with coral reefs within their protected territories: (1) the Parque Nacional Natural Tayrona, which includes most of the coral formations of the Santa Marta area; (2) the Parque Nacional Natural Corales del Rosario y de San Bernardo, which cover almost all the coral reefs of Barfi island and the Rosario and San Bemardo archipelagos; and (3) the Parque Nacional Natural Manglar de MacBean, which includes some reefs in front of the NE coast of Isla de Providencia. Any extractive or disturbing activities, as well as construction for development, is prohibited within the national parks. However, infrastructure and resources are still very scarce for effective control and to enforce regulations. Consequently, some illegal activities, such as dynamite fishing, are still performed to some extent in coral reef areas, including national parks. Management plans and legislation are being prepared for the sustainable use and conservation of the coastal zones in Colombia, with an emphasis on natural parks and reserves and on strategic ecosystems like coral reefs. ACKNOWLEDGMENTS Most of our work on Colombian reefs has been funded by grants from COLCIENCIAS -BID (CO-215-09-008-87, 2105-09-023-93, 2105-09-120-97 and 2105-09-327-97). INVEMAR has provided most of the required logistics and indirect costs. Other institutions that have contributed substantially with funds and/or logistical support are CORALINA, CEINER, the UAESPNN, and the Ministry of the Environment of Colombia. Numerous colleagues from INVEMAR and other institutions have participated directly in the big task of assessing and mapping Colombian reefs (L. Barrios, M. Cano, G. Diaz, D.L. Gil, A.M. Gonz~ilez, M. L6pez, L.S. Mejia, G. Ospina, F. Parra, J. Pinz6n, A. Rodriguez, J.A. S~nchez, S. Zea), as well as many students. Thanks a lot to all of them. Many thanks also to J. Cortrs for inviting us to participate in this book, as well as to the anonymous reviewers who contributed to improve this chapter. REFERENCES
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Monsalve, C.B. & J.D. Restrepo. 1989. Aproximaci6n a la fotointerpretaci6n y cartografia de ecosistemas arrecifales - Isla Caribaru (Caribe colombiano). B.Sc. thesis, Biol. Mar., Univ. Jorge Tadeo Lozano, BogotL 219 p. Penereiro, J.L., G.R. Navas, R.A. Montoya, F. Cleves & L.T. Moreno. 1990. Cartografia ecol6gica de los fondos submarinos adyacentes al conjunto de islas Latifundio-Minifundio, Parque Nacional Natural Corales del Rosario, Caribe colombiano. Mem. VII Semin. Nal. Cienc. Tecnol. Mar., CCO, Bogot~i: 184-194. Pfaff, R. 1969. Las scleractinas y milleporinas de las Islas del Rosario. Mitt. Inst. Colombo-Alerrfin Invest. Cient. Punta Betin 3:17-25. Pinz6n, J.E., A.M. Perdomo & J.M. Diaz. 1998. Isla Arena, una. formaci6n coralina saludable en el hrea de influencia de la pluma del rio Magdalena, plataforma continental del Caribe colombiano. Bol. Invest. Mar. Cost. 27:21-37. Prahl, H. von& H. Erhardt. 1985. Colombia corales y arrecifes coralinos. FEN Colombia, Bogolfi. 295 p. Ramirez, A. 1986. Ecologia descriptiva de las llanuras madreporarias del Parque Nacional Submarino Los Corales del Rosario (Mar Caribe), Colombia. Bol. Ecotr6pica Ecos. Trop. 14: 34-63. Ramirez, A., D. Miranda & G. Vifia. 1994. Estructura arrecifal del archipi61ago de San Bemardo (mar Caribe, Colombia), estudiode linea base. Trianea (Acta Cient. Tecn. Inderena) 5:189-219. S~nchez, J.A. 1995. Benthic communities and geomorphology of the Tesoro Island coral reef, Colombian Caribbean. An. Inst. Invest. Mar. Punta Betin 25: 55-78. S~chez, J.A., J.M. Diaz & S. Zea. 1997. Gorgonian communities in two contrasting environments on oceanic atolls of the southwestern Caribbean. Bull. Mar. Sci. 61: 453-465. Sarmiento, E., F. Flechas & G. Alvis. 1989. Evaluaci6n cuantitativa del estado actual de las especies coralinas del Parque Nacional Natural Corales del Rosario (PNNCR), Cartagena, Colombia. B.Sc.Thesis Biol. Mar., Univ. Jorge Tadeo Lozano, BogotL 144 p. Schonwald, N. 1998. Distribuci6n y composici6n de los habitats marinos asociados alas estructuras arrecifales del ~irea de Isla Grande, Archipi61ago de E1 Rosario, Caribe colombiano. B.Sc. Thesis, Universidad de Los Andes, Bogota. 57 p. Solano, O.D. 1987. Estructura y diversidad de la comtmidad de corales hermatipicos en la Bahia de Chengue (Parque Nacional Tayrona). M.Sc. Thesis, Biol. Mar., Univ. Nacional/INVEMAR, Bogot~/Santa Marta. 111 p. Solano, O.D. 1994. Corales, formaciones arrecifales y blanqueamiento de 1987 en Bahia Portete (Guajira, Colombia). An. Inst. Invest. Mar. Punta Betin 23: 149-163. Solano, O.D., G. Navas & S.K. Moreno-Forero. 1993. Blanqueamiento coralino de 1990 en el Parque Nacional Natural Corales del Rosario (Caribe colombiano). An. Inst. Invest. Mar. Punta Betin 22: 97-111. Torres, D.F. 1993. Abundancia y diversidad de 26 familias de peces arrecifales del costado oeste del Caribe colombiano. B.Sc. Thesis, Biol. Mar., Univ. Jorge Tadeo Lozano, Cartagena. 118 p. Vemette, G. 1985. La plate-forme contientale caraibe de Colombie (du debuch6 du Magdalena au golfe de Morrosquillo), importance du diapirisjme argilieux sur la morphologie et la sedimentation. Ph.D. dissert., Univ. Bordeaux, France. 387 p. Wells, S. (Ed.). 1988. Coral Reefs of the World. Volume 1: Atlantic and eastern Pacific. UNEP/IUCN, Gland, Switzerland. 373 p.
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Werding, B. 1978. Los porcelfinidos (Crustacea: Anomura: Porcellanidae) de la regi6n de Acandi (Golfo de Urab~), con algunos encuentros nuevos de la regi6n de Santa Marta (Colombia). An. Inst. Invest. Mar. Punta Betin 10:213-221. Werding, B. and H. Erhardt. 1976. Los corales (Anthozoa e Hidrozoa) de la Bahia de Chengue en el Parque Nacional Tayrona (Colombia). Mitt. Inst. Colombo-Alernfin Invest. Cient. Punta Betin, 8: 45-58. Werding, B. & G. Manjarr6s. 1978. Informe sobre las estructuras litorales y la flora y fauna marinas en el noroeste del Golfo de Urabfi. Project Final Report., INVEMAR, Santa Marta. 87 p. Werding, B. & H. Sfinchez. 1979. Informe faunistico y floristico de las Islas del Rosario en la costa norte de Colombia. I. Situaci6n general y estmcturas arrecifales. An. Inst. Invest. Mar. Punta Betin 11: 7-20. Werding, B. & H. S~inchez. 1988. Deterioro observado en las formaciones coralinas de la Bahia de Santa Marta, Colombia. An. Inst. Invest. Mar. Punta Betin 18: 9-16. Werding, B. & H. S~inchez. 1989. The coral formations and their distributional patterns along a wave exposure gradient in the area of Santa Marta, Colombia. Medio Ambiente 10: 61-68. Werding, B., J. Garz6n & S. Zea (Eds.). 1981. Informe sobre los resultados de la expedici6n Providencia I a las islas de Providencia y Santa Catalina (Colombia). Project Final Report, INVEMAR, Santa Marta. 117 p Zea, S. 1987. Esponjas del Caribe colombiano. Ed. Catfilogo Cientifico, Bogotfi. 286 p. Zea, S. 1993. Cover of sponges and other sessile organisms in rocky and coral reef habitats of Santa Marta, Colombian Caribbean Sea. Carib. J. Sci. 29: 75-88. Zea, S. 1994. Patterns of coral and sponge abundance in stressed coral reefs at Santa Marta, Colombian Caribbean: 257-264. In: R.W.M. van Soest et aL (eds.), Sponges in time and space. Balkema, Rotterdam, The Netherlands. Zea, S. & F. Duque. 1989. Bleaching of reef organisms in the Santa Marta region, Colombia: 1987 Caribbean-wide event. Trianea (Acta Cient. Tecn. Inderena) 3: 37-51. Zea, S, J. Geister, J. Garz6n-Ferreira & J.M. Diaz. 1998. Biotic changes in the reef complex of San Andr6s Island (Southwestern Caribbean Sea, Colombia) occun-ing over nearly three decades. Atoll Res. Bull. 456: 1-30.
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The corals and coral reefs of Venezuela Ernesto W e i l
Department of Marine Sciences, University of Puerto Rico, PO BOX 908, Lajas, Puerto Rico 00667 and Fundacifn Cientifica Los Roques, Caracas, Venezuela ABSTRACT: Venezuela has some of the most diverse and -well developed coral reefs in the Caribbean, although they are limited in their distribution mainly by geomorphologic and environmental factors. Anthropogenic effects are increasing in importance. The only extensive reef formations along the mainland of Venezuela are found in the west, in the Morrocoy and San Esteban National Parks. In this region a wide, shallow continental platform and limited river runoff have allowed good fringing and patch reefs to develop with moderate scleractinian diversity (55-48 scleractinian species). In the 1980's, live coral coverage in Morrocoy ranged between 20 and 50%. Today the live coral coverage in the area is significantly lower due to natural and anthropogenic changes in environment, such as high sedimentation rates and a mass-mortality event that occurred in 1996. Along the eastern mainland coast, coral reef development and coral diversity are limited by unfavorable conditions produced by seasonal upwelling, fiver outflow and unstable substrate. Small fringing coral reefs and patch reefs dominated by Millepora spp. and Montastraea spp. occur on shallow, rocky outcrops in the Mochima Bay National Park, off islands close to shore, the continental platform and in the Gulf of Cariaco. Live coral cover ranges between 5 and 15% and coral diversity between 18 and 37 species. Coral communities with low diversities of reef organisms and no reef accretion are common on eastern rocky shores along the mainland and around near-shore islands. The central coast drops abruptly into deeper waters and reef development is restricted to small bays where rocky areas have scattered colonies of the major reef organisms. The best developed and more diverse coral reefs of Venezuela are located offshore, away from continental influences and direct anthropogenic impact. Coral reef formations are well developed, either as fringing reefs, patch reef or atoll-like structures, along a string of islands on a chain of submarine plateaus (guyots) extending from the northeast of Margarita Island westward to the Netherlands Antilles, 100-120 km north of the mainland. These coral reef systems are among the best developed and more diverse in the Caribbean. Sixty nine scleractinian species are known and coral cover can reach up to 75 % in some localities. Octocoral and sponge diversity is also high and several new species have been discovered in recent years. Coastal reefs are threatened by uncontrolled land development, over-fishing and tourism, coastal refineries, petrochemical plants, deforestation, eutrophication and ship tank wash and dumping, while island reefs north of Venezuela are mostly impacted by over-fishing, uncontrolled tourism, and the occasional oil slick or shipwreck.
1. I N T R O D U C T I O N V e n e z u e l a has a p p r o x i m a t e l y 4,000 k m o f coastline with the longest C a r i b b e a n shoreline ( 2 7 2 0 km) o f all the countries in the region. M a n y coral r e e f areas can be found along the n o r t h e r n shores and offshore islands (Fig. 1). O n the m a i n l a n d coast, well d e v e l o p e d coral reefs are only found in the west, in the M o r r o c o y and San E s t e b a n N a t i o n a l Parks. L i m i t e d river outflow and wide continental s h e l f ( W e i s s and G o d d a r d 1977) h a v e f a v o r e d r e e f d e v e l o p m e n t in this area. The coast is c h a r a c t e r i z e d b y a dry, Latin American Coral Reefs, Edited by Jorge Cortrs 9 2003 Elsevier Science B.V. All rights reserved.
rn'W
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Ernesto Weil
Fig. 1. Map of the Venezuelan coast showing the location of major coral reef developments,other coral communities along the main coast (letters) and the offshore islands (numbers).
The corals and coral reefs of Venezuela
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arid climate. The Morrocoy area has a tropical-savanna climate with "monzonic" influence (Ko~pen 1948). Further to the west, the climate is drier, and coastal platforms are exposed to heavy seas, currents and sedimentation. Corals and associated organisms have formed large flinging carbonate structures usually bordering low, sandy and mangrove cays or extensive coastal sea grass communities and mangrove forests. Several patch reefs of many different sizes and forms are found in the shallow waters of the lagoon and adjacent fringing reefs. Coral cover and diversity ranged from moderate to high, however, recent events have significantly reduced live coral cover and diversity. In eastern Venezuela, most of the mainland coast and islands either have unstable, sandy substrate or are under the seasonal influence of low-temperature, high-nutrient upwelling waters from the 1600 m deep Cariaco Trench (Okuda et al. 1968; Antonius 1980), and/or are influenced by river outflow. All these factors, independently or in association, prevent good coral reef development in this region. Nevertheless, low-accretion fringing and patch reefs are found in the Mochima Bay National Park, the Gulf of Cariaco, the east and north shores of the islands of Coche and Cubagua and on the Cumberland bank, southeast of Margarita island. Coral cover and diversity are on average low with some particular reefs showing moderate coral cover. Most of the islands have rocky shores and a diverse community of reef organisms with scattered coral colonies. Along the central coast of Venezuela, the continental platform is narrow, dropping steeply to depths unsuitable for coral reef development (Maloney 1966, 1967), although minor reef formations are found in small, protected bays. River runoff, unstable substrate and coastal development are also limiting reef development in this region. Most high energy rocky shores and other localities along the continental shoreline where coastal development and river runoff are limited, support low diversity and low density coral communities with scattered colonies of corals, octocorals, sponges, zoanthids and other common reef invertebrates. TABLE 1 Percent cover of scleractinian corals and other reef organisms and substrates in different reef localities along the main coast of Venezuela. Geographic localtion of reef is ordered from west to east. Other cnidarians includes zoanthids, hydrocorals and octocorals. Miscelaneous organisms includes mostly macro and turf algae and sponges.Other substrates includes sand, rubble, bare rock and crustose algae. For the Gulf of Cariaco, percentages were recalculated from Antonius (1980) data in which corals and hydrocorals were included under hard corals, and other coelenterates include only soft-bodied ones. Locality Chichiriviche Chichiriviche Morrocoy Morrocoy Morrocoy Morrocoy Morrocoy Mochima Mochima Mochima Sucre
Reef Cayo Sal Cayo Muerto Pescadores C. de los Muertos Playa Caiman Bajo Caiman Playuela Inner Bay Middle Bay Bay Mouth Gulf of Cariaco
Type Fringing Fringing Fringing Fringing Fringing Patch Fringing Fringing Fringing Fringing Fringing
Hard corals 20 26 21 43 37 24 33 2 21 40 29
Other Miscel. Seagrass Other Cnidarians organism beds substrates 0.5 5 4 6 12 7 7 14 17 10 2.2
22 27 24 20 17 31 16 5 18 20 50.1
40.5 28 23 12 17 19 4 69 16 0 0
Sources: 1= Bone 1980; 2= Weil 1980; 3= Antonius 1980; 4= Wei11985; 5= Bone 1993; 6= Pauls 1982.
17 14 28 19 17 19 40 10 28 30 18
Source 1 1 1,2,4,5 1,2,4,5 1,2,4,5 1,2,4,5 1,2,4,5 6 6 6 3
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Ernesto Veil
Fig. 2. Variability in scleractinian coral biodiversity across island (A) and coastal (B) reef communities. (C) Variation in mean coral cover between the platform and slope habitats for those reefs for which there is quantitativeinformation.
The main coral reef development in Venezuela occurs along the chain of islands and archipelagos that nm parallel to the coast in an east-to-west direction, 100-120 km offshore from the central and eastern main coast. These islands are the emergent summits of a submarine mountain system that also underlies the Netherland islands of Curazao, Aruba and Bonaire and that extends almost to the eastern coast of Colombia (Maloney 1967, 1971). Optimal environmental conditions have allowed the establishment of extremely well developed and diverse coral reefs around these islands with some of the highest scleractinian coral, gorgonian and sponge diversities and highest live coral cover of the Caribbean region (Urich 1977; M6ndez 1978, 1985; Hung 1985; Alvarez et al. 1985; Weil 1985). Major coral reef formations in Venezuela include atoll-like complexes, like the archipelago Los Roques, extensive fringing reefs bordering coralline cays and islands that can be over 10 km in length, and numerous patch and bank reefs (Table 1, Fig. 1) in shallow and
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deep lagoons. These reefs are usually dominated by Acropora cervicornis, Montastraea faveolata, M. annularis, Millepora spp., ColpophyIlia natans, Diploria strigosa, Porites astreoides, P. porites, and Siderastrea siderea, and developed under clear, warm waters with low sediment input, no river or continental influence, and very low human impact. Offshore reefs show high carbonate accretion rates and sustain complex and diverse coral reef communities down to a depth of 45 rn. In general, coral diversity decreases from west to east in both island and main land coral reef communities (Fig. 2). 2. HISTORY OF CORAL REEF RESEARCH A significant amount of research has been carried out at many different localities along the coast and on a few of the islands in the last 30 years. However, most of the information is in technical reports and college theses which are readily available. This chapter represents a first attempt to summarize this information and present a comprehensive view of the corals and coral reefs of Venezuela. Coral reef research in Venezuela started with short descriptions of intertidal and shallow corals and coral communities around the coral islands of Las Aves (De Burgafia and Jam 1942; Buisonje et al. 1957), and the islands of Margarita and Cubagua (Rodriguez 1959). Later, most reef research concentrated on the depauperated reefs of the eastern islands and eastern mainland coast of Venezuela. Antonius (1969) compiled the first list of coral species and their depth distribution in the Gulf of Cariaco and subsequently, completed a semi-quantitative study of the reef community (Antonious 1980). The octocoral composition of these communities was described by Gonz~ilez (1972). The ecology of Isla de Ayes and the island shallow water environments with emphasis on the fishes was described by Brownell and Guzn~n (1972) and later, the geology and biology of the bottom around the island described by Almeida and Goddard (1974). A compilation of most of the information (geological, ecological and biological) as well as the geopolitical importance of Isla de Aves was presented in a book by the office of Geography and Cartography of the Armed Forces in 1988. Olivares (1971), and Olivares and Leonard (1971) did taxonomic reviews of scleractinian corals in the Gulf of Cariaco and the Mochima Bay National Park area respectively, which were followed by the description and distribution of scleractinians in the reef communities of Mochima National Park (Campos 1972; G6mez 1972) and Margarita island (Ramirez-Villarroel 1975). The most comprehensive study of the reefs of the Mochima National Park was done by Pauls (1982) who undertook a quantitative study of the community structure and diversity of 18 reef localities (Fig. 3). Ramirez-Villarroel and Gonz~ilez (1974) and Ramirez-Villarroel (1975, 1978) studied the diversity and distribution of octocorals and scleractinian corals in the north-eastern islands of Coche and Cubagua respectively. More recently, Buccimazza (1984) listed scleractinian species and their environmental relationships for the island of Coche. Reef research in the western region of the Venezuelan coast began with a qualitative description and list of coral species for several coral reefs within the Morrocoy National Park in the Tucacas-Cayo Sombrero area of the State of Falc6n (Almeida, 1976). Later on, more comprehensive studies of the reefs in the Park produced quantitative descriptions of the community structure, zonation and biodiversity of coral communities (Weil 1980), an assessment of the impact of human activities (Bone 1980; Bone et al. 1993), and data on the distribution, size structure, population dynamics and bioerosion impact
308 Ernesto Weil
Fig. 3. Map of the Caribbean coast of Venezuela showing the four reef areas for which there is quantitative data. Arrows within the insets are pointing to the sample areas. In the Mochima National Park, 26 localities were sampled by Pads (1982).
The corals and coral reefs of Venezuela
309
of the black sea urchin Diadema antillarum (Weil 1980; Weil et al. 1984). Other studies have concentrated on different aspects of the octocoral community (Diaz 1983), octocoral mortality (Alvarez 1981), coral predation (Gonzfilez 1996) and the functional structure and growth differences of various species of octocorals in different reefs (Fuenmayor 1983). The black band disease on Montastraea spp. was studied by RamosFlores (1981, 1983). Several reef, seagrass and mangrove localities have been described and are currently being monitored under the Venezuela chapter of the CARICOMP program (Bone et aL 1998). More recent research in the area include studies of coral and hydrocoral tissue regeneration after predation by Hermodice carunculata (Martin and Losada 1991), and an evaluation of some reef communities in the Morrocoy National Park after the mass mortality of 1996 (Villamizar 1999). Toward the central mainland coast, reef development is reduced and limited too only a few localities. The best reef development lies within the recently created San Esteban National Park. The Park includes the Quizandal Bay and adjacent coral reefs, extensive mangrove areas, seagrass beds, and sandy bottom communities. Several studies on different aspects of coral reef and sea grass ecology, as well as aspects of human impact in this area have been carried out by the staff and students of the Universidad Sim6n Bolivar (Garcia 1987; Bastidas 1997; Bastidas and Bone 1996; Bastidas and Garcia 1997) which has a marine station in the area. These reefs are close to the busiest port-city of the country and are exposed to sedimentation from coastal development, pollutants and uncontrolled tourism. Further to the east of the central coast, minor reef developments occur inside small, protected bays. One of these reef communities, in Patanemo Bay, was described by Hunt and Araud (1976), and more recently Ortiz et al. (1999) characterized a reef community in the bay of Chichiriviche de la Costa. Coral reef research on the islands north of the central coast started with geological studies of the islands between Los Roques and Margarita (Schubert and Moticska 1972) and a description of the quaternary geology of La Orchila (Schubert and Velastro 1976) (Fig. 3). The first quantitative description of a coral reef community was done by Urich (1977) of La Orchila. The geomorphology and geological history of two atoll-like formations, the Archipelago de los Roques and Archipelago de las Aves, was described together with a detailed characterization and bathymetric distribution of ecological zones for los Roques (major biological communities) by M6ndez (1978). He also described the major human activities in these islands. In Los Roques, most reef-related research has been conducted from the Dos Mosquises Marine Station of the Fundaci6n Cientifica Los Roques, a non-profit institution based in Caracas. Many of these studies dealt with the taxonomy, biology, ecology, larval culture, and fisheries of important economic reef and sea grass invertebrate and vertebrate species (i.e. Work 1969; Cobo de Barany 1970; Cobo de Barany et al. 1975; Provenzano and Brownell 1976; Brownell 1977, Brownell et aL 1977; Buitriago 1980, 1981, 1987; Cervig6n 1980, 1985a,b; Grajal 1981; Laughlin and Weil 1982a,b; Laughlin et al. 1982, 1983, 1984; 1985; Weil and Laughlin 1984, 1985; Alvarez et al. 1985; Diaz et al. 1985, 1987; Alcala 1987), and the interactions of different organisms with scleractinian corals (Grajal 1981; Grajal and Laughlin 1984; Pulido 1983; Villamizar 1985; Villamizar and Laughlin 1991). Coral reefs around the Dos Mosquises Marine Station on the southwest end of the archipelago were quantitatively characterized by Hung (1985), and the population dynamics of Acropora cervicornis in the western end of the Park was studied by Sandia and Medina (1987). A comprehensive list of scleractinian coral species for Los Roques, compiled by
310
Ernesto Weil
Weil (1985), is updated here in appendix 1. The molecular and morphometric taxonomy of Porites from Los Roques was studied by Weil (1992 a, b). The octocoral community in the Dos Mosquises reef was characterized by La Schiazza (1985), and more recently, the relationship of reef community structure and reef slope in this same reef was studied by Cr6quer (1998) and Cr6quer and Villamizar (1998). Other more general reports on different aspects of coral reef communities and/or their associated organisms include a brief description of coral reefs of Venezuela (Laughlin 1984), their importance (Losada 1983) and the pattern of coelenterate bleaching in some Venezuelan reefs (Losada 1988). 3. DESCRIPTION OF CORAL REEF AREAS Coral reef localities are briefly described from east to west for both the coastal and offshore island reef areas (Table 1 and Figs. 1, 3). A summary of most of the quantitative data that has been gathered in several of these areas in the past 25 years is presented (Fig. 4). Data published in the original studies was reorganized and standardized to produce comparable tables and figures. 3.1. Coastal Reefs 3.1.1. Golfo de Cariaco
The easternmost coral reefs of the main coast are found in the Golfo de Cariaco (Fig. 1). This area is characterized by detrimental environmental conditions for reef development (Okuda et al. 1968), and therefore, coral reefs are usually not well developed, have low accretion rates, and low diversity (Antonius 1969, 1980) (Fig. 2B). Litoral areas are turbid and cold due to high nutrient, upwelling waters that increase plankton productivity and produce a very steep temperature gradient. The result is a steep biological zonation and inhibited reef development and coral growth below 15 m depth. Coral colonies and other reef invertebrates grow on rocky shores forming sparse coral communities in many areas including the coast of the peninsulas of Paria and Araya. Mean coral cover is 29% with a high variability from locality to locality. Macro-algae, turf-algae and bare substrate make the highest percentage of other substrates (18,75 and 38.7% respectively) (Fig. 4). Other soft cnidarians and sponges had 5.5% and 2.35% cover respectively (Antonius 1980) (Table 2). Eighteen scleractinian, zooxanthellate species in 14 genera and three hydrocoral species have been recorded for the area (Antonius 1969, 1980; Olivares 1971) (Table 1, Appendix 1). M. faveolata, M. cavernosa, S. siderea, D. strigosa and M. complanata are the most common species (Appendix 1). 3.1.2. Mochima National Park
The Mochima National Park was created in 1973. It is located on the eastern coast of Venezuela (10~176 and 64~176 (Fig. 3). The Park has an area of 94,935 ha of which 50,000 are marine and the remainder, coastal or sea level to low terrestrial up to 1,500 m in elevation. Reef formations are mostly found along the shores of the Mochima Bay and few small outcrops on the exposed coast. The rest of the coast is fringed by sandy, rocky and cliff formations and covered with scattered colonies of corals and other reef organisms. The Bay is 8 km long and between 0.3 and 3.5 km wide. The mouth of the bay is 1.5 km wide and 60 rn deep and connects directly to the
The corals and coral reefs of Venezuela
311
45 30
15 0
O t h e r enidarians
45
~ 3o I.
ts
o ~
o
~
45
~
30
~
Alga
o 45
Substrates
0
C~Yr~'~'x~'o'e "~~176 ~,o$'~~
"~A~162
Ce.~'x~'r176Locality
Fig. 4. Mean percentage cover of scleractinian corals, other cnidarians (Hydrocorals), and algae (macro-, turf- and crustose) in five important coral reef localities of Venezuela. Localities ordered from west to east. Los Roques is the only offshore-island locality for which quantitative information was available.
TABLE 2 Average percent cover of scleractinian corals and other reef organisms and substrates in different reef localities in the Archipelago de los Roques National Park. Miscellaneous organisms include other cnidarians and turf algae. Other substrates include sand, rubble, bare substrate and crustose algae. Locality Los Roques Los Roques Los Roques Los Roques Los Roques
Reef
Type
Cayo Sal Fringing Dos Mosquises 1 Fringing Dos Mosquises 2 Fringing Patch 1 Patch Patch 2 Fringing
Hard corals
Miscel. organisms
Algae
Sponges
65 40 29 25 27
17 22 29 37 31
6 16 12 7 8
5 2 1 3 4
Other Source substrates 7 20 29 28 30
1 2 2 2 2
Sources: 1= Weil (unpub. data); 2-- Hung 1985.
Cariaco trench (Fosa de Cariaco). Easterly trade winds produce extreme conditions for coral reef development due to nutrient-rich, cold water upwelling from the Cariaco trench during the winter months. From May to November, a marked thermocline develops (Pauls 1982). Water currents in the bay run from west to east, salinity ranges from 32 %o to 17 %0 and surface water temperatures from 19 to 28~ (Okuda et al. 1968; Campos-Villarroel 1972; Pauls 1982). Climate around the bay is semi-arid, typical of the Venezuelan coast, average rainfall varies from 127 mm on the coast to 2,100 mm in the mountains.
312
Ernesto Weil 45
.-. o-~
0 45
a)
30
o o
15
v I,.
Corals
Miscellaneous
4) O)
m 0 "r )45 a) "o L
30
r
lS
Algae
0 45
Substrates
30
18
~oe~
!! 11K~d~d3e I~,
0 ~%e~
Area
Fig. 5. Mean percentage cover of scleractinian corals and other major groups in different areas of the Mochima Bay National Park. Areas represent habitats in the inner, middle and mouth regions of the bay. Miscellaneous includes hydrocorals sponges and other cnidarians. Substrates include bare, sand and rubble. Seagrass cover, a major component of the benthic communities in the inner bay is not included.
Reef development is poor and limited by availability of hard substrate (rocky areas), cold upwelling waters towards the mouth and high sedimentation with low salinity towards the inner localities. Reef communities are dominated by the hydrocoral Millepora alcicornis and those scleractinian species resistant to high sedimentation and low temperature (S. siderea; M. cavernosa, P. porites, D. strigosa). Coral cover ranges from 2% to 40% and is highly variable between localities (Table 2, Fig. 5). Thirty seven scleractinian species (34 zooxanthellate) and one ecomorph in 23 genera, and three hydrocorals have been reported (Olivares and Leonard 1971; Campos-Villarroel 1972; Pauls1982; Weil per. obs.) (Table 1, appendix 1). In her study, Pauls (1982), follows the earlier division of the long bay in three sections (Caravallo 1968): (a) the interior zone, with a regular topography, extensive seagrass beds, and Millepora stands, low reef development and diversity. Maximum depth is 15 m; (2) the middle or central zone, with steep slopes on both sides, scattered reef formation, low diversity and a maximum depth of 27 m, and (C) the mouth zone close to the open sea, where the best conditions for reef growth are found. The common species are M. faveolata, A. palmata, T. aurea, M.
annularis, C. natans, P. porites, M. cavernosa, D. strigosa, S. siderea, M. complanata and M. alcicornis. Major threats to the reef communities are deforestation of surrounding areas, uncontrolled fishing and tourism activities, and lack of implementation of a sustainable development and management plan for the Park.
The corals and coral reefs of Venezuela
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3.1.3. San Esteban National Park and the central coast The San Esteban National Park (10~176 and 67~176 '' W) (Fig. 2) was created in 1987 and covers an estimated area of 44,000 ha, most on the mainland but including about 3,500 ha of marine environments. It includes several fringing and patch reefs, seagrass, mangrove and sandy bottom communities in Quizandal Bay near Puerto Cabello, the main port-city of the country. Many ships carrying oil, chemicals and other potential pollutants move through the area frequently. Sunken WW-II ships are found in the area and constitute a major attraction for divers. Forty eight species (42 zooxanthellate) and two ecomorphs in 30 genera have been observed in this area (Table 1, appendix 1). Other important groups on the reef are hydrocorals, zoanthids, sponges, crustose and turf algae, and anemones. Reefs formations are mostly narrow fringing reefs and patch reefs which end over sandy bottoms around 15-18 m depth. Most common species are M. faveolata, M. cavernosa, A. palmata, Tubastrea aurea, M. annularis, M. franksi, C. natans, D. strigosa, D. clivosa, P. astreoides, P. porites, and S. siderea. Pollution, coastal development, and uncontrolled tourism are major threats to coral reef communities. Along the rest of the eastward main coast, as far as Cabo Codera, the coastal mountain chain drops into the ocean and the continental platform has a steep slope in many areas. High energy seas dominate the shores where coral colonies and colonies of other reef invertebrates are found scattered along the rocky substrate, sometimes forming dense coral communities, but with no accretion. In the small bay areas, where wave and current energy are lower, sandy bottom communities and the occasional small patch reef could be found. The rest of the eastern coast, towards the Mochima National Park and the Golfo de Cariaco, is formed by a wide, shallow, sedimentary platform with extensive sandy bottoms, beaches, coastal lagoons, mangrove forests, and no coral reef formations. The island of La Tortuga, to the north, is the closest locality with well developed coral reefs. 3.1.4. The Morrocoy National Park The Morrocoy National Park is located on the eastern coast of the state of Falc6n, in western Venezuela (10~ and 10~ 68~ and 68~ The Park has an estimated area of 32,000 ha, of which 22,600 are marine environments (Fig. 3). The area has a tropical-savanna climate with a monzonic influence (Ko~pen 1948). The north-east trade winds blow most of the year with a mean speed of 4.5 km h 1. Mean annual air temperature is 26.5~ and average rain fall is 1,213 mm. This area was under intensive local tourism pressure, with many stilted-houses built on top of patch and fringing reefs, until it was declared a National Park in 1974. The area is dominated by mangrove forests that fringe the coastline and form islands inside extensive lagoons protected by fringing reefs towards the east and north. There are extensive seagrass and sandy bottom communities. The main coral reef formations are fringing and patch reefs which extend down to 17 m in some localities. There are two main areas within the park, the Chichiriviche area includes mostly well developed fringing reefs around calcareous islands and extensive bank reefs up to 25 m in depth towards the west. The Morrocoy area (Tucacas-Cayo Sombrero) includes most of the Park's fringing and patch reefs, towards the south-east (Fig. 3). Three small coral islands are located about 8 km to the east of the Park. They have extremely well developed and diverse coral reefs down to 20 m depth (Weil 1980; Weil et al. 1984; Bone 1980; Bone et al. 1994).
314
Ernesto Weil 45 30 15 0 45
Other cnidarlans
3O
4)
0
~
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4)
3o
-,9
15
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Miscellaneous
~ A a Grasses
4
3O
Substrates
G. ~o$ ""
r-
-?eS~
?Xsys v
~o
"
,~,=o,o
Fig. 6. Mean percentage cover of major benthic groups and substrates in different coral reef areas of the Morrocoy National Park. Miscellaneous includes all the algae groups and other sessile cnidarians such as hydrocorals and zoanthids. Substrate includes bare, sand and rubble. Localities ordered from northwest to south east.
Before the mass mortality of 1996, mean coral cover varied between 20% and 47% (Table 2), with coral cover and diversity increasing from Chichiriviche to Morrocoy, and a higher coral cover in the exposed fringing reefs (Fig. 6). Coral diversity varied between 25 and 52 species in the localities sampled. Fifty eight scleractinian species (51 zooxanthellate) and seven ecomorphs from 32 genera, and 4 hydrocoral species were reported for the area (Almeida 1972; Weil 1980, per. obs.) (Table 1, Appendix 1). Most common species were M. faveolata, M. cavernosa, M. franksL M. annularis, C. natans,
D. strigosa, D. clivosa, D. labyrinthiformis, P. astreoides, P. porites, Acropora palmata, A. cervicornis, Stephanocoenia intersepta, Madracis decactis and S. siderea. Urban and coastal development, deforestation, over-fishing, chemical pollution and uncontrolled tourism are the major anthropogenic problems affecting the natural communities in the region. In early 1996, an extensive mass mortality wiped out extensive populations of many important reef species including corals, octocorals, sponges, zoanthids, and fish among others. The cause is still under debate with two leading hypotheses: natural causes, produced by oxygen depletion after a population explosion of planktonic organisms, and chemical pollution, from a nearby spill or wash-waters from a tanker. Recent surveys of several reef localities by the author in 1999, indicate that coral cover dropped to zero in many areas that used to have 30-50% live cover, reefs appear devastated with few small live colonies of S. intersepta, M. faveolata, M. franksi, M. cavernosa, P. astreoides, Madracis senaria, M. decactis, etc. It is likely that many species of corals, octocorals, sponges and hydrozoans may have gone locally
The corals and coral reefs of Venezuela
315
extinct. On the positive side, there were substantial numbers of what look like new recruits in some of the affected areas, like Boca Grande. Even with active programs of coral transplantation, and good natural recruitment rates, it will take many years for this area to recover. Further west, along the coast of Falcon, some minor reef development occurs in San Juan de Los Cayos and other localities. Coral communities formed by scattered colonies of corals and other reef invertebrates and algae are found at other localities. 3.2. Island Reefs 3.2.1. Isla La Blanquilla Together with the small archipelago of Los Hermanos, La Blanquilla (11~ and 64~ rest on a shallow submarine platform close to the western extreme of the Aves Ridge, a long submarine mountain system that runs north to south for over 400 km in the eastern Caribbean. La Blanquilla is located about 100 km to the northwest of Margarita Island and 162 km to the east of La Orchila (Fig. 3). Most of the island is formed by three wide, uplifted fossil reef platforms (Maloney 1971; Schubert and Moticska 1972). The major living coral reef formations are in the south and west of the island. The east and north are steep drop-offs exposed to the open, high energy seas. In a short visit to the island in 1984 the author was able to dive in the south area. Reefs are well developed with large colonies of the common reef-building species M. faveolata, M. annularis, M. franksi, M. cavernosa, S. siderea, D. strigosa, P. astreoides, P. porites, A. palmata, A. cervicornis, M. mirabilis, D. cylindrus, M. complanata, and M. cervicornis. Forty seven scleractinian species (43 zooxanthellate) and 1 ecomorph were identified in two reefs areas that were briefly surveyed by the author (Table 1, Appendix 1). These numbers may increase once a more comprehensive study of the reefs is carried out. The island is visited by fisherman from Margarita, and the occasional tourist in private yachts or small planes. It also has a potential to become a tourist attraction and therefore, may be developed in the coming years. 3.2.2. Coche and Cubagua Two low islands located south of Margarita (north of the Mochima National Park and the Cariaco Trench (Fig. 1). The islands are surrounded by shallow waters (< 40 m) dominated by extensive sea grass and sandy communities. Upwelling waters (high nutrient and low temperatures) from the Cariaco Trench (Okuda et al. 1968) limit reef development. Small patch reefs occur offshore and near the islands, and coral communities can be found on rocky shores. Millepora spp., M. cavernosa, C. natans, C. amaranthus, M. franksi, M. faveolata, Oculina spp. and D. strigosa are the most common reef building corals and hydrocorals in this region. Up to 31 scleractinian species (26 zooxanthellate) in 21 genera have been reported for this area (Table 1, Appendix 1) (Rodriguez 1959; Rarnirez-Villarroel and Gonzfilez 1974; Ramirez-Villarroel 1975, 1978; Buccimazza 1984; Weil per. obs.). The area is heavily fished and there are some tourist developments on the island of Coche. Plans to develop the islands with large tourism complexes could become a future threat to these minor reef formations. 3.2.3. Isla de Aves The northernmost possession of Venezuela, Isla de Aves is the only emergent feature of the long submarine system known as the Aves Ridge. It is located 700 km north of
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Ernesto Weil
the Venezuelan coast, 350 km south-east of Puerto Rico (15~ and 63~ (Table 1, Fig. 1). This rather small coralline island (400 rn long and 70 rn wide) rests on a shallow (5-10 rn depth) fiat platform, which drops steeply to great depths at the edges, and is the main nesting locality for the green turtle (Chelonia mydas) in the eastern Caribbean sea (Brownell and Gttzrnfin 1972; Almeida and Goddard 1973; Gremone and G6mez 1983; Office of Geography and Cartography of the Armed Forces 1988; Weil per. obs.). The wide reefal platform to the west is mostly sandy substrate with scattered coral, hydrocoral and octocoral colonies and some small patch reefs. Caves and wide spur and grooves with large colonies of green A. purpurea, L. cucullata, P. astreoides and D. clivosa dominate the north section. The eastern platform is a well developed coral reef environment with spur and groove structures, patch reefs and high densities of octocorals and Millepora spp. colonies over the extensive platform. The fringing and bank reefs characteristic of this island are well developed at the edges but show signs of being battered by hurricanes in the past (Weil per. obs.). This island is the only Venezuelan territory that is in the hurricane corridor of the eastern Caribbean (Office of Geography and Cartography of the Armed Forces 1988, and references therein). It has been hit by several strong hurricanes in the last century, some of which (David in 1979 and Allen in 1980) produced substantial damage to the shallow water communities. During hurricane David for example, the island was completely under water for about 8 hours and was drastically reduced in size and divided into two portions (Weil per. obs.). Most of the sand was removed by the waves and wind and deposited in the lagoon, covering patch reefs and isolated colonies. Close to 50,000 turtle eggs were lost and the island was littered with all kinds of dead marine invertebrates (large coral and octocoral colonies, sponges, zoanthids, etc.) and fish deposited there by the waves. A total of 46 scleractinian species (42 zooxanthellate) and 5 ecomorphs were observed by the author in 1979. Reef structures show high coral cover and densities down to 35 m in some areas. Large colonies of the main Caribbean reef builders (M. annularis, M. faveolata, C. natans, D, strigosa, D, labyrinthiformis, A. palmata, etc.) are found growing on the platform and the edge. No direct human threat is present for this coral reef system now, and in the near future. It is far away from the main ship routes and is isolated (> 300 km) from the nearest human population). The Venezuelan Navy and the Instituto Hidrogr~ifico run a scientific-military base built on top of a tall platform on the south-west end of the island. This provides a good platform for coral reef research on this isolated Caribbean island. More research on the coral reef community structure and dynamics of the coral reefs around the isolated island is needed.
3.2.4. Isla La Tortuga La Tortuga is the second largest Venezuelan island (171 km 2) and is located 72 km to the NE of Cabo Codera (10~ and 65~ (Fig. 1). Most of the island is a fiat emerged coral limestone terrace scarcely vegetated (de Jel 1945). The highest elevation is 40 m. The island and fringing coral reefs have developed on a submarine plateau located on the north-western edge of the Cariaco trench. Water depths of 1,500 m are found less than 8 km from the southern coast of the island. The north shore is more protected with extensive sandy beaches and a wide platform that supports well developed coral reefs. Fringing reefs border most of the island shores and the small cays on the northwest side. Some small patch reefs are also found along the north shore. There is very little information about the morphology, composition, distribution and biodiversity
The corals and coral reefs of Venezuela
317
of coral reefs around this island. There are no permanent inhabitants and the island is mostly visited by fisherman and local boaters from the main coast and Margarita Island. The area has a potential for tourism development and it is imperative that natural communities be characterized, described and protected before this happens. 3.2.5. Isla La Orchila The island of La Orchila (11~176 and 66~176 is located 125 km north of Cabo Codera (56 km east of Los Roques). The complex is formed by a irregular, triangle-shaped main island (93.5 km2) and several mangrove and sandy cays towards the north-east. Most of the island surface is fiat with a short series of hills (140 m tall) towards the west. The climate is arid with high temperatures and low precipitation (Williams-Trujillo, 1980). There is a naval station in the southwest and visits to the island and surrounding waters requires authorization by the Venezuelan Navy. This island has extremely well developed, diverse and long coral reefs fringing all the south and east coast. One reef locality towards the southwest was quantitatively described by Urich (1977). Coral cover can reach 60%. Sixty two scleractinian species (54 zooxanthellate) and 8 ecomorphs in 25 genera have been reported for this area (Table 1, Appendix 1). Large colonies of the main Caribbean reef builders (M. annularis, M. faveolata, C. natans, D. strigosa, D. labyrinthiformis, S. siderea, A. palmata, A. cervicornis, Agaricia spp. Porites spp. etc.) form the fringing reefs down to 30 m in some areas. The structure, composition and diversity is very similar to that of the archipelago Los Roques (Weil per. obs.). 3.2.6. Archipielago de Los Roques National Park The Archipelago de los Roques National Park (ll~176 and 66o32' 42"W-66~ was created in 1972. It is located 125 km north ofLa Guaira on the main coast, and 36 km east of the archipelago Las Aves (Fig. 3). This large reef complex rests on a flat submarine mountain (guyot) surrounded by deep waters (>1,000 m). It is an elongated complex (36.6 km in length and 24.4 km in width covering an approximate area of 894 km2), with a central lagoon, and has been characterized as an atoll (Williams-Trujillo 1980) or as a "semi-atoll" (M6ndez 1978). Four main geomorphological formations were identified by M6ndez (1978); coral reefs, coral rubble cays, the igneous Gran Roque island, and a central lagoon. E1 Gran Roque is the main island and the only one with exposed igneous and sedimentary rocks. It has an estimated area of 1.7 km2 and supports the main fisherman town (1,000 people), now a major ecotourism center. It is separated from the middle and south west islands by a deep lagoon (50-70 rn deep). The archipelago and reef complex is formed by about 52 cays, over 200 reef banks, hundreds of small patch and pinnacle reefs, and fringing mangrove forests and islands. Most islands around the lagoon have well-developed fringing reefs on their exposed side. The inner shores, towards the lagoon, are usually fringed by mangrove forests and/or turtle-nesting sandy beaches. The wide, shallow central lagoon (Ensenada de los Corales) covers an area of approximately 300 km2 with an average depth of 4 m. It is formed by coarse calcareous sediment that supports extensive sea grass and sandy bottom communities, sand banks, and hundreds of patch reefs. These lagoon reefs were built by dense thickets of A. cervicornis with massive and columnar Montastraea spp., Millepora, P. astreoides and P. porites and serve as refuges for many commercial fish, lobster and the Caribbean king crab, Mitrax spinosissimus.
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Ernesto Weil
Two long fringing reef systems limit the atoll complex on the east and south. The one on the east is 24 km long, nms in a north-south direction, has an average width of 300 m and a gentle slope that serves as a barrier to waves and currents coming from the east (M6ndez 1978). The southern fringing reef runs almost continuously for about 25 km from east to west, it is narrow with a step drop-off in many areas. The reef system is well developed and diverse. It provided the material (coral rubble) for the formation of the southern storm terraces, and the long sandy and rubble cays. There are several areas with underwater caves and terraces at 20 and 45 m deep along this reef. The southern reef system shows a typical depth-gradient zonation of coral species with well developed A. palmata banks in the shallow areas down to 5 m. Extensive and diverse octocoral communities have developed along the platform and intermediate depth areas. Reef areas are dominated by large columnar, massive, crustose, and platy colonies of Montastraea spp., P. astreoides, Diploria spp., D. cylindrus, Colpophyllia spp., S. intersepta, D. stockesii, Agaricia spp. and S. siderea. Extensive areas of reef present a steep, wall-like slope that can drop 25-30 m from the edge of the reef to a sandy bottom platform that starts at around 50 m deep and has a gentle slope down to the edge of the guyot. These walls are covered by a high diversity of invertebrates and algae. Deeper areas are dominated by platy and crustose colonies of M. franksi, Mycetophyllia spp, Madracis spp., Agaricia spp., and sponges. A high diversity of sponges represented by a large variety of colors, sizes and morphologies is found throughout these reef systems. Coral cover varies from 65 % in the exposed reef of Cayo Sal to 25% in patch reefs in deep lagoonal areas with high sediment-resuspension rates (Fig.7, Table 2). Sixty nine scleractinian species (61 zooxanthellate) and 8 ecomorphs in 33 genera have been identified in the area (Table 1, Appendix 1). This represents the highest coral diversity reported for Venezuela and one of the highest for the Caribbean (Weil 1985, 1999, per. obs.). Octocorals and sponges are also very abundant and diverse in the area (Alvarez et al. 1985; La Schiazza 1985). M. faveolata, M. annularis, M. franksL M. cavernosa, S.
siderea, D. strigosa, P. astreoides, P. porites, A. palmata, A. cervicornis, M. mirabilis, D. cylindrus and M. complanata are among the most common species.
3.2.7. Archipielago Las Aves The archipelago La Aves is an atoll-like formation 125 km north of the central main coast and 75 km east of Bonaire (12~176 and 67~176 It is formed by two arcs of islands and cays, the Aves de Barlovento and Aves de Sotavento (Fig. 1). Low sandy and mangrove cays are surrounded by well developed and highly diverse flinging reefs. The internal lagoon has several mound-like patch reefs rising from sandy and/or seagrass beds at 10 m depth. The biology and geology of the seabed down to 10 m was described by Almeida and Goddard (1974), Alevizon and Brooks (1975) and M6ndez (1978). Alevizon and Brooks (1975) reported coral cover of up to 75% and 85% in some localities in the exposed fringing reef south of the island. The common Caribbean reef builder species are abundant and form the bulk of the reef structure. There are no permanent inhabitants on these islands with the exception of an officer from the Department of the Interior who controls visitors from the Netherland Antilles. Most human impact is from uncontrolled fishing activities, the occasional vessel grounding, oil spills, and a few tourists. The reefs in these islands need further investigation and quantitative descriptions of the communities. The coral reefs and the islands should be considered as candidates for natural sanctuary areas or a National Coral Reef Reserve.
The corals and coral reefs of Venezuela
319
0 6O 40 i.,, Q > 2O 0 1,,I 0 o Ol m 60
Miscellaneous
Macroalgae
c q) 4O U i.,. =i 20 11. 0 60
S u bstrates
40
2O
0 9
9"
9~"
Gs'J ~ v
Reefs
Fig. 7. Mean percentage cover of major biological groups and substrates in deep coral reef patches (P-l, P-2) and fringing reef in the Archipelago Los Roques National Park, 112 km north of the main coast of Venezuela. Miscellaneous includes turf algae, hydrocorals, sponges, and other cnidarians. Substrates include bare, sand and rubble.
3.2.8. Archipielago Los Monjes
This is a group of nine small islands and rocks located 35 km offshore the from extreme western border of Venezuela (12~176 and 70~176 ' 40"W) (Fig. 3). They are grouped in three clusters, the Monjes del Norte (6 islands), Monjes del Sur (2 islands) and an isolated island named Monje del este. The largest islands are in the second group (0.21 km2 and 70 m in height). Some of these islands have well developed coral reef communities around them. However, little information about the distribution, structure, composition and biodiversity of these reefs is available. The only study is by Rodriguez del Villar (1976) who described the island natural resources. 4. NATURAL DISTURBANCES - ENVIRONMENTAL INFLUENCES
Easterly trade winds produce dry and semi-arid conditions along most of the low coastal plains and islands on the eastern coast. Most of the main coast and island shores have unstable, sandy substrate and are under the seasonal (winter months) influence of low-temperature, high-nutrient upwelling waters from the Cariaco Trench (1,600 m deep), a consequence of the trade winds (Okuda et al. 1968; Antonius 1969). In some areas, a marked thermocline develops from May to November (Pauls 1982) and surface water temperatures vary from 19 to 28~ (Okuda et al. 1968; Campos-Villarroel 1972; Pauls 1982). Average rainfall in the Mochima bay area is about 127 mm per year. These factors play a role in preventing good reef development in this region. Low-accretion
320
Ernesto Weil
reefs are found in the Mochima Bay National Park, the Gulf of Cariaco, the east and north shores of the islands of Coche and Cubagua, the Cumberland Bank and in some of the other small islands of the region (Los Frailes, Los Hemanos, Los Testigos, La Sola, etc.). Along the central coast, from Cabo Codera to the Puerto Cabello area, the coast is fringed by the Cordillera de la Costa mountain range, which receives substantial rainfall. This fresh water nms down in small rivers and creeks into the sea. In areas where there is coastal development and/or road construction, these creeks carry large loads of sediments into coastal waters. Nevertheless, some areas are suitable for reef development, and have significant reef formations like the San Esteban National Park. High energy, rocky shores support low diversity and low density coral communities; this is also the case for many areas along the continental shoreline, where river runoff is limited and stable substrate is available. These communities are formed by scattered, usually crustose coral colonies, many octocorals, sponges, zoanthids and other common reef invertebrates. The most common natural disturbances affecting coastal reefs include sedimentation by riverine outflow during wet, rainy months and bleaching during summer months. Several events of fish die-off due to "turbios" (similar to red tides) have occurred in many areas of the coast. Population explosions of planktonic organisms which drove the O2 concentration of the water to very low levels has been postulated as an explanation for the coral reef massive mortality in the Morrocoy National Park in 1996 (Bone et al. 1998). Coral mass mortalities due to disease (white band disease plague in the early 1980's) affected Acroporid populations in coastal and island reefs (Weil 1999, per. obs.). Recent surveys in the Morrocoy and Los Roques National Parks showed low incidence of coral diseases in general (0-4.66% diseased colonies). Yellow Band Disease (YBD), white plague (WP), and dark spots disease type II (DSD-II) were the most common infections in both areas (Weil and Urreiztieta 1999). The D i a d e m a die-off in 1983 (Lessios et al. 1984) brought little consequences to the reef community in comparison with other Caribbean areas (Weil per. obs.). Abundance of herbivorous fishes kept algae populations on check in most coral reef areas preventing widespread coral mortalities. In recent years, bleaching has been observed to happen in many areas; however, no widespread mortalities have been reported. 5. ANTHROPOGENIC DISTURBANCES The major anthropogenic effects on coastal coral reefs include environmental changes induced by increased sediment loads, industrial and home waste waters, and chemical or oil spills. There is very little documentation of community changes due to human impacts in Venezuela. In the Morrocoy area, uncontrolled coastal development, lack of treatment plants, and deforestation play an important role in the deterioration of reef communities (Weiss and Goddard 1977; Bone 1980; Bone et al. 1993). Uncontrolled fishing and tourism activities and the increased frequency of chemical spills, have also been implicated in reef deterioration. Deforestation of river heads and banks has increased sediment loads to coastal waters and nearby reefs. The associated effects of turbidity and low light penetration affect zooxanthellate corals and other symbiotic reef organisms, reducing reef accretion rates. Waste waters increase nutrient content in the water, favoring growth of microflora and algae that can induce coral mortality. Even though most of the coastal coral reefs are under protection, because they are located within National Parks with special regulations, lack of personnel and the logistical and
The corals and coral reefs of Venezuela
321
fmancial capacity, prevent enforcement of the regulations. Detrimental human activities within the Park boundaries remains a constant threat to these reef communities. The offshore island reefs along the main coast are far away from continental influences and direct human impacts. Fishing activities, and the now booming "eco-tourism" industry represent the major human threats to these reefs. Occasional oil slicks, probably from tankers cleaning their tanks in open oceans, may collect along these offshore islands. Heavy tanker and cargo ship traffic near some of these islands represents another potential threat if there is a grounding accident. Two of the major island coral reef developments are under protection; the Archipelago de Los Roques National Park, under special rules, and La Orchila, where the Venezuelan Navy has a station, and a restricted vacation center for high ranking officials, and therefore, is off limits for fishing and tourism activities. 6. PROTECTION POLICIES AND LAWS The Venezuelan legislation on environmental issues and protection of natural resources is extensive and complete. It is supported by judiciary instruments, from the National Constitution to established laws, decrees, and resolutions that range from specifics to generalities. There are legal instruments, which state the Government resolution to protect the environment and natural resources of the country. The Constitution establishes the norms that allow the Government to develop environmental and resource policies. It specifically cites the marine environments and communities as important National resources, and states that the Government will supervise the sustainable use of these communities. Several international treaties and cooperative documents have been signed by the Venezuelan Government. Many of these include specific studies of coastal and marine pollution by oil and derived products, water quality, creation of graduate programs in marine sciences, management plans for marine systems, depositories of data, etc. The Government entity in charge is the Ministry of the Environment and Natural Resources. In the last 30 years, a total of six important coral reef areas have been put under special administration regimes in the form of National Parks. The three main coral reef areas on the main coast are included in National Park areas. Only one major coral reef complex of the offshore-island coral reefs was declared a National Park, the Archipelago los Roques. However, the coral reef communities located around the island of La Orchila are more or less protected by the presence of the Navy station on this island. It seems that, with these measures, a large proportion of the coral reef communities in Venezuela are under some kind of legal protection. However, reality is different, lack of funding, trained personnel, and equipment, render these important efforts ineffective in most of the coral reef areas. ACKNOWLEDGMENTS I would like to thank Isabel Urreiztieta, David Bone, Eddar Brunneti, Juan Carlos Fernandez, Eduardo Klein and the Fundaci6n Cientifica los Roques for their help in localizing and providing references and information for this chapter. I would also like to thank four anonymous reviewers for their comments and suggestion in an earlier draft. To Dr. Jorge Cort6s, for his kind invitation to be part of this book.
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Ernesto Weil
REFERENCES
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Weil, E. 1992a. Genetic and Morphological Variation in Porites Across the Isthmus of Panama. Ph.D dissert., Univ. Texas, Austin. 238 p. Weil, E. 1992b. Genetic and morphologic variation in Caribbean and eastern Pacific Porites: Preliminary results. Proc. 7th Int. Coral Symp., Guam 2: 643-656. Weil, E. 1999. The coral and coral reefs of Venezuela: Status and importance. Abstract, 29th Meet. Association of Marine Laboratories (AMLC) of the Caribbean, Cumanfi, Venezuela: 15. Weil, E. & R. Laughlin. 1984. The biology, population dynamics and reproduction of the queen conch, Strombus gigas Linnaeus, in the Archipi61ago de Los Roques National Park, Venezuela. J. Shellfish Res. 4: 45-62. Weil, E. & R. Laughlin. 1985. Ecologia, cultivo y repoblaci6n del Botuto Strombus gigas Linnaeus, en el Parque Nacional Archipi61ago de Los Roques. Informe final proyecto S1-1182 CONICIT, Venezuela. 320 p. Weil, E. & I. Urreiztieta. 1999. Latitudinal variability in the incidence of coral diseases in the wider Caribbean. Abstract, IASI Meeting, Panama. Weil, E., D. Bone & F. Losada. 1984. Spatial variations in density and size structure of the echinoid Diadema antillarum Philippi on some Venezuelan coral reefs. Bijdreg. Dierk. 54: 73-82. Weiss, M.P. & D.A. Goddard. 1977. Man's impact on coastal reefs. An example from Venezuela. Amer. Assoc. Petrol. Geol., Studies Geol. 4:11-124. Work, R.C. 1969. Systematics, ecology and distribution of the mollusks of Los Roques, Venezuela. Bull. Mar. Sci. 19:614-711.
328
E r n e s t o Weil
APPENDIX
1
Relative abundance of shallow water scleractinian corals and hydrocorals in some coral reefs of Venezuela. Localities ordered from west to east. *** = abundant; ** = eonmmn; * = rare. Type of reefs: F = flinging, and P= patch reef. Geographic location of reefs: C = main coast; I = offshore island. * = non-zooxanthellate species; EM = ecomorph. Locality
Morroco
San
N. Park Esteban Reef type / locality
Los
La
Roques
Orchila F,P/I
F,P/I
***
***
***
***
F,P/C
F,P/C
F,P/I
***
***
***
La
Bahia
Blanquilla Mochima F/C
Golfo de Isla de
Margarita-
Cariaco
Aves
Cubagua
F/C
F/I
P/I
Genus / species Stephanocoenia 1
S. intersepta Madracis
2
M. decactis
3
M. mirabilis
**
4
M. pharensisP*
***
EM?
M. pharensisG
*
5 6
***
M. formosa M. senaria
**
Acropora 7 8 9
A. palmata A. cervicornis A. prolifera
***
***
***
***
**
**~
***
**
*
*
***
*~*
***
*~*
***
**~
*~*
***
***
***
***
*~*
***
~**
*** *** *
Porites 10
P. porites
***
11
P. furcata
***
12
P. divaricata
**
13
P. "branneri"
**
P. astreoides
***
14
Montastraea
15
M. annularis
***
16
M. faveolata
***
17
M.franksi
***
18
M. cavernosa
EM?
M. cavernosa-2 Diploria
19
D. strigosa
***
20
D. clivosa
***
21
D. labyrinthyformis
***
D. clivosa-sp
**
EM?
Colpophyllia
22
C. natans
23
C. amaranthus
*
24
C. breviserialis
*
***
Solenastrea
25
S. bournoni
26
S. hyades
**
Favia
27
F. fragum
28
F. conferta
***
***
The corals and coral reefs o f Venezuela
329
Cont. A p p e n d i x 1 Locality Reef type / locality Genus / species
Manicina 29 30
M. aerolata M. mayori Meandrina
31
M. meandrites
32
M. memorialis
33
M. brasiliensis Agaricia
34
A. fragilis
35
A. lamarcki
36
A. grahamae
37
A. undata
38
A. verrili
39
A. pumila Undaria
40
U. agaricites
41
U. humilis
42
U. purpurea
43
U. danae
44
U. tenuifolia
EM?
U. carinata
EM?
U. crassa Helioseris
45 EM?
H .cucullata H. cucullata-2 Leptoseris
46
L .cailleti Dendrogyra
47
D. cylindrus Dichocoenia
48 49
D.stockesii D. stellaris Siderastrea
50 51
S. siderea S. radians Mycetophyllia
52
M. aliciae
53
M. lamarckiana
54
M. danaana
55
M. ferox Scolymia
56
S.cubensis
57
S.lacera
58
S.wellsi
Morrocoy
San
Los
N. Park
Esteban
Roques
F,P/C
F,P/C
F,P/I
La
La
Mochima Golfo de
Orchila Blanquilla N. Park F,P/I
F,P/I
F/C
Isla de Margarita-
Cariaco
Ayes
Cubagua
F/C
F/I
P/I
330
Ernesto
Weil
Los
La
Cont. A p p e n d i x 1 Locality Reef type / locality
Morrocoy
San
N. Park
Esteban
F,P/C
F,P/C
**
**
**
**
**
*
La
Mochima Golfo de Isla de
Roques Orchila Blanquilla N. Park F,P/I
F,P/I
F,P/I
F/C
***
***
**
*
**
**
Aves
Cubagua
F/C
F/I
P/I
Genus / species..... Mu$$a
59
M.angulosa Isophyllastrea
60
Lrigida Isophyllia
61 EM?
l.sinuosa L multiflora
*
*
Eusmilia
62
E.fastigiata
**
**
**
**
**
*
Cladocora
63
C.arbuscula Oculina
64
O.diffusa
65
O.varicosa
**
O. v a l e c i e n n e s i
*
66
**
*
**
Phylangia
67
P.americana*
**
**
**
*
***
***
Astrangia
68
A. s o l i t a r i a * Tubastrea
69
T. a u r e a * Rhyzosmilia
70
R. m a c u l a t a *
*
**
*
Caryophyllia
71
C. s m i t h i i *
*
*
Colangia
72
C. i n m e r s a *
*
Gardineria
73
G. m i n o r *
*
Millepora
1
M. alcicorni$
***
***
***
***
***
**
**
2
M. complanata
***
***
***
***
***
***
***
3
M. s q u a r r o s a
4
Millepora-sp
***
***
***
***
***
**
***
*
**
Stylaster
5
S. roseus*
Margarita-
Cariaco
*
331
Coral reefs of the Pacific coast of M6xico Hrctor Reyes-Bonilla Universidad Aut6noma de Baja California Sur. Departamento de Biologia Marina. Apartado postal 19-B, CP 23080. La Paz, B.C.S., M6xico Present address: Divisi6n of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149-1098 USA
ABSTRACT: Coral reefs and communities of the Pacific coast of Mdxico have been studied since the 19th Century, but considered as rare, and of little importance. Nevertheless, new discoveries during the last decade have brought a renewed interest into these systems. Due to differences in the biological characteristics and composition of the coral communities, the reefs of the west coast of M6xico are naturally divided into three groups: those of the Gulf of California, the Revillagigedo Archipelago, and the tropical Mexican Pacific. In the Gulf, there are abundant coral patches, but only three structures that can be considered reefs; one of them, Cabo Pulmo (23~ is the most studied reef on the west coast of the country. Frameworks are small, communities are dominated by Pocillopora spp., and zonation is weak. The oceanic Revillagigedo Archipelago (18~ has fringing reefs in Clari6n and Socorro, where pocilloporids prevail in shallow water and massive species in deeper areas. Reefs can attain 3 m in thickness, and present the highest coral species richness in westem Mrxico (18 taxa). The tropical Pacific shows the best reef development in Mrxico at Nayarit (21 ~ and Oaxaca (15~ coral cover is high but diversity is low, because the well-consolidated frameworks are mostly composed of Pocillopora spp. Between these reef areas, long tracts of sandy beaches hinder coral settlement and growth, but some small and isolated communities exist. Along the Pacific coast of M6xico, natural perturbations are common and affect reefs in different ways, depending on their geographic position. Corallivores and bioeroders are widespread, but few studies have been conducted to determine their importance on coral communities. The sea star Acanthaster, Lithophaga bivalves and the urchins Eucidaris and Diadema appear to be the most important species, but because of their low abundance and the high coral cover, accretion seems to be higher than erosion or predation, resulting in net positive growth of reefs. On the other hand, oceanographic and atmospheric events such as hurricanes and the El Nifio-Southem Oscillation are suggested to be much more important in determining coral abundance and community structure in Mrxico, both on short- and long-term scales. However, their effects are not catastrophic. Human-induced perturbations (in particular fisheries, tourism and sedimentation) are still very localized and of relatively low scale, but they may turn into demanding problems in the coming years because of the lack of official and public attention to the Pacific reefs, the slow implementation of management plans and other protective procedures, and the economic need to develop Mrxico's west coastal areas. 1. I N T R O D U C T I O N C o r a l reefs a n d c o m m u n i t i e s o f the Pacific c o a s t o f M r x i c o w e r e o n c e c o n s i d e r e d rare a n d o f little i m p o r t a n c e r e l a t i v e to the b e t t e r d e v e l o p e d , c o m p l e x , a n d o l d e r C e n t r a l A m e r i c a n Pacific reefs o f Panarn~, Costa Rica, and the Gal~ipagos Islands ( G l y n n and W e l l i n g t o n 1983). H o w e v e r , after the c a t a s t r o p h i c effects o f the 1 9 8 2 - 8 3 E1 NifioLatin American Coral Reefs, Edited by Jorge Cortrs 9 2003 Elsevier Science B.V. All rights reserved.
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Southem Oscillation in the equatorial eastem Pacific, and the apparent absence of damage to Mexican coral communities (Glynn 1994; Reyes-Bonilla and Calder6n-Aguilera 1994), the latter have achieved a new status and are nowadays considered among the most important in the eastern Pacific (Reyes-Bonilla 1993a; Glynn 1997a; Glynn and Ault 2000). Several papers have discussed the main characteristics and status of coral communities of the Pacific coast of Mdxico, either considering them as a whole or analyzing specific sites or regions; particular attention has been given to the Gulf of California (Durham 1947; Squires 1959; Glynn and Wellington 1983; Anonymous 1988; Glynn 1982, 1997b; Guzrnfin and Cortds 1993; Cortds 1997; Spalding et al. 2001). However, recent studies in the country have advanced significantly in number, quality and scope in the last few years, and justify an update of the current information. The objective of this paper is to review the history of research and describe the main attributes of coral reefs and communities from the Gulf of California (3 I~ to the coast of Oaxaca (15~ with an emphasis on recent published data and research in progress. 2. HISTORY OF RESEARCH The history of research on hermatypic corals of the west coast of Mdxico can be divided into three stages: 19'h century, the first part of the 20 th century (1900 to 1952), and recent years (1952 to date). Readers interested in a more detailed treatment of this topic are encouraged to consult Durham (1947), Durham and Bamard (1952), Squires (1959) and Reyes-Bonilla (1993a). 2.1. The 19 th Century The existence of coral reefs on the Pacific coast of Mdxico was not reported by the European naturalists who visited the country from the 16th to 18th centuries (Trabulse 1994), although Spanish missionaries observed corals in the Gulf of California (del Barco 1757). Darwin (1842) and Dana (1848) believed that reefs were absent from the eastern Pacific because of cold water currents, but at about the same time Grewingk (1848, in Squires 1959) found a colony of Porites panamensis at Isla Carmen (25~ Fig. 1), in the Gulf of California, the first record of a coral from the Pacific coast of Mrxico. Several decades later, Verrill (1864, 1868, 1870a, b) published the first descriptions and analyses of distribution of the eastern Pacific corals based on colonies deposited in U.S. museums, many of them collected in Mdxico. No other monograph on the corals of the west coast of the country appeared for more than 40 years after Verrill's work. 2.2. The Early 20 th Century From 1900 to 1952, studies of Mexican Pacific corals were focused on fossil communities, and the taxonomy and distribution of species. Vaughan (1917) found well developed Miocene to Pliocene reefs in the northern Gulf of California, consisting of Atlantic coral genera such as Diploria and Siderastrea. Palmer (1928) and Durham (1947), among others, mentioned the presence of Pleistocene Pocillopora communities in Oaxaca (16~ Magdalena Bay (24~ on the west side of the Baja California peninsula) and the Gulf (Fig. 1), and showed that Porites was the dominant genus in both the Pliocene and Pleistocene in Mdxico, while Pocillopora, Pavona, and Psammocora were
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of secondary in~ortance. In 1941, Steinbeck and Ricketts published the first characterization of the Cabo Pulmo reef (23~ Figs. 1 and 2), and mentioned numerous invertebrate and fish species that lived in association with corals in the Sea of Cort6s. Later, Durham (1947) and Durham and Bamard (1952) listed all recent species of the Pacific coast of America, and described many corals whose type localities are in M6xico. These authors firmly established that eastern Pacific coral communities are dominated by Indo-Pacific species. 2.3. The Late 2 0 th Century During the past few decades, investigations on Mexican Pacific corals made important advances in taxonomy and biogeography, and significantly increased our knowledge of the species biology. During this phase, Mexican researchers carried out the most relevant contributions; ViUalobos (1960) first published data on corals of the Pacific coast (Socorro Island, Revillagigedo Archipelago, 18~ Fig. 1). Squires (1959) and Reyes-Bonilla (1992, 1993a, in press a) discussed and modernized the scleractinian nomenclature in use for this region, after analyzing large numbers of specimens (both in the field and in scientific collections), and introducing updated methods of taxonomic research (e.g. Veron 1986). The first studies on the biogeography of the Mexican Pacific coral fauna were those of Wilson (1991) and Reyes-Bonilla (1993c), who suggested that the presence of permanem oceanic fronts at the mouth of the Gulf of California may function as a filter for scleractinian colonization of this inner sea. The distribution, provincial affmities, and similarities among Mexican Pacific reefs were studied by Reyes-Bonilla (1992), Ketchum and Reyes-Bonilla (1997) and Reyes-Bonilla and L6pez-P6rez (1998). In general, they proposed that: a) the Gulf of California was a refuge zone for coral faunas during Pleistocene glaciations; b) the Mexican Pacific region is actively being colonized from the Indo-Pacific by two main routes: the "classic" path (starting in the west or central Pacific and proceeding to Central America and M6xico via the Costa Pica Current), and a secondary one, with the same source, but using Clipperton Atoll (10~ 109~ and the Revillagigedo Archipelago as "stepping stones" for dispersal to the mouth of the Gulf of California and nearby areas in the state of Nayarit (Fig. 1); and c) the current coral composition in the Pacific coast of M6xico is quite different in the Gulf, the Revillagigedo Islands and at the mainland, south of 20~ Coral community structure is another area under active study. To date, information on species richness and coral cover of many localities from the west coast of M6xico is available (Gulf of California: Brusca and Thomson 1975; Brusca 1980; Robinson and Thomson 1992; Reyes-Bonilla 1993a, b, c; Reyes-Bonilla et al. 1997a, 1997b; Guerrero: SalcedoMartinez et al. 1988; Oaxaca: Leyte-Morales 1997; Glynn and Leyte-Morales 1997), although community diversity and evenness values exist only for Nayarit (Carriquiry and Reyes-Bonilla 1997). Research on population biology, evolutionary history, biogeochemistry and physiology is also being developed (Reyes-Bonilla 1992; Reyes-Bonilla and Calder6n-Aguilera 1994; Bemal and Carriquiry 2001; J.D. Carriquiry per. com.; R. Iglesias Prieto per. com.) and should produce important results in the coming decades.
3. DESCRIPTIONS OF REEFS AND CORAL COMMUNITIES Because of the extem and variety of the geomorphology and oceanographic conditions along the Mexican Pacific coast, the characteristics and composition of coral communities
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Fig. 1. Location of the main coral communities and reefs ofthe Pacific coast of M6xico. 1) Carmen Island; 2) San Gabriel Bay (at Espiritu Santo Island); 3) Magdalena Bay; 4) Cabo San Lucas; 5) Chileno Bay; 6) Cabo Pulmo; 7) Revillagigedo Archipelago; 8) Marias Islands; 9) Banderas Bay; 10) Los Arcos; 11) Tenacatita; 12) Manzanillo; 13) Punta San Telmo; 14) Zihuatanejo; 15) Acapulco; 16) Huatulco. N[ A I)
A
. SAN h GABRIEL
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.
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.
ISABE ISLAND \
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.
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SOCORRO
9. C L A R I O N .. . . . .
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ROCA PARTIDA P
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PUERTO ANGEL
Fig. 2. Main reef systems of the w e s t coast of M6xico (different scales have been used). Individual reefs indicated by shading. A) Gulf of California; B) RevillagigedoArchipelago;C) Nayarit region; D) Oaxaca region.
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Coral reefs of the Pacific coast of M~xico
TABLE 1 Distribution of hermatypic coral species on the Mexican Pacific coast (data from Reyes-Bonilla and L6pezP6rez 1998; Veron 2000; Glynn and Ault 2000; Reyes-Bonilla 2002). Main bibliographic sources: Gulf of California: Squires 1959; Reyes-Bonilla 1992, 1993a. Revillagigedo Islands: Glynn et al. 1996; Ketchum and Reyes-Bonilla 1997. Tropical Pacific: Carriquiry and Reyes-Bonilla 1997; Glynn and Leyte-Morales 1997. Key: A: Abundant species (appearing in more than 50% of the reefs or coral communities); C: Common species (present in 20% to 50% of the reefs). R: Rare species (found in less than 20% of the reefs). Gulf of California and nearby areas
Revillagigedo Islands
Pocillopora capitata Verrill, 1864 P. damicornis (Linnaeus, 1758) P. efusus Veron, 2000 P. eydouxi Milne Edwards and Haime, 1860 P. inflata Glynn, 1999 P. meandrina Dana, 1846 P. verrucosa (Ellis and Solander, 1786)= P. elegans
C C
R R
R R A
C
Dana, 1846
A
A R
A
21
19
Species
P. woodjonesi Vaughan, 1918 Porites arnaudi Reyes-Bonilla and Carricart-
C
Tropical Pacific (Nayaritto Oaxaca) C A R R R C
Ganivet, 2000 Porites australiensis Vaughan, 1918 P. baueri Squires, 1959 P. lichen Dana, 1846 P. lobata Dana, 1846 P. lutea Milne Edwards and Haime, 1860 P. sverdrupi Durham,, 1947 P. panamensis Verrill, 1866 Psammocora brighami Vaughan, 1907 P. stellata (Vendll, 1866) P. superficialis Gardiner, 1898 Gardineroseris planulata Dana, 1846 Leptoseris papyracea (Dana, 1846) Pavona clavus (Dana, 1846) P. duerdeni Vaughan, 1907 P. gigantea Verrill, 1869 P. maldivensis (Gardiner, 1905) P. minuta Wells, 1954 P. varians Verrill, 1864 Diaseris curvata (Hoeksema, 1989) D. distorta Michelin, 1842
TOTAL
R A R C R C R A
R R 16
change appreciably (Table 1). For purposes of this paper, the coastal region will be divided into three main parts: the Gulf of California, the Revillagigedo Archipelago, and the Mexican tropical Pacific (Figs. 1 and 2). 3.1. G u l f of California The most complete information on coral biology and distribution for the west coast of M6xico is from the G u l f o f California. Studies have been conducted here for more than a
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century, and this is clearly reflected in the relatively large number of publications on the regional fauna (Reyes-Bonilla 1993a). Coral reefs in the gulf are scarce and not fully developed; in fact, there are only three sites where true reefs occur: Cabo Pulmo, San Gabriel (24~ at Espiritu Santo Island), and Chileno Bay (23~ Fig. 2). Their frameworks are small (not thicker than 2 to 3 m) and almost completely built by pocilloporids (especially Pocillopora verrucosa; Table 1). Poritids and agariciids are relatively uncommon in shallow water and do not contribute large amounts of carbonate material to the reef structure (Reyes-Bonilla 1993a), but they become more abundant from 6 to 12 m deep, thus establishing a weak pattern of zonation. San Gabriel and Chileno reefs occupy less than 5 hectares. Cabo Pulmo is much larger; the main "coral bar" (Squires 1959) is more than 2 km long and several hundred meters wide (Reyes-Bonilla 1993b). While true reefs are rare in the Gulf of California, isolated patches or coral heads of the genera Pocillopora, Porites, Pavona, and Psammocora are ubiquitous in rocky areas south of 25~ (Squires 1959; Reyes-Bonilla 1992; Fig. 1). North of this point as well as on the Pacific side of the Baja California Peninsula, Porites becomes the dominant coral genus in the region, while Pavona appears occasionally up to 26~ inside the Gulf (Reyes-Bonilla 1993a). In all of this area, fragments of colonies are frequently carried to deeper water and sometimes can be an important component of rhodolith beds (ReyesBonilla et al. 1997). In sandy bottoms near La Paz (24~ Fig. 2), dense beds of Diaseris distorta (> 500 ind rn2) occupy hundreds of square meters at 20 to 30 m depth (L6pez Forment and Reyes-Bonilla in prep.). Those occurrences are rare in the eastern Pacific and have previously been observed only in the Gal/lpagos and the west coast of Costa Rica (Feingold 1996; Cort6s and Guzrmin 1998). The Gulf of California has only a single endemic coral: Porites sverdrupi. For some time it was considered to be a deep-water form of P. panamensis (Wells 1983). However, field observations and morphological analyses (Reyes-Bonilla 1992, 1993a; L6pez-P6rez 1998) have demonstrated that the species is taxonomically valid. In the years following its discovery, P. sverdrupi was repeatedly collected in the Gulf (Durham 1947; Durham and Bamard 1952; Squires 1959), and the fossil record indicated its presence locally in the Pliocene and Pleistocene, when it was distributed as far as the Marias Islands (20~ Fig. 2). However, recent surveys show that populations are absent south of 25~ and declining north of this point (Reyes-Bonilla 1993a; Reyes-Bonilla et al. 1997). Possible causes of these changes are unknown, but they are not attributable to direct human disturbances, as P. sverdrupi is not exploited or used in any way.
3.2. The Revillagigedo Archipelago This group of four volcanic islands (Socorro, Clari6n, San Benedicto and Roca Partida; Figs. 1 and 2) originated from the activity of the Clari6n Fracture Zone during the Pliocene-Pleistocene (Bautista-Romero et al. 1994). The first biological studies mentioned that there were only small coral patches in the islands and that a reef existed at Clari6n (Villalobos 1960; Anonymous 1988; Reyes-Bonilla 1993a). Recent work has shown that the four islands have numerous coral patches, and that Socorro and Clari6n do have true reefs, although they are of small size (less than one hectare each; Glynn et al. 1996, Ketchum and Reyes-Bonilla 1997, in press). In addition, 21 hermatypic species have been recorded from the archipelago, the highest species richness in western M6xico (Reyes-
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Bonilla and L6pez-P6rez 1998; Table 1). This number may actually be higher, since there is morphological evidence of local hybridization in Porites spp. (Ketchum and Reyes-Bonilla 1997, in press), a process that can produce new species by "reticulate evolution" (sensu Veron 1995). Most of the reported corals of the archipelago are IndoPacific, and four of them (Porites arnaudi, Porites australiensis, P. lutea and P. lichen) are not known elsewhere in the entire eastern Pacific (Glynn et al. 1996; Reyes-Bonilla and L6pez-P6rez 1998; Reyes-Bonilla and Carricart-Ganivet 2000). Socorro and Clari6n have fringing reefs, all located in protected bays on the south and west sides of the islands, possibly because there they receive protection from the numerous cyclones and tropical storms that impact the archipelago (Ketchum and ReyesBonilla 1997). Reefs around both islands showed a clear zonation, with Pocillopora in shallow water and Porites and Pavona from 5 to 30 m depth, although below 15 m there is only coral rubble and isolated colonies. The framework of the main reef area (4 to 7 m water depth) can attain a thickness of 3 m or slightly more at Clari6n, and 2 m at Socorro, a difference that could result in part from the fact that Clari6n is almost a million years older (Bautista-Romero et al. 1994). San Benedicto and Roca Partida islands are much smaller than the others and do not have well developed reefs, a possible consequence of volcanic activity and island morphology. In San Benedicto, Bfircena volcano was active as recently as 1952 and basalt from this eruption forms a large part of the south of the island (Richards 1966). The main lava delta was devoid of coral recruits in 1995, presumably because of turbidity and sedimentation caused by the very high erosion of the volcanic rock (Reyes-Bonilla 1995). Although a very small fringing reef exists in the west side of San Benedicto, it is possible that these and the rest of the coral communities around the island have suffered some kind of damage resulting in retarded or inhibited coral growth. In Roca Partida, available substrata for corals to development are limited; the island is only a small rocky peak protruding from the ocean, with no horizontal rocky surfaces. Corals do exist (Glynn et al. 1996) but do not build extensive carbonate structures.
3.3. Mexican tropical Pacific This region includes the coast from 2 I~ (Nayarit) to 15~ (the Gulf of Tehuantepec). Its most important coral reefs are located in Nayarit and Oaxaca (Fig. 1 and 2), and all of them are considered fringing reefs (Greenfield et al. 1970; Geister 1977; ReyesBonilla 1993a; Glynn and Leyte-Morales 1997; Carriquiry et al. 2001). In addition, numerous small communities and patches exist in the remaining areas, especially at Guerrero and Michoac~n (Brand et al. 1958; Salcedo-Martinez et al. 1988). The biological attributes of these sites differ considerably from those of the Gulf of California and the Revillagigedo Islands. First, reefs in Oaxaca and Nayarit are well consolidated and have the best developed frameworks in M6xico, attaining several hectares in area and up to 6 m in thickness (Carriquiry and Reyes-Bonilla 1997; Glynn and Leyte-Morales 1997; Carriquiry et al. 2001). Coral cover ranges from 20% to more than 50%; however, diversity and evenness are low, as the reefs are completely dominated by Pocillopora spp. Zonation is very clear: pocilloporids in shallow water (down to 5 m) with a gradual increase of Pavona and Porites in deeper areas (Carriquiry and ReyesBoniUa 1997; Glynn and Leyte-Morales 1997; Reyes-Bonilla and Leyte- Morales 1998).
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In the tropical Mexican Pacific there is a nominal endemic coral species: Porites baueri, confmed to the Marias Islands (Squires 1959; Reyes-Bonilla 1993a). Recently, its taxonomic status has been questioned as studies suggest it may be a misidentification of P. lobata (Glynn 1997b; Reyes-Bonilla et al. 1999). Coral species composition in this region also provides evidence for the two colonizing routes previously mentioned. Species like Porites lobata, P. lutea and P. minuta have been found only in Nayarit as well as in the Revillagigedos and Clipperton Atoll, while in Oaxaca, Gardineroseris planulata and Leptoseris papyracea have been collected (Table 1); both of which also inhabit Central America. Large tracts of sandy beaches dominate the coastline between the two more important reef areas of the tropical Mexican Pacific (Nayarit and Oaxaca), no doubt making larval connections between them very difficult (Glynn and Wellington 1983; Reyes-Bonilla 1993a). Corals may cross this area by gradually occupying small rock patches where colonies have been observed (Fig. 1). There are references in the literature of Pocillopora capitata, P. damicornis, Porites panamensis and Pavona gigantea in Zihuatanejo (17~ Salcedo-Martinez et al. 1988), and Pocillopora sp. at several bays around Punta San Telmo (18~ Brand et al. 1958), while field observations have located Porites panamensis and Pocillopora spp. near Puma San Telmo (M.D. Herrero-P&ezrul, per. com.) and P. damir P. verrucosa, P. panamensis, and Pavona gigantea in Acapulco (16~ per. obs.). In Jalisco and Colima there are no reefs but corals appear at many sites, especially near Manzanillo (18~ and Tenacatita (19~ The genus Pocillopora again dominates in these communities but there are exceptions: in several sites in the south of Banderas Bay (20~ an area exposed to occasional up-welling, Porites lobata was the most abundant coral, perhaps because turbidity caused by nearby fiver discharge and high productivity affects the pocilloporids (P&ez-Vivar et al. in prep.). 4. NATURAL PERTURBATIONS The eastern Pacific region in general is not suitable for the development of large reefs because of the presence of upwelling, coastal lagoons, mangrove areas and long sandy beaches (Glynn and Wellington 1983). On the west coast of M6xico these physiographic features are an essential part of the landscape, and their presence precludes reef growth (Reyes-BoniUa 1993a). However, there are other kinds of natural perturbations that affect corals in different ways and to varying degrees depending on geographic position. Here, predation, bioerosion, hurricanes and E1 Nifio-Southem Oscillation events will be discussed, all of which have the potential to change coral community structure.
4.1. Coral predation Corallivores have been widely studied along the west coast of America (reviews in Guzm/tn and Cort6s 1993; Cort6s 1997), however, knowledge of their biology in Mexican reefs is limited. Acanthaster planci (L., 1758) received much attention in the Gulf of California in the 1970's (Dana and Wolfson 1970; Barham et al. 1973; de Alba 1978), and studies concluded that as the starfish had relatively large populations in the Gulf and was selective in its diet, it may be important in determining abundances of certain species, and even community structure in sites of low coral cover. Reyes-Bonilla (1993b, in prep.) estimated the population density of this sea star in Cabo Pulmo from 1987 to
Coral reefs of the Pacific coast of Mdxico
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1999, and noticed that it fluctuated from 16 to >40 ind ha ~ in those years. These numbers were higher than those reported for Panarr~ or Costa Rica (Guzrrmn 1988; Glynn 1990) but since corals were abundant at Pulmo reef, Acanthaster effects on the community structure were probably low (Reyes-Bonilla and Calder6n-Aguilera 1999). Glynn (1974) noticed that Acanthaster distribution was discontinuous between Central America and the Gulf of California and the Revillagigedo Islands, but suggested that with more studies, this would prove incorrect. However, recent data indicates that the distribution is disjunct: south of 20~ the sea star is actually absent in mainland coral communities (Salcedo Martinez et at. 1988; Glynn and Leyte Morales 1997; Reyes-Bonilla in prep.), reappearing again at Carlo Island and Golfo Dulce, Costa Pica (8~ almost 1,000 km to the south (Glynn 1974, Guzm~in and Cort6s 1989). This unusual pattern indicates that the species may follow the "two route" model of coral biogeography, as it also occurs in Clipperton and the Revillagigedo Islands (Bautista Romero et al. 1994; Glylm et al. 1996). As A. planci larvae do not tolerate cold water (Glynn 1990), it may have not been able to cross the Papagayo and Tehuantepec gulfs because of local upwellings (Glynn and Wellington 1983). Another well known corallivore, the pufferfish Arothron meleagris (Bloch and Schneider, 1801) can also be found in Mexican Pacific reefs. In 1992, its abundance at Cabo Pulmo was 40 ind hat (Reyes-Bonilla 1993b), very similar to that found by Guzm~n and Robertson (1989) in Central American reefs. Considering the pufferfish consumption rate and coral cover at Pulmo, it was estimated that the local population ate about 5% of the coral standing stock of the reef each year, a low amount (Reyes-Bonilla and Calder6n-Aguilera 1999). Reyes-Bonilla (1993b, 1995), Reyes-Bonilla and Calder6nAguilera (1999) and Rosales-Estrada and Reyes-Bonilla (in press) calculated the population density of Eucidaris thouarsii (Valenciennes, 1846) at Cabo Pulmo and Isla Socorro (Revillagigedo Archipelago) as less than one individual per square meter. They noticed that these numbers were orders of magnitude lower than that found by Glyrm (1988) and Glyrm and Wellington (1983) in Central America and the Gal~ipagos, respectively. All this points the species is having a small effect on Mexican coral communities. 4.2. Bioerosion There are multiple species that bore coral colonies in the eastern Pacific, including sea urchins, polychaetes, sipunculids, bivalves and sponges (Guzrn~n and Cort6s 1993; Fonseca and Cort6s 1998). Their activities after the 1982-83 E1 Nifio in Panarn~, Costa Rica and the Galfipagos were so intense that some reefs were slowly turning into carbonate sediment (Glynn 1994, 1997a; Eakin 1996). In M6xico, bioeroders are also common but unfortunately few quantitative data exist on their abundances. Sufirez-Gonz~ilez (2001) found less than 1 ind It"~ in live Pocillopora spp. colonies at Punta Arenas, east of La Paz, Gulf of California (Fig. 2). Coralla of Porites panamensis near the mainland, and of P. lobata around oceanic islands, are frequently observed to have lost from 10% to 50% of their skeleton from erosion caused by Lithophaga spp. Notwithstanding, recruitment caused by breakage of colonies, considered common elsewhere (Guzl~n and Cort6s 1993; Cort6s 1997), is not as prevalent in Mexican reefs. At Cabo Pulmo, less than 5% of the P. panamensis or Pavona gigantea colonies are produced by fragmentation, whereas Pocillopora spp. generate between 30% to 40% of their recruits this way (Reyes-Bonilla 1993b; Reyes-Bonilla and Calder6n-Aguilera 1994).
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Other important bioeroders are sea urchins. Populations of some species (especially of Diadema mexicanum Agassiz, 1863) are large in the Revillagigedo Islands and Oaxaca (Reyes-Bonilla 1995; Glynn and Leyte-Morales 1997; Rosales-Estrada and ReyesBonilla in press). There are no estimates of Diadema effects on Mexican reef frameworks, but considering its density can exceed 70 ind m z, it is possible that the species generates important amounts of carbonate sediment. However, as the coral is still actively growing, accretion must be similar or larger than erosion, resulting in a balance or a net positive development of the reefs (Rosales-Estrada and Reyes-Bonilla in press). 4.3. Hurricanes The west coast of M6xico is influenced by tropical storms and hurricanes from May to November (Ketchum and Reyes-Bonilla 1997). Of all reef areas, the Revillagigedo Islands are by far the most affected, since they annualy receive an average of 3 hurricanes; the main coral communities in Oaxaca, Nayarit and the Gulf of California are impacted less than once each year (Ketchum in prep.). There are scant published data on the direct effects that a tropical storm or hurricane has on a coral community of this region. Glynn et al. (1998) noticed that even after three storms passed over coral reefs at Huatulco, Oaxaca in 1997 (Fig. 2), the community resisted well and damage was patchy. In contrast, Gonzfilez-Pelfiez et al. (in prep.) observed that after the passage of hurricane "Isis" over a small patch reef in the Gulf of California (24~ in August 1998, practically all colonies from zero to -2 m depth were tipped from the rocks or had their branches broken, and coral cover diminished about 50%. However, in deeper areas, damage was minimal. Mortality of associated species (mostly crabs, gastropods and sea urchins) was very high. On a larger scale, there is only one study, conducted in the southern Gulf of California, that has related coral community structure to hurricanes (Beltrfin-Ramirez 1999). Results indicated that in places where mean hurricane incidence from 1955 to 1996 was zero or more than one event per year (very low or high, respectively), current species richness and diversity are low. On the other hand, when average intensity was about 0.5 to 0.6 hurricanes yr t, both community indices reach their highest values, an observation that supports the intermediate disturbance hypothesis (Rogers 1993). 4.4. El Nifio Southern Oscillation (ENSO) The damage caused by the 1982-83 ENSO on eastern Pacific coral reefs is well known (Glynn 1990; Cort6s 1997). Recovery in Central America has been slow if at all, but in many cases reefs have been significantly eroded (Glynn, 1997a). The actual effects of this event on Mexican reefs are unknown. Reyes-Bonilla and Calder6n-Aguilera (1994) indicated that the cohort of Porites panamensis born at Cabo Pulmo in 1982-83 was much lower that that of the previous and following year, although in contrast, the population of Pavona gigantea from the same locality did not show the same pattern (Reyes-Bonilla 1993b). Carriquiry and Reyes-Bonilla (1997) and Reyes-Bonilla (2001) found that thermal anomalies near Nayarit and Gulf of California reefs exceeded 1.S~ C in less than 10% of all months during the 1957-58, 1972-73 and 1982-83 ENSO's, and that their effects on the corals were probably minimal. For the 1987-88 E1 Nifio, Reyes-Bonilla (1993d) reported bleaching and total mortality of 10% of the Pocillopora spp. population at Pulmo reef, probably caused by temperatures of 29~ or more from August to November. Wilson (1990) and Williams and Bunkley-
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Williams (1990) mentioned another coral mortality at Pulmo and Los Cabos region (23~ Fig. 2) in winter-spring, 1988. This time, the presence of a strong negative anomaly in sea surface temperature near the entrance of the Gulf of California (indicated by the COADS data) and related to the Anti-E1 Nifio (sensu Glynn 1990) seems to have been the cause of mortality. Notwithstanding, total coral cover at Cabo Pulmo never went below 30% in those years. This information apparently suggests that ENSO events are not so important in determining coral abundances and community structure in the Mexican Pacific reefs. The most recent E1 Nifio (1997-98), maybe the strongest in this century, proved that wrong. In the west coast of the country, surface temperatures exceeded 29~ from July to October, and reached 32~ in August. The first bleaching appeared in July in the southern Gulf of California and Nayarit, affecting all coral species at depths from zero to -30 m, but especially in areas shallower than 5 m. By August, damage extended to 25~ in the Gulf and to the Revillagigedo and Marias islands, away from the mainland. September and October marked the peak in the number of bleaching events, intensity (from 30% of total colonies in the Gulf to 80% in Nayarit) and geographic range (26~ N to 18~ also the first major coral mortalities, which were also reflected in changes in distribution and abundance of reef associated invertebrates (Sufirez-Gonz~dez et al. 2001). Coral recovery started in the last months of 1997; the temperature anomaly was still high but surface temperatures were already lower than 28~ Surveys of the same areas in 1998 and 1999 showed that the reefs suffered different degrees of damage: in Oaxaca, changes were minimum in early 1998, but afterwards mortality exceeded 60%. It has been suggested that strong upwelling in the Gulf of Tehuantepec that year, lowered sea temperature so much as to be the cause of mortality (Reyes-Bonilla et al. in prep.); in the Revillagigedo Islands and the Gulf of California, mortality did not exceeded 20% of coral populations, but in Nayarit the impact was dramatic. More than 60% of total coral cover died and all species were affected. Large pocilloporid frameworks were covered with coralline and filamentous algae, and in the process of being invaded by Diadema. It is still unclear how these ENSO-induced changes will develop in subsequent years. For example, in the Gulf of California, coral recruitment over dead colonies was apparent in the spring and the summer of 1998, but sea urchins were already eroding damaged areas. Interestingly, they are not Diadema mexicanum but Tripneustes depressus Agassiz, 1863, the dominant species in the southern Gulf. Whatever the cause, it can be concluded that E1 Nifio events are not as catastrophic on reefs of the west coast of M6xico as elsewhere in the eastern Pacific. It is reasonable to surmise that Mexican reefs receive some protection against excessive temperature elevations by the cooling effects of hurricanes in summer and autunma, and by upwelling or mixing in areas like the Gulf of Tehuantepec, Banderas Bay and the mouth of the Gulf of California (Reyes-Bonilla 2001). 5. ANTHROPOGENIC PERTURBATIONS The corals of the west coast of M6xico have been hardly affected by human activities because only a few cities and towns were developed before the 1980's (Reyes-Bonilla 1993a). However, human use of reefs has greatly increased in the last decade, especially
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after highways, large resorts and other tourist-oriented infrastructure were built in Oaxaca and the Gulf of California. 5.1. Fisheries In reef areas along the Pacific coast of Mrxico, multispecific artisanal fisheries have been the traditional way to exploit resources. They have focused on fishes (families Serranidae, Lutjanidae and Balistidae), mollusks (bivalves as Pinctada or gastropods like Murex and Strombus) and crustaceans (Panulirus lobsters) (Fisher et al. 1995). No pu-blished data exist on the amounts extracted, but fishermen affin~ that Oaxaca and Nayarit reefs are overfished, and that they now rather capture species from rocky areas, or sharks in open waters. Recently, the harvest of tropical echinoderms (sea urchins like Diadema and the holothurian Isostichopus fuscus (Ludwig, 1875)) have been increasing in Mrxico (Fajardo-Le6n et al. 1995; Espino-Barr et al. 1996; Conand 1997), but their populations do not seem to be abundant enough to support large scale, systematic fishing. Consequently, it is expected that in a few years, populations are likely to be significantly reduced, as it happened with Isostichopus in Mrxico and elsewhere (Conand 1997; Herrero-P&ezml et a/. 1999). A very different problem is caused by those who catch fishes or take coral heads to sell in aquariums and curio stores. This activity is prohibited in Mrxico without official permission. However, it was common in the last decade, particularly in the Gulf of California and the Revillagigedo Islands (Reyes-Bonilla 1993a). The authorities successfully solved this problem, at least in protected areas, and today these activities are rare, occurring mostly on isolated coral patches from 21~ to 18~ (Nayarit, Jalisco and Colima). Buyers of the products still exist, so illegal fishing will probably not stop in the near future. 5.2. Diving As in many other sites in the world, diving has become a potential and actual threat for coral communities of the Pacific coast of Mrxico. Official regulations for diving activities do not exist in the country, and it remains in the hands of dive masters or shops owners to determine how many people will dive in a given area. Fortunately, of all mexican Pacific reefs, only Cabo Pulmo, Huatulco (in Oaxaca; 15~ and Los Arcos, Jalisco (20~ Fig. 2) are heavily used by sport divers. With the exception of the first locality, it is still common to observe boats of all sizes (from 2 m inflatable boats to > 10 m yachts) anchored nearby or on coral heads, tearing up the bottom. Other problems are caused by inexperienced divers or snorkelers who break Pocillopora branches by kicking, grabbing or using them to move underwater or to submerge. A preliminary study of the divers that visit Pulmo reef indicated that more than 50% of them had done less than 10 dives, and that such persons touch corals much more frequently than skilled divers. This may be a common pattem in most coral communities of Mrxico. 5.3. Sedimentation The Mexican west coast receives abundant fluvial discharges, but the most important reefs are not located near rivers. So, natural sedimentation is not a problem. Unforttmately, deforestation caused by coastal development and bad management policies has seriously increased the amount of terrigenous material deposited on mainland reefs, in particular
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during the wet season (May to November). Data are anecdotal at best, but several reefs in the Gulf of California, Nayarit, Guerrero and Oaxaca seem to have been damaged during the construction of tourist facilities (Reyes-Bonilla 1993a, c). In the only documented case of induced sedimentation, Ochoa-L6pez et al. (1998) described how the feeding and trampling of vegetation by feral sheep caused excessive siltation and coral mortality in 1994 at Socorro Island (Revillagigedo Archipelago). As this mammal has lived in the island for the last century and its population is rising (Alvarez et al. 1994), it is possible that noticeable differences between the coral communities of the south and north of Socorro (the former dominated by massive, sediment resistant corals like Porites lobata, and the latter by Pocillopora spp.; Ketchum-Mejia 1998) may result from the sheep's activities. 6. MANAGEMENT AND CONSERVATION M6xico is known as a country interested in protecting its natural resources and biological communities, and it has also been successf~al in conserving many endemic and key species. However, marine taxa have received little official and public attention, especially those of the Pacific coast. For example, of the fishes and invertebrates officially protected, less than 10% occur in the Pacific and no stony or soft coral is listed (Anonymous 1994). Among marine protected areas in western M6xico, six have coral communities: the Gulf of California islands, the Revillagigedo Archipelago, Cabo Pulmo reef, the Los Cabos region, Los Arcos, and Huatulco. They differ in their conservation category (the first two are Biosphere Reserves and the others, federal or state Parks) and consequently, in the level of human use they receive; in M6xico, a Biosphere Reserve grants complete care of the habitat and species, while Marine Parks allow some level of use, previously determined in the management plan. Unfortunately, only at Huatulco is a management plan being implemented to date, and thus anthropogenic impacts are common, although limited, elsewhere. Research related to the proposal of Cabo Pulmo as a protected area began in 1987 and proceeded slowly. Nevertheless, in 1994 the work was finished and the following year the park decree was published (Reyes-Bonilla 1997). As the management plan is still not operational, several protection methods have been established in the area by the local residents and diving operators; among the most important are the complete prohibition of fishing on the reef (except for subsistence purposes), the installation of mooting buoys to avoid boat anchoring, and the rotation of diving areas to prevent overuse and damage to the portions of the reef most used by tourists. In the Revillagigedo islands, the only regulations are fishing prohibitions, and avoidance of the use of knives by tourists, encouraged by dive guides. Even though official response has been slow, organized conservation efforts have taken place in Los Arcos and Huatulco. There, local dive shops, fishermen, residents and researchers have instituted or proposed methods to protect coral communities, even though these procedures are not officially supported. They include the installation of mooring buoys for small vessels and boats, and restriction of use of knifes or gloves by divers (Glynn 1997a). However, while government agencies dedicated to conservation matters do not take an active role in this problem, local protection efforts will be useless, because of strong economic pressures to develop M6xico's coastal areas.
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ACKNOWLEDGMENTS
This review was greatly improved by the comments, suggestions and additions of Jorge Cortrs (Universidad de Costa Rica), Peter W. Glynn (University of Miami) and Hrctor GuzmAn (STRI, Panarrm). Also, Oscar Arizpe (UABCS), James Ketchum (CICIMAR, La Paz), Edgardo Ochoa (STRI-PanaroA), Michael S. Foster (Moss Landing Marine Laboratories), Andrrs L6pez (University of Iowa), Jos6 Carriquiry (UABC, Ensenada), Martha L6pez-Forment (UC-Berkeley), Eric Jor&in, Roberto Iglesias, Victor Hugo Beltrfin, Tito Livio-Prrez (ICMyL-UNAM, Puerto Morelos), Gerardo Leyte (UMar), Amilcar Cupul, Emesto L6pez (UdG, Puerto Vallarta and Guadalajara), Gabriela Cruz (ECOSUR, Chetumal), Alma Dora Morelos (CINVESTAV-Mrrida), and Gabriela Anaya (SEMARNAT, La Paz), read and criticized parts of the manuscript. Dinorah Herrero (CICIMAR) and countless students and friends have heard and discussed the ideas here presented in seminars and talks (formal and informal), and their questions and remarks were extremely valuable. Most of the mentioned persons and others, especially Carlos Cintra (University of Arizona), Zeida Foubert (UABCS), Sergio S. Gonzfilez (CIBNOR, La Paz), IrOn Su~rez (CICIMAR), Pedro Medina (UdG, Puerto Vallarta) and Juan Carlos Solis (UABCS) collaborated in the extensive field work done. The paper is dedicated to my father (d. 2001), to Dr. John W. Wells (d. 1994), and to the new generation of Mexican coral researchers, who are duty-bound to make our "new data" completely obsolete as soon as they can. REFERENCES
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Reyes-Bonilla, H. & J.P. Carricart-Ganivet. 2000. Porites arnaudi, a new species of stony coral (Anthozoa: Scleractinia: Poritidae) from oceanic islands of the eastern Pacific Ocean. Proc. Biol. Soc. Wash. 113: 561-571. Reyes-Bonilla, H. & G.E. Leyte-Morales. 1998. Corals and coral reefs of the Puerto Angel region, Oaxaca, Pacific coast of Mrxico. Rev. Biol. Trop. 46:679-681. Reyes-Bonilla, H. & A. L6pez-Prrez. 1998. Biogeography of scleractinian corals of the Pacific coast of Mrxico. Cienc. Mar. 24:211-224. Reyes-Bonilla, H., R. Riosmena-Rodriguez & M.S. Foster. 1997a. Hermatypic corals associated with rhodolith beds in the Gulf of California. Pac. Sci. 51: 328-337. Reyes-Bonilla, H., F. Sinsel-Duarte & O. Arizpe-Covarrubias. 1997b. Gorgonias y corales prtreos (Anthozoa: Gorgonacea y Scleractinia) de Cabo Pulmo, Mrxico. Rev. Biol. Trop. 45: 1439-1443. Reyes-Bonilla, H., T.L. Prrez-Vivar & J.T. Ketchum-Mejia. 1999. Distribuci6n geogrfifica y aspectos ecol6gicos de Porites lobata (Anthozoa: Scleractinia) en la costa occidental de Mrxico. Rev. Biol. Trop. 47: 273-279. Richards, A.F. 1966. Geology of the Islas Revillagigedo, Mexico. 2. Geology and petrography oflsla San Benedicto. Proc. Calif. Acad. Sci., 4 th ser. 33: 361-414. Robinson, J.A. & D.A. Thomson. 1992. Status of the Pulmo coral reefs in the lower Gulf of California. Environ. Conserv. 19: 261-264. Rogers, C.S. 1993. Hurricanes and coral reefs: the intermediate disturbance hypothesis revisited. Coral Reefs 12: 127-137. Rosales-Estrada, M. & H. Reyes-Bonilla. In press. Distribuci6n espacial de cuatro especies de erizos (Echinodermata: Echinoidea) en Isla Socorro, Archipirlago de Revillagigedo, Mrxico. Rev. Inv. Mar., Univ. Habana. Salcedo-Martinez, S., G. Green., A. Gamboa-Contreras & P. G6mez. 1988. Inventario de macroalgas y macroinvertebrados brnticos, presentes en areas rocosas de la regi6n de Zihuatanejo, Guerrero, Mrxico. An. Inst. Cienc. Mar Limnol., UNAM 15: 73-96. Spalding, M.D., C. Ravilious & E.P. Green. 2001. World Atlas of Coral Reefs. UNEPWCMC-University of California Press, Berkeley. 424 p. Squires, D.R. 1959. Corals and coral reefs in the Gulf of California. Bull. Amer. Mus. Nat. Hist. 118:370-431. Su/Lrez-Gonz/dez, I. 2001. Estructura de la comunidad de moluscos (Mollusca: Bivalvia y Gastropoda) asociados a cabezas de Pocillopora (Scleractinia) en Punta Arenas, Baja California Sur, Mrxico, durante 1997-1998. B.Sc. thesis, Universidad Autrnoma de Baja California Sur, La Paz. 72 p. Steinbeck, J. & E.F. Ricketts. 1941. Sea of Cortez. Viking Press, New York. 514 p. Trabulse, E. 1994. Historia de la ciencia en Mrxico. Fondo de Cultura Econ6mica /Consejo Nacional de Ciencia y Tecnologia, Mrxico. 542 p. Vaughan, T.W. 1917. The coral reef fauna of Carrizo Creek, Imperial County, California, and its significance. U.S. Geol. Surv. Prof. Pap. 98: 355-386. Veron, J.E.N. 1986. Corals of Australia and the Indo Pacific. Angus and Robertson, Sydney. 644 p. Veron, J.E.N. 1995. Corals in Space and Time. Comstock/Comell, Ithaca. 321 p. Veron, J.E.N. 2000. Corals of the World. Australian Institute of Marine Science, Townsville. Vols. 1-3.
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Verrill, A.E. 1864. List of the polyps and corals sent by the Museum of Comparative Zo61ogy to other institutions in exchange, with annotations. Bull. Mus. Comp. Zool., Harvard College. 1: 29-60. Verrill, A.E. 1868. Review of the corals and polyps of the west coast of America. Trans. Connecticut Acad. Arts Sci. 1: 377-558. VerriU, A.E. 1870a. On the geographical distribution of the polyps and corals of the west coast of America. Trans. Connecticut Acad. Arts Sci. 1: 559-567. Verrill, A.E. 1870b. Descriptions of echinoderms and corals from the Gulf of California. Amer. J. Sci. 49: 93-100. Villalobos, A. 1960. Notas acerca del aspecto hidrobiol6gico de la isla. In: J. Adem, E. Cobo, L. Bl~quez, A. Villalobos, E. Miranda, T. Herrera. B. Villa & L. V~isquez (eds.), La Isla Socorro, Archipi61ago de las Revillagigedo. Monog. Inst. Geofis., UNAM 2: 154-180. Wells, J.W. 1983. Annotated list of the scleractinian corals of the Gal~pagos Islands: 212-295. In: P.W. Glynn & G.M. Wellington, Corals and Coral Reefs of the Gal~pagos Islands. Univ. California Press, Berkeley. Wilson, E.C. 1990. Mass mortality of the reef coral Pocillopora on the south coast of Baja California Sur, M6xico. Bull. So. Calif. Acad. Sci. 89:39-41. Wilson, E.C. 1991. Geographic ranges of Recent hermatypic coral genera in Baja California Sur, M6xico. Bull. So. Calif. Acad. Sci. 90: 134-136. Williams, E.H. & L. Bunkley-Williams. 1990. The world-wide coral reef bleaching cycle and related sources of coral mortality. Atoll Res. Bull. 335:1-71.
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Corals and associated marine communities from El Salvador H r c t o r R e y e s - B o n i l l a a and Jos6 E n r i q u e B a r r a z a b *Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149-1098 USA bMinisterio de Medio Ambiente y Recursos Naturales, Direcci6n General de Patrimonio Natural, San Salvador, E1 Salvador
ABSTRACT: The segment of coast from Nicaragua to Guatemala, known as the "Pacific Central American Faunal Gap", has been scarcely studied but it is relevant from the biogeographic point of view. Apparently, this region lacks coral communities except at Los C6banos, a small rocky area in western E1 Salvador (13~ 89~ and in two other locations of that country (the Gulf of Fonseca and Maculis). We describe the general conditions of these assemblages (with special attention to Los C6banos) on basis of information from literature and underwater surveys conducted in October 2001. The Los C6banos area is extremely turbid (visibility less than 2 m), but nonetheless is inhabited by numerous marine species that aggregate on rocky substrata; among the most conspicuous ones are bivalve mollusks (e.g. Pinctada mazatlanica), sea urchins (Eucidaris thouarsii) and fishes (especially damselfishes; Stegastes spp.). We also found 9 species of stony corals (Anthozoa: Scleractinia) from 5 genus and 3 families, which added to those reported in the literature, yield a total of 15 species (10 zooxanthellate and 5 azooxanthellate) from 7 genus and 5 families, for the Pacific coast of E1 Salvador. Judging from field observations, the reef coral Pocillopora damicornis was dominant in shallow water at Los C6banos, while the dendrophylliid Cladopsammia eguchii was the most abundant in deeper areas (5 to 20 m). Human impacts on coral communities of E1 Salvador are multiple, and had occurred from many years. Among them, removal of carbonate rock and corals to produce cement, extraction of colonies to be sold as souvenirs, and damage to target populations by uncontrolled fisheries. In addition, deforestation has increased coastal sedimentation, and the runoff transported several types of pollutants to the coast and coral areas. Considering the high local species richness, and the fact that rocky and coral environments are very scarce in E1 Salvador, we recommend the Los C6banos area to be officially protected, in order to guarantee safeguard of its marine diversity.
1. I N T R O D U C T I O N C o r a l c o m m u n i t i e s a n d reefs o f the eastern tropical Pacific w e r e t a k e n as inexistent in all m o n o g r a p h s on r e e f corals p u b l i s h e d b e f o r e the 20 th Century, b u t r e s e a r c h cond u c t e d e s p e c i a l l y in the last 20 years c h a n g e d that idea ( C o r t r s 1997). Studies at P a n a nail, E c u a d o r , C o s t a Rica, M r x i c o and C o l o m b i a h a v e d i s c o v e r e d w e l l d e v e l o p e d reefs in those areas, and also d e m o n s t r a t e d that they are e x p o s e d to v e r y s e v e r e environLatin American Coral Reefs, Edited by Jorge Cortds 9 2003 Elsevier Science B.V. All rights reserved.
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mental conditions due, among other factors, to upwelling and the repeated occurrence of E1 Nifio Southern Oscillation, that caused severe coral bleaching and mortality in 1983 and 1997 (Glynn 1990; Glynn et al. 2001). Among the least known marine areas of the eastern Pacific is the coastal stretch between Guatemala and Nicaragua, labeled by Springer (1958) as the "Pacific Central American Faunal Gap". Current publications mentioned that there are practically no reefs or coral communities of consideration there (Spalding et al. 2001). Notwithstanding, the zone is in~ortant from the biogeographic point of view, since it separates the two main areas of coral occurrence in the region (Glynn and Ault 2000): the western coast of M6xico (including the Gulf of California and the Revillagigedo Islands), and Central and South America (from Costa Rica to Ecuador, and the Gal~ipagos Islands). The only place in the faunal gap where the literature refers to the presence of significant coral communities is the coast of E1 Salvador, a small country with a coastal margin of about 300 km (Cotsapas et al. 2000; Fig. 1). Information on marine communities of E1 Salvador is scarce, and was reviewed in Gierloff-Emden (1976), Orellana-Amador (1985) and Barraza (2000). These authors mentioned that the most important coral assemblages are located 11 km south-east of Acajutla, in a locality known as Los C6banos (Fig. 2), and that they are not true reefs, but only groups of isolated colonies growing on rocky substrata ("coral communities"). In E1 Salvador, the only scientific repository with marine taxa from Los C6banos is in the Museo de Historia Natural de E1 Salvador, and other material is deposited in the Escuela de Biologia, Universidad de E1 Salvador, but both of these are very small. Fortunately, the collections of the former institution were enriched recently (2001) with the incorporation of specimens collected in expeditions sponsored by the Smithsonian Tropical Research Institute. The objective of this paper is to describe the coral communities of E1 Salvador, but also aims to provide valuable information to be included in a future proposal for establishing the first marine protected area of E1 Salvador, at Los C6banos. 2. LOS COBANOS The rocky reefs of Los C6banos (Fig. 2) harbor the most well developed and diverse marine communities described to date in E1 Salvador. According to TRD (1989; cited by Foer 1992) and Barraza (in prep.), the reefs are actually small outcrops of volcanic rock (most of them not larger than 30 m2), that occupy a total of 159 km z of a large marine terrace that fringes the coast (8,000 ha in area). The patches of hard bottom occur from as the intertidal to 30 to 40 m deep, but in the intertidal and upper subtidal zone, volcanic rocks and sand with crumbled shells are the dominant elements (OrellanaAmador 1985). Marine communities are under continuous sedimentation stress at Los C6banos, which is more intense from May to October, during the rainy season. The particulate material comes from eight rivers located in the Acajutla area (GierloffEmden 1976), and is deposited at depths up to 35 rn. Salinity in the area fluctuates from 35 psu in the dry season, to 28 psu in September and October, months when rainfall is over 500 mm (Molina 1996). In October 2001, three locations in Los C6banos were inspected by SCUBA diving at depths of 5 to 25 m (La Zavaleta: 13~ 89~ Jaj/L: 13~ 89~ La Pichelera: 13~ 89~ Fig. 1). In addition, the adjacent beaches were surveyed in search of coral fragments, which were found in abun-
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dance at "Del Amor" beach (13~ 89~ The specimens were taxonomically determined following Cairns (1991), Cort6s and Guzmfin (1998), Veron (2000) and Ketchum and Reyes-Bonilla (2001) criteria. Voucher specimens (fragments of live coral colonies) were collected underwater, and other samples were gathered from the beach; all material was deposited at the Ministerio de Medio Ambiente y Recursos Naturales, E1 Salvador. Conditions for underwater observation were not good at the time of our visit, as visibility was less than 2 m and strong currents were present. However, this was not an unusual situation when diving in this site. 2.1. Corals
During our survey we found 9 coral species (5 zooxanthellate and 4 azooxanthellate; three of these are tentative identifications. Table 1). In relation to reef corals, no specimens were observed when diving but nevertheless, abundant fragments of colonies of Pocillopora were found stranded at "Del Amor" beach. According to local residents and literature (Orellana-Amador 1985; Gotuzzo 1996), there is a small coral community composed of corals of this genus, growing around large rocks and boulders placed about 200 m from the beach. The colonies are small (30 cm or less in height) and do not form a true framework. The fragments gathered in the beach were in good shape, and from them we could positively identify three species: P. capitata, P. meandrina and P. damicornis. The latter was also reported by Gotuzzo (1996, Fig. 13-22) from Los C6banos. Other coral pieces were similar to branches of P. elegans, and P. effusus (sensu Veron 2000) but they were eroded enough to prevent positive taxonomic deter minations. In shallower areas of the same location, colonies of Porites lobata were reported by Lemus et aL (1994) and Molina (1996), and illustrated by Gotuzzo (1996, Fig. 13-23), but specimens were not observed during the surveys or on the beach. Molina (1996, p. 19) presented an illustration of a coral identified as Porites lobata, but that actually appears to be P. panamensis. In addition, Hodgson (1995) indicated the presence of Pavona gigantea in E1 Salvador, a report taken as valid by Reyes-Bonilla (2002). Taking in consideration the literature reports and the conducted field work, reef coral species richness at Los C6banos may be eight (including two dubious records). In deeper water, turbidity was extreme at the time of our visit; visibility was no more than 2 m. Notwithstanding, we found large populations of the dendrophyllid azooxanthellate coral Cladopsammia eguchii. The record of this species is relevant because in the eastern Pacific, it has only been collected or reported in the Galfipagos Islands, Panamfi Bay, the southern Gulf of California (Cairns 1991, 1995; Reyes-Bonilla 2002) and Costa Rica (J. Cort6s per. com.). This was the most abundant scleractinian observed at Los C6banos; at any depth, practically all stones had many small colonies (from 3 to 8 cm in larger diameter) or individual corallites growing on their undersides. This species has no symbiont algae in its tissues, and apparently thrived in the turbid, dynamic conditions of the region, which may constantly provide colonies with abundant food. Another species of the Family Dendrophylliidae observed at Los C6banos was Tubastraea coccinea, pictured by Gotuzzo (1996, Figs. 13-24 and 13-26). This species appeared in the same habitat and depth that C. eguchii, however, its abundance was lower; colonies were found in less than half of the rocks surveyed. In addition, the size of T. coccinea colonies at Los C6banos was small. Usually, they can attain over 10 cm in larger diameter in eastern Pacific localities (Wells 1983; Cairns 1991; Reyes-Bonilla et al. 1997), but in E1 Salvador, the largest colony observed was about 7 cm in diameter. It was
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TABLE 1 Systematic list of scleractinian corals reported or found at E1 Salvador. (*) Species recorded in the field in 2001. (**) Report from literature; all references are presented in the text. (?) Taxonomic determination not confirmed. (+) Zooxanthellate species. (=) Azooxanthellate species. Phylum Cnidaria Hatschek, 1888 Class Anthozoa Ehrenberg, 1834 Order Scleractinia Bourne, 1900 Family Pocilloporidae Gray, 1842 Genus Pocillopora Lamarck, 1816 (+) P. capitata Verrill, 1864 (*) (+) P. damicornis (Linnaeus, 1758) (*) (+) P. effusus Veron, 2000 (*) (?) (+) P. elegans Dana, 1846 (*) (?) (+) P. meandrina Dana, 1846 (*) Family Poritidae Gray, 1842 Genus Porites Link, 1807 (+) P. lobata Dana, 1846 (**) (+) P. panamensis Verrill, 1866 (**) Family Agariciidae Gray, 1847 Genus Pavona Lamarck, 1801 (+) P. gigantea Verrill, 1869 (**) Family Rhizangiidae D'Orbigny, 1851 Genus Astrangia Milne Edwards and Haime, 1848 (=) Astrangia sp. (*) Genus Oulangia Milne Edwards and Haime, 1848 (=) O. bradleyi Verrill, 1866 (*, **) Family Dendrophylliidae Gray, 1847 Genus Cladopsammia Lacaze-Duthiers, 1897 (=) C. eguchii (Wells, 1982) (*) Genus Tubastraea Lesson, 1829 (=) T. coccinea Lesson, 1829 (*, **) (=) T.faulkneri Wells, 1982 (**) (?)
also interesting to notice that polyps of T. coccinea were extended during the day, a behavior that is common only at night. The color of the specimens of C. eguchii and T. coccinea was vermillion to orange, and yellow to orange, respectively, which corresponds to that described in the literature. Gotuzzo (1996) referred the presence of T. faulkneri at E1 Salvador, a report that has to be taken with caution because that species has only been found at the Gakipagos Islands (Wells 1983, Cairns 1991), and was not observed at Los C6banos during field work. Similarly, Gotuzzo (1996) cited BalanophylIia badiiana (sic; it may be an error of spelling of B. bairdiana) and Scolymia australis for the country, but shows no specimens or indicated where they are located. However, as none of those corals is reported for any other location of the eastern Pacific (Reyes-Bonilla 2002) and they exclusively live in the central and western Pacific (Cairns et al. 1999), it is quite possible that the material studied by the author was misidentified. Considering the morphology of B. bairdiana (corallum strongly compressed, with elliptical calices; Cairns and Parker 1992), Gotuzzo (1996) may have confused that species with C. eguchii, as both have the same general form (Cairns 1991, 1995), although they are very different in size (greater calicular diameter of B. bairdiana is 28 mm, while in C. eguchii is less than 10 rrma). Also, pictures of small individuals of S. australis resemble coralla of Oulangia bradleyi, a species that lives in the area (see be-
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low), and that may have caused confusion, but again, the calicular diameter of the former species is much larger than of the latter (Veron 2000). Two other corals have been recorded for Los C6banos, both belonging to the Family RhJzangiidae, but we were not able to get specimens. We found a solitary corallite of Oulangia bradleyi under a rock boulder at 20 m depth. According with the observations done with artificial light, the color of the polyp was dull brown and the primary and secondary septa (larger than the rest) were conspicuous. An illustration of the same species found at E1 Salvador (but not determined taxonomically) was published by Gotuzzo (1996, Fig. 13-25). The other coral of this family that we encountered was Astrangia sp. One small live colony was examined on the underside of a large volcanic rock at 10 m depth, and another eroded colony was located on the beach. There are eight species of this genus reported for the eastern Pacific (Reyes-BoniUa 2002) and taxonomic determination of most of them requires analysis of calicular structures, impossible to do in the field or with damaged material. Notwithstanding, the record at genus level is valid. Recapitulating the information that was presented, we propose that richness of scleractinian corals of E1 Salvador is 13 species (8 zooxanthellate; 5 azooxanthellate), although some of those reports have to be confirmed. 2.2. Invertebrates As mentioned in Section 2, outcrops of volcanic rock characterized the sea bottom at Los C6banos. At the time of our visit, the upper surface of those structures was completely covered by very f'me sediment, turf algae and abundant specimens of the colonial octocoral, Carijoa multiflora. Most of the soft coral species in the area occur deeper than 2 m; for example, the octocorallians Pacifigorgia adamsii, P. agassizii, Pacifigorgia sp. and Muricea sp. are common between 4 and 8 m deep (Lemus et al. 1994; Molina 1996). Moreover, in dredges done during the cruise conducted by the Smithsonian Institution in March 2001, colonies of the black coral Antipathes galapagensis were found at 25-meter depth in a station located in front of Los C6banos. In the undersurfaces of the large boulders that characterize the bottom of the site, animal diversity was noticeably high. We observed numerous sponges, stony and soft corals (including hydrozoans like Aglaophenia sp., anemones, and octocorals such as Lophogorgia sp. cf. alba), bryozoans, tube polychaetes and arrow crabs (Stenorhynchus sp.). In interstices and sediment-free areas between rocks we noticed larger invertebrates; especially abundant were bivalves (including commercial species such as Pinctada mazatlanica, Spondylus calcifer, and Nodipecten subnodosus), small fasciolarid gastropods, and sea urchins (Eucidaris thouarsii), and we also saw several juvenile lobsters (Panulirus gracilis). Guti6rrez (1996) reported that the macroalgae Briopsis, Halimeda, Codium, Caulerpa (chlorophytes), Sargassum, Padina (phaeophytes) and calcareous algae (rhodophytes) are common at Los C6banos, although as mentioned, turf algae were dominant on rocky substrata in 2001. 2.3. Fishes Fishes were not abundant, but we noticed the presence of several species that are typically associated to rocky and coral reefs throughout the eastern Pacific. Among them are the moray eel Gymnothorax castaneus, the squirrelfishes Myripristis leiognathos and Sargocentron suborbitalis, the scorpionfish Scorpaena sp., the basses Dermatolepis dermatolepis, Epinephelus labriformis, the wrasses Halichoeres notospilus, Thalassoma
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lucasanum, the snapper Lutjanus viridis, the grunt Haemulon sexfasciatum, the chub Kyphosus analogus, the angelfishes Pomacanthus zonipectus and Holacanthus passer, the butterflyfish Chaetodon humeralis, the darnselfishes Chromis atrilobata, Stegastes acapulcoensis, S. rectifraenum and .4budefduf troschelli, the surgeonfish Prionurus punctatus, the triggerfish Pseudobalistes naufragium, the blenny Ophioblennius steindachneri, and surprisingly, the golden puffer Arothron meleagris, a well known corallivore (Guzrrfin and Robertson 1989), as well as the Moorish idol Zanclus canescens, a typical species of coral reefs in the western Pacific (Allen and Robertson 1994). Five of these fish species (M. leiognathos, D. dermatolepis, L. viridis, H. passer and Z. canescens) are new records for the area, according to the list provided by OrellanaAmador (1985). 3. OTHER AREAS OF THE COUNTRY WITH PRESENCE OF CORALS Researchers have repeatedly visited the coast of E1 Salvador since 1999, and stony corals have been observed in localities other than Los C6banos, especially in the Gulf of Fonseca and Maculis (Fig. 1). The gulf is an area of high primary productivity, with a predominantly sandy coast, and is well known as a wetland area that includes RAMSAR sites and wildlife refuges (Spalding et al. 2001). Nevertheless, there are small rocky outcrops in the coast and also a number of islands with hard substrata available for coral colonization. The scleractinian assemblages recorded in those islands are composed of azooxanthellate species, and the dominant elements are colonies of Tubastraea and Astrangia, which mostly occur in the undersides of large boulders or in small caves at depths from 2 to 30 m. Soft corals (gorgonians in particular) are much more abundant in this area than at Los C6banos, and colonies of Carijoa multiflora also appear quite frequently in underwater surveys. Data on Maculis are scarce; water turbidity is high in the area, but Gotuzzo (1996) indicated the presence of unidentified stony corals there. Gorgonians are the dominant type of anthozoan in the area, especially Pacifigorgia spp. 4. ANTHROPOGENIC IMPACTS Coral communities of E1 Salvador are small, and consequently, very delicate. Notwithstanding, tourists commonly visit them, and the local resources are under exploitation by fishermen. These activities have to be adequately regulated, but the task is difficult to execute because there are no marine protected areas in the cotmtry and in consequence, any kind of management or conservation effort is difficult to accomplish. Fortunately, the government of E1 Salvador and a number of NGO's has shown interest in protecting the marine environment, and it is expected that the situation will change in coming years. Human impacts on E1 Salvador reefs are multiple, and had occurred for many years. In the 1950's, a company used intertidal calcareous rock from Los C6banos (including scleractinian corals) to produce cement, and although the impact was never assessed, Lemus et al. (1994) assumed that it was significant and depleted the shallow areas of reef corals. The main anthropogenic activities these days are fisheries, especially concentrated in fish and oyster populations. No clear regulation on catch existed, and again, no estimation of its effect at community level is available. However, a new fisheries law was promulgated in 2002 and this updated legislation imposes more strict
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regulations on fishing activities. The principal problem here is not the legal background, but the lack of personnel to conduct vigilance and assure implementation of the rules. The fishing activities have not only impacted the target species but also damaged corals because of the breakage of colonies by anchors, and the stranding of nets (Molina 1996). Finally, there are indications that at least in some degree, the excessive sedimentation at Los C6banos and nearby coastal areas is caused by bad management of forests and other near-coastal vegetation. The runoff also transports pollutants to the ocean, as evidenced by the presence of DDT-related chemicals, copper, polychlorinated biphenols (PCB's) and polynuclear aromatic hydrocarbons (PAH's) in oysters collected at Acajutla Port and Los C6banos (RPI 1995). The pollutants eventually reach the coral area by littoral transportation and tide cycles. In addition, contamination by solid wastes (especially garbage and plastics) and extraction of corals, gastropods and gorgonians to be sold as souvenirs to tourists are two problems that have not been addressed, and consequently their impact on reefs is undetermined. Molina (1996) suggested that from 30 to 40 colonies are collected daily at Los C6banos, and commercialized. 5. CONSERVATION ISSUES AND FUTURE STUDIES A recent review of the marine fauna of the coast of Mesoamerica (from central west M6xico to Panarnfi; Reyes-Bonilla 2001) indicates that assemblages in E1 Salvador are qualitatively very similar to those from Guatemala to Nicaragua, and that they are relatively rich for a country with so small a coastline. If we take into account this information and the fact that the visited reefs are unique habitats in E1 Salvador, it is easy to understand why we patently recommend that Los C6banos have to be officially protected, in order to safeguard its marine diversity. The formal proposal is currently in preparation, and will probably be ready in 2002. The creation of a marine park in this area will be a milestone in the history of environmental conservation in E1 Salvador, and also will represent another advance in the development of a network of marine protected areas in the tropical eastern Pacific, an initiative that is being discussed as complementary to the Mesoamerican Biological Corridor. There is still much work to be done in areas with presence of corals in E1 Salvador. For exmrqale, Reyes-Bonilla (2001) indicated that most species that have been reported south and north of any given country of the tropical eastern Pacific, conceivably have populations occupying areas in between. If this is the case, the presence of reef coral species such as Gardineroseris planulata, Leptoseris papyracea or Psammocora stellata in Costa Rica and southern M6xico (Reyes-Bonilla 2002) suggests that they actually live in E1 Salvador, although their populations must be small and geographically restricted to the scarce rocky outcrops of the country. To look for these isolated demes has to be a priority for research in forthcoming years. On the other hand, it would be stimulating to search for clues to explain the remarkable resilience of the coral assemblage of Los C6banos, that has not built a true reef but nevertheless it has been long lasting (at least during the last three decades) in an environment clearly not suitable for reef corals. Finally, coral bleaching and mortality caused by positive thermal anomalies of surface water resulting from E1 Nifio in 1982-83 and 1997-98, were observed practically in the entire eastern Pacific region (Glynn et al. 2001). It would be interesting to analyze size structure or growth anomalies of massive colonies, to evidence if corals from Los C6banos were also affected by those events.
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ACKNOWLEDGMENTS
The visit of HRB to E1 Salvador and Los C6banos was financed by the Organizing Committee of the V Congreso de la Sociedad Mesoamericana para la Biologia y la Conservaci6n, and the Ministerio de Medio Ambiente y Recursos Naturales de E1 Salvador. Alex Hasbfin (El Salvador Divers) provided diving and logistic support in the study area. Peter W. Glynn (University of Miami) and Jorge Cort6s (Universidad de Costa Rica) reviewed the manuscript. Wilfredo Fuentes (MARN) collaborated in preparing the figures. REFERENCES Allen, G.R. & D.R. Robertson. 1994. Fishes of the Tropical Eastem Pacific. Univ. Hawaii Press, Honolulu. 332 p. Barraza, J.E. 2000. Comentarios sobre la diversidad de macroinvertebrados marinos de E1 Salvador. Publicaci6n Ocasional No. 2. Ministerio de Medio Ambiente y Recursos Naturales, San Salvador. 15 p. Cairns, S.D. 1991. A revision of the ahermatypic Scleractinia of the Gal~ipagos and Cocos islands. Smiths. Contrib. Zool. 504: 1-32. Cairns, S.D. 1995. The marine fauna of New Zealand: Scleractinia (Cnidaria: Anthozoa). New Zealand Ocean. Inst. Mem. 103:1-210. Cairns, S.D. & S.A. Parker. 1992. Review of the Recent Scleracfinia (stony corals) of south Australia, Victoria and Tasmania. Rec. S. Austral. Mus. Monog. Ser. 3: 1-82. Cairns, S.D., B.W. Hoeksema & J. van der Land. 1999. List of extant stony corals. Atoll Res. Bull. 459: 13-46. Cort6s, J. 1997. Biology and geology of eastern Pacific coral reefs. Coral Reefs 16 Suppl.: $39-$46. Cort6s, J. & H.M. Guzrr~n. 1998. Organismos de los arrecifes coralinos de Costa Rica: descripci6n, distribuci6n geogr~fica e historia natural de los corales zooxantelados (Anthozoa: Scleractinia) del Pacifico. Rev. Biol. Trop. 46: 55-92. Cotsapas, L., S.A. Zengel & J.E. Barraza. 2000. E1 Salvador: 106-137. In: C.R.C. Sheppard (ed.), Seas at The Millennium: An Environmental Evaluation. Pergamon, London. Foer, G. 1992. Diagn6stico de los recursos costeros de E1 Salvador: 106-137. In: G. Foer & S. Olson (eds.), Las Costas de Centroam6rica: Diagn6sticos y Agenda para la Acci6n. US-AID, Narragansett, Rhode Island. Gierloff-Emden, H.G. 1976. La costa de E1 Salvador. Ministerio de Educaci6n. Direcci6n de Publicaciones, San Salvador. 286 p. Glynn, P.W. 1990. Coral mortality and disturbances to coral reefs in the tropical eastern Pacific: 55-126. In: P.W. Glynn (ed.), Global Ecological Consequences of the 198283 E1Nifio-Southem Oscillation. Elsevier, Amsterdam. Glynn, P.W. & J.S. Ault. 2000. A biogeographic analysis and review of the far eastern Pacific coral reef region. Coral Reefs 19: 1-23. Glynn, P.W., J.L. Mat6, A.C. Baker & M.O. Calder6n. 2001. Coral bleaching and mortality in Panama and Ecuador during the 1997-1998 El Nifio-Southem Oscillation event: spatial/temporal patterns and comparisons with the 1982-1983 event. Bull. Mar. Sci. 69: 79-109.
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Gotuzzo, R. 1996. Celenterados: 51-64. In: F. Serrano (ed.), Historia Natural y Ecologia de E1 Salvador. Tomo II. Ministerio de Educaci6n, San Salvador, E1 Salvador. Guti6rrez, L.A. 1996. Algas. 13-22. In: F. Serrano (ed.), Historia Natural y Ecologia de E1 Salvador. Tomo II. Ministerio de Educaci6n, San Salvador, E1 Salvador. Guzrn~n, H.M. & D.R. Robertson. 1989. Population and feeding responses of the corallivorous pufferfish Arothron meleagris to coral mortality in the eastem Pacific. Mar. Ecol. Prog. Ser. 55: 121-131. Hodgson, G. 1995. Corales p6treos masivos (Tipo Cnidaria, Orden Scleractinia): 83-97. In: W. Fisher, F. Krupp, W. Schneider, C. Sommer, K.E. Carpenter and V.H. Niem (eds.), Guia FAO para la identificaci6n de especies para los fines de la pesca. Vol. I. Algas e invertebrados. FAO, Roma. Ketchum, J.T. & H. Reyes-Bonilla. 2001. Taxonomia y distribuci6n de los corales hermatipicos (Scleractinia) del Archipi61ago de Revillagigedo, M6xico. Rev. Biol. Trop. 49: 727-773. Lemus, L.G., J.A. Pocasangre & T.D. Zelaya. 1994. Evaluaci6n del estado actual de la distribuci6n y cobertura de los arrecifes coralinos de la zona de Los C6banos, Departamento de Sonsonate. B.Sc. thesis. Escuela de Biologia, Facultad de Ciencias Naturales y Matem~tica, Universidad de E1 Salvador, San Salvador. 40 p. Molina, O. A. 1996. Comparaci6n de la cobertura de los arrecifes coralinos antes y despu6s del derrame de petr61eo. Los C6banos, Sonsonate. 1993-1995. Intemal Report, Escuela de Biologia, Univ. E1 Salvador, San Salvador. 36 p. Orellana-Amador, J.J. 1985. Especies marinas de Los C6banos. Peces de E1 Salvador. Mandarin Offset International LTD, Hong Kong. 126 p. Research Planning, Inc. (RPI). 1995. Diagn6stico ambiental en el medio costero marino de la zona de Acajutla, San Salvador, E1 Salvador. RPI, San Salvador. 75 p. Reyes-Bonilla, H. 2001. La costa occidental de Mesoam6rica: Luna unidad biogeogrfifica marina? Res. V Cong. Soc. Mesoam. Biol. Conserv., San Salvador, E1 Salvador: 104-105. Reyes-Bonilla, H. 2002. Checklist of valid names and synonyms of stony corals (Anthozoa: Scleractinia) of the eastern Pacific Ocean. J. Nat. Hist. 39: 1-13. Reyes-Bonilla, H., T.L. P6rez Vivar & J. Ketchum Mejia. 1997. Nuevos registros del coral ahermatipico Tubastraea coccinea Lesson, 1829 (Scleractinia: Dendrophylliidae) en el Pacifico de M6xico. Rev. Inv. Cient. UABCS, Ser. Cienc. Mar 8: 31-34. Spalding, M.D., C. Ravilious & E.P. Green. 2001. World Atlas of Coral Reefs. UNEP/ WCMC and Univ. California Press, Berkeley. 424 p. Springer, V.G. 1958. Systematics and zoogeography of the clinid fishes of the subtribe Labrisomini Hubbs. Pub. Inst. Mar. Sci. Univ. Texas 5:417-492. Veron, J.E.N. 2000. Corals of the World. Volumes 1-3. Australian Institute of Marine Science, Townsville. Wells, J.W. 1983. Annotated list of the scleractinian corals of the Gal~ipagos: 213-292. In: P.W. Glynn & G.M. Wellington, Corals and Coral Reefs of the Galfipagos Islands. Univ. California Press, Berkeley.
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Corals and coral reefs of the Pacific of Costa Rica: history, research and status Jorge Cort6s a and Carlos Jim6nez a' b aCentro de Investigaci6n en Ciencias del Mar y Limnologia (CIMAR), and Escuela de Biologia, Universidad de Costa Rica, San Pedro, San Jos6 2060, Costa Rica. bZentrum for Marine Tropen6kologie, Universit~itBremen, Fahrenheitstr. 6, D-28359 Bremen, Deutschland.
ABSTRACT: Coral communities, reefs, and isolated coral colonies can be found along the Pacific coast of Costa Rica and offshore islands. In this chapter a brief history of research, and descriptions of the coral communities and reefs of the Pacific coast of Costa Rica are presented. On the north, the reefs are exposed to seasonal upwelling but they are well-developed and the growth rates of several species are higher than in non-upwelling areas. On the south, some reefs have been growing for over 5,000 years, resulting in thick accumulations. There are also reefs at Isla del Coco, 500 km from the coast. Species that are absent or rare in other eastern Pacific sites are found in Costa Rica, e.g. Porites rus and Leptoseris papyracea. The main impact on Pacific reefs has been bleaching and death of corals associated with E1 Nifio warming events. Other reefs exposed to high sediment loads are greatly degraded. Most coral reefs and coral communities of the Pacific coast of Costa Rica are located within protected areas. 1. I N T R O D U C T I O N
1.1 The Pacific coast of Costa Rica The Pacific coast o f Costa Rica is 1,160 km long. It has a high diversity of habitats: rocky shores o f a wide variety of rock types, sandy beaches of several compositions and grain sizes, mangrove forests, estuaries, a tropical fjord, islands o f various sizes, and several gulfs and bays (Fig. 1). The northern section of the coast is characterized by a dry tropical forest, with a dry season that extends from December to April, and a rainy season from M a y to November. The southern end of the coast is covered with tropical rain forest. Here it rains year-round, with a low between December and April. The central section of the coast is a transitional area from dry to humid climate (Herrera 1986). Tides are semi-diurnal, with a range of about 3 m. The Costa Rican Current runs from the southeast to the northwest, paralleling the coastline. Closer to shore eddies m o v e in the opposite direction. The northern section of the coast experiences upwelling of cool, nutrient-rich waters during the dry season, when the NE Trade Winds cross the lowlands from the Caribbean to the Pacific (Legeckis 1988; McCreary et al. 1989). The Latin American Coral Reefs, Edited by Jorge Cort6s 9 2003 Elsevier Science B.V. All rights reserved.
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Fig. 1. Map of the Pacific coast of Costa Rica with the divisions used in this chapter (see below).
high mountains of the central and especially the southern parts of the country block the Trades, preventing coastal upwelling in the area. The absence of upwelling has resulted in the continuous development of coral reefs in the south. Coral communities, reefs and isolated coral colonies can be found on the Pacific coast of Costa Rica, which we have divided into seven regions (Fig. 1): 1. Santa Elena, the northern section of the coast next to the border with Nicaragua; 2. Bahia Culebra, to the south of Santa Elena and north of Peninsula de Nicoya; 3. Peninsula de Nicoya, including mainly the seaward side of the peninsula, since the inner section is an estuarine environment with very little coral growth; 4. Pacifico Central, extending from the east end of Golfo de Nicoya to the largest mangrove area of Costa Rica, the SierpeT6rraba complex; 5. Peninsula de Osa, including the outer section of the peninsula and part of the entrance to Golfo Dulce; 6. Golfo Dulce, including the reefs within the gulf; and 7. Offshore islands, including Isla del Carlo (15 km from the coast) and Isla del Coco (more than 500 km from the coast). In this chapter, we describe the coral communities and reefs of the Pacific coast of Costa Rica. Information concerning natural and anthropogenic impacts is also provided, as well as comments on protection and management.
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1.2. History of research Marine organisms from Costa Rican waters were first described in the early 19th century (Sowerby 1832). By mid-century, several works were published on mollusks (M6rch 1859, 1860) and octocorals (Verrill 1869/70). Those collections were made by ship captains or traveling naturalists. In the late 19th and early to mid 20th century, several expeditions sampled along the Pacific coast of Costa Rica, visiting some of the coral reef areas, incluiding also Isla del Coco: the U.S. Fisheries Commission Expedition lead by Alexander Agassiz in 1891; the Hopkins-Stanford Expedition of 1898-1899; the California Academy of Sciences expeditions of 1921 and 1928; the Arcturus Oceanographic Expedition of 1925 headed by William Beebe; the 1932 Templeton-Crocker Expedition; the expeditions to the eastern Pacific of the New York Zoological Society in 1937 and 1938; F. D. Roosevelt's Presidential Cruise of 1938; the Allan Hancock Foundation's Expeditions to the eastern Pacific between 1931 and 1954; the 1968 Stanford Oceanographic expedition; and finally the Searcher expedition of 1972. As a result of the Allan Hancock expeditions, J.W. Durham published a series of papers on the scleractinian corals of the region, including specimens from Costa Rica, mostly from Isla del Coco (Durham and Bamard 1952; Durham 1962, 1966). In the following years, individual scientists studied the coral reefs in Costa Rica. Dawson (1960) described several species of algae from the reefs at Isla del Carlo. Bakus (1975) published a description of a reef from Isla del Coco. In the mid 1970s, Peter W. Glynn studied the coral communities and reefs of the Pacific coast of Costa Rica and published the first synoptic map of coral communities, and live and dead coral reefs along Costa Rican Pacific shores (Glynn et al. 1983). By the late 1970s, studies of the coral reefs of Costa Rica by Costa Rican scientists were initiated. The first comprehensive study of the Pacific coral reefs was published by Cort6s and Murillo (1985). Other papers followed in which reefs of different areas were described in more detail: Isla del Carlo (Guzrn~n 1986; Guzn~n and Cort6s 1989a, 2001), Golfo Dulce (Cort6s 1990a, b), Isla del Coco (Guz-rr~n and Cort6s 1992), the southern section of the coast (Cort6s and Jim6nez 1996), and the northern section of the coast (Cort6s 1996/1997a). Areas being studied in detail at the present time include: Bahia Culebra (Jim6nez 1997, 1998, 2001; Jim6nez et al. 2001) and the Archipi61ago de las Islas Murci61ago (Jim6nez and Cort6s in prep.). Several papers concerning the ecology and/or taxonomy of organisms associated with reef formations have been published: corallivores (Guzm~ 1988a, b), meiofauna (Guzmfin et al. 1987), zooplankton (Guzm~ and Obando 1988; GuzroAn et al. 1988), and bioeroders (Scott and Risk 1988; Cort6s 1991; Fonseca and Cort6s 1998). Two papers were published on sediments adjacent to reefs (Cort6s et aL 1996; Hebbeln et al. 1996), and two papers on the Holocene growth history of reefs in Golfo Dulce, Isla del Carlo, and Isla del Coco (Macintyre et al. 1992; Cort6s et al. 1994). Four papers have been published on the stable isotopic signature of E1 Nifio-Southem Oscillation (ENSO) events in Porites lobata from Isla del Carlo (Carriquiry et al. 1988, 1994; Carriquiry 1994; Wellington and Dunbar 1995). The ~SiSOsignal at Isla del Carlo records strong to very strong ENSOs (Wellington and Dunbar 1995). Also, stable isotope analyses were used to compare the conditions in Golfo Dulce about 1,000 years ago with conditions today (Cort6s 1990a). The gulf today has a much higher freshwater discharge which has altered reef growth compared to previous conditions, when the isotopic signal was similar to today's corals from Isla del Carlo (Cort6s 1990a).
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Fig. 2. Protected areas of Costa Rica includingtheir marine territory. Six theses have been written on Costa Rican Pacific coral reefs: reef structure at Isla del Carlo (GuzroAn 1986), Holocene growth history of a reef in Golfo Dulce (Cort6s 1990a), coral communities and reefs of Bahia Culebra (Jim6nez 1998), reef fishes of Bahia Culebra (Dominici 1999, Alperman 2001) and bioerosion at Golfo Dulce and Isla del Carlo (Fonseca 1999). Work in progress include: environmental and coral reef monitoring, biodiversity of invertebrates, environmental education, paleoclimate reconstructions, and coral population dynamics. 2. DESCRIPTION OF THE REEF AREAS 2.1. Santa Elena Communities and coral reefs to the north and south of Peninsula de Santa Elena (mostly within the Area de Conservaci6n Guanacaste, Figs. 1, 2, 3) have been described by Cort6s (1996/1997a). Ten species of reef-building corals (Cort6s 1996/1997a, b; Cort6s and Guzmfin 1998; Jim6nez and Cort6s, in prep.) and three species of ahermatypic corals (Cort6s in prep.) were reported for the northern section of the coast. Corals norreally found in low densities in other parts of the eastern Pacific formed small patch reefs there. A reef constructed by Pavona gigantea was found northeast of Santa Elena, and one 50 m Ereef formed exclusively by Pocillopora eydouxi was located off the central northern section of the peninsula. Porites panamensis, which is rare in the southem part
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Fig. 3. Coralreefs and reef communitiesof the Santa Elena section. of Costa Rica, was found in abundance in the Santa Elena region, while its congener, P. lobata, had the opposite distribution; it was rare in the north and predominant in the south section of the coast of Costa Rica. Gardineroseris planulata and Pavona gigantea are minor components of reefs in the south, but major reef builders in the north. Coral communities formed by various species assemblages were found at the Archipi61ago de las Islas Murci61ago, on the south side of Peninsula de Santa Elena (Fig. 3). One reef extending over 2,000 m 2, and from 2 to 12 m in depth, is constructed mainly by Pocillopora damicornis and Pocillopora elegans. Other species present are Pocillopora eydouxi, P. meandrina, Pavona clavus, P. varians and a new species, Pocillopora inflata (Glynn 1999). This reef grows on the north side of Isla San Pedrito, one of the Islas Murci61ago (Fig. 3), and is thus protected from the full impact of the seasonal upwelling in the region, and from strong wave action. Live coral coverage ranged from 47.5 to 95.2%.
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Fig. 4. Coral reefs and reef communities Bahia Culebra. Pocillopora damicornis predominate in the shallow section, while Psammocora stellata predominate in the deeper sections. Patch reefs from a few meters to several hundred square meters of other species have been found in several protected bays of the Islas Murci61ago. These include reefs of Pavona clavus and of Gardineroseris planulata. Some of those G. planulata colonies are the largest found to date in the country for that species, 1.2 m high by 1.5 m in diameter. Rocky substrates are covered by dense stands of octocorals and barnacles down to 15 - 20 m; below 20 m, black corals over 1 rn high predominate. Other species present, in order of abundance, included Pavona gigantea, Tubastrea coccinea, and Carijoa sp.; Porites lobata is rarely observed. Leptoseris scabra, a rare species in the eastern Pacific except at Clipperton Atoll (Glynn et al. 1996a), was found in the deep environments (Jim6nez y Cort6s in prep.). 2.2. Bahia Culebra The section of the coast including Bahia Culebra extends from the southem end of the previous section, i.e. from the border of the Area de Conservaci6n Guanacaste to Punta Gorda, where the next section begins (Figs. 1, 4). The coral reefs and communities of Bahia Culebra were briefly described by Glynn et al. (1983), Cort6s and Murillo
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(1985), and in more detail by Jimrnez (1997, 1998, 2001). The reef fish community structure of Bahia Culebra was described by Dominici (1999), with emphasis on four important aquarium (commercial) species. 2.2.1. Corals. Sixteen species of reef-building scleractinian corals (Cortrs and Guzmfin 1998), including rare species such as Pocillopora meandrina, Leptoseris papyracea and Fungia (Cycloseris) curvata, and four species of ahermatypic corals (Cortrs in prep.) are present in this region. Pocillopora meandrina was not a common species in the eastern Pacific, but it was found in abundance in Bahia Culebra in the early 1980's. However, it is now a rare species due to overexploitation for commercial purposes (Cortrs and Murillo 1985). Recently, Jimrnez (1998) examined the growth rates of seven species of corals. For three species that have been studied elsewhere in the eastern Pacific, coral growth at Bahia Culebra is the highest (Table 1). These high rates in what appears to be a marginal area of reef development (due to the upweUing) may be the result of heterotrophic feeding by the corals and less dependance on the zooxanthellae (work in progress). TABLE 1 Growth rates (mm/year) of coral species from Bahia Culebra, data from Jimrnez (1998 and unpublished data), compared to means and extreme values reported from other regions in the eastern Pacific, data from Guzm~inand Cortrs (1989b, 1992). Species
Bahia Culebra Mean Range
Eastern Pacific Mean Extreme values
Pavona clavus Pocillopora damicornis Pocillopora elegans Pocillopora eydouxi Pocillopora inflata Pocillopora meandrina Psammocora stellata
20.6 47.8 44.5 30.8 31.5 38.5 13.9
13.2 5.4- 17.4 38.6 17.3 -43.7 34.8 19.3 - 38.6 No data available No data available No data available No data available
8.5 - 28.0 28.0 - 75.6 29.0 - 67.2 21.0- 39.0 20.0 - 44.0 18.0- 56.0 6.0 - 21.6
2.2.2. Coral communities and reefs. Bahia Culebra is characterized by rare and unique coral communities and reefs. One of the coral reefs consisted almost exclusively of large colonies of Pavona clavus; with one colony 10 m in diameter, growing laterally by shedding blocks to the sides (Jimrnez 1998; Jimrnez and Cortrs in prep.). Another build-up is constructed by Leptoseris papyracea, but was severely reduced by the 1997-98 E1 Ni_~o warming event (Jimrnez et al. 2001). The mushroom coral, Fungia (Cycloseris)curvata, has only been found alive on this reef. Dead coral reefs in the area, due to the intensification ofupwelling during the Little Ice Age, were studied and described by Glynn et al. (1983). Bahia Culebra has nine live coral reefs, ranging in size from 0.8 to 2.3 hectares. Pocilloporid corals are the main reef builders in shallow waters (<10 m depth), while Pavona clavus, Psammocora spp. and Leptoseris papyracea dominate at greater depths (_>13 m). Coral thermal tolerance and exposure to cool upwelling waters during the dry season may play a role in structuring the species dominance observed in the bay (Jimrnez 2001). Three rhodolith beds with abundant P. damicornis colonies occur in the inner littoral of the bay.
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Live coral cover is high (average 44.0 + 3.3%, n = 52) among reefs of the bay, followed by coral communities on sand (21.5 + 2.3%, n = 156) and basalt (19.5 _+ 1.1%, n = 48). On the reefs, branching (mainly Pocillopora damicornis) and massive (mainly Pavona clavus) corals accounted for 42% and 30% of live cover, respectively. Other important contributors were Leptoseris papyracea (12%) and Psammocora spp. (16%). For coral communities on sand substrates, the major contributors were branching species (mostly Pocillopora elegans, 68%) followed by massive corals (Pavona clavus, 29%). Branching species (mainly P. elegans) accounted for more than 80% of coral cover, while massive corals (Pavona gigantea) contributed only 19% of the surface of coral communities on basalt substrate. The octocoral Carijoa sp. was the most abundant community member (more than 40%) inhabiting deep waters (>20 m depth). From Bahia Culebra south to Punta Gorda, many submerged or exposed banks were found; e.g., Bajo Tiburones (Fig. 5). These are popular diving sites, and the cnidarians present in decreasing order of abundance were: Pavona clavus, Pavona gigantea, Tubastrea coccinea, Carijoa sp., Pavona varians, Pocillopora elegans, Porites lobata, and Porites panamensis. These coral communities are abundant down to 20 m; in deeper waters, there are more octocorals and some black corals. The small coves in this area had patch reefs from a few square meters to several hectares (particularly in Matapalo, Fig. 5), growing on dead reefs. Abundant corals included, in decreasing order, Pocillopora
elegans, Pocillopora damicornis, Pocillopora meandrina, Pavona clavus, Pavona gigantea, Porites panamensis, and Pavona varians. In addition, a recent study found seventy five species of reef fishes in the Bahia Culebra area. The most abundant species included Chromis atrilobata, Thalassoma lucasanum, Abudefduf troschelii and Halichoeres dispilus. Shallow and deep-water fish communities differed in species composition (Dominici 1999).
2.3. Peninsula de Nieoya From south of Bahia Culebra (Punta Gorda) to the entrance of the largest estuary in Costa Rica, is the Peninsula de Nicoya (Figs. 1, 5). This large section of the coast contains coral communities and a few small coral reefs (Glynn et al. 1983, Cort6s and Murillo 1985). Seven species ofhermatypic corals (Cort6s and Gttzrr~n 1998) and seven species of ahermatypic corals (Cort6s in prep.) have been collected from this area. Most of this section of the coast is exposed to strong wave action, which may preclude the development of coral reefs. One area, Samara (Fig. 5), stands apart with small Pocillopora or Porites lobata fringing and patch reefs present. Also, the only specimens of Porites (Synarea) rus that have been collected in the eastern Pacific come from this area (Cort6s and Murillo 1985). Dendrophyllia californica has been collected only from S~imara on the mainland coast of Costa Rica (Cort6s 1996/1997b). Octocorals and isolated coral communities are abundant on rocky outcrops, and on islands and islets off Peninsula de Nicoya, especially at the Reserva Natural Absoluta Cabo Blanco (Figs. 2, 5). Patch reefs made up of Pocillopora spp. grow over large dead reefs in protected bays; e.g., Playa Muertos in Bahia Ballena (Fig. 5). There are many coral communities between Bahia Ballena and C t ~ (Jim6nez and Cort6s in prep.), where the predominant species were Pavona gigantea, Porites lobata, Pavona clavus, Pocillopora elegans, Pavona varians, and Tubastrea coccinea. These communities extend from the rocky cliffs, where P. gigantea is particularly abundant, down to 12 - 18 m deep, where isolated corals can be observed on the sandy bottom.
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Fig. 5. Coralcommunitiesof Peninsula de Nicoya. The inner section of Golfo de Nicoya extends north of a line across the mouth of the gulf from Islas Negritos to Herradura (Figs. 1, 5, 6). There, no reef develops because of the presence of freshwater and sediments. On the outer section of the gulf several small dead coral communities have been located. One of these consists mainly of Pavona gigantea and Pocillopora elegans, and is located on the western littoral zone of the gulf (Fig. 5), where it was found covered with sediments. Three dead reef patches of Pocillopora spp. and Psammocora spp. were observed buried under sediments at Punta Coral (Fig. 5). Dead patches of Pocillopora damicornis have been observed at Punta Leona (H.M. Guzmfin, per. com.). Only one ahermatypic coral, Astrangia sp., was found inside the gulf (Cort6s in prep.). 2.4. Paeifieo Central
The central section of the Pacific coast of Costa Rica, from Herradura to the SierpeT6rraba mangrove complex (Figs. 1, 6), supports few reefs (Glynn et al. 1983; Cort6s and Murillo 1985). Nine species of reef-building corals (Cort6s and Guzrnfin 1998) and two species of ahermatypic corals (Cort6s in prep.) have been reported from this section of the coast. Isolated corals and small coral communities can be found on rocky outcrops along the coast, including Parque Nacional Manuel Antonio and Parque Marino Ballena (Figs. 2, 6). Patch reefs of Porites lobata have been found in protected coves and near sandy beaches. Also, dead Pocillopora frameworks overgrown with live colonies of P. elegans, P. damicornis, and Psammocora spp. have been observed. Coral communities present on the islets of the Park, particularly in their deeper areas (below 15 m), consist mainly ofPorites lobata, some Pavona gigantea, and a few pocilloporid colonies.
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Fig. 6. Coral communities and reefs of the Pacifico Central. Porites lobata patch reefs have been observed near Punta Dominical and Punta Uvita, which are part of the Parque Marino Ballena (Figs. 2, 6). Rich coral communities have been found on the islands and islets of Parque Marino Ballena. The exposed flanks of these structures were covered with octocorals, and there were submerged banks with coral communities, consisting mainly of Porites lobata and Pavona gigantea, and with some Pavona varians. Average coral cover was: 19.7 + 2.0% (range 0.34 - 51.8%) with the remainder of the epibionts consisting mainly of algae, with some octocorals and sponges. The predominant species at all depths, down to 20 m, was P. lobata. P. gigantea was more common than P. clavus, and branching corals were scarce and found only in small communities (Jim~nez and Cortes 2001); these corals were severely affected by the 1992 E1 Nifio event. Over 50% of all observed colonies were bleached, and covered by sediments and algae. More than 80% of all branching corals observed were bleached (Jim6nez and Cort6s 2001). The large fresh water lens between Parque Marino Ballena and Peninsula de Osa, a result of the Sierpe-T&raba mangrove-river complex (Fig. 1, 6), precludes or interferes with the development of coral reefs.
2.5. Peninsula de Osa The second largest peninsula on the Pacific coast of Costa Rica is Peninsula de Osa (Figs. 1, 7). Ten species of zooxanthellate corals (Cort6s and Jim6nez 1996; Cort6s and Guzm,Sn 1998) and one species of ahermatypic coral (Cort6s in prep.) have been found so
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Fig. 7. Coralreefs and communitiesof Peninsula de Osa. far in communities at Peninsula de Osa. Cort6s and Jim6nez (1996) described the coral communities and reefs at Peninsula de Osa; a 250 m z Pocillopora patch reef at Punta Llorona (Fig. 7) consisted of close to 100% live cover of Pocillopora damicornis. Exposed rocky substrates were covered by octocorals, and isolated corals were found on all rocky outcrops. 2.6. Golfo Dulce
2.6.1. Extant reefs. Golfo Dulce, located in the southem part of Costa Rica, is about 50 km long by 10 to 15 km wide, and is oriented NW to SE (Figs. 1, 8). It is an enclosed embayment of tectonic origin with a 60 rn deep sill and depths of 200 rn in its deeper parts (Hebbeln et al. 1996). The deep waters are anoxic most of the time, which is why it is considered a tropical fjord (Richards et al. 1971; Thamdrup et al. 1996; Hebbeln and Cort6s 2001). Several types of coral reefs and coral communities have been found in the gulf. They can be divided into two groups based on species diversity and reef structure: those of the inner section of the gulf, and those of the outer section (Cort6s 1990a, b). Ten species of reef-building corals (Cort6s and Guzmfin 1998) and four species of ahermatypic corals (Cort6s in prep.) have been collected in the gulf. The inner gulf reefs consisted of live and dead Porites lobata on the reef front, and dead Pocillopora damicornis and Psammocora stellata on the reef fiat. Coral diversity was low and topographic relief was high, with steep reef-fronts and sides. Live coral cover ranged from less than 1 to 8%. The outer gulf reefs were characterized by a relatively high live coral coverage (ranging from 29 to 46%), high coral diversity, and low topographic relief. The shallow areas of the reef at S~indalo (Fig. 8) were composed of
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Fig. 8. Coral reefs and coral communitiesof Golfo Dulce.
Porites lobata, while several species were found in the deeper section, the most abundant being Pocillopora damicornis. Also in this deeper section, the largest colonies of Pavona frondifera that have been found in the eastem Pacific were observed (Cort6s 1990b, Cort6s and Guzmfin 1998). Another outer reef, Punta E1Bajo (Fig. 8), had 100% live coverage ofPsammocora obtusangula (Cort6s 1990b; Cort6s and Guzmfin 1998). The reefs at Golfo Dulce are being destroyed by several species of extemal and intemal bioeroders (Fonseca 1999). The main internal bioeroders (Cort6s 1991) included two species of Lithophaga and Gastrochaena rugulosa. Other intemal bioeroders (Fonseca and Cort6s 1998) are the sipunculan Aspidosiphon (,4.) elegans, with densities as high as 300 individuals per 1,000 cm 3, and the upogebid crustacean Pomatogebia rugosa. Taking into account accretion and bioerosion, the reefs in Golfo Dulce have a net production of-2.05 to -0.30 kg m "2 year l, i.e. they are being destroyed faster than they are accreting (Fonseca 1999). 2.6.2. Holocene growth history. The coral reef at Punta Islotes (Fig. 8) started growing over on Cretaceous basalt about 5,500 years ago. The Holocene growth history of this reef can be divided into four stages (Cort6s 1991; Cort6s et al. 1994). First, the initial reef: was formed when Pocillopora damicornis was recruited to elevated basaltic areas, forming small patch reefs. The fragments from these reefs covered the surrounding muds, and over them massive corals later grew. Next, the reef entered its establishment
Corals and coral reefs of the Pacific of Costa Rica
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stage; a period extending from 4,000 to 1,500 years Before Present (yr BP). It was characterized by continual accumulation of Pocillopora, culminating in a fringing reef which masked the antecedent topography. During this stage, Porites lobata started growing on the reef front and talus slope. Between 1,500 and 500 yr BP, the reef passed through a flourishing stage, where it grew vigorously, resulting in accumulation rates of 5 to 8.3 m 1,000 yr 1. The last 500 years have seen a slow degradation of the reef at Punta Islotes as it entered the fourth stage, final reef degradation. First, there was an increase in freshwater (Cort6s 1990a), and then during the last 50 years there was a significant increase in terrigenous sediment loads, which have almost completely killed the reef (Cort6s et aL 1994). 2.7. Offshore islands 2.7.1. lsla del Carlo Description o f the reefs. Isla del Carlo is located 15 km offshore of Peninsula de Osa
(Fig. 1). The coral reefs of the island were described during the 1980's (Guzrnfin 1986). The sediments arotmd the island are of terrigenous origin, with minor contributions of carbonates from the island's coral reefs (Cort6s et al. 1996). Isla del Carlo has five coral reef fiats, ranging in size from 0.8 to 4.2 hectares (Fig. 9). These fringing reef fiats are built mainly by dead pocilloporid corals, covered by crustose coralline algae, with
Fig. 9. Coralreefs of Isla del Carlo.
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isolated live colonies of pocilloporids and poritids, and microatolls of Porites lobata. The reef slope and base are dominated by the massive coral Porites lobata, which is the most abundant species found at the island. The shallow sections of the reef were structured mainly by physical factors: wave action, temperature and salinity fluctuatiom, and low tidal exposure. In contrast, the deeper sections is controlled by biological interactions: bioerosion, damselfish algal lawns, and corallivores (Guzrrfin 1988a; Gtmnfin and Cort6s 1989a). The corals of Isla del Carlo were impacted by the 1982-83 E1 Nifio disturbance, with losses of up to 50% of the live coral coverage (Guzrrfin et al. 1987). Again, during 1992 and especially during the 1997-1998 E1 Nifio, there was extensive bleaching of corals at the island, but mortality was low, reaching only about 5% (Guznfin and Cort6s 2001). Reef growth at Isla del Carlo is recent, with radiocarbon dates ranging from 180 to 450 yrBP (Macintyre et al. 1992). With a growth rate for Porites lobata of 11.7 mm yr~ (Guzmfin and Cort6s 1989b) the largest colonies are less than 300 to 400 years old, corroborating the recent age of the reefs at Isla del Carlo. Macintyre et al. (1992) proposed that on oceanic islands of the eastern Pacific, reefs have difficulties becoming established and developing became of widely fluctuating oceanic water temperatures. Isolated corals are found all around the island. The south side is exposed to heavy wave action, and extensive octocoral fields occur there on submerged rock pinnacles or banks (Guzmfin and Cort6s 1989a, work in progress). One of these pinnacles, located west of the island, Bajo E1 Diablo, has strong currents, and about 10% live coral cover: pocilloporids were the most abundant, followed by Tubastrea, and octocorals covered around 12% (unpublished data). Another bank located between the island and the continent, called Paraiso, has mainly pocilloporids and some Pavona gigantea. Extensive rhodolith beds are present on the south side of the island. Corals. Fifteen species of reef-building corals (Cort6s and Gtmmfin 1998) and three ahermatypic coral species (Cort6s in prep.) have been identified from Isla del Carlo. Guzmfin and Cort6s (1989b) determined the growth rate of eight of the reef-builder corals. Growth rates of the predominant species, Porites lobata, and pocilloporids, were greater during the dry season. It seems that temperature was not a controlling factor, instead light (i.e., turbidity, cloud cover) and other physical factors probably control the seasonal growth of corals at Isla del Carlo (Guzm,Sn and Cort6s 1989b). Studies on the reproductive ecology of six species of reef-building corals (Gardineroseris planulata, Pavona gigantea, Pavona varians, Pocillopora damicornis, Pocillopora elegans, Porites lobata and Porites panamensis) from Isla del Carlo (Table 2) showed that all species exhibit year-round reproduction; twenty to 76% of all colonies had gonads present. In these species, gonadal activity increased around the full and/or new moon, and the maximum number of annual spawning cycles were estimated to range from one to seven. All species are gonochoric with more females than males, except for Pocillopora elegans and Porites panamensis, which have male-biased sex ratios. All species also have hermaphroditic colonies, except P. panamensis. The hermaphroditic form is dominant in P. gigantea and in the pocilloporids (Table 2). Oocytes of all species studied had zooxanthellae (Glynn et al. 1991, 1994, 1996b, 2000). Colonies of P. lobata were collected from Costa Rica, Pananfi, and the Gal/lpagos Islands, but only those from Isla del Carlo were hermaphroditic (Glynn et al. 1994). Fecundity estimates of annual egg production of Pavona varians were significantly higher at Isla del Carlo than at Panamai or Gal/lpagos (Glynn et al. 2000).
375
Corals and coral reej~ of the Pacific of Costa Rica
TABLE2 Reproductive ecologyof seven speciesof corals fromIsladel Carlo. Sourceof information:Pocillopora damicornis and P. elegans fromGlynnet al. (1991);Porites lobata and P. panamensis fromGlynn et al. (1994); Pavona gigantea and Gardineroserisplanulata from Glynn et al. (1996b); Pavona varians from Glynn et al. (2000). Herm= hermaphroditic, gono = gonochoric, m = males, f = females. Species G. planulata P. gigantea P. varians P. damicornis P. elegans P. lobata P. panamensis
No. colonies 81 95 88 78 117 104 5
% with male female herm gonads 19.8 36.8 76.1 32.0 59.5 48.0 60.0
6 3 21 2 7 11 2
9 10 41 3 3 25 1
1 22 5 20 59 7 0
sex ratio m:f
gono:herm
1:1.40 1:1.30 1:1.77 1:1.50 1:0.43 1:1.78 1:0.50
1:0.07 1:1.69 1:0.08 1:4.00 1:5.90 1:0.14
Another study at Isla del Carlo focused on the ultrastmcture of Pocillopora damicornis and P. elegans spermatozoa and found that they have bullet-shaped nuclei and elongated mitochondria. These characteristics are distinctive of the Suborder Astrocoeniina, while Pavona gigantea had a conical-shaped sperm head, typical of gonochoric species (Steiner and Cort6s 1996). Even though there was gonadal development in all species studied at all eastern Pacific localities (Glynn et al. 1991, 1994, 1996b), only at Isla del Carlo has significant recruitment been observed (GuzmAn and Cort6s in press). Another important form of reproduction is by fragmentation (GuzroAn 1988b, 1991; Guzrrfin and Cort6s 1989a). The massive coral Porites lobata had high densities of the boring bivalves Lithophaga spp., which weaken the skeletal structure (Scott and Risk 1988). Two triggerfish species, Sufflamen verres and Pseudobalistes naufragium, remove fragments of coral in their search for bivalves. The fragments of P. lobata often survive and sometimes can form new colonies (GuzmAn 1988a, per. obs.). In a study on bioerosion, Fonseca (1999) found 23 species of macro-bioeroders at Isla del Carlo. The main bioeroders are bivalves, Lithophaga spp. and the sipunculan, Phascolosoma perlucens. The reefs at Carlo have a net carbonate production of 2.76 kg m "2 year "1 (Fonseca 1999). 2.7.2. lsla del Coco. Isla del Coco World Heritage Site (1997) is located at 5~ and 87~ (Fig. 1), approximately 500 km southwest of the Costa Rican mainland. Seventeen species of zooxanthellate corals (Cort6s and Guzrnfin 1998), and 13 ahermatypes (Cairns 1991; Cort6s in prep.) have been reported from Isla del Coco. Isla del Coco has the highest number of zooxanthellate corals of any Pacific site in Costa Rica, followed by Bahia Culebra with 16 and Isla del Carlo with 15 (Cort6s and Guzrnfin 1998). Isla del Coco also has the highest number of ahermatypic corals, but more than half of these corals were collected in deep water, below 100 m in depth (Cairns 1991; Cort6s in prep.). Fringing reefs ranging in size from less than one hectare to more than 50 hectares have formed around Isla del Coco (Fig. 10). Most of the reefs were constructed of Porites lobata, but there were also extensive zones of agariciids: Pavona spp. and Gardineroseris
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Fig. 10. Coral reefs and coral communitiesof Isla del Coco. planulata. Most of the coral died during the 1982-1983 E1Nifio (Guzm~ and Cort6s 1992). In 1987, live coral cover was between 2.6 and 3.5% (GuzmAn and Cort6s 1992), but by 1994 live coral cover had reached 30% in some reefs (Cort6s and Jim6nez unpublished
data).
Densities of the corallivorous seastar Acanthaster plancL the pufferfish Arothron meleagris, and the sea urchin Diadema mexicanum were relatively high. For example, densities of D. mexicanum ranged from 3 to 45 ind m 2, with an average of 25.5 + 9.5 ind m "z, n=25). The feeding and erosional activities of D. mexicanum were concentrated on colonies that had survived the 1982-83 E1 Nifio and were responsible for most of the erosion of the reefs. From field measurements, Guzrrfin and Cort6s (1992) predicted that recovery of the original reef-framework thickness would require on the order of centuries. Unfortunately, the 1997-1998 E1 Nifio event bleached large amounts of coral in these same populations, probably reversing the recovery trend observed in 1994. Isla del Coco is important in the eastern Pacific because it is one of the first shallow platforms in the region encountered by the easterly flowing North Equatorial CounterCurrent, potentially transporting larvae from the Central Pacific (Glynn et al. 1996a). The island acts as a stepping stone for organisms that can colonize tropical eastern Pacific continental shores.
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of Costa Rica, was found in abundance in the Santa Elena region, while its congener, P. lobata, had the opposite distribution; it was rare in the north and predominant in the south section of the coast of Costa Rica. Gardineroseris planulata and Pavona gigantea are minor components of reefs in the south, but major reef builders in the north. Coral communities formed by various species assemblages were found at the Archipi61ago de las Islas Murci6lago, on the south side of Peninsula de Santa Elena (Fig. 3). One reef extending over 2,000 m 2, and from 2 to 12 m in depth, is constructed mainly by Pocillopora damicornis and Pocillopora elegans. Other species present are Pocillopora eydouxi, P. meandrina, Pavona clavus, P. varians and a new species, Pocillopora inflata (Glynn 1999). This reef grows on the north side of Isla San Pedrito, one of the Islas Murci61ago (Fig. 3), and is thus protected from the full impact of the seasonal upwelling in the region, and from strong wave action. Live coral coverage ranged from 47.5 to 95.2%.
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J. Cortds & C. Jimdnez
3.3. Low tidal exposure Mid-day low tidal exposures affecting eastern Pacific reefs during La Nifia years can cause extensive mortality of reef-fiat organisms (Eakin and Glynn 1996). Mortality due to low tidal exposures has been observed at Isla del Carlo (Gtmm,Sn 1986), Samara (O. Breedy per. com.) and at Peninsula de Osa (per. obs.). 3.4. Storms Gtmmfin (1986) showed coral blocks that were probably deposited on the reef flat at Isla del Carlo by storms. Jimtnez (1998) described the impact of a very strong storm, in June 1996, on reefs at Bahia Culebra. The few large patches of seagrass (Ruppia maritima) on the Pacific coast were uprooted from the inner part of Bahia Culebra during this storm. One of the largest known Costa Rican populations of the bivalve Pinna rugosa living in the seagrass community, was killed due to the loss of the seagrass. At Islas Pelonas (Fig. 4), waves mainly from the west broke up patches of Pocillopora, and the destruction reached a depth of 7 m. The damage to corals was caused directly by the waves and by rocks moved by the surge. The most affected species, in decreasing order, were Pocillopora elegans, P. eydouxL and P. damicornis. Mean fragment length was 16.9 + 0.69 cm (range 1 to 47 crn; n = 234). The fragments were piled in crevices or between colonies and rocks, and in channels between rocky platforms. Some fragments were bleached (> 3%), but very few were dead at the time of the survey (26.VI.1997). Over 93% of the fragments were larger than 4 crn, the minimum size considered to have 80% survivorship (Guzrnfin 1991). A high survivorship was noted five months later, with fusion and growth reorientation in many of the colonies. With the breakage of large branching corals, bottom topographic relief (index sensu Bythell and Bythell, 1992) was significantly reduced (t-student, p<0.01) from greater than 1.8 to 1.3 (Jimtnez 1998) at monitoring sites in Bahia Culebra. 3.5. Little Ice Age Cool waters are a limiting factor for the growth of coral reefs (Stoddard 1969). For a long time it was thought that reefs were absent in the eastern Pacific because of low temperatures (Verrill 1866; Cortts 1997), but this is not the case. With the 1982-1983 E1 Nifio, it became obvious that a limiting factor in reef development in the eastern Pacific was high temperature (Glynn and Colgan 1992). In fact, low temperatures probably have less in~act than high temperatures (Glynn and D'Croz 1990). Historically, however, low temperatures may have been responsible for the death of some pocilloporid reefs in the eastern Pacific. Glynn et al. (1983) found many dead reefs on the northern section of the coast of Costa Rica and live reefs on the south. The northern section is exposed to upwelling of cool waters from December to April, when the Trade Winds cross the lowlands of southern Nicaragua and northern Costa Rica. The southern part of the coast is not subject to upwelling because the high mountains of the Talamanca Range deflect the winds (Coen 1983). Most of the reefs in the north died between 150 to 400 years ago. Glynn et al. (1983) attributed their death to the intensification of upwelling during the Little Ice Age. 3.6. Freshwater Coral reefs develop in marine waters of normal salinities; freshwater limits reef development, and if salinity is notably low, corals will die due to osmotic stress. This
Corals and coral reefs of the Pacific of Costa Rica
379
was observed at Punta Islotes, Golfo Dulce. Between 1500 and 500 yrBP, salinity in the gulf was the same as that presently found in marine environments outside the gulf, such as Isla del Carlo (Cort6s 1990a, 1991). About 500 years ago, due to tectonic uplift, several rivers started flowing into the inner section of the gulf, reducing the salinity of the waters, slowing reef accretion, and killing several reefs altogether (Cort6s 1990a; Cort6s et al. 1994). 4. ANTHROPOGENIC IMPACTS 4.1. Siltation
Terrigenous sediments have affected coral communities and reefs on the Pacific coast (Cort6s and Murillo 1985), including those at Bahia Culebra (Jim6nez 2001), Golfo Dulce (Cort6s 1990a, b, 1991; Cort6s et al. 1994), and at Parque Marino Ballena (per. obs.). Sedimentation has increased in recent years due to deforestation of the watersheds, construction of road and tourist complexes, and inappropriate agricultural practices (Cort6s 1990a, b; Jim6nez 1998). For example, at Bahia Culebra in 1994, a small patch reef of P. gigantea was buried under sediments dumped during construction of a tourist resort, causing over 80% coral mortality (Jim6nez 2001). In 1995, a P. clavus reef was affected by sedimentation produced when most of an unpaved coastal road was washed away by rain (Jim6nez 1997). At Golfo Dulce, a reef observed in 1975 was buried under mud in 1985 (Cort6s 1990b). Live coral cover is low (less than 8%) on most reefs in the inner section of Golfo Dulce due to high terrigenous sediment loads (Cort6s 1990b). A significant reduction in reef accretion has been observed over the last 50 years in cores from the reef at Punta Islotes; this has been attributed to recent terrigenous sedimentation since the area was deforested for banana plantations (Cort6s et al. 1994). 4.2. Coral and fish extraction
Several species of corals have been extracted for the local curio trade. Populations of Pocillopora meandrina, an attractive branching coral present at Bahia Culebra, have been reduced due to over-exploitation (Cort6s and Murillo 1985). Tubastrea coccinea, a
coral particularly attractive for the aquarium trade, was also extensively extracted in the bay. On one day in 1996, more than 200 colonies were removed from a submerged bank. Another preferred species at Bahia Ctflebra was Pocillopora eydouxi. In 1997, a 1 m high colony was primed with a hacksaw to obtain the branches for sale, leaving only the colony base; other practices are even more harmful. For instance, when metal rods are used to break branches or detach whole colonies, other branching colonies nearby are damaged in the process. In one monitored zone at Bahia Culebra, patches of broken coral of up to 25 m 2 have been observed where divers broke corals to extract fish and shrimps for the aquarium trade (Jim6nez 1997). The size of those coral fragments was smaller (9.7 + 0.5 cm, range 1.3 to 35.5, n = 136) than those produced by sharks (11.2 • 4.6 cm, Jim6nez 1996) or storms (see above). Survival was very low because the divers moved the fragments in search of other organisms, abrading the coral tissue. Aquarium fish divers can inflict all this damage in one dive. Black corals also are extracted from the shallow banks south of Bahia Culebra to Punta Gorda, and less intensively from Islas Murci61ago (Fig. 3, 4). All deep reefs at Bahia Culebra reveal the cut bases of large colonies of black corals.
380
J. Cortes & C. Jim~nez
A study of the fisheries of ornamental fishes in the province of Guanacaste shows a decline in the catch between 1994 and 2000. This decline may be due to a reduction in fishing effort because of low income of the fisherman. But, analysis of fish populations indicate that the fisheries can not expand any more (Alperman 2001). 4.3. Tourism
Tourist activities have direct and indirect effects on the coral reefs (Cort6s and Murillo 1985; Jim6nez 1997). Direct effects include coral extraction, and damage to colonies by divers and boat anchors. Indirect effects include over-exploitation of resources, increased sewage, and increased sediment loads from the construction of tourist-support facilities. When not supervised by a conscientious divemaster, recreational and novice divers can cause coral damage while diving on reef areas. At Islas Murci61ago, one novice diver destroyed approximately 0.7 m 2 of Pocillopora spp. by stepping on the reef, producing fragments of 18.3 + 8.5 cm length (range 3.6 to 33 cm, n=31). Two other recreational divers produced fragments of Pocillopora spp. colonies with their f'ms measuring 11.2 + 6.7 cm (3.6 to 23.7 cm, n=25) and 17.4 + 10.2 cm (6.5 to 46 cm, n=21), at Punta Gorda and Bahia Culebra, respectively (Jim6nez unpublished data). Also at Bahia Culebra and Punta Gorda (Figs. 4, 5), boat anchors used by recreational divers and commercial fish collectors have destroyed several square meters of pocilloporid reefs in the last six years. Broken coral fragments were extremely small (4.3 + 3 cm, range 0.9 to 23 cm, n=247), because boats anchored in the same spots every time; also, sediments were stirred up when the anchors were raised. Several years later no reef was left; continuous anchoring have destroyed the branching corals and their recruits. Additionally, large massive colonies were turned over by the anchors. 5. PROTECTION AND MANAGEMENT Most coral reefs and the larger coral communities are located within protected areas, with the outstanding exception of Bahia Culebra (Figs. 1, 2). The Protected Areas from north to south are presented next (Fig. 2). Area de Conservaci6n Guanacaste is a large protected area including two National Parks and two Wildlife Refuges, which are managed as a unit. Protection is adequate in the terrestrial environments, but not in the marine portions. For example, no controls have been established for commercial activities, some of them destructive, such as reef fish extraction (Cort6s 1996/1997a). Reserva Absoluta de Cabo Blanco (Absolute Reserve), located on the Peninsula de Nicoya, has coral communities that have been only partially protected. There is a sporadic commercial fishing activity within this reserve. On the central Pacific coast are Parque Nacional Manuel Antonio (National Park), and Parque Marino Ballena (Marine Park). Because of logistic, political and social problems in the surrounding areas, especially at Ballena, the marine portions of these parks have not been protected or managed. Parque Nacional Corcovado includes a large marine area that has received limited protection from the shore by patrolling park rangers (Cort6s and Jim6nez 1996). Reserva Biol6gica Isla del Carlo (Biological Reserve) and Parque Nacional Isla del Coco are the best protected and managed marine areas in Costa Rica. These island parks include a marine portion that is patrolled, diving is permitted only in certain areas, and commercial fishing is prohibited.
Corals and coral reefs of the Pacific of Costa Rica
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Management and protection must be implemented in other marine areas of Costa Rica, especially at Bahia Culebra because of its biological and economic importance for tourism. Most reef fishes studied at Bahia Culebra (Dominici 1999) showed a significant positive correlation with live coral cover. As the reefs of this region are being degraded due to human activity (Jim6nez 2001), it is expected that the fish communities will also be impacted. There are signs of over-exploitation of the main aquarium trade species (Dominici 1999) and destructive fishing practices have been reported (Alperman 2001). Commercial fishing of all types must be stopped within the parks and reserve boundaries. The only viable populations of many commercially in~ortant species remaining, e.g. conch and lobster, are within protected areas (Cort6s and Jim6nez 1996). Coral collection is prohibited within the protected areas, and this ban is enforced in most of them, but is permitted outside these areas. As previously noted, some coral species have been almost depleted due to extraction for the curio trade (Cort6s and Murillo 1985). Collection of all reef organisms must be prohibited, or at least regulated in order to sustain the vitality of coral reef ecosystems. ACKNOWLEDGMENTS Research on coral reefs of the Pacific of Costa Rica has been possible through grants from: Vicerrectoria de Investigaci6n, Universidad de Costa Rica; CONICIT (Project 90326-BID), U.S. National Science Foundation grants to P.W. Glynn; ProAmbi; and USIsrael Cooperative Development Research Program (Grant TA MOU-97-C14015). M.M. MuriUo, H.M. Guzrnfin, A. Le6n, E. Ruiz, C. Gamboa, J. Mateo, O. Breedy, A.C. Fonseca, B. Bofill, A. Segura and G. Bassey helped at different times in the field and in the laboratory. The manuscript was greatly improved by the comments of: H.M. Gtmmfin, M. Reaka-Kudla, K. Qualtrough, A.I. Dittel, C. Lorion and P.W. Glynn. REFERENCES
Alperman, T.J. 2001. The fisheries of omamental fishes in Guanacaste, Costa Rica, with special emphasis on the population dynamics of the Cortez Rainbow Wrasse, Thalassoma lucasanum (Gill 1863). M.Sc. Thesis, Univ. Bremen, Bremen, Germany. 84 p. Bakus, G.J. 1975. Marine zonation and ecology of Cocos Island, off Central America. Atoll Res. Bull. 179: 1-9. Bythell, J. & M. BytheU. 1992. Coral reefs commtmity structure assessment based on planar and three-dimensional area cover: a comparison of techniques: 29-39. In: J. Bythell, E. Gladfelter & M. Bythell (eds.), Ecological studies of Buck Island Reef National Monument, St. Croix, U.S. Virgin Islands. US Dept. Interior, National Park Service. Cairns, S.D. 1991. A revision of the ahermatypic Scleractinia of the Gahipagos and Cocos Islands. Smithson. Contr. Zool. 504: 1-33. Carriquiry, J.D. 1994. Fraccionamiento del 180 en la aragonita coralina de Porites lobata: Implicaciones en los estudios de paleotemperatura oce~inica. Ciencias Marinas 20: 585-606. Carriquiry, J.D., M.J. Risk & H.P. Schwarcz. 1988. Timing and temperature record from stable isotopes of the 1982-1983 E1 Nifio warming event in eastern Pacific corals. Palaios 3" 359-364.
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Fonseca E., A.C. 1999. Bioerosi6n y bioacreci6n en arrecifes coralinos del Pacifico sur de Costa Rica. M.Sc. thesis, Universidad de Costa Rica, San Pedro, Costa Rica. 206 p. Fonseca E., A.C.& J. Cort6s. 1998. Coral borers of the eastern Pacific: the sipunculan Aspidosiphon (.4.) elegans and the crustacean Pomatogebia rugosa. Pac. Sci. 52: 170-175. Glynn, P.W. 1999. Pocillopora inflata, a new species of scleractinian coral (Cnidaria: Anthozoa) from the tropical eastern Pacific. Pac. Sci.: In press. Glynn, P.W. & M.W. Colgan. 1992. Sporadic disturbances in fluctuating coral reef environments: E1 Nifio and coral reef development in the eastern Pacific. Amer. Zool. 32: 707-718. Glynn, P.W. & L. D'Croz. 1990..Experimental evidence for high temperature stress as the cause of E1Nifio-coincident coral mortality. Coral Reefs, 8: 181-191. Glynn, P.W., E.M. Druffel & R.B. Dunbar. 1983. A dead Central American coral reef tract: possible link with the Little Ice Age. J. Mar. Res. 41: 605-637. Glynn, P.W., J. Cort6s, H.M. Guzl~n & R.H. Richmond. 1988. E1 Nifio (1982-83) associated coral mortality and relationship to sea surface temperature deviations in the tropical eastern Pacific. Proc. 6th Int. Coral Reef Symp., Australia 3: 237-243. Glynn, P.W., N.J. Gassman, C.M. Eakin, J. Cort6s, D.B. Smith & H.M. Guzmfin. 1991. Reef coral reproduction in the eastem Pacific: Costa Rica, Panama, and Gal~pagos Islands (Ecuador), I. Pocilloporidae. Mar. Biol. 109: 355-368. Glynn, P.W., S.B. Colley, C.M. Eakin, D.B. Smith, J. Cort6s, N.J. Gassman, H.M. Guzrr~n, J.B. del Rosario & J. Feingold. 1994. Reef coral reproduction in the eastern Pacific: Costa Rica, Panama, and Galfipagos Islands (Ecuador), II. Poritidae. Mar. Biol. 118: 191-208. Glynn, P.W., J.E.N. Veron & G.M. Wellington. 1996a. Clipperton Atoll (eastern Pacific): oceanography, geomorphology, reef-building and coral ecology and biogeography. Coral Reefs 15:71-99. Glynn, P.W., S.B. Colley, N.J. Gassman, K. Black, J. Cort6s & J.L. Mat6. 1996b. Reef coral reproduction in the eastern Pacific: Costa Rica, Panama, and Gal~ipagos Islands (Ecuador) III. Agariciidae (Pavona gigantea and Gardineroseris planulata). Mar. Biol. 125: 579-601. Glynn, P.W., S.B. CoUey, J.H. Ting, J.L. Mat6 & H.M. Guzmfin. 2000. Reef coral reproduction in the eastern Pacific" Costa Rica, Panama, and Gal~ipagos Islands (Ecuador) IV. Agariciidae, recruitment and recovery of Pavona varians and Pavona sp.a. Mar. Biol. 136: 785-805. Guzm~n, H.M. 1986. Estructura de la comunidad arrecifal de la Isla del Carlo, Costa Rica, y el efecto de perturbaciones naturales severas. M.Sc. thesis, Universidad de Costa Rica, San Pedro, Costa Rica. 179 p. Guzmfin, H.M. 1988a. Distribuci6n y abundancia de organismos coralivoros en los arrecifes coralinos de la Isla del Carlo, Costa Rica. Rev. Biol. Trop. 36:191-207. Guzm~n, H.M. 1988b. Feeding behavior of the gastropod corallivore Quoyula monodonta (Blainville). Rev. Biol. Trop. 36: 209-212. Guzm~n, H.M. 1991. Restoration of coral reefs in Pacific Costa Rica. Conserv. Biol. 5: 189-195. GuzroAn, H.M. & J. Cort6s. 1989a. Coral reef community structure at Carlo Island, Pacific Costa Rica. P.S.Z.N.I: Mar. Ecol. 10:23-41.
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Guzm,Sn, H.M. & J. Cort6s. 1989b. Growth rates of eight species of scleractinian corals in the eastern Pacific (Costa Rica). Bull. Mar. Sci. 44:1194-1186. Guzrn~n, H.M. & J. Cort6s. 1992. Cocos Island (Pacific of Costa Rica) coral reefs after the 1982-83 E1Nifio disturbance. Rev. Biol. Trop. 40: 309-324. G ~ H.M. & J. Cort6s. 2001. Changes in reef community structure after fifteen years of natural disturbances in the eastern Pacific (Costa Rica). Bull. Mar. Sci. 69: 133-149. GuzroAn, H.M. & V.L. Obando. 1988. Diversidad y abundancia diaria y estacional del zooplancton marino de la Isla del Carlo, Costa Rica. Rev. Biol. Trop. 36: 139-150. GuzmAn, H.M., V.L. Obando & J. Cort6s. 1987. Meiofauna associated with a Pacific coral reef in Costa Rica. Coral Reefs 6:107-112. Guzm~n, H.M., J. Cort6s, R.H. Richmond & P.W. Glynn. 1987. Efectos del fen6meno de "El Nifio-Oscilaci6n Surefia" 1982/83 en los arrecifes de la Isla del Carlo, Costa Rica. Rev. Biol. Trop. 35: 325-332. GuzmAn, H.M., V.L. Obando, R.C. Brusca & P.M. Delaney. 1988. Aspects of the population biology of the marine isopod Excorallana tricornis occidentalis Richardson, 1905 (Crustacea: Isopoda: Corallanidae) at Carlo Island, Pacific Costa Rica. Bull. Mar. Sci. 43: 77-87. GuzmAn, H.M., J. Cort6s, P.W. Glynn & R.H. Richmond. 1990. Coral mortality associated with dynoflagellate blooms in the eastern Pacific (Costa Rica and Panama). Mar. Ecol. Prog. Ser. 60: 299-303. Hebbeln, D. & J. Cort6s. 2001. Sedimentation in a tropical fjord: Golfo Dulce, Costa Rica. Geo-Marine Letters 20: 142-148. Hebbeln, D., D. Beese & J. Cort6s. 1996. Morphology and sediment structure in Golfo Dulce, Costa Rica. Rev. Biol. Trop. 44 (Suppl. 3): 1-10. Herrera, W. 1986. Clima de Costa Rica. Editorial Universidad Estatal a Distancia, San Jos6, Costa Rica. 118 p. Jim6nez, C. 1996. Coral colonies fragmentation by white-tip reef sharks at Coiba Island National Park, PanamA. Rev. Biol. Trop. 45" 698-700. Jim6nez, C.E. 1997. Corals and coral reefs of Culebra Bay, Pacific coast of Costa Rica: anarchy in the reef. Proc. 8th Int. Coral Reef Symp., Panarn~ 1: 329-334. Jim6nez, C.E. 1998. Arrecifes y comunidades coralinas de Bahia Culebra, Pacifico norte de Costa Rica (Golfo de Papagayo). M.Sc. thesis, Universidad de Costa Rica, San Pedro, Costa Rica. 218 p. Jim6nez, C. E. 2001. Arrecifes y ambientes coralinos de Bahia Culebra, Pacifico de Costa Rica: aspectos biol6gicos, econ6micos, recreativos y de manejo. Rev. Biol. Trop. 49 (Supl. 2): 215-231. Jim6nez, C. E. & J. Cort6s. 2001. Effects of the 1991-1992 E1 Nifio on scleractinian corals of the Costa Rican central Pacific coast. Rev. Biol. Trop. 49 (Supl. 2): 239250. Jim6nez, C. E., J. Cort6s, A. Le6n & E. Ruiz. 2001. Coral bleaching and mortality associated with E1 Nifio 1997/98 event in an upwelling environment at the eastern Pacific (Gulf of Papagayo, Costa Rica). Bull. Mar. Sci. 69:151-169. Legeckis, R. 1988. Upwelling off the Gulfs of PanaroA and Papagayo in the tropical Pacific during march 1985. J. Geophys. Res. 93:15489-15489. Macintyre, I.G., P.W. Glynn & J. Cort6s. 1992. Holocene reef history in the eastern Pacific" mainland Costa Rica, Carlo Island, Cocos Island, and Gal~pagos Islands. Proc. 7th Int. Coral Reef Symp., Guam 2:1174-1184.
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Corals and coral reefs of the Pacific coast of Panam~ J. L. Mat6 a' b aSmithsonian Tropical Research Institute, P.O. Box 2072, Balboa, Repfiblica de Panama bUniversity of Miami, Rosenstiel School of Marine and Atmospheric Science, Division of Marine Biology and Fisheries, 4600 Rickenbacker Causeway, Miami, Florida 33149, USA ABSTRACT: Diverse environments including rocky, sandy and muddy shores as well as mangrove forests, small isolated seagrass beds, and coral reefs are typical of the Pacific coast of Panamfi. The coast is divided by the Azuero Peninsula into two major areas with contrasting oceanographic settings, the non-upwelling Gulf of Chiriqui to the west and the upwelling Gulf of Panamfi to the east. The largest coral reef development is in the Gulf of Chiriqui. Whereas, cool upwelling waters are probably responsible for the poor development of coral reefs in the Gulf of Panama. Most coral reefs and coral communities are located on islands distant from the mainland runoff and tidal exposure. The branching coral Pocillopora is the chief reef-builder in shallower areas (< 5 m) while massive Porites and Pavona play a more important role at greater depths. There are 23 zooxanthellate scleractinians plus three zooxanthellate milleporid corals currently reported for the Pacific coast of Panamfi. Nineteen species are found in the GulfofChiriqui, and 17 species in the Gulf of Panama. Of these, six species occur only in the Gulf of Chiriqui and four occur only in the Gulf of Panamfi. The three most speciose coral genera are Pavona, Pocillopora and Psammocorawith seven, five and four species respectively. Twenty-two coral reefs and coral communities are described in terms of their coral species richness. Coral reef studies in the Panamanian Pacific have focused around two main topics: (a) the reproductive ecology of coral species, and (b) the ecological responses of coral communities to E1Nifio sea warming. The former study has shown that the coral reproductive activity is related to thermal regimes and has resulted in five publications involving eight species in four genera. The latter is probably the most important natural disturbance influencing Pacific Panamanian reefs and is treated with five other natural disturbances including upwelling, subaerial exposures, dinoflagellate blooms, terrestrial runoff and Acanthasterplanci which play important roles in structuring coral reef communities in Panama. In addition, there are four main anthropogenic stressors influencing Panamanian reefs: coral extraction, ship groundings, herbicides, and overfishing. There are three National Parks and two Wildlife Refuge that include coral reefs or coral communities in the Panamanian Pacific. Additional aspects of management and protection of coral reefs related are addressed.
1. I N T R O D U C T I O N The e m e r g e n c e o f the Isthmus o f Panarnfi s o m e 3.2 to 3.5 mi l l i on years ago m a r k e d the closure o f the B o l i v a r Seaway, which until then s u p p o r t e d a c o n t i n u o u s Pacific and C a r i b b e a n m a r i n e biota ( C o a t e s et al. 1992). The environmental changes resulting from this event h a d i m p o r t a n t implications on the d i v e r g e n ce o f transisthmian e n v i r o n m e n t s that included coral r e e f formations and their respective biotas (Porter 1974; Glyrm 1982; B u d d 1989). N o P l e i s t o c e n e r e e f outcrops or coral fossils have b e e n found on the Pacific shores o f P a n a m a p r o b a b l y due to the active t e c t o n i s m and v u l c a n i s m that has significantly Latin American Coral Reefs, Edited by Jorge Cort6s 9 2003 Elsevier Science B.V. All rights reserved.
388 J. L. Mat6
Fig. 1. A. Map of Panama showingexplored and collecting sites in detail: B, the central portion ofthe Gulf of Chiriqui; C, Bay of Panama; and D, the Pearl Islands. Encircled numbers point to 23 sites to which descriptions or species compositions are provided in this paper: 1, Coiba Island; 2, Uva Island; 3, Unnamed Island; 4, Canal de Afuera Island 5 , Silva de AfueraIsland; 6, Restinge Island; 7, Ladrones Islands; 8, Montuosa Island; 9, Jicar6n Island; 10, JicaritaIsland; 11, Cdbaco Island; 12, Iguana Island; 13, Taboga Island; 14, Urabh Island; 15, Taboguilla Island; 16, Otoque Island; 17, Saboga Island; 18, Contadora Island; 19, San Telmo Island; 20, Pacheca Island; 21, Cavada Island;22, Southwesternmost Island; 23, Mogo Mogo Island.
Corals and coral reefs of the Pacific coast of Panam6
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contributed to the land formation of the region (Glynn and Mat6 1997). The La Boca Formation of mid-Miocene age, which contains the youngest fossil reefs on Panama, contain a mixture of modem Pacific and Caribbean genera, e.g., Acropora, Montastraea, Porites, Astreopora, Goniopora, Goniastrea, Pavona, Pocillopora and Stylophora (Budd et al. 1994). The 2,866 km of coastline of the Republic of Panarrfi on the Caribbean Sea and Pacific Ocean is bordered by diverse environments that include rocky, sandy and muddy shores as well as mangrove, limited seagrass beds and coral reefs to the south, the Pacific coast of Panarrfi, extends for 1,697 km and is divided by the Azuero Peninsula into two major oceanographic areas, the Gulf of Chiriqui to the west and the Gulf of Panarmi to the east (Fig. 1). These areas are exposed to different regimes of seawater temperature, salinity and nutrient concentrations as a result of the wind-induced nutricline shoaling and upwelling that occurs during the dry season (D'Croz et al. 1991). The dry season in Panarr~ that extends l~om mid-December to mid-April is the result of the movement of the Intertropical Converge Zone (ITCZ) south of Panam~ (Wooster 1959). During this time, there are clear skies and strong North-East to North Trades Winds. Trade winds crossing the Isthmus are twice as strong in the Gulf of Panarmi than in the Gulf of Chiriqui. The upweUing that occurs during the dry season in the Gulf of Panamh decreases sea surface temperatures from 27-28~ to 1822~ (Glynn and Mat6 1997). The upwelling cool waters are probably partly responsible for the poor development of coral reefs in the tropical eastern Pacific generally and in the Gulf of Panarrfi in particular (Dana 1975; Glynn 1982; Glynn and Wellington 1983). The Field Guide to the Pacific Coral Reefs ofPanam~ (Glynn and Mat6 1997) is the only compilation of research done on the Panamanian Pacific reefs. This chapter expands the information presented in Glynn and Mat6 (1997) field guide, describing new areas and providing more insight into past and current research, problems and management plans for the Pacific coast of Panal~. First, aspects of coral reef diversity are presented. The exploration of new sites has revealed a rich coral biota. New species have been found, some of which have been akeady described or are in process of being described. Second, information on 23 coral communities and coral reefs in the Panamanian Pacific is provided. Third, the results of major advances on coral reproductive ecology are addressed. These results come from a major research effort initiated by P.W. Glynn and colleagues approximately fifteen years ago. Fourth, natural disturbances and anthropogenic stresses that periodically or permanently influenced Panamanian reefs are discussed: six types of natural disturbances and four types of anthropogenic stresses are discussed. Fifth and finally, the findings of years of coral reef research in Panal~ have contributed to the implementation of new management laws and the creation of protected areas. 2. SPECIES DIVERSITY
There have been seven provisional lists ofzooxanthellate scleractinian and zooxanthellate hydrocorals from the Pacific coast ofPanarrfi (Glyrm 1972; Glynn et al. 1972; Porter 1972; Hoist and Guzmain 1993; Glynn 1997a; Glynn and Mat6 1997; Glynn and Ault 2000). The Hoist and Guzn~n (1993) list has remained relatively tmchanged with the only modifications related to the addition of new species: Siderastrea glynni Budd & Guzm~ (1994), Pocillopora inflata Glynn (1999), and three tmdescribed species, Pavona sp.a (the species has been recently described as Pavona chiriquiensis Glynn, Mat6 and Stemann 2001), Pavona sp.b and Psammocora sp.a. The two most specious genera are Pavona and
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Pocillopora with seven and five species respectively, followed by P s a m m o c o r a with four. The
maximum number of living zooxanthellate corals (scleractinian and hydrocorals) found in the GulfofChiriqui is 19, while in the GulfofPanarrfi 17 species (Tables 1, 2). The total number of coral species in the Panamanian Pacific will certainly change as the number of sites explored increases, and previously misidentify species are reviewed, and as both natural and anthropogenic events cause local extinctions of species (e.g., E1Nifio events, see Glynn et al. 2001). Glynn et al. (1972) stated that many of the taxonomic problems posed by species of Pavona, Porites and Pocillopora have not been resolved. Many of these problems still exist today. Although, multidisplinary techniques (e.g. molecular, ecological and morphological) are helping to resolve them. An update on the status of the newest species, as well as, current research on coral systematics in the Panamanian Pacific is provided below. TABLE 1 Zooxanthellate scleractinia, and zooxanthellate hydrocorals from the Pacific coast of Panam~i. ?: species presence not confirmed by the author; x: species present at that site; -: species not observed at the site; *: only found dead. Species Pocillopora damicornis (Linnaeus) Pocillopora elegans Dana Pocillopora meandrina Dana Pocillopora eydouxi Milne-Edwards and Haime Pocillopora inflata Glynn Porites lobata Dana Porites panamensis Verrill Pavona gigantea Verrill Pavona clavus (Dana) Pavona maldivensis (Gardiner) Pavona varians Verfill Pavona frondifera (Lamarck) Pavona chiriquiensis Glynn, Mat6 and Stemann Pavona sp.b Leptoseris papyracea (Dana) Gardineroseris planulata (Dana) Psammocora stellata (Verrill) Psammocora superficialis Gardiner Psammocora obtusangula (Lamarck) Psammocora sp.a Siderastrea glynni Budd and Guzm~m Millepora intricata Milne-Edwards Millepora boschmai Weerdt and Glynn Millepora platyphylla Ehrenberg Diaseris distorta (Michelin) Cycloseris curvata (Verrill)
Number of species
Gulf of Panama
Gulf of Chiriqui
x
x
x
x
-
x
x
x
x
*
x
x
x
x
x
x
x
x
9
?
x
x
x
x
x
x
x x* x
x
x
x
x
x
-
x
o
x
x
-
-
x
-
x*
-
x*
x*
x*
x*
x
20
22
Corals and coral reefs of the Pacific coast of Panamd
391
Fig. 2. Views of colonies of (A) Siderastrea glynni; (B) Pocillopora inflata; (C) Cycloseris curvata; (D) Millepora intricata surroundingPocillopora elegans; (E) DeadMillepora boschmai; (F) Pavona sp.b. Siderastrea glynni Budd and Guzn~n (Fig. 2A) is an extremely rare and possibly an endangered species that is endemic to Urab~ Island (site 14, Fig. 1B), Panama Bay (Budd and Guzm~ 1994). The four known colonies of this species are unattached (coralliths or"rolling stones" sensu Glynn 1974a), spheroidal in shape and approximately 7-10 cm in diameter at a depth of 7-8.5 m along the upper sand-coral rubble reef slope. Due to the unhealthy state of the corals, they were moved to the Smithsonian Tropical Research (STRI) aquaria. Pocillopora inflata Glynn (Fig. 2B) is a rare to uncommon eastern Pacific pociUoporid coral recently described (Glyrm 1999). It is found only in upwelling environments within the Gal~pagos Islands, PanamA, Costa Rica and M6xico. Pocillopora inflata is distinguished from other Pocillopora by the swollen terminal or subterminal branches, the acute verrucae which are few in number or absent, and the columellae prominent in calices at mid to lower branch levels (Glynn 1999). In Panamfi it is found at two sites, Saboga and Contadora Islands (sites 17-18, Fig. 1D). The largest known population of this species is found at the former site (Glynn 1999).
x x
2 x x
Pocillopora eydowci Pocillopora inflata Porites lobata Porites panamensis Pavona gigantea Pavona clavus Pavona maldivensis
-
x
3 x x x
-
-
-
x x x x
x x x x
x x x x
?
-
-
x x x
x x x
x -
-
-
x x -
x x x
1
Pavona varians Pavonafrondifera Pavona chiriquiensis Pavona sp.b Gardineroseris planulata Psammocora stellata Psammocora superfcialis Psammocora obtusangula Psammocora sp.a Siderastrea glynni Cycloseris curvata Tubastrea coccinea Millepora intricata Number of species
-
-
x x x
-
-
x x 15
x x x x x x x
x x x 14
5 x x x x x x
6 x x x x x x
7 x x x x x x x
8 x x x
9 x x x
10 x x -
-
-
-
x x x
x x x x
x x x x
-
-
-
11 x x -
12 x x x
13 x x
x x
15 x x
16 x x
17 x x
18 x x
-
x x x x
x x x x
x x x x x
x x x x x
x x x
x x x x
-
x x
x -
x -
-
-
-
14
-
-
-
x x x x
x x x x
x x x x
x x x x
-
?
-
-
x
x
x
x
x
x
x
x
x
x
x
-
x
x
x
x
-
x
-
x
x
-
-
-
-
-
-
-
-
-
x -
x x
x x x
x x x
x
-
-
-
x x 14
4
-
-
-
x x 11
x 11
x
x
x x x
_ x
-
x
-
x
-
x -
-
-
-
_
x
x
-
x
-
_ _ -
-
-
-
-
x
x
x
-
-
-
-
20 x x
-
-
x x
-
-
-
x x x
x -
x
-
-
_
-
-
x
x
x
x 9
-
-
-
-
x
-
-
-
x
x
x
-
x
x
x
-
-
-
-
-
-
-
-
-
-
-
13
12
11
10
11
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Pocillopora damicornis Pocillopora elegans Pocillopora meandrina
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TABLE 2 Living zooxanthellate, one azooxanthellate, and zooxanthellate hydrocorals from the Pacific coast of P a n a d . Gulf of Chiriqui: 1, Coiba Island; 2, Uva Island; 3, Unnamed Island; 4, Canal de Afuera Island; 5, Silva de Afuera I; 6, Restinge Island; 7, Ladrones Island; 8, Montuosa Island; 9, Jicar6n Island; 10, Jicarita Island; 11, Cebaco Island. Gulf of P a n a d : 12, Iguana Island; 13. Taboga Island; 14, Uraba Island; 15, Taboguilla Island; 16, Otoque Island; 17, Saboga Island; 18, Contadora Island; 19, San Telmo Island; 20, Pacheca Island. Four species are currently believed to be locally extinct Leptoseris papyracea, Diaseris distorta, Millepora plafyphylla, and Millepora boschmai. x: species present at that site; -: species not observed at that site; ?: species presence not confirmed by the author.
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The two Porites species from the Pacific coast ofPanam~ (Porites lobata and P. panamensis) can be identified by allozyme electrophoresis and morphometrics analyses (Weil 1992). In addition, populations of P. panamensis from both the Gulf of Panarrfi and the Gulf of Chiriqui are not only genetically distinct, but also morphologically distinct. Colonies from the Gulf of Panamfi are characterized by crustose-massive, yellow or yellow-green colonies, while those specimens from the Gulf of Chiriqui are smaller, foliose and green (Weil 1992). Cycloseris curvata (Fig. 2C) status on Panamanian reefs has been upgraded from only known from dead specimens (Glynn and Mat6 1997) to live specimens observed recently. Two specimens were found at 14 m depth in the slopes of Unnamed Island (Secas Islands; site 3, Fig. 1B) during February 2001. Four species of zooxanthellate hydrocorals are known from the eastern Pacific, Millepora intricata (Fig. 2D) Milne Edwards, Millepora platyphylla Hemprich and Ehrenberg (Boschma), Millepora boschmai (Fig. 2E) de Weerdt and Glynn, and Millepora exaesa Forsk~l. The former three species are found in Gulf ofChiriqui (Glynn et al. 1972) and the latter species is found at Clipperton Atoll (Glynn et al. 1996a). Millepora boschmai is endemic to the Gulf of Chiriqui. Millepora platyphylla is believed to be locally extinct since no live colonies have been seen in the Gulf of Chiriqui since 1983 (Glynn et al. 2001). While Millepora boschmai was reported as extinct at the time of the species description (de Weerdt and Glynn 1991), five live colonies were later found at Uva Island (Glynn and Feingold 1992). These colonies are now dead and no other live colonies have been found at Uva Island during the latest February 2001 survey. Three other colonies ofM. boschmai that survived the 1992-83 E1Nifio were reported from Coiba Island (Brenes et al. 1993). One of the colonies was found dead during May 2000 survey. This species is believed to be extinct (Glynn et al. 2001). In a recent study, Mat6 (2001) studied the ecological, electrophoretic and morphological differences of six species of the coral genus Pavona reported from the Pacific coast of Pananfi and one new species that will be named in a forthcoming study. These seven species are Pavona clavus, P. gigantea, P. maldivensis, P. varians, P. frondifera, Pavona sp. a (has been described as P. chiriquiensis by Glynn et al. 2001) and Pavona sp. b (Fig. 2F). P. maldivensis was not found in Panarrfi during this study.
3. DESCRIPTION OF REEF AREAS Nearly all reef development occurs on protected shores, i.e. in areas not subject to continuous, strong wave assault. Some reefs are found on exposed shores, however, at the Secas Islands (see below). Panamanian Pacific coral reefs have Pocillopora (Fig. 3A) as the main reef constructor on the shallower areas (< 5 m). The reef framework is stabilized by rigid interlocking Pocillopora branches (Glynn et al. 1972). Massive coral species, such as Porites and Pavona (Fig. 3B), play a more important role than Pocillopora around the reef base and at greater depths (Glyrm et al. 1972).
3.1. Gulf of Chiriqui The best coral reef development on the Pacific coast of Panarrfi occurs in the Gulf of Chiriqui (Figs. 1A, B; Glynn and Mat6 1997). Core drilling of these reefs has shown that the reefs rest on basaltic foundations (Glyrm and Macintyre 1977). The best-developed reefs have vertical buildups of 10 - 12 rn and maximum ages of 5,600 years (Glyrm and Macintyre
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Fig. 3. (A) Pocillopora damicornis is the chief reef builder in the Panamanian Pacific. Pocilloporid corals dominate the shallower sections of the reef up to a 5 m depth. 03) Large massive species such as Pavona clavus dominate the deeper parts of the reef below 5 m depth.
1977). Most coral reefs and coral communities are located off islands, however, there are a few fringing and patch pocilloporid reefs on the mainland, mainly at Ensenada de Muertos and between Bahia Honda and Punta Entrada (Fig. 1B; Glynn and Mat6 1997). Table 2 presents the distribution of living zooxanthellate, one non zooxanthellate and hydrocorals at 11 sites in the Gulf of Chiriqui.
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3.1.1. Coiba Island. Coiba, the largest island in the Panamanian Pacific harbors a 136 ha reef that it is considered the largest reef in the continental coast of the Americas (site 1, Fig. 1B). The reef is divided into three groups of 46.1 ha, 20.3 ha and 69.6 ha (Anonymous 1993). The maximum reef thickness is 9.4 m (Glynn and Macintyre 1977). The largest massive (Porites lobata and Pavona spp.) corals in the reef, reaching up to 4 rn in diameter, are found in the first group (Glynn and Mat6 1997). Reef development occurs close to a small river delta with abundant sediment up to a depth of 5.5 m. Extensive mud/sand fiats are present between the sand beach and the shallowest occurring corals on the reef fiat. Mean live coral cover on the reef was 17.1%. Specific composition along reef transects surveyed included Pocillopora damicornis (90.5%); Psammocora spp. (8.6%), P. varians (0.7%) and Porites lobata (0.7%). Few live corals occur deeper than 10 m. 3.1.2. Contreras Islands. The Contreras Archipelago, slightly to the northeast of Coiba Island, is compose of three main islands: Uva, Brincanco and Pfijaros, and several islets. While corals are abundant on the islands, only Uva Island has a well developed reef framework. Uva Island. The 2.5 ha patch reef located at the north side of Uva Island (site 2, Fig. 1B) has been continuously studied since 1970 (Glynn and Mat6 1997). Reef accumulation rates of 2 to 10 m/l,000 years are possible (Glynn and Macintyre 1977). Four major areas are identified on the reef (Eakin 1991): 1. seaward reef base, 2. fore reef slope, 3. reef flat, 4. leeward back reef. The first two areas are bordered by sand/rubble while the other two areas are bordered by sand/silt. Reef building is most active at deep of 1 to 3 m in the reef slope zone, which is dominated for pocilloporid corals. The belt of live coral, ranging from 3 to 30 m wide, completely surrounds the reef flat (Glynn and Mat6 1997). This nearly continuous tracts of interlocking pocilloporids impart a certain cohesiveness and strength to this part of the reef. Gardineroserisplanulata is the main massive species. The reef flat, dominated by crustose coralline algae, with live coral cover accounting for only (10-20%) except in depressions and along the seaward front where live coral cover may approach 70-80% (Glynn and Mat6 1997). The reef flat experiences extreme tidal exposures that subject the coral to cycles of growth, death and regeneration that seems to contribute to the persistence of this geomorphologic structure (Glynn and Mat6 1997; Eakin in press). Total live coral cover has been reduced from 45.0% in 1981 (Glynn 1985a) to 28.2% in 1988 (Guzrn~n and Robertson 1989). This reduction in coral cover has been mainly attributed to E1Nifio sea warming and red tides coral mortalities. Coral cover began a steady increase in the mid- 1990s reaching 36% in 2000 (Eakin 2001). Coral cover was not affected greatly by the 1997-98 E1 Nifio (Eakin 2001). 3.1.3. Seeas Islands. The Secas Islands are located northwest of the Contreras Islands and are composed by approximately 15 basaltic islands, islets and many shoals (Fig. 1B). There are five major islands with four of them harboring structural or incipient reefs (Glynn et al. 1972). Cavada Island is the largest of the Secas Islands and the only one with a proper name. Unnamed Island. This 7.6 ha reef is probably one of the most scenic reefs in the Gulf of Chiriqui and has been under continuous study since the early 1970s (site 3, Fig. 1B, see Glynn and Mat6 1997). The reef has a maximum reef thickness is 13.4 m. The morphology of the reef front changes from year to year due to the collapse of framework blocks that
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break away from the main reef structure. This collapse give to the fore reef (2-8 m depth) a landscape of meter-size pocilloporid blocks to attain various positions-uptight, tilted, overturned, slmnped and occasionally upside down (Glynn and Mat6 1997). The collapse of the pociloporid blocks at the northwest comer of the reef have exposed numerous colonies of the normally cryptic non zooxantheUate coral Tubastrea coccinea. These are know 2-3 m depth, attached to pocilloporid blocks and directly exposed to downwelling irradiance (Fig. 4). Large massive species are scattered on the seaward slopes along the sand-rubble bottom including Porites lobata, Pavona clavus, P. gigantea and Gardineroseris planulata. Porites lobata colonies may attain 3-4 rn in height. The fire coral Millepora intricata is patchily distributed in both the northwest and southeast comers of the reef up to a depth of 20 m. These colonies are ephemeral, appear and suddenly, proliferating rapidly and then dying off, all over a period of about 3 years (Glynn and Mat6 1997). The reef flat is solid and can be easily transverse at low fide. A 2-4 m deep, 15-40 m wide basin is present between the back side of the reef flat and the shoreline (Glynn and Mat6 1997). The internal structure of the pocilloporid framework underlying the leeward reef fiat can be easily examined on the exposed sides of the reef fiat. This is one of the few reefs in the Panamanian Pacific were Acanthaster planci can be found. Cavada Island. The 5.1 ha reef has a maximum reef thickness of 9.4 m (site 21, Fig. 1B; Glynn and Macintyre 1977). There are extensive rubble/sand beds below 4 m depth. Scarce colonies ofPsammocora stellata and Pocillopora damicornis intermingling with algal mats are found between 10-15 m depth. Most of the reef framework is dead and covered by algae. The only live reef framework is located in the central-north section of the reef and formed by patches of Pocillopora damicornis and P. elegans approximately 6 x 10 rn in planar dimension. Massive coral species are relatively small (< 30 cm in diameter), with sexual recruits of Porites lobata being abundant. The reef framework begins at approximately 5 m depth. The seaward side of the reef has meter-size pocilloporid coral blocks in normal growth position. Coral condition is generally poor. The massive species are mostly dead with small section of live tissue more commonly seen along the rim of the colonies. Southwestern most island in the Seeas group. The description from this site (site 22, Fig. 1B) comes from Glynn et al. (1972). Since no scientific visits to the island have been made since Glynn's publication, no details are provided on current condition. In contrast to most reefs in the Panamanian Pacific, this large structural reef is located on the seaward and south side of the island. This reef is developed in the central portion of the mouths of coves, and not along the exposed headlands. Extensive patches of Pocillopora dominate the shallow sections of the reef up to 5 m depth. Large dislodged pocilloporid blocks at 3-4 m depth attest to storm and swell damage (Porter 1972). Large colonies ofPavona clavus (P. clivosa in Glynn's paper) appear at 5 rn depth and intermingle with Pocillopora species. At depths of 7-10 rn, large colonies of Pavona clavus (2 m in height and 3-4 m in diameter) dominate the area. Abundant coral growth was found at depth greater than 10 m. Adjacent to the reef base, the rubble bottom contains numerous coralline algal nodules. 3.1.4. Canal de Afuera Island. The 1.2 ha reef is located on the leeward north shore of the island, is shared with an islet that protects its north flank (site 4; Fig. 1B). The reef is constructed almost exclusively by Pocillopora damicornis. Reef framework construction can be observed up to a depth of 3.6 m. Live coral cover is 30.9% (Anonymous 1993).
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Fig. 4. Collapsedpocilloporidblocks at the northwestside of the unnamed island reef, Secas Islands,have exposed numerous colonies of the normally cryptic azooxanthellate coral Tubastrea coccinea to well illuminated areas in pocilloporidblocks. Species such as Pocillopora elegans, Porites lobata, Pavona varians and Psammocora stellata are often encountered in the reef. The basaltic rocky shores around the island have a richer coral fauna than the reef itself. This is one of two sites in Panal~ where Pocillopora meandrina has been found. Afuerita Island, located NW of Canal de Afuera Island, harbors the only known population of the fire coralMillepora intricata in that area (Glynn and Mat6 1997), however, its current status is unknown. 3.1.5. Silva de Afuera Island. Even though the coral reef at Silva de Afuera is one of the closest to mainland and is subject to runoff during the rainy season, there is an extensive Pocillopora framework on the northeast side of the island (site 5, Fig. 1B). The Pocillopora framework is built over a basaltic rock substrate dominated by large boulders where a diverse coral community exists. The most abundant species outside the reef framework are Pavona clavus and Porites lobata which dominate the sandy substratum adjacent to the rocky boulders. Other less common species included Pocillopora eydouxL Gardineroseris
planulata, Psammocora superficialis, Pavona gigantea, P. varians, Pavona chiriquiensis and Porites panamensis. A diverse octocoral community that thrives below 15 m includes Pacifigorgia, Leptogorgia and Muricea. 3.1.6. Restinge Island. No coral reefs are present on the island. However, a few small patches (1 m 2) consolidated P. damicornis framework were observed between 2-4 m, on the northeast side of the island (site 6, Fig. 1A). Deeper parts of the reef (4-6 m) were dominated by Pavona clavus. The presence of Pavona chiriquiensis, represents the easternmost distribution of this species in the Gulf of Chiriqui. The northwest side of the
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Island is subject to intense wave action, and is dominated by octocorals (particularly sea fans) and sponges. Scleractinian corals are extremely rare in the area and, when present, are limited to small encrusting forms. 3.1.7. Ladrones Islands. The Ladrones are composed of three basaltic islands and is one of two sites in Panarrfi where Pocillopora meandrina has been found (site 7, Fig. 1B). Dana (1975) provided the first report of corals at Ladrones Islands, however, no coral reefs were present. An incipient Pavona clavus reef can be found at the northeastern side of the islands. The branching coral P. elegans and large massive species such as Porites lobata, P. gigantea and Gardineroseris planulata, reaching sizes over 1 m in diameter, are the most common species. Other coral species observed in patchy distributions included Pavona
varians, Pavona chiriquiensis, Porites panamensis, Pocillopora damicornis and P. eydouxi. 3.1.8. Montuosa Island. Montuosa is the most isolated island in the Panamanian Pacific (site 8, Fig. 1B). The island was visited in the early 1970s (Glynn et al. 1972, Dana 1975) who reported the presence of coral communities in the area, without describing them in detail. Porites lobata is by far the most common scleractinian species with >300 colonies (>1.5 m) recorded along the north shore (NE-NW). A solid reef framework is located at the northeast side of the island. In contrast to other reefs in the Panamanian Pacific, this reef is completely built by Porites lobata with some intermingled colonies of Pavona clavus, which is also very common. The highest coral diversity is on rocky outcrops within 2 km of the island. Corals have been observed at depths to 20 rn, with Porites lobata, Pavona clavus and Pocillopora eydouxi being the most common species at those depths. Two of the less common species include Porites panamensis and Pavona gigantea. There is much less coral on the south side of the island, which experiences heavy swells. 3.1.9. Jiear6n Island. Jicar6n Island (site 9, Fig. 1B) is the second largest island in the Parque Nacional Coiba after Coiba Island itself. There are no true coral reefs present at Jicar6n. The northern part of the island is dominated by a rich coral community where large massive corals, mainly Porites lobata, Pavona clavus and Gardineroserisplanulata, are the most conspicuous species. Other species found in the area include the pocilloporid corals Pocillopora damicornis and P. elegans. Uncommon species include Pavona gigantea and Porites panamensis. Only one specimen ofPocillopora eydouxi and no hydrocorals have been observed at this site. 3.1.10. Jiearita Island. Jicarita Island is the southernmost island on the Panamanian Pacific shelf (site 10, Fig. 1B). There are no true coral reefs present at Jicarita. However, the embayment on the northeast side of the island harbors a rich coral reef community dominated by large massive species such as Porites lobata, Pavona clavus, P. gigantea, and Gardineroseris planulata, the first two of which are the largest and most abundant. Other species present include Pavona chiriquiensis, Psammocora superficialis, Pocillopora damicornis, P. elegans, and the non-zooxanthellate scleractinian Tubastrea coccinea. No hydrocorals have been observed at this site. Basaltic rock is the main substratum for coral settlement. Pocilloporid corals, especially Pocillopora elegans, are more common on the denuded basaltic rock close to mean low water sea level. However, Pocillopora damicornis is most common in the deeper areas of the rocky outcrop and on sandy rubble substrates (10
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m depth). Large numbers of sea fans occur on the west side of the island, which is exposed to strong wave action. The north side of the island is separated from Jicar6n Island by a shallow (<10 m) sand channel. Large numbers of Porites lobata colonies (>2 m in diameter) dominate rocky protected areas in the channel. The south side of Jicarita is a near vertical rocky cliff exposed to heavy wave action. The bottom flattens out at approximately 34 m depth. Large and thick branching styUasterinid corals are very common in the basaltic walls below 15 m. These styllasterinid corals have not been found elsewhere on the Pacific coast of PanamA. Octocorals, including species of Pacifigorgia and Leptogorgia, are extremely abundant at all depths and attain large sizes. Porites lobata is found at 30 m depth and represents the species with the deepest distribution in the Pacific coast of Panamfi. Pavona gigantea is commonly seen at 20 m depth. However, these colonies rarely exceed 10 cm in diameter, and grow encrusting the substratum. 3.1.11. Cfibaeo Island. No coral reefs were observed, but coral reef communities developing on basaltic boulders are extremely abundant and appeared to be in good condition with little impact from the 1997-98 E1 Nifio (site 11, Fig. 1A). Massive species such as Pavona clavus, P. gigantea and Porites lobata are abundant but rarely exceed 2 m in diameter. The branching species Pocillopora elegans is more common than Pocillopora damicornis, as is commonly the case on rocky substrata in the Panamanian Pacific. Other species included Pavona varians, some colonies coveting an area >25 m2. Some large colonies of Porites panamensis can also be seen (10 x 5 cm). The massive species Gardineroseris planulata is rare. 3.2. Gulf of Panamh Three major areas where corals and coral reefs have been identified in the Gulf of Panamfi are: the larger islands of PanaroA Bay (Figs. 1A, C), the Pearl Islands, mainly in the northern sector of the Archipelago (Figs. 1A, D), and Iguana Island (site 12, Fig. 1A). Core drilling of these reefs has shown that they rest on basalt foundations (Glynn and Macintyre 1977). The best-developed reefs have vertical buildups of 5.6-6.1 rn and maximum ages of 4,500 years. Even though reef development in the Gulf of Panamfi occurs almost exclusively on islands, a small patch reef is found on the mainland in Pifias Bay, near the Colombian border (Fig. 1A; Glynn and Mat6 1997).
3.2.1. Panam~i Bay. Panarnfi Bay, located at the northern end of the GulfofPanarnfi (Figs. 1A, C), differs from the rest of the Gulf in terms of its hydrography and proximity to anthropogenic sources of stress (D'Croz 1988; D'Croz et al. 1991; Jackson and D'Croz 1997). Coral reefs and coral communities are found mainly in the islands of Taboga, Taboguilla, Urabfi and Otoque (Birkeland 1977; Glynn 1982; Guzrnfin and Hoist 1994). There are also other smaller islands where scattered corals can be found, such as Charnfi, T6rtola and Melones (Guzmfin and Hoist 1994). Taboga Island. The 2 ha pocilloporid reef structure in the northeast sector of the island just in front of the town of Taboga (site 13, Fig. 1C) is almost completely dead (Guzrnfin and Hoist 1994). The death of this reef has been attributed to the seawater warming during the 1982-83 E1Nifio (Glynn 1984a). Live coral cover before 1983 was 53.9%. After the 1982-83 E1Nifio coral cover was reduced to 5.9% (Glynn 1984a). A more recent survey revealed less than 0.5% coral cover (Guzmfin and Hoist 1994). Coral rubble substratum is
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almost entirely covered by crustose coralline algae. On the northwest side of the island one of the richest coral communities on the island has been observed. This community has formed on basaltic rock and is dominated by large massive species such as Pavona gigantea, P. clavus and Porites lobata. Other common coral species are Pocillopora damicornis, P. elegans, Pavona varians, Porites panamensis and Psammocora stellata. This last species is represented by a single patch approximately 60 cm in diameter. Urabti Island. Even though this is a small reef close to the Pacific entrance of the Panarrfi Canal (site 14, Fig. 1C), it is the largest aggregation of living pocilloporid corals in Panam,~ Bay. The community is dominated by Pocillopora damicornis. GuzlIfin and Hoist (1994) estimated the Pocillopora cover at 20%, with two other species - Pavona clavus and Psammocora sp. - contributing with 2% cover each. The deeper parts of the community are dominated by medium (> 1 m) size colonies ofPavona gigantea. Siderastrea glynni Budd and Guzrrfin the only siderastreid in the eastern Pacific, is found only at Urab~ Island, with a population of a mere four colonies on the deep sand-rubble slopes. However, as reported previously they have been moved to the STRI aquaria. Taboguilla Island. One of the first reports of corals at Taboguilla Island comes from Birkeland (1977), who noted the presence of an extensive area of nearly solid Pocillopora cover, and large colonies of Porites forming an incipient reef on the north side, opposite to the upwelling (site 15, Fig. 1C). In addition, he found scattered colonies of Pocillopora and Pavona on the south (upwelling exposed) side of the island. The coral on this reef is mostly dead. Guznfin and Hoist (1994) reported the presence of small (200 m 2) patches of corals on the northwest side of the island. These colonies are growing over a rocky or sandy bottom. Large numbers ofPavona gigantea have also been found on the southwest side of the island. Colonies are growing at the base of the rocky substratum or on the sandy bottom at >10 m. The shallower rocky areas are almost denuded of corals, although a few encrusting colonies ofPociIlopora elegans and Porites panamensis do occur. Otoque Island. This site was visited very briefly during 1995. The reef was located at the northeast end of the island (site 16, Fig. 1C) and was completely dominated by Pocillopora damicornis and P. elegans. On the north side of the island, where the bottom is dominated by sand and basalt boulders, a few medium sizes colonies ofPavona gigantea have been found. 3.2.2. Pearl Islands. The Pearl Islands, a group of 53 basaltic rock islands, islets and many shoals, are located about 73 km southeast of Panarrfi city and 31 km offshore from the main coast of Panarrfi (Figs. 1A, C). The largest aggregation of coral reefs in the GulfofPanan~ occurs here (Glynn and Mat~ 1997). Coral reef development is more abundant and attains greater dimensions on the northem and eastern sides of the islands, where they are sheltered from the coldest upwelling waters (Glynn and Stewart 1973; Glynn 1977a; Glynn and Macintyre 1977). Coral reefs are always developed shoreward of the 5 to 6 m isobaths. Saboga Island. The Saboga reef(site 17, Fig. 1D), located on the northeast shore of the island, has an estimated age of 3,800-4,500 yr and a mean accumulation rate of 1.3 m/l,000 yr (Glynn and Macintyre 1977). Tuffaceous sandstone forms the basement of this 14.3 ha reef. The reef has a maximum thickness frameworks of 5.6 m (Glynn and Macintyre 1977). The reef structure is dominated by pocilloporid corals, mainly Pocillopora damicornis, and extends to 3-4 m below mean low water. The pocilloporid corals cover 70-80% of the bottom of the seaward slope zone. Pocillopora elegans and massive species of Pavona,
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Porites and Gardineroseris also contribute to the reef structure. Coral cover for the whole reef is 39.5% (Guzmgn and Robertson 1989). Three areas on the Saboga reef can be distinguished (Glyrm and Mat6 1997). The largest area is a monospecific patch of Pocillopora damicornis. A large patch ofPavona clavus is located at the southeast border of the patch (Glynn and Mat6 1997), and the northwest edge of the patch is border by Pavona gigantea and Gardineroserisplanulata. Close to the G. planulata colonies are the only known colonies of Pavona frondifera in the Gulf of Panan'ui. The second area is located near an emergent basaltic shoal. It is formed mainly by a nearly monospecific stand of Pocillopora elegans, with a mixture of highly eroded mushroom-shaped colonies of Porites lobata (Glynn and Mat6 1997). The third and smallest area is composed of a patch of Pocillopora inflata (Glynn 1999). More than 100 colonies of Pocillopora inflata are intermixed with Pocillopora damicornis at about 5 m depth. It is possible to find dead and intact (suggesting they are freshly dead) fragments (5-10 mm long) of Leptoserispapyracea scattered among the bottom sediments, but live specimens have not yet been found anywhere in Panarn~ (Glynn and Mat6 1997). This is one of two sites where Pavona chiriquiensis can be found in the Gulf of Panarn~. Contaflora Island. The relatively narrow shelf that borders the north coast of Contadora has many small patch reefs (site 18, Fig. 1D). The largest of these reefs is formed on tuffaceous sandstone and is located at the northeast end of Contadora. It measures 11.7 ha and has a maximum reef thickness of 4.6 m (Glynn and Macintyre 1977). Maximum depth of reef framework construction is 3-4 m below mean low water level (Glynn and Mat6 1997). Coral cover is approximately 15% (Guzm~n and Robertson 1989). The reef flat is covered by sand, crustose coralline algae and small eroded fragments of dead Pocillopora branches. The west section of the reef is dominated by hundreds of micro-atoll colonies of Porites lobata located on a wide and shallow shelf. These microatolls form monospecific patches where Pocillopora spp usually predominates. The northwest sector of Contadom supports reef development covering nearly 6 ha reef development occurs on a series of juxtaposed tuffaceous sandstone ridges (Glynn and Stewart 1973). Branching pocilloporid species predominate in the deeper zone, while larger colonies of the massive coral Gardineroseris planulata and Pavona clavus (measuring > 3 m in diameter) are more abundant in the shallower zone. Scattered colonies of Pavona gigantea (0.5-1 m in diameter) are found deeper than the pocilloporids. Porites panamensis dominates the exposed sandstone ridges. Paeheea Island. Pacheca, and its satellite island Pachequilla are the northernmost of the Pearl Islands (site 20, Fig. 1D). The islands serve as a rookery for seabirds during the upwelling season. The 3.13 ha reef at the northeast side of the island developed on a tuffaceous sandstone outcrop (Glynn and Macintyre 1977). This reef died during the 198283 E1Nifio and has been replaced by sand/rubble plains formed mainly by broken branches of PocilIopora damicornis. Coral cover is approximately 1% (Guzn~n and Robertson 1989). An algal biostrome formed mainly of living coralline algae and the coral Psammocora stellata is also present (Glynn 1974a). The deeper parts of the sand/rabble plains are dominated by Pavona (mainly P. gigantea), Gardineroseris and Porites. Coralliths of these species reaching densities of 100 individuals m "2 are more common here than elsewhere in the Pearl Islands (Glynn 1974a). At the northeast end of the island, facing Pachequilla Island, there is an extensive development of what appears to be a new Pavona species that I refer as Pavona sp. b (see Mat6 2001). This Pavona species reaches 15 m in
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diameter and up to 3 meters in height. The colonies occur in association with Pavona gigantea. The southern shore of Pacheca has rocky areas with solid basalt extending for tens of meters. These rocky areas are dominated by octocorals, sponges, and the occasional colony of Pocillopora elegans and Pavona gigantea, which can exceed 1 m in diameter and height. Mogo Mogo Island. Mogo Mogo Island is also locally known as Pfijaros Island (site 23, Fig. 1D). Reef development occurs on the west shore of the island both to the north (5.3 ha) and the south (3.9 ha) (Glynn and Stewart 1973). The reef at the southwest end ofthe island is formed by pocilloporid corals (mainly P. damicornis), crustose coralline algae and Psammocora stellata. Gardineroseris planulata, Pavona gigantea, P. clavus and Porites lobata occur as encrusting colonies of low relief. Small colonies ofPocillopora damicornis and P. elegans are also found scattered on the shallow areas. Coralliths ofPavona gigantea, P. varians and Porites panamensis are common in the sand/rubble plains. Pocilloporid corals are the main reef builders but in contrast to the southwest reef, this reef is dominated by Pocillopora elegans. Large dead colonies of Pavona gigantea and Porites lobata (> 1.5 m in height) are present. These colonies probably died during the 1982-83 E1Nifio (Glynn et al. 1988). Colonies of Gardineroseris planulata up to 50 cm in diameter are commonly seen. 3.2.3. Iguana Island. The Iguana Island coral reef (site 12, Fig. 1A), located on the southwest side of the island, has a maximum reef thickness of 6.1 m (Glynn and Macintyre 1977) and an extension of 16 ha (GuzmAn et al. 1991). Both measurements are the largest reported for a reef in the Gulf of Panarn,5. This coral reef probably has the highest coral cover and healthiest corals in the entirely coast of Panarrui. Eleven zooxanthellate coral species are found around the island (Guzrnfin et al. 1991; Mat6 2001). Pocillopora damicornis and P. elegans are the main reef-building species with Porites lobata, Pavona gigantea and Gardineroserisplanulata being the most common massive species. Total live coral cover has been estimated at 36.7%, of which pocilloporid corals were responsible for 94.6%, Porites lobata 2.4%, and Pavona clavus 1.7% (Guzmfin et al. 1991). The large Porites lobata and Pavona clavus colonies attain sizes > 4 m in diameter and three meters in height. The oldest of four Porites colonies dated by ~4C was 410-a:70 years old (Guzrnfin et al. 1991). Despite its geographic location, the coral fauna of Iguana more closely resembles that of the Gulf of Chiriqui than the Gulf of Panamfi, due to the presence of Pocillopora eydouxi and Pavona chiriquiensis. The east side of the island lacks any reef formation and is dominated by sand-rubble plains and large basaltic boulders. There are extensive coral communities along rocky extensions near these boulders, where corals are in excellent condition. Large colonies of Pavona clavus and Porites lobata are extremely abundant here. 4. CORAL REPRODUCTIVE ECOLOGY In 1984, a major scientific effort was initiated in Costa Rica, PanamA, and the Gal~pagos Islands to study the reproductive ecology of eastern Pacific corals. Five publications involving eight species in four genera have resulted from this work (Glynn et al. 1991, 1994, 1996b, 2000; Smith 1991). These studies have indicated that the reproductive activity in the eastern Pacific is related to thermal regimes. High incidence of gravid corals is observed at sites with stable, warm water conditions or during wamfing periods in areas that experienced significant seasonal variation (Glynn et al. 1991, 1994, 1996b, 2000).
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4.1. Pocilloporidae Even though Pocillopora damicornis and P. elegans have not been observed to spawn, histological data indicates they are broadcast spawners (Glynn et al. 1991). Both in the Gulf of Panamfi and the Gulf of Chiriqui, few gonads are present in both species during the dry season (mid-December to mid-April). Gonad maturity increases during the wet season particularly around the new and full moons regardless of sex. Pocillopora inflata is the only pocilloporid observed to spawn in PanaroA (Glynn 1999). Spawning occurred at 0730- 0930 on 23rd March 1998 at Saboga Island. In contrast to what histological examination ofP. damicornis and P. elegans may indicate, P. inflata spawned at the peak of the upwelling season. 4.2. Poritidae Two reproductive modes are evident in Panamanian Porites. Porites lobata is a gonochoristic and presumably broadcast spawner (Glynn et al. 1994). Porites panamensis is a gonochoristic brooder (Smith 1991; Glynn et al. 1994). As it has been observed in the genus Porites (Kojis and Quinn 1981), zooxanthellae are present in mature oocytes of both species as well as in all planulae stages of P. panamensis. Sex ratios of P. lobata are 1:1 (Glyrm et al. 1994). In the GulfofChiriqui, Porites lobata gametogenesis is especially high in the dry season but, also increases during the wet season suggesting two reproductive peaks in the year. Lunar patterns are better defmed than seasonal patterns with gametogenesis being more frequent at or near full moon. In the Gulf ofPanarrfi, P. lobata gametogenesis occurs only after the dry season upwelling. In both the Gulf of Panarrfi and the Gulf of Chiriqui Porites panamensis is sexually active throughout the year but, in the former locality there is a decline during the strongest upwelling (Smith 1991; Glynn et al. 1994). 4.3. Agariciidae Two gonochoric species, Pavona gigantea and Gardineroseris planulata increase their reproductive activity following the cold dry season and continue through the warm postupwelling season (Wellington and Glynn 1983; Glynn et al. 1996b). Minimum reproductive size in these species is >200 cm2 (Glynn et al. 1996b). Even though, no spawning has been observed in these species, the sudden emptying of gonads following new and full moons provides strong circumstantial evidence that both species undergo at least two annual spawning cycles. Two other species, Pavona varians and Pavona sp. a (now P. chiriquiensis) have their reproductive peak during the dry season in the Gulf of Chiriqui and have been observed to spawn then. At Uva Island, spawning occurred between January and May; P. varians spawned just before sunrise and Pavona chiriquiensis spawned just after sunset (Glynn et al. 2000). 4.4. Other species The azooxanthellate coral Tubastrea coccinea has been observed to planulate monthly from February to April (Richmond 1985; Richmond and Hunter 1990) and by the author around the new moon of May. However, the amount of planulac released appeared to indicate that most of the brooding occurred in previous months. Glynn's laboratory is analyzing samples of T. coccinea, Psammocora stellata, P. superficialis, Pavona clavus, and Millepora intricata. Preliminary results indicate that all species, with the exception of T. coccinea and M. intricata are spawners following lunarpattems similar to those of the species previously described. T. coccinea is a brooder and M. intricate releases medusa.
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5. NATURAL DISTURBANCES I have identified six natural disturbances that play an important role in shaping coral reefs in the Panamanian Pacific. Some of the disturbance events may have catastrophic impacts on the coral communities (e.g. severe E1 Nifio events) or may just cause routine chronic mortalities in reef corals (e.g. upwelling, subaerial exposures). 5.1. El Nifio-Southern Oscillation (ENSO) The warm waters of E1 Nifio are responsible for extensive bleaching and mortality in eastern Pacific corals (Glynn 1984a). Two major E1Nifio events have severely disturbed the Panamanian Pacific reefs in the last two decades, the 1982-83 and the 1997-98 events. During both events, the hydrocorals were among the first zooxanthellate species to bleach and subsequently experienced the highest mortalities of all affected reef organisms (Glynn and de Weerdt 1991, Glynn et al. 2001). These mortalities resulted in the local disappearance ofMillepora platyphylla and Millepora boschmai following the 1982-83 and 1997-98 E1Nifio events respectively (Glynn 1990; de Weerdt and Glynn 1991; Glynn et al. 2001). Thus, E1Nifio events may be in~ortant in reducing the coral diversity in the eastern Pacific.
5.1.1. The 1982-83 El Nifio. The first report of coral mortality during the 1982-83 event in PanaroA came from Glynn (1983a), "we are presently suffering very heavy mortality on the Pacific side of PanaroA - to a degree I have never seen before: it is astounding". Bleaching was first observed in the Gulf of Chiriqui on 18 March 1983, and by the end of April bleaching had reached 83.1% (Glynn 1984a). Coral mortality associated with this disturbance reduced the total living cover at Uva Island to 1.0% (18.6% before the disturbance) and at the Secas Islands to 5.1% (16.5% before the disturbance) (Glynn 1984a). The four most affected species in the Gulf of Chiriqui were Millepora intn'cata, M. boschmai, M. platyphylla and Porites panamensis. Other species such as Pavona gigantea and Psammocora stellata showed only slight bleaching or no bleaching at all (Glynn 1983b, 1984a). Bleaching in the Gulf of Panarrfi began three months after the Gulf of Chiriqui (Glynn 1984a). By mid-September, bleaching at the Pearl Islands reached 22.7-80%. The delay in responses between both Gulfs was attributed to the 1983 seasonal upwelling that kept sea surface temperatures (SSTs) low until it ended in late May - early June (Glynn 1990, PodestA and Glynn 1997). Bleached and partially bleached specimens exhibited varying degrees of tissue atrophy and necrosis (Glynn et al. 1985a). Podestfi and Glynn (1997) provided evidence that the SST threshold in Pananfi is 30~ and that only strong E1 Nifio-Southern Oscillation events have a SST signature in Panarrfi. After the 1983 seasonal upwelling ended in late May - early June, SSTs of 30~ were reached in the GulfofPanamfi and bleaching was first reported (Glynn 1990). There is a strong geographical relationship between coral mortality and the intensity of SST warming in Panama (Glynn et al. 1988; Podest~ and Glynn 1997). Total coral mortality was lower (75%) in the warm stable waters of the Gulf of Chiriqui than in the seasonal cool waters of the Gulf ofPanamfi (85%) (Glynn et al. 1988). Pocilloporid mortality was 75% in the Gulf of Chiriqui and 92% in the Gulf of PanamA. Densities of the sea urchin Diadema mexicanum at Uva Island increased from 3 ind rn"2 before the 1982-83 E1 Nifio to 50-80 ind. mz after the disturbance (Glynn 1988; Eakin 1992). Although, sea urchin densities have now decreased to <1 urchin m "2(Eakin 2001).
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Erosion on the reef has amounted to 10 to 20 kg CaCO3 m'2yr (Eakin 1992; Glynn 1997b). These rates of bioerosion have been shown to exceed net carbonate production of 10 kg CaCO3 m'2yr (Glynn 1997b). Bioeroders (including urchins) are removing reef framework at 22 mm yr vertically and causing the collapse and recession of framework walls at 44 mm yr. If these rates ofbioerosion persists without any increase in coral recruitment, it is highly likely that the reef formations in the eastern Pacific will disappear (Glynn 1997b). The damselfish Stegastes acapulcoensis (Fowler) has been shown to play an important role in structuring communities on some eastern Pacific reefs (Wellington 1982). Also, this fish is able to maintain algal lawns. Eakin (1987, 1991) provided strong evidence that demonstrate the existence of a symbiosis between damselfish and algal lawns. The damselfish/algal lawns symbiosis may play an important role in reducing the rates of erosion and the collapse of reef framework (by 70%) in some reef by removing the sea urchin Diadema from its territory (Eakin 1988, 1991, 1992, 1996). 5.1.2. The 1997-98 El Nifio. In PanamA, the warm waters of 1997-98 E1Nifio reached only the Gulf of Chiriqui (Glynn et al. 2001). Two bleaching episodes were evident in the Gulf of Chiriqui (late July 1997 and March 1998) when temperatures raised to 30~ Mean zooxanthellate coral mortality in the Gulf of Chiriqui during 1997-98 was low 13.1% compared to 75% during the 1982-83 event. Coral mortalities during 1997-98 were significantly higher at offshore sites (Montuosa Island, 5.8%; Jicar6n and Jicarita Islands, 11.9%) compared to nearshore sites (Uva and Silva de Afuera Islands, <4%). The most sensitive species included Millepora intricata (Fig. 5), Millepora boschmai, Pavona chiriquiensis and Poritespanamensis. No living colonies ofMillepora boschmai have been found during the latest survey (February 2001). Extensive information on the effects of the E1 Nifio 1997-98 event can be found in Glynn et al. (2001).
Fig. 5. RecentlykilledMillepora intricata beenovergrownbyfilamentousalgae,UvaIsland,September1997. Mortalityin this speciesreached 100%in shallowerareas(to 10m depth).
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5.2. Seasonal Upwelling Seasonal upwelling in Panamfi is restricted to the Gulf of PanamA. There are three reports of coral bleaching/mortality associated with cold water upwelling, 19 March 1985; 27-28 February 1989; 23 February 2001 (Fig. 6). During the 1985 and 1989 upwelling, 27% and 100% of the Pocillopora species were partially or totally bleached respectively (Podestfi and Glynn 1997). The most recent mortality (Pearl Islands) occurred during the 2001 upweUing season, which has been extremely cold, reaching 14.7~ rapid Pocillopora mortality occurred and dead coral were colonized by filamentous algae. In addition to coral mortality, coral reef distribution in the Pearl Island has been largely attributed to the cold waters resulting from the seasonal upwelling in the Gulf of Panarnfi. Reefs are mainly confined to the north and eastern sides of islands where favorably thermal conditions occur (Glynn and Stewart 1973). Later, Glynn (1977a) noticed a significant relationship between coral growth and water temperature. Coral growth in the upwelling GulfofPanamfi (3.1 cm yr) is about 80% of that observed in the thermally stable Gulf of Chiriqui (3.9 cm yr). This represents a reduction in growth rate to 1.0 mm mo ~ when temperatures drop to 20-2 I~ The changes in growth rates are reflected in the coral banding patterns. The low density annual band is accreted over the upwelling dry season and represents increases in linear skeletal extension and calcification rates relative to the high density band which forms during the wet season. It is reported that the low density band in Pavona clavus from the Gulf of Panarnfi can be more than 1.5 times wider than the high density band (Wellington and Glynn 1983).
Fig. 6. Dailysea temperaturereadingsat SabogaIsland,GulfofPanamfi. Datacollectedat 2 m depth (relative to Mean Low WaterSpringTidalDatum)usingTidbittemperatureloggers. Straightlines in the plot indicate data gaps. Blackarrowpoints to the 2001 coralmortalityassociatedwith cold water temperatures.
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Fig. 7. Subaerialexposure of the Uva Island coral reef. The white appearance is due to bleached and death corals affected by an extreme exposurethe day before (20 February 1992). 5.3. Subaerial exposures Subaerial exposures (Fig. 7) of reef flat corals can result from extreme low tides, ENSOrelated sea level drops or tectonic uplifts (Glynn 1984a). Low tidal exposures seem to be only a minor problem for corals, except when corals are exposed to high or low temperatures, increased solar radiation including the detrimental UV radiation, desiccation, and sea water dilution by heavy rains (Glynn 1976, 1996; Eakin et al. 1989; Eakin and Glynn 1996; Glynn and Mat6 1997). Low tides of-60 cm or lower usually result in prolonged (>2 h) reef flat exposures (Glynn 1977a). A reef fiat exposure during January 1974 resulted in Pocillopora mortalities of 40-60% (Glynn 1976). Two to three weeks later, algae began to grow over the dead coral skeletons. A severe coral mortality occurred also during February 1975 after an extreme exposure caused by a -88 cm fide. On 8 February 1989, an extreme tidal exposure of the Uva Island reef flat resulted in the death of 97% of the corals as well as many fishes and invertebrates that got trapped in the exposed reef fiat (Eakin and Glynn 1996). More recently, a midnight exposure of the Uva reef flat (-34 cm) on 16 May 1999 coincided with a heavy rain that night. Extensive coral mortality and tissue sloughing was evident in Pocillopora damicornis, P. elegans, Porites lobata, Pavona varians and Gardineroseris planulata on 17-18 May. 5.4. Dinoflagellate blooms There has been only one report of coral death associated with phytoplankton blooms in the Pacific coast of Panarrfi (Guzmfin et al. 1990). The intense upwelling of 1985 were related to La Nifia (Glynn 1990). During October and November 1985, a dinoflagellate bloom occurred at Uva Island as a result of the shoaling of the nutricline in the nonupwelling Gulf of Chiriqui. The dinoflagellate bloom was responsible for the bleaching and mortality ofpocilloporid corals that occurred at 1 to 2 m depth. Live Pocillopora spp. cover
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was reduced by 12.8% at 3 m depth (Guzrnfin et al. 1990). The mortality of reef organisms at Uva was associated with a viscous foam produced by the dinoflageUates which may have caused a) toxicity, b) oxygen depletion, and c) smothering by mucus. 5.5. Terrestrial run-off and sedimentation
There have been no published studies that clearly demonstrated the effects of terrestrial runoff in the Panamanian Pacific coral reefs. However, the local distribution of reefs appears to be affected by these conditions (Dana 1975; Anonymous 1993, Guzmfin and Hoist 1994). Two examples of this situation are presented, one for the Gulf of Chiriqui at Coiba Island and one at Panarn,5 Bay. The Coiba reef located at Ensenada Maria appears to be protected from the runoff of the Boca Grande Estuary by a submerged rocky outcrop that may block the movement of the sediments brought by the river into the reef. Contrarily, at the northern end of Bahia Damas, which has similar conditions as Ensenada Maria but it is larger, there are few coral reef formations. The difference in coral development in both areas have been attributed to the presence of the San Juan River mouth in the center of the Bay. The river discharges sediments which are deposited on the bay increasing the turbidity of the water and probably i n , airing the development of coral reefs (Brenes et al. 1993). Guzrnfin and Hoist (1994) proposed that the large sedimentation resulting from tidal changes in Panarnfi Bay may be a limiting factor for the coral reef development on the islands close to the continent even though these places present large rocky substrata. An experimental study by Gonzfilez and Polo (1982) on the effects of sedimentation on the coral growth of three Panamanian Pacific coral species demonstrated that after 103 days of experimentation, Pavona varians grows considerably more in filtered than unfiltered seawater. Pavona gigantea and Porites lobata show no significant differences in growth when exposed to the same experimental conditions. Pavona gigantea and Porites lobata are probably the most widely disperse coral species in the Panamanian Pacific, particularly in the Gulf of PanaroA. At many sites in the Gulf ofPanarnfi, Pavona gigantea is normally the only species observed. This species appears to have a great tolerance for sedimentation and low light levels since it is found mainly in the murkiest waters. 5.6. Acanthaster planci
In the eastem Pacific, Acanthasterplanci preys preferably on massive species of Pavona and Gardineroseris, but also feeds on Porites, Pocillopora, Psammocora, and Millepora (Birkeland and Lucas 1990; Glynn 1973,1974b, 1976, 1977b, 1983c,d, 1987). Porites lobata is generally avoided by the seastar (Glynn 1983c, d). In Panamfi, Acanthaster is found only in the Gulf of Chiriqui (Glynn 1970a, 1970b, 1972; Wellington 1982; Glynn and Mat6 1997). Acanthaster has never become a plague in Panamfi, with peak densities during 1970s-1980s at 7 to 30 ind ha~. Present starfish densities are at 1-2 ind ha ~. The predatory shrimp Hymerocera picta Dana and the scavenging worm Pherecardia striata (Kinberg) may be responsible for maintaining the number of Acanthaster low (Glynn 1981, 1984b). Mean annual rates of coral destruction in Panamfi have been estimated in 5.4 m 2 (Glynn 1973), with feeding rates over a two day period at 60 cm2 day"~ for Gardineroseris planulata, and Pavona varians (Glynn 1977). Acanthasterplanci normally ranges over reef flanks and along the reef base (Glynn 1973) and does not cross continuous stands of live Pocillopora (Glynn 1985a, b). The avoidance of these large stands of Pocillopora by the
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starfish has been attributed to the presence of crustaceans symbionts of Pocillopora that repeal the starfish attack and to the damselfish Stegastes acapulcoensis (Glynn 1983c, d). The mortality of pocilloporid corals during the 1982-83 allowed the starfish to reach the massive coral (preferred prey) and feed on these species previously isolated from the starfish (Glynn 1983a, 1985a; Macintyre 1991a, b). Fong and Glynn (1998, 2001) have proposed this predation as a powerful factor in shaping the reef structure at Uva Island. 6. ANTHROPOGENIC STRESSES I have identified four human-induced stresses that may impact coral reef communities in the Pacific coast of Panamfi. However, there are other stressors that may influence reef areas even though they originated some distance away (i.e. Municipal garbage dumping sites close to estuaries, during spring tides, garbage drag by currents is deposited into nearby reefs and beaches). Even though the effects ofanthropogenic impacts of Panamanian Pacific reefs can not be neglected, there effect in relation to natural disturbances appears to be minor, except in very localized areas. In contrast, in the Caribbean coast of Panarnfi, anthropogenic stresses are probably more important than natural disturbances in structuring coral reef communities.
6.1. Coral extraction Prior to 1992 extraction of"live rocks" covered with fleshy algae and other encrusting organisms as well as extractions of massive corals occurred illegally in the sector of Taboga, Taboguilla and Urab/t Islands. After notifying the respective authorities (see section 7) the activity was stopped and is now discontinued (Guzmfin and Hoist 1994). Coral extraction has been one of the conditions that have detrimentally affected the coral reef at Iguana Island (Guzrnfin et al. 1991). 6.2. Ship groundings and anchor damage Two ship groundings during 1996 and 1997 caused damage to the Uva Island (Gulf of Chiriqui) coral reef. While the groundings were not observed, their impacts on the reef were evident. On both occasions the groundings penetrated into the reef framework up to depth of approximately 40 cm. The 1997 grounding should have occurred between mid-September and mid-October. During the 1997 grounding, two large colonies of Gardineroseris planulata (> 1 m in diameter) as well as pocilloporid corals in the path of the grounding were either completely smashed into pieces or crushed with no live fragments evident. At the coral reef at Urabfi Island (Gulf of Panamfi) there is a large ship grounding that occurred in the first half of 1900's. This ship did not directly impacted the coral reef and now serves as settlement place for the azooxanthellate coral Tubastrea coccinea as well as many hydroids and sponges. Other ship groundings affecting the reef framework in the Gulf of Panama are seen at Iguana Island. Also, at this site, the path of anchor damage is noted as crushed Pocillopora fragments paths several meters in length. Shrimp boats have also been observed to anchor in the vicinity of the reef. 6.3. Herbicides The Chiriqui Province in the western sector of Panarnfi is an area subject to intense agricultural activity and in consequence an intensive use of herbicides and pesticides. High
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levels of pesticides and insecticides have been found in corals, however, they have not been responsible for any coral mortality (Glynn et al. 1984). The herbicides 2,4-D and 2,4,5-T as well as phenoxy acids were found in the coral tissues of seven scleractinians and one hydrocoral species collected from the Uva Island coral reef(Glynn et al. 1984). Pocillopora damicornis had the highest concentrations ofphenoxy acid in its tissues (20,050 ng g'~ dry wt of 2,4-D and 19,380 ng g~ dry wt of 2,4,5-T).
6.4. Overfishing The extraction of coral reef fishes has been reported as affecting detrimentally the coral reef at Iguana Island (Guzrnfin et al. 1991). While no other published study makes reference to the removal of organisms from Panamanian reefs, their disappearance or drastic reduction in numbers is evident in our study sites. For example, at Uva Island, we were able to observe large numbers of the conch Strombus galeatus Swainson. Currently, few and small individuals are present, and, many shells are found on the beaches of the island with their apical ends broken off. This offer good evidence that the mortality of these gastropods is caused by local fishermen and is not due to natural causes. Another example is the shark fisheries which were a common practice in PanaroA. We use to observe several white tip reef sharks (10 or more resting on the bottom of larger coral colonies) in our study site at Uva Island, however, in the last five years we have not observed a single shark in the area. It is a common practice for fishermen to clean their capture on the shores of several islands (e.g., Uva, Cavada and Iguana Islands) where the fresh carcasses of the animals can be seen. A third example, during our visit to Restinge Island in July 1998, the lack of fishes and invertebrate species normally used in artisanal fisheries was evident. This suggests that there may be an overexploitation of the resources in the area. No lobsters and conch were observed in the area even though the local fishermen made the assertion that they were common there. A similar situation has been observed in most other reef areas visited during our surveys. While already treated above, additional damage to the reef is caused by the fishermen when they drop their anchors and deploy their nets on the reef, that most of the time get entangled on the coral colonies and have to be left there, resulting to the death of the coral. 7. M A N A G E M E N T AND P R O T E C T I O N Chapter 7 of the Ecological Regime of the Political Constitution of the Republic of Panarrfi established on Article 116 that the State will regulate, supervise and enforce the necessary actions to warrant the protection, renovation and permanence of natural resources in the country. In this regard, Panarrfi has ratified most International and Regional Protocols that intend to regulate the dmnping of toxic waste into the ocean, as well as the Conservation and Management of Marine and Coastal Protected Areas of the Southeast Pacific. Recently, concrete steps taken to define a national policy to manage the coastal zone and its resources have resulted in the creation of the Maritime Authority of Panan~ (AMP, Autoridad Maritima de Panarrfi) and the National Authority of the Environment (ANAM, Autoridad Nacional del Ambiente). AMP is responsible for the management, conservation and exploitation of the marine coastal resources as well as the coordination and the execution of the National Marine Strategy. ANAM is in charge of establishing the policy about natural resources and environment on the Republic of Panarrfi as well as the management and protection of Wildlife Protected Areas in Panarrfi.
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Fig. 8. Protected areas in the Republic of Panam~i that include coral reefs or extensive coral communities within their boundaries: the National Parks (Gulf of Chiriqui): Cerro Hoya, Coiba and Marino Golfo de Chiriqui; and the Wildlife Refuges (Gulf of Panama,): Iguana Island, and Taboga Island. TABLE 3 Wildlife protected areas containing coral reefs or coral communities in the Republic of Panam~i. cc: coral communities, no true coral reef present; u: unknown; *: estimated.
Managment Status 9 National Park Cerro Hoya
Coiba Marino Golfo de Chiriqui Wildlife Refuge lsla Iguana Taboga
Surface (ha)
Date of creation
Reef area (ha)
32,557
Oct. 2, 1984
270,125
Dec. 17, 1991
cc 136
14,740
Aug. 2, 1994
u
58
Jun. 15, 1981
16
258
Oct. 2, 1984
> 4*
Specific regulations to warrant the protection of coral reef species include the Resolution No. JD-037-93 approved by Director's Board of INRENARE on 29 September 1993. This resolution forbid the extraction and exportation, for commercial reasons, of live or death corals in the Panamanian Territory (INKENARE 1993). In addition, Pananfi is signatory of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES 1996). ANAM is the institution responsible for granting the permits to collect, research, and export the species listed in CITES. There are five Protected Areas in the Panamanian Pacific that include coral reefs or extensive coral communities within their boundaries (Fig. 8, Table 3): three National Parks, Cerro Hoya, Coiba and Marino Golfo de Chiriqui; and two Wildlife Refuges: Iguana Island and Taboga. 7.1. The case of the Coiba National Park Coiba Island harbors a 136 ha coral reef which is considered the largest continental coral reef in the eastern Pacific Ocean (Glynn and Mat6 1997). The establishment of a penal
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colony on the island in 1919 and the presence of a custodial police force have combined to preserve the area for more than 80 years. Thus, the reef and the island have remained relatively unaltered. Coiba, 50,340 ha in area, is the largest island in the Panamanian Pacific. On 17 December 1991, the Government of Panama established Coiba National Park, encompassing a 270,125 ha area, of which 53,528 ha are insular territory and the remaining 216,543 ha marine (Fig. 8). The park includes not only the best-developed and diverse coral reefs in the continental Pacific coast of America but also coral species that are endemic and several endangered species (Glynn et al. 2001). The penal colony is scheduled to close by the end of September 2001, and the remaining prisoners will transfer to mainland facilities. The closure of the penal colony and removal of the police force make the park immediately vulnerable to illegal loggers, poachers, and over-fishing. These activities threaten to start a sequence of events leading to major disturbance, including the degradation of the coral reef communities. So far the major impact on coral communities in the area is from E1Nifio sea-warming episodes (Glynn et al. 2001). Coral reefs have been recovering slowly from this natural disturbance, but additional human-induced stress may hamper the recovery potential of this community, as has occurred in other Pacific reefs (Maragos and Payri 1997; Chou 1997; White et al. 1997). ACKNOWLEDGMENTS I would like to thank Jorge Cort6s for inviting me to write this chapter. I would like to give special thanks to Andrew Baker, Jorge Cort6s, Luis D'Croz, Peter Glynn and H6ctor Gtmm,Sn, Jos6 H. Leal and Nancy Knowlton for providing comments to the manuscript. To Villay Aswani, Zeida Batista, Magnolia Calder6n, Marcos Diaz, Mark Eakin, H6ctor Guznfin and Xenia Guerra for providing and helping with the photos and digitized maps. To Indra Candanedo, Dinis Ramos, and Leticia Polo of the Autoridad Nacional del Ambiente (ANAM) for providing information about Protected Areas in Panarrfi. REFERENCES
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Corals and coral reefs of the Pacific coast of Colombia F e m a n d o A. Zapata" and B e m a r d o V a r g a s - A n g e l b "Departamento de Biologia, Universidad del Valle. Apartado A6reo 25360, Cali, Colombia bNational Coral Reef Institute, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, Florida 33004 USA ABSTRACT: Based on a literature review and our own research, we examine coral reef development on the Pacific coast of Colombia. Several. We provide a historical outline of the research, a summary of studies on coral community distribution, composition and ecological structure, a discussion on natural and anthropogenic impacts and effects, and finally, an overview of the current conservation and management status. Coral reef development in this area of the eastern Pacific is marginal, and communities are small, species poor (only 21 species of zooxanthellate corals), and discontinuously distributed. They occur in a variety of environmental settings ranging from coastal (Ensenada de Utria and Tebada), to continental insular (Gorgona Island), to oceanic (Malpelo Island). The largest (--10 ha), most developed (up to ---8 m thick), and species-rich coral reefs are located at Gorgona Island. These fringing reefs show a diffuse zonation pattern characterized by the dominance of pocilloporid corals on the shallow reef fiat and the presence of massive colonies of Pavona and Gardineroseris on the deeper outer reef base. Coral and coral reef development on the Pacific of Colombia is limited due to suboptimal climatic and oceanographic conditions such as a narrow continental shelf, intense rainfall (which results in elevated terrestrial run-off and turbidity, and reduced light and salinity conditions), and extreme temperature fluctuations caused by sporadic upwelling and E1 Nifio. Most important among these are El Nifio warming events, which have caused coral bleaching and mortality since at least 1983. In addition to recurrent E1 Nifio conditions, other natural disturbances affect the coral reefs in this region, including periodic sub-aerial exposure during extreme low tides, high sedimentation, seasonal upwelling, and tectonic activity. Most of the areas with coral reef development on the Colombian Pacific are legally protected. However, all are subject to sporadic anthropogenic impacts. Human disturbances are lowest on the remote Malpelo Island and highest on the northern coastal reefs. Corals reefs of the Colombian Pacific constitute a key marine biotope, and provide economic and social assets as habitats for artisanal fisheries, as well as recreation and educational activities. Further studies addressing basic questions and management and conservation issues are necessary.
1. I N T R O D U C T I O N T h e first o b s e r v a t i o n s on coral formations f r o m the C o l o m b i a n Pacific coast w e r e m a d e b y C r o s s l a n d (1927), w h o r e p o r t e d results o f the S.Y. St. G e o r g e E x p e d i t i o n to the south Pacific, and b y D u r h a m and B a r n a r d (1952), w h o r e p o r t e d results o f the V e l e r o III and I V cruises in the eastern Pacific. In 1968 the S t a n f o r d O c e a n o g r a p h i c E x p e d i t i o n 18 a b o a r d de R V T e V e g a m a d e short visits to G o r g o n a , B a h i a S o l a n o and Latin American Coral Reefs, Edited by Jorge Cortfs 9 2003 Elsevier Science B.V. All rights reserved.
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Bahia Cupica and briefly described subtidal stations and made limited observations on coral formations and associated fauna (Youngbluth 1968a, b). The first formal description of a coral formation in the Colombian Pacific was made by Birkeland et al. (1975) for Malpelo Island. The late H. von Prahl and his co-workers made qualitative descriptions of coral reef structure at Gorgona Island and discussed diverse ecological aspects (Prahl et al. 1979). Their pioneering work was later complemented by quantitative studies on the distribution, zonation, and community structure of corals and corallivores (Glynn et al. 1982; Cantera 1983). The structure and species diversity of coral formations in the northern portion of the Colombian coast, particularly at Ensenada de Utria, was later described (Vargas-Angel 1988, 1989, 1996). Species lists, illustrations, and accounts for identification purposes of Colombian Pacific corals were provided by Prahl (1985a, 1986b, 1987a) and Prahl and Erhardt (1985). Other works on corals and coral reefs from the Colombian Pacific include studies on coral growth at several localities (Prahl 1986d; Prahl et al. 1987; Prahl and Vargas-Angel 1990), coral growth forms and their implications for coral taxonomy and systematics (Cantera et al. 1989; Prahl and Estupififin 1990), biogeographical studies (Prahl 1986c; Prahl et al. 1990a, b), effects of the 1982-83 E1Nifio event (Prahl 1983a, 1986e, 1987b; Prahl et al. 1989), and the contribution of sea urchins (Toro 1998) and parrot fishes (Jim6nez 1999) to reef erosion. Taxonomic and ecological studies on animal communities associated with coral reefs in the Colombian Pacific include studies on symbiotic crustaceans associated with pocilloporids (Abele 1975; Castro 1982; Prahl 1982, 1983b, 1986f; Rios 1986, 1987; Escobar and Barbosa 1992; Navas 1993; Barbosa 1994), molluscan assemblages (Cantera et al. 1979; Cosel 1986; Cantera and Contreras 1988; Ocampo and Cantera 1988; Cantera and Arnaud 1995), echinoderms (Neira and Prahl 1986; Pardo 1989) and fishes (McCosker and Rosenblatt 1975; Findley 1975; Zapata 1982, 1987; Rubio 1986, 1990; Rubio et al. 1987, 1992; Estupifi~n et al. 1990; Guzmfin and L6pez 1991; Zapata and Morales 1997; Giraldo et al. 2001; Mora et al. 2001; Mora and Ospina 2001; Zapata and Herr6n in press). Much of the early information had already been summarized (Prahl and Erhardt 1985; Prahl 1986b; UNEP/IUCN 1988). This chapter provides a synthesis of current knowledge on the ecology of coral communities and coral reefs in the Colombian Pacific Ocean. Major emphasis is placed on the distribution of coral formations, the community structure of corals, and the effects of natural and anthropogenic disturbances on the reefs. 2. DESCRIPTION OF CORAL REEF AREAS 2.1. Distribution and community structure The distribution of corals and coral reef communities in the Colombian Pacific Ocean is directly related to the presence of hard substrates and clear waters, away from the influence of major fiver discharge and mangrove forests. According to their geographical location and following a nearshore-offshore gradient, coral formations in Colombian Pacific waters can be divided into three main groups (Fig. 1): 1) the northern, coastal reefs of the Gulf of Cupica and Ensenada de Utria; 2) the southern, continentalisland reefs of Gorgona; and 3) the oceanic-island coral formations of Malpelo. In general terms low species richness and strong dominance by one or two species characterize coral communities along the Pacific coast of Colombia and adjacent waters. A total of 21 coral species has been observed, with a minimum of 7 and a maximum of
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18 species occurring at any one locality (Table 1). Although these estimates are based on the best available information, the state of knowledge on coral taxonomy and systematic in the tropical eastern Pacific (TEP) is still inadequate. Despite the depauperate nature of the TEP coral fauna (Glynn and Ault 2000), new species are still being described (e.g., Glynn et al. 2001). A major revision of the genus Pocillopora is badly needed, and a revision of the genus Pavona is currently under way (J.L. Mat6 per. com.). Four new records have recently been added to the list of previously known coral species reported for the Colombian Pacific ocean (Table 1) and it is likely that a few other species will be added to the list as knowledge of coral taxonomy in the area improves. Climatic and oceanographic conditions in the Colombian Pacific are thought to be suboptimal for coral reef development (Glynn et al. 1982). On the one hand, narrow and steep platforms restrict reef development. On the other hand, salinity and light levels are severely reduced due to high river input and high cloud cover in one of the rainiest regions of the world. Mean annual precipitation exceeds 5000 mm over most of the coast,
F.A. Zapata & B. Vargas-,4ngel
422
TABLE 1 Known zooxanthellate scleractinian coral species from the Colombian Pacific Ocean. + = species present, ? = unconfirmed record. Numbers in parentheses indicate information sources as follows: 1 = Birkeland et al. (1975), 2 = Glynn et al. (1982), 3 = Cantera (1983), 4 = Prahl and Mejia (1985), 5 = Prahl and Erhardt (1985), 6 = Prahl (1986b), 7 -- Prahl (1990), 8 -- Guzm~in and Cort6s (1993), 9 = Vargas-Angel (1996), 10 = J. Garz6nFerreira, photographic record, 11 = Garz6n-Ferreira and Pinz6n, (1999), 12 = H.M. Guzm~in, per. com., 13 = B. Vargas-Angel, unpubl, data, 14 = F.A. Zapata, per. obs.
Species Malpelo
Pocillopora damicornis (Linnaeus) Pocillopora eydouxi Edwards & Haime Pocillopora capitata Verrill Pocillopora elegans Dana
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+ (5, 9) + (5, 9)
+ (13)
+ (5, 7) ?(10) +(11)
+ (2, 3, 5, 6)
+ (5, 9)
+ (13)
+(12) + (5) + (2, 5, 6)
+ (9)
+ (1, 5, 7)
+(14)
+ (2, 5, 6)
Cycloseris curvata (Verrill) Total = 21 species
(2, (2, (2, (2,
Tebada
?(13)
Psammocora brighami Vaughan Psammocora obtusangulata (Lamarck) Psammocora stellata (Verrill) Psammocora superficialis Gardiner Psammocora sp. Pavona clavus (Dana) Pavona varians Verrill Pavona sp. aft. frondifera (Lamarck) Pavona gigantea Verrill Pavona maldivensis (Gardiner) Pavona chiriquiensis Glynn et al. Leptoseris papyracea (Dana) Gardineroseris planulata (Dana)
+ + + +
Localities Ensenada de Utria
+ (4, 5, 6)
Acropora valida (Dana) Porites lobata Dana Porites panamensis Verrill
Gorgona
10 species
18 species
11 species
7 species
although it is lower in the south and greater in the north, reaching 7000 mm or more in some areas (West 1957; Eslava 1993). Intense rainfall during the rainy season increases the concentration of suspended particulate matter at sea, often leads to topsoil rtmoff, and even occasional landslides. Finally, coral reefs of the Pacific coast of Colombia are also subject to periodic, severe natural disturbances. Intense upwelling in the Gulf of Panama (Legeckis 1988) lowers sea surface temperatures (SST) down to as low as 16~ (Vargas-Angel 1996), whereas occasional very-strong E1 Nifio events increase SST causing thermal stress, bleaching and coral mortality (Prahl 1983a; Vargas-Angel 1996 per. obs.). 2.1.1. Coastal reefs. Few true coral reefs occur along the Colombian Pacific coast. Except for the small reefs in Ensenada de Utria and the Gulf of Cupica (Tebada), only isolated coral colonies and small build-ups are sparsely distributed along the coast at localities such as Cabo Corrientes, Bahia Solano, and Punta Cruces (Prahl and Erhardt
Corals and coral reefs of the Pacific coast of Colombia
423
II
77 o 24' W
Tebada oO "
~ 6~
[..:,
T
i
soom j
Cocalito Chola
~
N
0 :
.
1.0, 2.0 km I ....
Reef
~ ,
A
Diego
Punta1:6# Diego ~
~ )
,
..
Blanca
i. '
6oN "
Fig. 2. Location of the northern, coastal reefs of the Pacific coast of Colombia. A) Ensenada de Utria with planar view of La Chola Reef. Other sites with coral reefs (triangles) or coral communities (circles) are also shown. B) Locationof Tebada Reef. 1985; B. Vargas-/~mgel per. obs.). Isolated colonies of Pocillopora spp. occur as far south as Isla de Palma (Bahia de M~laga: Escobar and Neira 1992; per. obs.). Ensenada tie Utria. Coral reefs at Ensenada de Utria National Park have developed on relatively shallow substrates in sheltered bays. Two main coral reefs occur in the Utria region: these are La Chola reef (following Prahl and Erhardt 1985) and Diego reef (Fig. 2a). La Chola reef, is the largest coral reef (ca. 10.5 ha), and is located on the east margin of Ensenada de Utria. According to Prahl (19860, in 1981 La Chola reef was characterized by a lush and diverse coral assemblage, including several species of Pocillopora, as well as Psammocora stellata, Pavona clavus, Pavona gigantea and Porites spp. To date (Vargas-.~gel 1996, 2001), little or no evidence of the past occurrence of a complex and diverse coral community at La Chola reef has been found. Coral community surveys conducted in 1988-89 (Vargas-,~ngel 1996) showed that La Chola reef was composed predominantly of thin-branched ecomorphs of Pocillopora
424
F.A. Zapata & B. Vargas-Angel
damicornis (80% of colonies), and Psammocora stellata (16%). Other species present included Pocillopora capitata (approx. 4%), Pavona varians and Pavona gigantea (< 1%). Also, mean live-coral cover at La Chola reef was not greater than 33% and the spatial distribution of live corals was highly patchy. All areas where live cover exceeded 60% were associated with dense monospecific stands of Pocillopora damicornis. Lower coral cover (< 20%) occurred in areas where P. damicornis was less abundant or absent. In addition, diversity indices (Shannon-Wiener's H') were overall low (0-1.6), not only because of the reduced coral species richness, but also due to the overwhelming dominance of P. damicornis. Although mean percent cover at La Chola reef was greater along the northern sector (45.3%) than at the central and southern sectors (26.5% and 26.8%, respectively), differences were not significant. By contrast, coral cover was significantly lower on the seaward slope than on the reef flat and leeward zones. Live coral cover varied inversely with coral species diversity and richness, which were highest at the central and southern sectors of the reef. Only a weak coral zonation pattern was evident at La Chola reef, where coral cover decreased from north to south and from inshore to offshore (Vargas-/~mgel 1996). Coral community surveys conducted in 1995-96 (Vargas-.~-agel 2001) showed that neither mean coral cover nor species relative abundance had changed substantially at La Chola reef since 1989. By contrast, shifts in community composition have occurred, including: 1) the spatial re-distribution of the dense monospecific stands of Pocillopora damicornis from the leeward area to the central reef flat, and 2) a notable increase in macro-algal cover (Vargas-/~,ngel 2001). Although La Chola reef seems to have suffered a long history of sedimentation and siltation stress (discussed below, but see Murphy 1939; Prahl and Vargas-Juagel 1990; Vargas-/~uagel 1996, 2001), it is still premature to consider these recent changes in community structure as evidence of degradation. In fact, spatial and temporal heterogeneity in coral reef communities can result from adaptation and recovery to various stressors on numerous and complex scales (Cormell 1978; Brown and Howard 1985; Grigg and Dollar 1990; Reice 1994; Grigg 1995). Other coral communities at Utria include Diego reef, as well as sparse, small coral aggregations and build-ups at Punta Diego, Playa Blanca and Cocalito, which do not form true constructional reefs. In comparison to La Chola reef, Diego reef is a much smaller formation (ca. 1.5 ha). The reef flat starts at approximately I00 rn offshore; it extends seaward for approximately 150 rn at a depth of 2.0-2.5 m, and then slopes gradually to 6.0 to 8.0 rn depth at the reef base. Diego reef is covered mainly by coral rubble and encmsting coralline algae. According to Vargas-/~'agel (1996 and per. obs.) live cover does not exceed 2%; it consists mainly of Psammocora stellata, with very few sparsely scattered colonies of Pocillopora damicornis. No live or dead massive coral colonies have been found on Diego reef, yet large colonies of Pavona elavus, P. gigantea, and Porites lobata occur along the wave-exposed basaltic rocks of Punta Diego (Vargas/~gel per. obs). In 1981, when Prahl visited the zone, he characterized Diego reef (referred to as Playa Blanca reef by Prahl and Erhardt 1985, p. 281, see Vargas-/~gel 1996) as having a mature structure dominated by Pocilloporids and Psammocora, with isolated colonies of Pavona gigantea, P. r P. varians and Porites panamensis. Present day coral community composition and structure suggest that Diego reef has been severely disturbed, and community recovery to a pre-disturbance stage has not yet occurred. Severe bioerosion in excess of accretion (Vargas-/kngel in progress) seems to have been an important factor in reducing this reef structure to rubble and sediments.
Corals and coral reefs of the Pacific coast of Colombia
425
Trying to assess and characterize the causes of coral reef community deterioration at Utria (i.e., La Chola and Diego reefs) has been difficult due to the lack of data prior to 1989, when the first quantitative surveys were conducted. It has been suggested (Vargas,~mgel 1996) that natural and anthropogenic disturbances, including E1 Nifio Southern Oscillation (ENSO), terrigenous siltation, dynamite fishing, recurrent low tides (discussed below) and bioerosion must have played pivotal roles in coral community deterioration and demise at Utria. Sclerochronological and sedimentary studies have provided evidence that ENSO events and chronic siltation are important stressors limiting coral growth and reef development at Utria (Vargas-/~age12001; see bellow). Tebada. Tebada reef, (ca. 6~ 77~ is located south of Bahia Cupica (Fig. 1), and not at the north of it as presented in Prahl and Erhardt (1985 p. 279). Tebada reef is separated from the mainland by a channel of ca. 500 rn, and is protected from ocean surge by a chain of small islets and rocky outcrops (Fig. 2b). The reef is a shallow, gently-sloping platform of approximately 4.5 ha, which is not subaerially exposed during extreme low tides (mean depth close to 2.0 m). Although several species of reef corals are present, including Pavona varians, Pocillopora damicornis, and Pavona gigantea, Psammocora spp. are dominant, accounting for over 80% of the total live coral cover. Reef probings done in 1996 indicate that this reef has a vertical buildup of at least 4 rn on the reef fiat (B. Vargas-Juagel unpubl, data). 2.1.2. Insular reefs. There are two contrasting insular environments with significant coral formations within Colombian Pacific waters: Gorgona Island and Malpelo Island. Gorgona (2~ 78~ is a continental island located approximately 35 km off the nearest point on the Colombian Pacific coast (Fig. 1) within the area of influence of the Intertropical Convergence Zone (ITCZ). The periodical displacement of the ITCZ produces a unimodal, biseasonal pattern of precipitation at Gorgona with a wetter season between May and October. Mean annual precipitation is about 6700 mm at Gorgona and 4900 mm at the mainland in front of it (Rangel and Rudas 1990). Even though sea surface temperatures around Gorgona (normally between 26-29~ are within the range of temperatures for vigorous coral growth and reef development, salinity (between 30-33 ppt) and water clarity (< 5-25 m) are decreased by the freshwater input caused by the abundant rain. Therefore, the strong influence of the nearby continental estuarine environment most likely limits the development of coral reefs at Gorgona Island. In contrast, Malpelo (3~ ~ , 81 ~ is a small oceanic island of volcanic origin located approximately 400 km west of the Pacific coast of Colombia (Fig. 1). It is the only emergent pinnacle of the Malpelo ridge (Chase 1968), separated from mainland Central and South America by depths greater than 3000 m (Graham 1975). Malpelo island is thus surrounded by clear oceanic waters which allow corals to be present as deep as 30 m, which is close to the maximum depth for the occurrence of corals in the Panamic Province (Graham 1975) and second only to Clipperton Island in the TEP, where corals occur as deep as 60 rn (Glynn et al. 1996). SST at Malpelo normally ranges from 26-28~ but temperatures below 30 rn depth are often below 20~ Salini'ty is relatively constant, varying between 32-33 ppt, although occasionally it drops down to 30 ppt (Stevenson et al. 1970). Gorgona Island. Like most reefs in the tropical eastern Pacific, the coral reefs of Gorgona Island cover a small area, are patchily distributed and show modest development. Yet Gorgona's reefs are among the best developed within the region, similar to those in the Gulf of Chiriqui in Panama (Glynn and Wellington 1983; Guzrrfin and Cortrs
426
F.A. Zapata & B. Vargas-,4ngel 78~ I'
78~1o'w
Juan
Yundigua
PACIFIC
OCEAN
Playa Pizarro
La M~
Lo Cam~ ~0~1El Poblado Old Prison
La Camar( Reef
Pier Site POld Pier Reef
La Azufrada Reef GORGONILLA Los FaraUones Reef ISLET / ~ _ 9I ....
'unta Brava Playa Blanca Reef
2*56 '
~'ascr r~ ~'~-':_,e~_"La G6mez de Tasca " k . . . , ~ ~
.~,~
~iij 9 ,~Ik "La Ventana
o, o.~, ,.o, km
Fig. 3. Map of Gorgona Island showing distribution of coral formations, major topographic features and distribution of freshwater streams. Planar view of major coral formations are shown. Reefs with relatively high live coral cover are indicated in solid black, whereas formerreef areas reduced to rubble or significantly deteriorated are indicated with a dashed pattern. Based on aerial photographs from Institute Geogr~ifico "Agustin Codazzi", a map in Glynn et al. (1982), and personalobservations. 1993; Cortrs 1997). Additionally, Gorgona's reefs are unique in that they are located in a non-upwelling area of the TEP and are free of predation by a major corallivore, the crown-of-thorns starfish (Acanthaster planci: Glynn et al. 1982; Glynn and Wellington 1983). Coral formations around the island show varied degrees of development, including coral communities, incipient reefs, and well-developed fringing reefs. Some of these reefs are the most mature and best studied coral reefs of the Colombian Pacific (Prahl et al. 1979; Glynn et al. 1982; Prahl and Erhardt 1985; Prahl 1986b). Except for one small reef, all coral formations at Gorgona are located on the eastern, leeward side of the island (Fig. 3). Prahl et al. (1979) speculated about the causes of this uneven distribution of coral formations around Gorgona and attributed it to: 1) low salinity stress due to an assumed greater number of freshwater streams discharging on the west side of the island; 2) lower and more variable water temperatures on the western
Corals and coral reefs of the Pacific coast of Colombia
427
side of Gorgona; 3) stronger wave action on the westem shore causing resuspension of sediment, increased turbidity and decreased light penetration in addition to substrate fragmentation and instability; and 4) a smaller shelf area on the westem side. However, except for the fact that the number of freshwater streams on either side of the island is almost identical (west = 12, east = 11) thus not lending support to the first hypothesis, there is a lack of detailed knowledge on the local oceanography and the physical environment around Gorgona necessary to test the above hypotheses (but see general oceanographic descriptions by Prahl et al. 1979; Glynn et al. 1982; Prahl 1986a). Additionally, the relative inaccessibility of the western shore by both land and sea has made it difficult to study this side of the island. Coral communities. Coral communities (i.e., characterized by the dominance of hermatypic corals but lacking a significant reef frame buildup) are common around Gorgona. Several coral communities, with up to 30% live coral cover, are patchily distributed on rocky substrates from the northernmost tip of Gorgona and moving southward along the eastern coast (Fig. 3). These are briefly mentioned by most authors (Prahl et al. 1979; Glylm et al. 1982; Cantera 1983; Prahl and Erhardt 1985; Prahl 1986b), but remain largely undescribed except for limited observations (Glynn et al. 1982; L6pezGiraldo 1992). These communities are located at E1 Homo, E1 Remanso, Yundigua, and Playa Pizarro. These communities, but particularly those at E1 Remanso and Playa Pizarro appear to be the remains of former fringing reefs judging by the amount of coral rubble present in the area. Other coral formations previously reported at Gorgona (Glynn et al. 1982) but now reduced include those at La G6mez, La Ventana, and the Paso de Tasca area. Most likely, these reefs deteriorated significantly during the strong E1 Nifio event of 1982-83 and unlike other reefs at Gorgona have not yet recovered. Incipient reefs. At least four areas around Gorgona (Fig. 3) have incipient coral reef developments, which have been briefly described (Glynn et al. 1982; L6pez-Giraldo 1992). At La G6mez there is a series of linear ridges formed by pocilloporids, similar in appearance to those at La Camaronera (see below). The linear ridges appear to be formed in response to prevailing wind and wave conditions. The shallow shelf in the areas of La G6mez and La Ventana support dense stands of Pocillopora spp. with a vertical buildup of approximately 1 m (Glynn et al. 1982). In the Paso de Tasca area, the strait between Gorgona and the islet of Gorgonilla, there is one small reef (ca. 200-250 m long) located at the northern tip of Gorgonilla and a few, small coral patches built mainly by pocilloporids. This reef, also known as Los FaraUones reef, has a vertical buildup of 1-2 m, and is similar in structure and zonation to La Azufrada and Playa Blanca reefs (Glynn et al. 1982; Prahl and Erhardt 1985; Prahl 1986b; L6pez-Giraldo 1992). Much of the reef flat consists of a dead pocilloporid frame tightly bound by coralline algae, whereas the reef crest and upper slope are dominated by living pocilloporids (Glyrm et al. 1982). The outer reef base consists of a sandy and bioclastic plain dominated by many large colonies of massive species, mainly Pavona gigantea, growing a few meters apart (F.A. Zapata per. obs.). The main reef on the western side of the island, known as La Camaronera reef, is located on a rocky headland between the sandy beaches of La Camaronera and E1 Cocal. This area is characterized by strong wave action. Two kinds of coral formations in this area have been briefly described (Glynn et al. 1982): 1) a series of small, shallow reefs consisting of a reef flat formed by a tightly intermeshing framework of Pocillopora spp. lying on a basalt substrate, and sloping sharply to a sandy bottom at 4 m depth. 2) Several
428
F.A. Zapata & B. Vargas-,4ngel
linear spurs located further offshore and oriented parallel to the prevailing wave direction, formed by pocilloporids and having a vertical buildup of 2-3 rn. Some spurs lack any live coral and appear to be accumulations of coral rubble bound together by coralline algae. Along with these and further north, at the southern end of La Camaronera Beach, there are numerous hillocks of various sizes built also by pocilloporids. All of these formations lack any evident zonation. Crustose coralline algae binding the reef frame were more evident on these windward reefs than on those on the leeward side of the island (Glynn et al. 1982; F.A. Zapata per. obs.). Fringing reefs. Old Pier reef This small fringing reef (about 45 rn long and covering an area of about 0.16 ha) is located south of the remains of a large wooden pier destroyed in 1984. Although a total of 10 species of corals, including species of Psammoeora, Porites and Pavona, have been previously observed on this reef (Cantera 1983), it is now made up almost entirely of pocilloporids, mainly Pocillopora damicornis (F.A. Zapata per. obs.). Total live coral cover varies from 20% in the backreef and lower slope to 85% on the reef front. Whereas species richness tends to be greater on the reef flat and crest, species diversity increases steadily from the backreef to the reef front (Cantera 1983). Despite its small size, the reef is similar in structure and zonation to other larger fringing reefs on the island (see below). It has a relatively extensive reef flat followed by a steep (ca. 60 ~ reef front, and at about 6 m depth, by a sand plain composed of bioclastic and carbonate debris (Glynn et al. 1982; Cantera 1983; Prahl and Erhardt 1985; Prahl 1986b). The reef frame may have a vertical buildup of up to 6 m (Glynn et al. 1982). La Azufrada reef This is the largest, continuous coral reef of Gorgona Island, as well as the best studied (Prahl et al. 1979; Glynn et al. 1982; Prahl and Erhardt 1985; Prahl 1986b; see also Cantera and Arnaud 1995; Zapata and Morales 1997). Direct measurements made recently, however, indicate that it is slightly smaller (780 m long and 80-180 rn wide) than previously reported (Glynn et al. 1982), covering about 11.2 ha (F.A. Zapata et al. unpubl, data). Glynn et al. (1982) observed 10 coral species on this reef; it is clearly dominated by pocilloporids, but also includes (in decreasing order of in~ortance) species of Psammocora, Pavona, Porites, and Gardineroseris. Live coral cover varies from < 50% in the backreef up to > 80% on the reef crest and front (Glynn et al. 1982; Prahl 1986b; F.A. Zapata et al. unpubl, data). On the backreef and reef flat, the continuity of live coral is occasionally interrupted by relatively large patches of dead pocilloporid fragments, among which many small, live colonies of Psammor are found covering a significant proportion of the substrate (ca. 40%). Species richness and diversity are variable but overall higher on the reef crest and upper slope than elsewhere. The reef has a coral framework buildup varying from 2 to 8.3 m (Glynn et aL 1982). A unique feature of La Azufrada reef is the presence of a crater-like depression located on the northern portion of the reef near the crest. The depression is circular with a 40 m diameter and is completely surrounded by the thick coral growth typical of the reef crest. On the inner side of the rim coral cover decreases with increasing depth reaching a uniform soft-sediment bottom at approximately 10 rn depth. A few very large colonies of Gardineroseris planulata, with a high proportion of their surface dead and covered by algae, are scattered around the inner edge of coral growth. Glynn et al. (1982) speculated that the origin of this depression was likely the result of coral growth around a small submarine valley. This depression appears to have been present on the reef for at least a few decades since it is visible on aerial photographs taken in 1957 and 1962. A second
Corals and coralreefs of the Pacificcoast of Colombia
429
interesting feature of this reef is the unusually high abundance of Pocillopora eydouxi at the reef crest on the northernmost portion of the reef (F.A. Zapata per. obs.). Playa Blanca reef The reef at Playa Blanca consists of two patches separated by a channel approximately 60 m wide. The smaller, northernmost patch is ca. 240 m long and has a relatively uniform width of ca. 40 m due to the rapid increase in depth as one moves seaward. This patch exhibits a very diverse and "healthy" appearance, and has very dense coral growth. As on other reefs, pocilloporids dominate the shallow areas whereas massive corals, particularly Pavona varians and Gardineroseris planulata form large clusters at the outer reef base. Of particular interest at this site in early 1997 were 1) the high frequency of scars apparently caused by fish corallivores on massive species, 2) the frequent presence of dense patches of Poeillopora eydouxi, and 3) the presence of an as yet undentified species of Pavona, very similar to Pavona frondifera from the Indo-Pacific and previously unreported for Gorgona (F.A. Zapata per. obs.). Although Pavona frondifera has been previously reported for other localities in the TEP (GuzmAn and Cort6s 1993; Glynn 1997; Cort6s and Guzrnfin 1998), there remains some doubt about the specific status of the specimens collected at these localities and it is plausible that they belong to a species as yet undescribed (J.L. Mat6 per. com.). The second, southernmost reef patch at Playa Blanca is slightly longer (ca. 930 m) but more variable in width (ca. 60-230 m) than La Azufrada reef. Nonetheless, it is similar in areal coverage (9.9 ha; F.A. Zapata unpubl, data), general shape, structure and zonation to the reef at La Azufrada (Glynn et al. 1982; Prahl and Erhardt 1985). However, the backreef zone is wider and closer to the beach, the reef crest is not as noticeable, the forereef has a steeper slope, and the bioclastic sandplain is shallower than at La Azufrada. This reef's framework is also made up mostly of pocilloporids with large colonies of Pocillopora eydouxi abundant on the crest and forereef. Large colonies of Pavona clavus and P. gigantea are relatively abundant at the reef base (Glynn et al. 1982), but show a conspicuous patchy distribution. Patches of Gardineroseris planulata are occasionally found at the reef base as well. Zonation of Gorgona's fringing reefs. The coral reefs of Gorgona are in general characterized by their diffuse zonation pattern, although it is more defined on the larger than on the smaller coral formations. Nevertheless, published descriptions of zonation on the main reefs of Gorgona generally agree with the identification of major zones (Prahl et al. 1979; Glynn et aL 1982; Cantera 1983; Prahl and Erhardt 1985; Prahl 1986b; see also Zapata and Morales 1997). The following is a generalized zonation scheme from the beach seaward based on the latter works and our own observations (Fig. 4): 1) The reef is separated from the beach by a shallow, boat channel, 20-100 m-wide, characterized by fine-sediment substrate (partly derived from land runoff), and by the lack of coral growth. At Playa Blanca, a strip of coral rubble several meters wide and covered by algae follows the channel. 2) At La Azufrada, a few isolated coral colonies begin to appear at the boat channel-backreef interface, whereas at Playa Blanca the transition from coral rubble to denser live coral is more abrupt. The backreef is characterized by a low and patchy distribution of live-coral cover, which increases seaward from < 10% to < 50% over a stretch of 20-30 rn. Dominant species in this zone are in order of decreasing cover: Psammocora stellata (more abundant at La Azufrada), Pocillopora spp. (mostly P. damicornis) and very few, small Pavona varians. 3) Moving seaward, pocilloporids, particularly Pocillopora damicornis and P. elegans, dominate the reef fiat, although colonies of Porites panamensis, Pavona varians and Psammocora stellata are
F.A. Zapata&B. Vargas-Angel
430 E
o
--'
2
~: 0
4 "i'"'"'"
"Q 8 .c: " ~ 10 0
10
Transect 3 !
30
F
I
B
B
40
F
9
:
50
60
70
80
90
3
! 100 110 120 130 140 150
Distance from backreers edge (m)
B
Transect I ," Transect 2 L
20
2
F
I
C
I I C
C
I I
I
Fr
Fr
I I
S
I
$ Fr
~
I
......................
I
$
I
Fig. 4. Depth profiles of three transects at La Azufrada Reef, Gorgona Island, showing the approximate width of five reef zones as follows: B = backreef, F = reef flat, C = reef crest, Fr -- reef front, and S -- upper reef slope. Inset shows planar view of the reef and adjacent coastline with approximate location of transects. found interspersed amongst the pocilloporids. P. stellata can be abundant, particularly within pockets of dead coral and consolidated calcareous rock. Total live coral cover varies both within and between reefs in this zone and may reach up to 70%, whereas the remaining substrate is composed of consolidated calcareous algae, sand, and coral rubble. 4) Like many flinging reefs, Gorgona's reefs lack a true reef crest. Nonetheless, the outer portion of the reef fiat is slightly elevated, making it the shallowest portion of the reef, and thus a distinct zone frequently referred to as the crest. It is densely covered by Pocillopora spp., mainly P. damicornis, although notably large colonies of Pocillopora eydouxL P. elegans and P. capitata are more abundant here than elsewhere on the reef. Total live coral cover can be as high as 80%-90% due to the close packing of colonies. The backreef, the reef fiat, but particularly the crest, are occasionally exposed during extreme low tides. The effects of subaerial exposure create a mosaic of dead coral covered by algae patchily distributed over live coral, and contribute to the spatial heterogeneity of the reefs (see section "Natural disturbances, extreme low tides"). 5) In the reef front the bottom begins to slope steeply although live coral cover and species composition continue to be similar to those in the reef crest. The limit of the pocilloporid reef framework is located at the outermost portion of this zone. Relatively large blocks (up to 2 m long by 0.5 m wide) of the pocilloporid frame are often found tom off at this level. 6) On the upper reef slope, concomitant with a pronounced decrease in pocilloporid coral cover (to 20% or less) there is an increase in the amount of coral rubble and abundance of large (up to 2-3 m in diameter), massive colonies of Porites lobata, Pavona gigantea and Pavona clavus, or clusters of Pavona varians or Gardineroseris planulata, which produce high topographic complexity. Psammocora stellata becomes once again a dominant member of the community in terms of cover, whereas Pocillopora spp. occur as scattered, isolated colonies. 7) Finally, reefs may be followed by either a sand plain composed of bioclastic and carbonate debris (Old Pier reef and Playa Blanca) or by a lower slope largely
Corals and coral reefs of the Pacific coast of Colombia
431
composed of coral rabble and fine sediment, Psammocora stellata and a few and widely separated, small colonies of Pocillopora spp. and Pavona varians (La Azufrada reef). Malpelo Island. Because of its geographic location, both oceanic and continental currents influence Malpelo Island (Wyrtld 1965). However, despite the biogeographic importance of oceanic islands in the TEP as potential stepping stones for the invasion of Indo-Pacific species (Graham 1975; see also Glynn et aI. 1996; Robertson and Allen 1996; Glynn and Ault 2000), Malpelo Island has been overlooked. Due to the remote location of this small island few studies have addressed the ecological aspects of Malpelo's marine communities. After initial work by Birkeland et al. (1975), only three contributions have considered the coral formations at Malpelo (Prahl 1990; Brando et al. 1992; Garz6n-Ferreira and Pinz6n 1999). Steep cliffs and vertical walls characterize the perimeter of Malpelo Island. Hermatypic corals occur mostly as a veneer, interspersed with other benthic invertebrates, especially barnacles (Balanus peninsularis) and octocorals (Anthozoa: Alcyonaria). In some cases corals occur as shingled overhanging masses on the vertical rocky walls (Birkeland et al. 1975). Rich coral aggregations and build-ups occur only on the gradually sloping substrates. These observations led Birkeland et aL (1975) to conclude that no true reefs occur at Malpelo. However, there is no information about the extent of coral build up at Malpelo and reef probings are needed to confirm such conclusion. Of special interest is the coral formation found by Birkeland et aL (1975) in a small protected embayment on the east coast of the island. This is the largest and most developed coral formation at Malpelo and is known as "El Arrecife" (Fig. 5). Whereas Birkeland et al. (1975) reported that cover by hermatypic corals varied between 42% and 89% at E1 Arrecife in 1972, Garz6n-Ferreira and Pinz6n (1999) found values between 15% and 60% at the same reef in 1999. Here corals exhibit a clear zonation pattern (Birkeland et al. 1975). Colonies of Pocillopora capitata dominate (80-94% of live coral cover) between 9 and 12 m. In contrast, massive corals are more abundant on deeper substrates, also presenting specific depth preferences. Porites lobata and Pavona clavus are most abundant (80% and 54%, respectively) between 14 to 18 m. The deepest substrates (26-27 m) are dominated by Gardineroseris planulata (53%). These zonation results are in accordance with recent observations b), Garz6n-Ferreira and Pinz6n (1999). Similar observations were made by B. Vargas-Angel and F. Estupifi~n (unpub. data), who visited the island in 1990 and found a small coral community (ca. 0.1 ha) on the west coast of the island at the site known as "El Mirador". The shallow substrate between 5 and 10 m depth was dominated by low-profile colonies of Pocillopora capitata and Pocillopora eydouxi. Of special interest in these areas were the few colonies of P. eydouxi, which exhibited very broad and flattened branches. The second zone, between 10 and 20 m was densely covered (93-99%) by shingle-like colonies of Porites lobata. Below 20 m depth Pavona clavus and Pavona varians were abundant. Other smaller, undescribed, coral formations are located at two other sites known as "El N~ufrago" and "Bajo de Junior" (Fig. 5; S. Bessudo per. com.). The rich development of reef corals in the two coral formations described above suggests that conditions are favorable for coral growth at Malpelo (Birkeland et al. 1975). However, hermatypic coral growth is limited elsewhere around the island (~10%). Birkeland et al. (1975) suggested that two main factors limit reef development at Malpelo Island, namely sunlight and lack of a gently sloping shelf. Vertical surfaces are frequently shaded due to the sun angle and vertical irregularities of the walls. Moreover,
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F.A. Zapata & B. Vargas-Angel 81~ ' W ( ~ ) ~ ) LOSTres Mosqueteros 0 D'Artagnan
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Los Reyes
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Fig. 5. Map of Malpelo Island showing distribution of coral formations (black circles) and major topographic features. Names of sites are those commonly used by sport divers (S. Bessudo, per. com.).
vertical walls provide little or no support at all on which corals can build and develop a reef. Low water temperatures may also limit the depth distribution of corals at Malpelo. The occurrence of temperatures as low as 19.5~ below 30 m depth are evidently cold enough to limit coral growth (Birkeland et al. 1975). Additionally, oceanic swells may have a profound in~act on the development of coral formations at Malpelo. First, strong wave action is most likely the major cause of erosion of the island, causing frequent rockfalls (Stead 1975) that affect the development of coral buildups (Birkeland et al. 1975). Second, unusually strong wave action during occasional storms has long been known to disturb coral reefs (Brown 1997) and it is likely that it does at Malpelo as well. For instance, in June 1999 strong oceanic swells caused the breakage of many pocilloporid colonies, overturned many large colonies of massive species and caused severe perturbations to Malpelo's main reef in just one night (Garz6n-Ferreira and Pinz6n 1999).
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3. NATURAL DISTURBANCES 3.1. EL Nifio-Southern Oscillation
During 1982 and 1983 an increase in sea surface temperature (SST) occurred along the Colombian Pacific coast that lasted at least 16 months, causing bleaching and death of hermatypic corals. The bleaching event was preceded by increases of 1-2~ above the long-term norm over an 11-month period (June 1982 to April 1983: Prahl 1985b; Glynn 1990), while the greatest temperature deviation (3.5~ occurred in March of 1983. However, one temperature reading of 31.5~ obtained from Gorgona Island in February 1983 (3.2~ above the mean), suggests that coral reefs in this location may have experienced even greater sea warming (Glynn 1990). As at many other locations in the TEP, the first sign of coral thermal stress was the loss of endosymbiotic algae by corals. On the Pacific coast of Colombia, coral bleaching was only noticed in April 1983, although it may have begun as early as February. It reached widespread and catastrophic proportions by June 1983, when Prahl (1983a) reported coral bleaching in excess of ca. 85% in all the coral reefs of Gorgona Island. Massive corals along the reef base (> 6 m depth) showed bleached surfaces, while the bases of the colonies remained with normal coloration (Prahl 1983a). In addition, coral bleaching at Gorgona Island was accompanied also by decreased mucus release, mainly in pocilloporid corals, and a dramatic reduction of coral commensal symbionts (Prahl 1985b). In situ coral skeletal staining (Prahl 1986d) demonstrated not unexpectedly that bleached corals were incapable of calcification. By July 1983, most of the bleached coral colonies at La Azufrada reef were dead, and covered by macroalgae. However, Pocillopora eydouxi at La Azufrada and Playa Blanca reefs was the coral least affected by the warming event (Prahl 1983a). Recovery of coral reefs at Gorgona Island since 1983 has been slow, not only because most live corals were severely reduced by the 1982-83 warming event, but also because of low coral growth and recruitment rates, and secondary environmental disturbances. In November 1984, Prahl visited the island and noticed a slight recovery in coral cover of ca. 15%, mainly due to regeneration of pocilloporid colonies; however, no signs of recovery by the massive coral G. planulata was observed (Prahl 1985b). In October 1985 B. Vargas-Angel and C. Moreno (unpubl. data) still observed large extensions of dead coral at La Azufrada reef. In December 1987, reef corals, predominantly Psammocora stellata and Pocillopora damicornis, had recolonized most of the dead coral platform at the northern portion of La Azufrada reef (Prahl et al. 1988). Although substantial coral regeneration has occurred since 1983, full recovery of the coral community to a pre-disturbance stage has apparently not occurred yet any of the reefs in fiat Gorgona Island. However, comparisons of coral community structure at La Azufrada between 1979 (Glynn et al. 1982) and 1993, 1995 and 1996 showed that 1) live coral cover was similar across all years in all zones except the backreef (which was lower in 1979 due to high sedimentation); 2) species richness and diversity (H') did not differ significantly among years although they tended to be higher in the reef crest and front in 1979; and 3) evenness (J') was significantly greater in the reef fiat and reef front in 1979 (C.E. Bhrcenas et al. unpubl, data). Although massive corals, including species of Pavona, poritids and Gardineroseris planulata, are still present in all reef zones (but particularly on the upper reef slope), they occur only in relatively low abundance (Prahl et al. 1988; Guzm,Sn and L6pez 1991; per. obs. by the authors). Post-disturbance coral
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growth rates (23.6 mm yr-l for P. damicornis) were low compared to those reported by Glynn and Stewart ~1973) for Panama and were ascribed by Prahl (1985b) to slow coral regeneration after the 1982-83 warming event. However, reports of reduced coral growth rates during 1985-86 could have been the result of two non-mutually exclusive factors: 1) stained colonies were unattached to the bottom and free to wander on the reef, (E.J. Pefia per. com.), and 2) other disturbances after the ENSO event, such as the strong upwelling in the Gulf of Panama of 1985 (Legeckis 1988; Guzn~n et al. 1990), or extreme low tides, may have affected coral growth. Although the 1982-83 E1 Nifio warming lasted between 10 and 20 months (depending on location; see Glynn 1990), still little is known about long-term ecological changes affecting corals and coral reefs on the Pacific coast of Colombia. Glynn (1990) implicitly proposed that the 1982-83 E1 Nifio event was responsible for the extinction of Acropora valida at Gorgona Island, hence the eastern Pacific. However, the colonies of A. valida at Gorgona had a normal appearance when they were found in September of 1983, at the end of the warming episode (Prahl and Mejia 1985). Nonetheless, the occurrence of A. valida at Gorgona or elsewhere in the TEP was never confn'rned. It is thus unclear whether the 1982-83 E1 Nifio event drove A. valida to extinction in the TEP. Comparisons of maps of coral reef distribution around Gorgona made before the 1982-83 E1 Nifio (Prahl et al. 1979; Glynn et al. 1982) with maps made after (Prahl and Erhardt 1985; Prahl 1986b; L6pez-Giraldo 1992), in addition to our own observations, suggest that some reefs at Gorgona were more affected than others. Whereas the larger reefs of La Azufrada and Playa Blanca appear today almost as large and with similar live coral cover and species richness as before 1982, the smaller reefs at E1 Remanso, Yundigua, Playa Pizarro, E1 Muelle, La G6mez, La Ventana and Paso de Tasca are much smaller and show little coral buildup. Lack of detailed descriptions of most of these reefs prior to 1983, however, make it difficult to establish whether these changes were the result of the 1982-83 E1Nifio event. Between May 1997 and June 1998 the second strongest ENSO event of the century occurred. A particular feature of this event was the occurrence of two intensity peaks, one in August 1997 and another in May 1998. Satellite-obtained data images indicate that in the Pacific coast of Colombia SST increased up to 2~ above the long term mean between May-September 1997, and more than 3~ between April-June 1998. In coincidence with the occurrence of this event there was widespread coral bleaching in tropical reefs around the world (ISRS 1998, Strong et al. 1998). In the Pacific coast of Colombia moderate to severe coral bleaching and mortality were observed at Utria, Gorgona, and Malpelo (Vargas-.~mgel et al. 2001). The first unequivocal signs of bleaching were observed at Gorgona in September 1997, when patches of Pocillopora at various depths showed bleaching on the distal portion of branches. At this time, the extent of bleaching on massive species (mainly Pavona spp.) was much greater than on branching species, with a high proportion of the upper surface of colonies bleached. The extent of bleaching at the scale of the reefs was, however, low (ca. 1%). By December 1997 bleaching was evident reaching on average 21% by April 1998 and 25% by June 1998 at Playa Blanca reef. Similarly, at La Azufrada reef, coral bleaching was low during October 1997 (< 1%) but had reached 21% by May 1998 (Vargas-Angel et al. 2001). At Playa Blanca reef the extent of coral bleaching was not uniformly distributed among reef zones. In June of 1998 bleaching had reached 17% on the reef slope and 30% on the reef crest.
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Evidently the extent of bleaching and mortality during the 1997-98 ENSO event did not reach the catastrophic proportions of the 1982-83 event. Casual observations made in August 1998 on Gorgona's main reefs revealed that, although coral mortality inevitably occurred, much of the coral previously bleached had recovered its normal coloration. Massive corals, however, were less capable of recovery than branching corals and thus suffered the greatest mortality. This differential mortality of corals as a result of sea warming and bleaching provides yet another reason to explain the high dominance of pocilloporids on TEP coral reefs (Vargas-.~gel et al. 2001). Meanwhile, the effects of E1 Nifio events for locations such as Malpelo Island, Tebada, and Utria still remain to be studied. Sclerochronological evidence indicates that corals at Utfia and Tebada were also severely impacted by the 1982-83 E1 Nifio warming event. During this disturbance, skeletal growth in massive corals was halted across the region, and regeneration of tissues over dead coral surfaces required as long as 2-3 years (Vargas-.~mgel et al. 2001). In some cases, corals never recovered and eventually died. Interestingly, the skeletal growth interruption associated to the 1982-83 E1 Nifio was more prevalent and conspicuous in corals from Gorgona Island than from Utria and Tebada, suggesting that the impacts of the disturbance may have been greater at Gorgona than farther north (Vargas-/kngel et al. 2001). Nonetheless, growth records of massive reef corals can only provide evidence for individual colonies, and therefore inferences on ENSO effects at the community level can only be speculative. Because our knowledge about coral reef community structure at Utria, Tebada and Malpelo prior to the 1982-83 warming event is limited or nonexistent, a full understanding of the predisturbance/post-disturbance dynamics for those reefs is still precluded. A study of the possible synergistic effects of E1 Nifio with other anthropogenic or natural disturbances such as upwelling, sedimentation, and aerial exposure should provide a more complete understanding of the interplay among the varied disturbance regimes and their effects on reef dynamics. 3.2. Extreme low tides Aerial exposure of coral reefs during extreme low tides is an abiotic factor potentially important for population regulation and community organization of coral species in the TEP (Glynn 1976). Based on knowledge of the tidal regime and on the observation of large tracts of dead coral on the shallowest portions of a coral reef, Glynn et al. (1982) suggested the occurrence of tide-related mortality of corals at Gorgona Island. Indeed, anecdotal accounts indicate that aerial exposures of reef corals at Gorgona have long been known, and verified events have occurred regularly at least since 1993 when one of us (F.A.Z.) began to study this phenomenon. Aerial exposure of corals at La Azufrada reef occurs when the tidal level drops to - 0.4 m relative to MLLW, which is the relative position of the shallowest corals. The frequency of occurrence and duration of potential, diurnal, aerial exposure events at La Azufrada has been examined based on tidal predictiom for the period 1966-1996. For this purpose, one aerial exposure event was defined as the emersion of corals on one or more consecutive days during a single spring-tide series. This analysis revealed that aerial exposure events occur on average every 90 d, although intervals between two consecutive events range between 25 and 441 d. On average, reefs arc exposed more than twice during one spring tide series and occasionally up to five times. Exposure events occur only between January and April and between August and December (F.A. Zapata et al. unpubl, data). Because this analysis was based
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on tidal predictions, it is only indicative of the importance of aerial exposures as an agent of disturbance. In fact, aerial exposure of reefs may be more or less dramatic depending on local climatic conditions (e.g., atmospheric pressure, winds) during spring tides, and on large scale climatic and oceanographic conditions. For instance, under conditions of an E1 Nifio event, when sea level is higher, aerial exposures may be reduced both in frequency and magnitude, while the converse may occur during La Nifia, when sea level is depressed. Nocturnal emersiom do occur as well, but may be less impacting than diurnal ones. Not all aerial exposure events affect corals, but after repeated and prolonged exposures, exposed tissues (usually at the distal portions of branches) are bleached and later die. Filamentous algae rapidly colonize dead portions and eventually grow to cover the entire colony. As a result, abundant algal patches of varied sizes are typically formed on the most elevated portions of the reef crest and reef flat. This effect appears to be widespread at Gorgona since it is readily visible on most reefs around the island one to three months after the occurrence of an emersion event. Comparisons of algal cover and coral richness and diversity on the reef crest of La Azufrada reef at Gorgona Island following the occurrence of one or more verified exposure events for two pairs of consecutive years (1992-93 and 1995-96) indicate that filamentous algal cover increased from almost 0% in previous years to a maximum of 24% following aerial exposure. Whereas coral species richness and diversity were not affected in 1993 when compared to 1992, both decreased in 1996 relative to 1995 levels (F.A. Zapata et al. unpubl, data). At la Chola reef (Ensenada de Utria), extreme low tides are also potentially deleterious to reef corals. For example, in October 1988 severe and widespread bleaching was observed resulting from a prolonged sub-aerial tidal exposure (-0.4 m), which coincided with elevated mid-morning air temperatures (2930~ Unexpectedly, this event did not cause coral mortality and corals recovered their normal pigmentation within two weeks (Vargas-Angel 1996). Not only are corals affected by the aerial exposure of reefs, but their associated fauna can be severely affected as well. Anecdotal accounts (R. Franke per. com.) indicate the occurrence of high mortality in a broad variety of reef associated organisms during extreme low tides. This mortality appears to be related to increased water temperature, and to oxygen depletion in the pools formed during the exposure of reefs. These pools act also as traps for many species, particularly fish. In addition, stressed corals appear to release great amounts of mucus that accumulates on the water surface and may contribute to the deterioration of water conditions. At present we have only observed the short-term effects of aerial exposure of reefs. Following the succession of algal patches, particularly focusing on their use by reef herbivores and measuring any potential bioerosion caused by them, will allow a better evaluation of the long-term effects of aerial exposures on coral community structure and reef development. Furthermore, a more detailed assessment of the impact of aerial exposures on the reef-associated fauna is needed. 3.3. Sedimentation Terrigenous sediment influx in coral reef ecosystems can lead to coral bleaching, as well as coral tissue necrosis and colony death (Cort6s and Risk 1985; Hubbard 1986; Cort6s 1990). On the Pacific coast of Colombia, coral reefs have not been exempt from this kind of disturbance. From 1960 to 1983, Gorgona Island was the site of Colombia's
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top-security prison. During this time extensive forest clearing occurred as well as largescale enterprises, including the construction of the penal facility to accommodate about 2000 people, a pier, a road and several trails, and a landing strip for small aircraft. According to Prahl et al. (1979) extensive coral death was observed on the backreef at La Azufrada as a consequence of sediment accumulation, mainly caused by the runoff of unstable top soils due to indiscriminate excavation for the construction of the landing strip. Even after >15 years of natural reforestation, corals at the boat channel-backreef interface in front of the landing strip at La Azufrada reef are still covered with fine sediment. In addition, recent concem has arisen about the possibility of siltation stress to the marine fauna of Gorgona Island due to the Naranjo channel. The Naranjo channel is a major engineering pitfall of the early 1970's, responsible for the diversion of more than 80% of the waters and the formation of a new delta for the Patia river, on the Colombian mainland about 50 km south of Gorgona Island. Possible impacts of this disturbance to the marine communities of the island were never considered at the time of construction. Recent satellite imagery suggests that the sediment plume discharged from the new delta of the Patia River may have been reaching Gorgona during the last twenty years (C. Monge per. com.). Preliminary measurements of sedimentation rates made in 1996 at La Azufrada reef (L.H. Chasqui and G. Morales un_publ, data) suggest that these are greater on the reef slope (7.9 g m-2 d-1) than in the backreef (2.7 g m-2 d-l). This result is contrary to what one would expect if sediments were primarily derived from Gorgona itself, and compatible with the idea that sediments arrive from the mainland. However, estimates obtained between November 1999 and March 2000 reveled greater overall sedimentation rates and a more complex spatial patterns (Lozano et al. unpubl, data). Sedimentation rates on the slope of La Azufrada and Playa Blanca were lower (34 and 47 gm2 d"l, respectively) than on the back reef at both sites (95 and 293 gm2 d ~, respectively), suggesting that terrestrial run-off from the island is important. Nonetheless, because surrounding currents generally flow in a north-eastern direction, the greater rates of sedimentation at Playa Blanca than at La Azufrada are still compatible with the idea that continentally derives sediments may be reaching Gorgona, but more comprehensive studies are clearly needed. Prahl and Vargas-/~mgel (1990) proposed that suboptimal environmental conditions in association with high rates of sedimentation were causative factors for reduced growth rates (12.7 mm yr-1) of the main reef builder, Pocillopora damicornis at La Chola reef, Ensenada de Utria. Moreover, the fact that La Chola reef is dominated by freely branching ecomorphs of Pocillopora damicornis can be considered as supplementary evidence in support for coral sedimentation and turbidity stress at Utria (Prahl and Erhardt 1985; Prahl and Estupifi~in 1990). In addition, Vargas-/kngel (2001) observed an increase in macroalgal biomass cover at La Chola reef and severe coastal erosion, in contrast to earlier observations in 1988 (Vargas-/kngel 1996). It is possible that elevated sediment loads, turbidity levels and concomitant nutrient loading have led to coral stress, fostering the proliferation of macroalgal patches at La Chola reef. Macroalgal cover may have also increased, however, due to the effects of aerial exposures during extreme low tides. Sediment stratigraphic studies by Vargas-,~-agel (2001) offer evidence of chronic siltation stress at La Chola reef during part of its Holocene growth history. The development of a relatively vital calcifying community under environmentally "poor" conditions is thought to occur due to the interplay of physical and biological factors,
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including climate, water circulation, the presence of mangrove forest and coral colony morphology.
3.4. Strong upwelling Seasonal upwelling along the coast of Central America is most apparent from December to March. The main driving force for these events is the intermittent arrival of high atmospheric pressures from Canada to the Caribbean and Central America. Under these conditions, coastal surface waters can be rapidly blown offshore, coastal level is depressed, and coastal upweUing can reduce surface water temperatures by nearly 10~ in less than a day (Legeckis 1988). During March 1985, unusually persistent upwelling off the Gulfs of Panama and Papagayo caused red tides severely affecting corals and coral reefs in Central America (Guzm,Sn et al. 1990). According to Legeckis (1988) this phenomenon depressed SST by 6 to 10~ relative to the surrounding waters, and cooler waters extended southwest off Panama reaching the Galapagos Islands. There are no reports, however, of the effects of this event on the corals of the Pacific coast of Colombia. Nonetheless, corals at Utria and Gorgona may have been affected, both by long-term exposure to low water temperature, as well as to toxicity, oxygen depletion and reduced light penetration caused by the dinoflagellate bloom (see GuzmAn et al. 1990). In February 1989, low SST (16-18~ in association with red tides resulted in widespread coral bleaching at La Chola reef, Ensenada de Utria (Vargas-.~mgel 1996). On this occasion, blooms of Gymnodynium sp. were responsible for the red tides (B. Vargas-/~ngel and F. Estupifi~n unpubl, data). Bleaching of corals was observed only at Utria, where corals regained their normal pigmentation in about a week. In contrast, although SSTs as low as 18~ also were recorded for Gorgona Island at this time (F. Estupifi~in unpubl, data), no red tides or coral bleaching were observed. 3.5. Tectonism Tectonic activity is common along the Pacific coast of Colombia, and strong earthquakes are not infrequent in this area (Oppenheim 1952; Case et al. 1971; Wilches-Chaux et al. 1993). Tectonic subsidence is the main process occtmSng along coastal southwestem Colombia (Herd et al. 1981). During the great Tumaco earthquake of December 12, 1979 (magnitude 7.9-8.1), which occurred 80 km southwest of the town of Tumaco and 200 km southwest of Gorgona, the sea floor at the Strait of Tasca (which separates Gorgona Island from the islet of Gorgonilla) reportedly subsided by 0.8 m (Herd et al. 1981). Neither substrate collapse and subsidence nor the accompanying tsunami were reported to have caused negative impacts to the corals and coral reefs at Gorgona Island. Nonetheless, episodic events of this nature can, not only seriously affect reef corals (see Woesik 1996), but also exacerbate the effects of other natural disturbances (Cort6s et al. 1992). However, moderate subsidence of the magnitude recorded at Gorgona in 1979 could, at least temporarily, reduce the negative impacts of tidal-caused emersion. In contrast with Colombia's southwestern coast, tectonic uplift is more prevalent farther north along the coast of Choc6. Although several major earthquakes have shaken this region (e.g., at Bahia Solano in 1970: Rarnkez 1971a, b), there are no reports on the effects that these occurrences might have had on the coral communities in the area. However, earthquake-caused landslides, such as the one that occurred on the coastal Panamanian-Colombian border in 1976 (Garwood et al. 1979), could cause serious damage to coral reefs in this region (see also Cort6s et al. 1992).
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4. ANTHROPOGENIC IMPACTS, PROTECTION AND MANAGEMENT Most coral formations in the Colombian Pacific region are within legally protected areas. These were originally under the supervision and management of the Park Division of the Institute of Natural Renewable Resources (INDERENA, Spanish acronym). Law 99 of 1993 (known locally as the Law of the Environment) created the Ministry of the Environment, under which INDERENA's Park Division became the Special Administrative Unit of the System of National Natural Parks (UAESPNN, Spanish acronym), now in charge of protected and special management areas in Colombia. The first coral reef area in the Colombian Pacific to be protected was Gorgona Island, which was declared as National Natural Park in November 1983 and became fully operative as such in July 1984, once the prison had been removed. The park encompasses the entire islands of Gorgona and Gorgonilla, and adjacent waters covering 61,000 ha. The Utria National Natural Park was created in December 1986 becoming functional in October 1987. This park covers approximately 54,200 ha, including portions of the continental and marine areas of Ensenada de Utria. Since 1987, it has been managed under a joint program between a private environmental NGO (Fundaci6n Natura), and the UAESPNN. Management activities for the coral areas of the park have included: 1) demarcation and delimitation of La Chola reef using buoys to prevent boat traffic, and 2) the implementation of a coral replenishment experiment and monitoring program. Malpelo Island was designated as a Sanctuary of Flora and Fauna in October 1995, and is under the care of the Colombian Navy, which maintains a small post on this remote island. All areas have been subject to some degree of anthropogenic impact, although as one would expect, impact has varied inversely with ease of access. Thus, while Malpelo is perhaps the least disturbed area, Ensenada de Utria seems to be the most disturbed. Alvarado (1992) listed 13 types of anthropogenic impacts likely to occur on Colombian coral reefs. Of these only two occur at Malpelo (direct contact by divers and fishing). At Gorgona, anchoring, sailing activities, direct contact by divers, and fishing were common during the years of the prison and first years after becoming a park. During the 1960's and 1970's some coral was regularly used as primary material for craft making by prison inmates. Most trails on the island used to be covered with coral rubble, which mixed with cement and sand was also used for the construction of some of the buildings' floors. It is most likely, however, that this coral rubble was collected on the beaches rather than extracted from the reefs. Today, except for one site (Yundigua), the coral reefs of Gorgona Island are closed to visitors, although they remain open to researchers. This has reduced significantly the amount of damage caused by careless divers and boat anchoring, which used to be perhaps the major sources of human disturbance on these otherwise wellpreserved reefs. At Ensenada de Utria, landslides, coastal erosion, siltation, dynamite blasting, and coral collecting and plundering have been reported as significant anthropogenic impacts (Vargas-Angel 1996). Despite being protected, coral formations of the Pacific coast of Colombia are not totally exempt from human induced perturbations. For instance, fishing still occurs in all areas and is a major source of conflict between local fishermen and park authorities, although coral reef fishes are not preferred target species. Nonetheless, some species are used as bait for larger fish caught outside coral reef areas. At Malpelo it is not unusual to see foreign fishing boats exploiting the abundant fish populations. Some coral collecting still occurs on probably all coral reef areas of the Colombian Pacific, but particu-
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larly at Utria. Pocilloporids are used for making crafts, which are commonly sold in Buenaventura and other coastal towns. In 1998, 800 kg of coral collected at Gorgona were confiscated by park authorities in Buenaventura showing that protection efforts are still insufficient to prevent coral collecting and trading. Evidently, park authorities lack sufficient resources for effectively enforcing conservation and management policies. Although rare, oil spills are another source of human disturbance to coral reefs in the Pacific coast of Colombia. Since 1996 at least two crude oil spills have reached Gorgona Island, apparently transported from Ecuador by northward moving currents. During the latest event, in March of 1998, an oil spill passed about 8 km southeast of Gorgona. Although it not directly hit Gorgona, about 2000 kg of tar were collected from the beaches by park personnel. No significant mortality of marine organisms was observed, however. Few studies have been conducted with the aim of providing scientific knowledge that will serve as the basis for sound conservation and management policies of the coral reef areas of the Colombian Pacific coast. Fundaci6n Natura, under agreement with park authorities, carried out a study to provide a basic cartography of habitat types and an ecological zonation scheme at Ensenada de Utria (Vieira 1992). Similarly, L6pez-Giraldo (1992) did a relatively detailed characterization of community types and provided a zonation scheme for the management of the marine area around Gorgona Island. Under contract with park authorities, Villa (1999) did a preliminary evaluation of the artisanal fisheries resources at Gorgona to provide information on which to base management decisions to ease the conflict between fishermen and park authorities. Park authorities have recently tried to get scientists to increase their contribution to the solution of specific conservation and management problems within protected areas. However, a weakly developed marine scientific community and an overall insufficiency of f'mancial resources for both research and management make this a challenging problem for all. ACKNOWLEDGMENTS We thank Jorge Cort6s for his invitation to write this chapter, and P.W. Glynn, J. Cort6s, and H.M. Guzm~n for their comments and suggestions on an earlier version of the manuscript. The Unidad Administrativa Especial del Sistema de Parques Nacionales Naturales del Ministerio del Medio Ambiente (UAESPNN) has granted permits and provided logistic support for our continuing work at Gorgona, Utria, and Malpelo. We thank the park's chief officers, particularly C. Acevedo and G. Mayor. F.A.Z. gratefully acknowledges the help and motivation of his students, particularly, Y.A. Morales, C.E. Bilrcenas, J.M. Jim6nez, P.A. Herr6n, V. Francisco, S. Lozano, C. Mora, L.A. Serrano, and A.F. Ospina. F.A.Z. also thanks J.L. Mat6 and H.M. Guzm~n for sharing their knowledge about TEP corals, D. Fenner for help in obtaining literature on Pavona frondifera, and S. Bessudo for sharing her knowledge of Malpelo. Universidad del Valle, Fundaci6n para la Promoci6n de la Investigaci6n y la Tecnologia del Banco de la Repfiblica, and the Instituto Colombiano para el Desarrollo de la Ciencia y la Tecnologia (Colciencias) have provided financial support for F.A.Z.'s work. B.V.A. wishes to thank F. Estupifi~n, C. Moreno, A. Salinas and F. Ortega for their valuable collaboration with the field work. Financial support for B.V.A.'s work at Tebada, Utria and Gorgona has been provided by a doctoral scholarship from Colciencias and the Reitmeister fellowship from the University of Miami. Most of the original work by
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Coral communities and coral reefs of Ecuador Peter W. Glynn Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149-1098 USA
ABSTRACT: Reef-building coral formations along the mainland coast of Ecuador and in the Gal@agos
Islands are described with reference to coral species richness, community structure, relationship to physical and biotic controls, framework development and distribution. A brief history of coral studies in Ecuador is traced from the first notice of corals in the Gal~pagosIslands by C. Darwin in 1835 to the discovery of small patch and fringing coral reefs in the Gal~ipagosby G.M. Wellingtonin 1974. Recent ecologicalwork through 1998 is noted in the context of physical and biotic processes controllingthe developmentand maintenanceof these marginal eastern Pacific coral formations. Coral reefs also occur in the coastal waters of mainland Ecuador, but these have not yet (as of 2000) received detailed study. Most natural disturbances in the Gal~ipagos are local and varied, including, for example, tectonic uplift, rock slides, extreme low tidal exposures, and sea urchin bioerosion. Protracted sea warming associated with E1Nifio-SouthernOscillation (ENSO) events have in recent years caused extensive coral bleaching (i.e., the loss of zooxanthella endosymbionts from coral hosts), high mortality and the subsequent loss of reef frameworks by intense bioerosion. Anthropogenic disturbances from anchoring, entanglement of fishing lines and nets, coral extraction and, along the mainland, poor land use leading to extensive soil erosion, siltation and eutrophication, result in coral degradation. Despite the existence of the Machalilla National Park, whose boundaries include incipient coral reef frameworks at La Plata Island and the Machalilla fringing reef, no provisions for the protection of corals have been incorporated in the Machalilla park management plan. A management plan that provides for the protection of all wildlife in the Gal~ipagosreserve, including a 40 km perimeter in surrounding waters, is to some degree compromised by a lack of resources to ensure enforcement. With increasing fishing pressure, tourism and population buildup, the likelihoodof continued degradation of ENSO-damaged coral communities is high.
1. I N T R O D U C T I O N Reef-building corals are locally abundant along certain portions o f the Ecuadorean coast, on nearby coastal islands, and in the Gal~pagos Islands, located about 1,050 k m west o f continental South America (Fig. 1). Little is known o f the coral formations o f mainland Ecuador, which p r o b a b l y represents the s o u t h e m - m o s t limit o f significant coral d e v e l o p m e n t in the eastern Pacific region. Only occasional collections and m o d e s t reconnaissance studies have b e e n carried out along coastal mainland Ecuador. According to the U N E P / I U C N (1988) survey o f the coral resources o f mainland Ecuador, and a recent global assessment o f reefs at risk (Bryant et aI. 1998), no information is available either on the corals or their conservation status in this region. To help fill this void, some new inforLatin American Coral Reefs, Edited by Jorge Cort6s 9 2003 Elsevier Science B.V. All rights reserved.
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P. W. Glynn
Fig. 1. Locationofprincipal surfacewatermassesnorth(TropicalSurfaceWater)and south(EquatorialSurface Water) of the Equatorial Front, which migrates seasonallyacross the equatorial eastern Pacific. PF (Panam~i Flow)denotesa southerly-movingsurfacecurrentactiveduringthe northernhemisphericwinter(January-April), and EUC (EquatorialUndercurrent),a localizedareaof upwellingin the westernsectorof the Gal~pagosIslands. CC (ColombiaCurrent) is the northerlyflowingeasternbranchof the PanamaBightgyreand AENC(AnnualE1 NifioCurrent), formingduringthe PF period,followsthe Ecuadoreancoastto Peru (afterFiedler, 1992;Strubet al., 1998).
mation from surveys conducted along the central mainland coastal region in the 1990s (1991 and 1998) will be presented in this account. In contrast to the limited knowledge base of coastal Ecuador, the reef-building corals and coral formations of the Galfipagos Islands are reasonably well known, in large measure a result of the high level of interest in these celebrated islands. Ecological studies in the Galfipagos have disclosed some level of understanding vis-fi-vis the physical and biotic controls of coral abundance and distribution. Ironically, not long aiter the discovery of coral communities and coral reefs in the Galfipagos, the reefs have all but disappeared and most coral communities have been severely degraded following the 1982-83 E1Nifio-Southem Oscillation (ENSO) event. As a result, overall coral cover was reduced by 95 to 99% of the pre-disturbance amounts. This disturbance event was due mainly to prolonged sea warming, which resulted in widespread coral bleaching (i.e., the loss of symbiotic zooxanthellae), mortality and subsequent coral framework erosion. The present condition of coral formations in the Galfipagos is notably degraded compared with their pristine state in the 1970s, as described in Glynn and Wellington (1983). In order to better understand these changes, pre- and post-ENSO differences in community structure and reef integrity will be briefly examined. Also, the present condition of mainland and Gal/Lpagos coral communities is contrasted in light of the 1997-98 ENSO event. To help develop a broader perspective of Ecuadorean coral community development, additional topics discussed below are: (1) the history of reef-coral studies, from Darwin to the present (2000), (2) the oceanographic setting of the region, (3) the coral fauna, including the composition and structure of coral communities, and the distribution and current condition of coral reefs, (4) natural and anthropogenic impacts, and (5) existing measures for the protection and management of reef-coral resources.
Coral communitiesand coral reefs of Ecuador
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2. HISTORY OF REEF-CORAL STUDIES 2.1. From Darwin to Durham (1835-1966) One may begin the history of coral studies in Ecuador with Charles Darwin's visit to the Gal/tpagos Islands aboard HMS Beagle in 1835. Notwithstanding Darwin's keen observations and insights relative to the biology and ecology of numerous organisms, especially in the terrestrial realm, precious few words were written on the corals. Indeed, in his book "The Structure and Distribution of Coral Reefs" (1889) Darwin concluded, "There are no coral-reefs in the Galapagos archipelago, as I know from personal inspection,...". Darwin also concluded, from the observations of others, that the western shores of America were entirely without coral reefs. During the voyage of the Beagle, only one non-reef building coral (Tubastraea coccinea Lesson) was collected by Darwin and described several years later by Duncan (1876). Aside from the naming of two new Gal~ipagos species by Milne Edwards and Haime, a non-reef building coral (Flabellum gallapagense in 1848) and a doubtful record of a reefbuilder (Madrepora [Acropora] crassa in 1857-1860), the first noteworthy account of the presence of reef-building corals in the Gal~pagos was by Pourtal6s (1875). Pourtal~s documented the occurrence of 5 species collected on beaches during the brief visit of the Hassler in 1872 with Louis Agassiz in charge of the scientific party. Two decades later, Alexander Agassiz (1892), who served as chief scientist aboard the U.S. Fish Commission Steamer Albatross in 1891, remarked on the abundance of eroded corals on Gal~pagos beaches, concluding that nearly all islands in the archipelago have coral sand beaches. While not recognizing the presence of coral reefs, members of the Albatross expedition did observe sizeable coral communities -- "The coral is mainly made up of fragments of Pocillopora, which is found covering more or less extensive patches off these coral sand beaches, but which, as is well known, never forms true coral reefs in the Panamic district." This conclusion was repeated by Hornell in Crossland' s (1927) account of coral studies in the Gal/tpagos during the expedition of the St. George to the South Pacific in 1925. From collections made by the Velero III and Velero IV expeditions in the 1930s, and the Gal/tpagos Expedition of the Xarifa during 1953-1954, several new corals were added to the Gal~pagos inventory (Durham and Barnard 1952; Durham 1962). This work was supplemented by extensive collecting by scuba divers during the 1964 Gal~ipagos International Scientific Project, resulting in a total of 32 coral species, with 11 representing reefbuilding or zooxanthellate species (Durham 1966). 2.2. Discovery of Coral Reefs and Recent Studies (1974-2000) During subtidal surveys to develop a marine resource inventory in the early 1970s (report completed in 1974), G.M. Wellington, while a Peace Corps volunteer, was the first worker to observe and recognize the importance of coral reef formations in the Gal/Lpagos Islands. Wellington was joined by C. Birkeland, P.W. Glynn and J.W. Wells in 1975 to continue with coral reef studies. Field work was also performed in 1976, resulting in publication of the first comprehensive account of the systematics and ecology of Galfipagos corals and coral reefs (Glynn and Wellington 1983, with an annotated account by J.W. Wells). Subsequent ecological investigations have examined corallivore activities (Glynn et al. 1979), the role of ENSO disturbances on coral bleaching/mortality and rates of coral reef accretion (Glynn et al. 1988; Colgan 1990, 1991; Glynn 1990, 1994; Glynn and Colgan 1992; Macintyre et al. 1993), bioerosion (Reaka-Kudla et al. 1996), coral reproductive
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P. w. Glynn
ecology and recruitment (Glyrm et al. 1991, 1994, 1996, 2000), and the survival of relatively deep (15 m), ENSO-disturbed coral assemblages (Feingold 1995). The Urvina Bay (Isabela Island) coral community that was uplifted in 1954 has served as a model for paleoecologic studies (Colgan 1990, 1991; Malmquist 1991), and the fossil molluscan community at Villamil (Isabela Island south) offers some evidence that a coral reef community may have existed there over 500,000 years ago (Walker 1991). Core drilling of old, massive Galfipagos corals has offered material for several paleoclimate studies, showing skeletal growth patterns and oxygen and carbon isotopic signals that reflect variations in local SST, ambient light levels and ENSO activity (Druffel et al. 1990; Dunbar et al. 1994; Wellington et al. 1996). Analysis of the growth record of an extraordinarily large Urvina Bay P a v o n a colony, spanning a 350-year period, has revealed a pattern of increasing ENSO frequency from about 1700 to 1954. Studies of nutrient-like trace metals (Ba and Cd) on these coral cores can also serve as proxies of seasonal upwelling cycles and offer evidence for interannual interruptions of these cycles by E1Nifio and anti-E1Nifio (La Nifia) conditions (Shen and Sanford 1990; Shen et al. 1991, 1992). 3. OCEANOGRAPHIC SETTING Like the steep coastal margins of Peru and Chile, the continental shelf of Ecuador is narrow with the 200 m isobath located about 30 km from the shoreline north of the Gulf of Guayaquil (Fig. 2). From 10 to 20 km farther west, the continental slope descends abruptly to between 2000 and 3000 m depth. Deep waters also surround the oceanic Gal~pagos Islands, thus limiting shallow habitat areas for reef development. Ocean circulation processes are complex and highly variable over Ecuador's narrow latitudinal position. Major eastern tropical Pacific currents and water masses meet and migrate seasonally offshore, and local coastal currents and upwelling influence inshore areas (Houvenaghel 1984; Chavez and Brusca 1991; Fiedler 1992; Strub et al. 1998). The Equatorial Front (EF), an abrupt boundary separating tropical (TSW) and equatorial (ESW) surface waters, has a mean position at about 2~ near the coast, tilting to about I~ in the vicinity of the Gal~ipagos Islands (Fig. 1). During the northern (boreal) winter (DecemberMarch) the EF may migrate as far as 3-4~ and in the southern (austral) winter (JuneSeptember) it is located around 1-2~ TSW is characterized by temperatures normally in excess of 25~ and salinities less than 33.5 psu (practical salinity unit, -~%0). The relatively low salinities of TSW are a result of excess precipitation over evaporation near the Intertropical Convergence Zone (ITCZ), which migrates seasonally between about 5~ and 12~ A very sharp latitudinal gradient in precipitation occurs along the Ecuadorean coast. During the rainy season when the ITCZ is situated furthest south, the mean rainfall at I~ is 1.3 rn, and at 1o to 2 ~ S it is only 0.1 to 0.2 rm Equatorial surface waters, formed by the mixing of TSW, Perti Coastal Water and Subtropical Surface Water, generally has temperatures ranging between 20 ~ to 24~ and salinities of 33.5 to 35.0 psu. The chief currents that influence coastal Ecuador during the boreal winter are the southward-flowing Panarn,5 Bight gyre, here termed Panamfi Flow (PF), whose eastern-most branch joins the Annual E1Nifio Current (AENC). These currents bring warm, low salinity water (TSW) to the coastal region during the first part of the year (January-March). In this season, the Gal~ipagos also receive PF waters, which originate from the southward-moving
Coral communities and coral reefs of Ecuador
453
Fig. 2. CentralEcuadoreancoast, denotinglocaleswith knownor suspectedcoral formations. western branch of the Panarr~ Bight cyclonic gyre. Additionally, the westerly flowing Peni Current moves through the Galfipagos Islands at this time, and the Equatorial Undercurrent (EUC), a fast-flowing subsurface easterly directed current, results in upwelling where it surfaces in the western sector of the islands. Cool and nutrient-rich surface filaments move through the islands to the east and other branches of the EUC continue toward the South American coast and then poleward as subsurface and surface currents. Where upwelling is pronounced on the western side of the Gal~ipagos, with SSTs occasionally dropping to below 15~ it is not surprising that coral communities are absent. Coral community development does occur, however, in some areas sheltered from strong upwelling, such as in Urvina Bay (see below, '4.2.2 Galfipagos'). In the boreal summer, the Colombia Current is well developed along the Ecuadorean coast, where it moves northward and joins the eastern branch of the Panarmi Bight gyre.
454
P. 11I.Glynn
A southerly coastal current forms off Ecuador in the boreal winter, an extension of the western limb of the Panarrfi Bight gyre, which intensifies at this time due to strong northerly winds (the northeasterly Trades) moving across the Isthmus of Panarrfi. This coastal current flows to about 1 to 2 ~ S where it joins the Annual E1Nifio Current (AENC), which advects TSW to coastal Per6. The northward flowing Perti Coastal On'rent and Perti Current assume a more westerly course at about 5~ and eventually comingle to form a part of the northern edge of the South Equatorial Current. Upwelling on the west side of the Gal~pagos Islands continues during the boreal summer season. 4. CORAL C O M M U N I T I E S AND CORAL REEFS 4.1. The Coral Fauna The chief focus of this inventory will be on the colonial, reef-building or zooxanthellate corals, i.e. those scleractinian cnidarians harboring photosynthetic dinoflagellates in their gastrodermal cells. These endosymbionts facilitate rapid colony growth and skeletal calcification, allowing the host corals to accrete wave resistant structures with topographic relief. When large aggregations of corals build vertically into wave resistant features, often with the help of crustose coralline algae, this process results in the formation of structural coral reefs. Before the 1982-83 ENSO event, several small or incipient coral reefs, ranging from 0.5 to 5 m in vertical thickness (see Table 24 in Glynn and Wellington 1983), were present at several sites around the Gahipagos Islands (Figs. 3, 4). If corals do not build wave resistant structures, but are simply replaced by new generations of corals after death and .'
w
W
in I
,~
2;_ ,,o 6o eo /OOKM
Wolf I
'Bi
Pinto
I
e~
Isobelo I
I e Genoveso I J]]
O*
-
f - ......
~
~
Floreono
92* I
......
~
u'JSonto Fe I
t
LTso.
Espofiolo
90* I
c.J,tob,,,
I
..
88 ~ !_
Fig. 3. Gal~ipagos Islands, showing locations of chief coral community study sites (1-17) corresponding to those listed in Table 2.
Coral communities and coral reefs of Ecuador
455
Fig. 4. Pocilloporid incipient reef inside an extinct crater at Onslow Island (Devil's Crown) before the 1982-83 ENSO event (5 February 1976, 3 meters depth).
Fig. 5. Pavona clavus colonies exhibiting bleaching during the 1997-98 E1 Nifio event. Sides of colonies are bleached but still alive, tops of colonies are dead and covered with filamentous algae. Large colony in center is approximately 40 cm in diameter. OffPlaya Lapicona, Floreana Island, 12 m depth, 15 May 1998.
456
P. w. Glynn
erosion, then such aggregations are referred to as coral communities (Fig. 5). Notwithstanding this fundamental difference in building potential, both assemblages may exhibit high coral densities, species richness and diversity, and support high abundances of associated species. While coral reefs are relatively rare in the eastern Pacific and Ecuador, coral communities are often common-place under suitable environmental conditions (Glynn and Wellington 1983; Guzmfin and Cort6s 1993; Wellington 1997). With Ecuador's location within the equatorial eastern Pacific reef-coral province, which extends from mainland Ecuador to Costa Rica -- including the Galfipagos and Cocos Islands -- its surrounding waters support a relatively high coral species richness (Glynn and Ault 2000). Twenty-two species ofzooxanthellate corals are presently known from Ecuador, and approximately equal numbers occur at mainland and Galfipagos localities with 18 and 19 species, respectively, presently recognized (Table 1). The coral fauna of Ecuador has a close taxonomic affinity with central Pacific faunas (Wells in Glynn and Wellington 1983; Veron 1995; Glynn 1997; Glynn and Ault 2000). Eighteen of Ecuador's 22 species (81.8%) are also known from such localities as the Line Islands, Hawaii and French Polynesia. Four of Ecuador's coral species (18.2%), Pocillopora capitata, Pocillopora inflata, Porites panamensis and Pavona sp. a, are possibly eastern Pacific endemics, having evolved relatively recently in the isolated eastern Pacific region. Pavona sp. a is an uncommon coral, but occasionally present on volcanic rock substrates on the mainland coast and in the Galfipagos Islands (Fig. 6). Dana (1975) first suggested that the present-day eastern Pacific coral fauna was derived largely from Indo-Pacific migrants that dispersed from west to east via the North Equatorial Counter Current. This hypothesis is supported by the appearance of several central-west Pacific species, e.g. mollusks (Finet 1991; Kay 1991), echinoderms
Fig. 6. Pavonasp. a, an undescribedspeciesexhibitingbleachingduringthe 1997-98El Nifioevent. Colony lengthabout60 cm, encrustinga rockwall. Slightlydarkenedpatchesalonguppermarginofcolonywerepink. Playa Lapicona,FloreanaIsland, 7 m depth, 15 May 1999.
Coral communities and coral reefs of Ecuador
457
TABLE 1. Reef-building corals of coastal Ecuador and the Galfipagos Islands, based on swimming surveys over a 25-year period. Relative abundances of corals (maximum numbers of individuals determined from counts in local populations): A, abundant, 10,000; C, common, 1,000; U, uncommon, 100; R, rare, 10; -, unrecorded, t, denotes dredged dead specimens (Durham and Barnard 1952). AI, only a single living population known.
Mainland Ecuador
Gal/LpagosIslands
Pocillopora capitata Verrill
U
U
Pocillopora damicornis (Linnaeus)
U
U
Pocillopora elegans Dana
C
C
Pocillopora eydouxi Milne Edwards & Haime
R
R
Pocillopora inflata Glynn
-
U
Pocillopora meandrina Dana
-
R
Pocillopora verrucosa (Ellis & Solander)
U
Porites lobata Dana
R
Porites panamensis Verrill
R
Psammocora brighami (Vaughan)
R
R
Psammocora stellata (Verrill)
R
U
Psammocora superficialis Gardiner
R
U
Gardineroseris planulata (Dana)
R
R
Leptoseris papyracea (Dana)
Rt
Species
C
Leptoseris scabra Vaughan
-
R
Pavona clavus Dana
C
C
Pavona gigantea Verrill
U
C
Pavona maldivensis (Gardiner)
-
R
Pavona varians Verrill
R
U
Pavona sp. a
U
U
Cycloseris curvata (Hoeksema)
g,
g
Diaseris distorta (Michelin)
Rt
An
(Lessios et al. 1996) and fishes (Groves 1989), at eastern Pacific localities during recent ENSO activity when the volume and velocity of easterly flow increases. In the 1950s-60s, only 5 species were known from mainland Ecuador (Durham and Bamard 1952) and 11 from the Gal~pagos Islands (Durham 1966). The relative abundances in the present species list are current, reflecting changes following the severe mortality events of the 1982-83 and 1997-98 ENSOs. Some of the documented population declines in the Gahipagos Islands are remarkable, with species that were once abundant, i.e. with local populations of 104 or more colonies, now being uncommon, with populations reduced to 102
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colonies (Pocillopora damicornis, Psammocora stellata). Also, some formerly uncommon species (Gardineroseris planulata, Cycloseris curvata) are now rare, with only 1 or a few colonies known. Decadal scale changes in the relative abundances of mainland species cannot be evaluated because coral communities have not yet been monitored there. Two Galfipagos pocilloporid species not known from the mainland are Pocillopora inflata and Poeillopora meandrina, and one mainland species, Pocillopora verrucosa, has not been reported from the Galfipagos Islands. P. inflata is found at several island sites, but is uncommon (Fig. 7). Pocillopora eydouxi is a recently discovered new record from the mainland, with a few colonies occurring at La Plata Island. Porites lobata is seldom seen in mainland coral communities, but is common in the oceanic setting of the Galfipagos, a distribution pattern repeated in the coastal and oceanic localities ofM6xico (Reyes Bonilla in press, this volume). Poritespanamensis occurs only on the mainland. This eastern Pacific endemic species broods planulae, which, once released, have only a limited (few to several hours) free-swimming larval stage (Glynn et al. 1994), a condition that might explain its absence from distant islands. All three species of Psammocora are found at both coastal and oceanic Ecuadorean localities. Gardineroseris planulata also occurs in mainland and Galfipagos coral communities, but is a rare species at both localities. Different species of Leptoseris are known at coastal and oceanic localities. Although not stated, it is likely that only dead specimens of L. papyracea were collected off La Plata Island (Durham & Bamard 1952). Four of five Pavona species are recorded from both localities. Only a few colonies ofPavona maldivensis have been found in the northern (Wenman and Culpepper) Galfipagos Islands. Two fungiid coral species, Cycloseris curvata and Diaseris distorta, are known from Ecuador, but living individuals have been collected only at Floreana Island,
Fig. 7. Pocilloporainflata,a recently-namedcoral species first recognizedin the Gal/LpagosIslands. An approximately 20 cm diametercolony on a basalt substrate, Punta Carri6n, Santa Cruz Island, 5 m depth, 23 November 1999, courtesyF. Rivera.
Coralcommunitiesand coralreefsof Ecuador
459
Gal/tpagos Islands. These zooxanthellate corals are typically found on coarse sand bottoms in slightly deeper water (12-20 meters) than other species. 4.2. Coral Communities
Coral communities are paucispecific (consisting of few species) in Ecuadorean waters, as is generally the case in the eastern Pacific. They are usually present on fn'rn rocky substrates at shallow depths (_<20 meters), in relatively clear water ofmarine salinity (32-35 psu) with moderate to vigorous circulation. Some exceptions occur along the coast and are noted below. The predominant taxa are ramose Pocillopora species, notably P. elegans and P. damicornis, and a few massive species, usually Porites lobata, Pavona clavus and Pavona gigantea. 4.2.1. Mainland
Before large-scale coral harvesting by commercial entrepreneurs and mortality resulting from the 1982-83 ENSO disturbance, pocilloporid communities were prevalent off Ayangtie, at Salango Island, Los Frailes, Sucre Island and La Plata Island (Fig. 2). The predominant species in these areas now are mostly Pavona clavus and, to a lesser degree, Pocillopora elegans and Pocillopora damicornis. Subordinate species, uncommon to rare in abundance, are Pocillopora capitata, Pocillopora eydouxi, Pavona varians, Pavona sp. a, Pavona gigantea, Gardineroseris planulata and Psammocora superficialis. Most near-shore communities range in depth from about 1 to 8 meters. In May 1998, at the end ofthe 199798 ENSO, high turbidity due to flooding and excessive river runoff reduced visibility over nearshore coral communities to 0.5-1.5 meters. This suggests that some corals can tolerate periods of unusually high turbidity and low salinities. Coral communities, and possibly modest reef building, have been reported at Santa Clara Island in the Gulf of Guayaquil (Ren6 Espinosa pers. comm., Fig. 2), an area subject to one of the highest freshwater discharge rates in the eastern tropical Pacific (Glynn and Ault 2000). High density coral assemblages typically increase local topographic complexity and species diversity, offering habitat niches to many other taxa. Only a brief sketch of associated biota, chiefly animal species that can have important effects on corals, is offered here. More information can be found in Glynn and Wellington (1983), James (1991), Guzmfin and Cort6s (1993), Glynn and Mat6 (1997), and Wellington (1997). Aside from the occasional presence of plants in the genera Caulerpa, Dictyota and Padina, macroalgae are generally not abundant in coastal coral communities. Intermingled with zooxanthellate corals, especially on vertically-oriented rock substrates, brilliant orange-colored nonzooxanthellate species such as Tubastraea coccinea and Dendrophyllia gracilis Milne Edwards & Haime are often present. A variety of crustaceans (shrimps, crabs, stomatopods and others) take refuge on the live surfaces of ramose colonies and in the internal spaces of massive, encrusting and nodular species. Of the numerous vagile crustaceans that move among coral colonies may be noted spiny lobsters [Panutirus pencillatus (Oliver)], two species of Trapezia, spider crabs and hermit crabs. Two large hermit crab species, Trizopagurus magnificus (Bouvier) and Aniculus elegans Stimpson are often seen on the branches of Pocillopora spp. corals where they scrape and consume live colony surfaces. Jenneria pusmlata (Lightfoot), an ovulid gastropod, is sometimes seen feeding on Pocillopora spp., from which it strips polyps and other soft tissues. Another potentially important mollusk is the bivalve Lithophaga aristata (Dillwyn), which bores into the skeletons of mainly dead massive corals. Heavy infestations can cause the weakening and eventual disintegration of
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coral skeletons. Large Venus clams, such as Periglypta multicostata (Sowerby) and Megapitaria aurantiaca (Sowerby), are often buried in coarse sand surrounding corals. These clams are excavated, broken open and consumed by the powerful Blunthead TriggerfishPseudobalistes naufragium (Jordan & Starks). This triggerfish, which reaches 100 cm in length (Allen and Robertson 1994), frequents coastal coral commtmities where its foraging activities often cause the uprooting and burial of corals. The most conspicuous echinoderm in mainland coral communities is Diadema mexicanum A. Agassiz, sometimes forming aggregations of 20-30 individuals. The generally high abundance of this herbivore and several herbivorous fish species probably in large measure account for the paucity of macroalgae in coastal coral communities. 4.2.2. Gahipagos Most of the coral species and associated biota noted in mainland coral communities are also present in the Galfipagos Islands. The locations of coral communities surveyed in the mid-1970s at 17 island sites (Glynn & Wellington 1983) are noted in Figure 3. Corresponding brief characterizations of these communities, including damage suffered in 1982-83, subsequent recovery and present condition, are summarized in Table 2. Generally, coral communities are not well developed on the western sides of some islands, e.g. Fernandina and Isabela Islands, where upwelling frequently occurs and algal macrophytic communities predominate. Areas strongly influenced by the EUC, such as the northwestern and southwestern extremeties of Isabela and the western shores of Femandina, are devoid ofzooxanthellate corals. However, some areas sheltered from the full effects of upwelling, such as the narrow passage between Femandina and Isabela Islands, do harbor relatively diverse coral communities. Since water clarity is generally high in the Gal/tpagos, particularly away from upwelling centers and in areas influenced by the Peni Oceanic Current, coral communities may occur as deep as 30 m. Pocilloporid corals usually predominate at shallow depths (1-15 m), and massive and nodular species are generally most abundant at greater depths (10-20 m). Black corals, particularly Antipathes panamensis Verrill and Antipathes galapaganus Deichmann, begin to appear at 10-30 m depth, often increasing in abundance below the deeper limits of zooxanthellate corals. Pocilloporid communities were well developed at the northeastern sectors of San Crist6bal, Espafiola and Floreana Islands (sites 1-3, Fig. 3) until the early 1980s. These communities have disappeared following the 1982-83 E1Nifio disturbance, a result of high SSTinduced bleaching, mortality and bioerosion. The most recent surveys have revealed minimal coral recruitment after 10 to 15 years, with coral rubble and basalt rocks making up the substrata. Eucidaris galapagensis D/Sderlein [formerly confused with Eucidaris thouarsi (Valenciennes), see Lessios et al. (1999)], the blunt-spined sea urchin, is usually the most abundant macroinvertebrate in these former coral communities (Fig. 8). It is possible that their deep-rasping feeding activities are interfering with the settlement and growth of coral recruits. Massive Porites colonies suffered 100% mortality at Punta Pitt (site 1) in 1983, but only partial mortality at Onslow Island (- Devil's Crown), with substantial recent recovery (site 3). All Onslow Island Porites colonies that bleached in 1998 had regained their normal pigmentation by 1999 and revealed only minimal tissue damage. The only known living fungiid coral community in the Gal~ipagos occurs on a coarse sand bottom subject to strong currents at 12-15 meters depth just east of Onslow Island (site 4). Literally tens of thousands of individuals ofDiaseris distorta dominate this community,
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TABLE 2. Coral community disturbances caused by the 1982-83 ENSO event, extent of recovery and condition following the 1997-98 ENSO. Location
Community type
1982-83 E1 Nifio damage
Recovery
Present condition
1 -San Crist6bal, Pta. Pitt
~ 1 m thick pocilloporid reef
100% coral mortality
nil
coral rubble bottom
1-3 m diam. Porites colonies
100% coral mortality
nil
eroded colonies
2 -Espafiola, Gardner Bay
pocilloporid community
100% coral mortality
nil
rock with crustose coralline algae
3 -Floreana, Onslow Is. (Devil's Crown)
~ 1 m thick pocilloporid reef
99% coral mortality
Porites tissue regeneration
low live coral cover
4 -Floreana, east of Onslow
fungiid coral community
bleaching, low coral mortality
total
good
5 -Champion Is.
4-5 m thick Pavona reef
100% coral mortality
nil
coral rubble bottom
6 -Santa Fe, NE sector
0.5 m pocilloporid reef
100% coral mortality
nil
coral rubble bottom
7 -Santa Cruz, Academy Bay
- 25 colonies (_<1m diam.) of Gardineroseris
97% coral mortality
nil, 1 colonywith 3 small live patches
basalt boulder bottom
8 -Isabela, Cartago 1 m thick Pavona Bay framework
100% coral mortality
nil
basalt rock bottom
9 -Isabela, Villamil
3-4 m thick pocilloporid reef
100% coral mortalityI
nil
coral rubble/sand bottom
10 -Santiago, Bartolom6 Is.
4-5 m thick Porites reef
97% coral mortality
nil
biocrodcdcolonies, few Pocil~opora recruits
11 -Isabela, Urvina Bay
scattered massive Pavona and Porites colonies
severe, many large colonies killed ~
moderate among colonies with surviving tissues
coral cover relatively high
12 -Fernandina, ~ 1 m thick pocilloporid Pta. Espinosa laval reef pools
100% coral mortality
nil
coral rubble and rock/sand bottom
13 -Genovesa, Darwin Bay
~ 1m thick pocilloprod reef
100% coral mortality
nil
coral rubble/rock bottom
2-3 m thick Pavona reef
100% coral mortality
nil
coral rubble/rock bottom
severe I
high, Porites recruits abundant
high live coral cover
14-Marchena, Pta. MixedPocillopora/Pavona Espejo community 15 -Pinta, W of Cape Ibbetson
MixedPociUopora/Pavona/ Porites/Psammocora community
severe I
nil
coral rubble bottom
16 -Wolf, E side
Dominantly Pavona and Porites communities
severe I
high
live coral cover similar to 1975 survey
17 -Darwin
~ 1 m thick pocilloporid reef
severe 1
nil
coral rubble/rock bottom
moderate
relatively high coral cover
mixed Pocillopora/Pavona/ severe t Porites community
t Presumably killed during 1982-83 ENSO although observed after the disturbance event.
462
P. w. Glynn
often two layers thick, and dispersed over 1 to 2 ha. Small numbers of Cycloseris curvata also occur intermingled with D. distorta as well as Psammocora stellata, the latter attaining high abundances in some areas. At present, while fewer individuals of C. curvata are found than in the 1970s, D. distorta numbers have not been reduced by recent ENSO events (Feingold 1996). Large aggregations of the sea star Pentaceraster cumingi (Gray), formerly known as Oreaster occidentalis Verrill, are often seen moving through the fungiid conmamity. This sea star feeds on a variety of p r e y - algae, sponges and sea urchins - including the corals P. stellata, and to a lesser extent, D. distorta. A similar, but entirely dead fungiid community also occurs on the eastern end of Espafiola Island (site 2). Living fungiids were last seen there in the 1970s (Glynn and Wellington 1983). The cause of their demise is unknown. Massive coral species have contributed importantly to coral communities at Champion (site 5), Santa Fe (site 6) and Santa Cruz (site 7) Islands, but have dwindled markedly in abundance since 1982-83. The only known aggregation of some 25 colonies of Gardineroserisplanulata in the Gal~ipagos Islands, at Punta Estrada, Santa Cruz Island (site 7), was reduced to a single, nearly dead colony in the aftermath of the 1982-83 ENSO. According to J. Feingold (per. com.), who surveyed this site as recently as May 1999, the remnant live patches could not be found where they previously occurred and are probably now buffed beneath basalt rubble. With only two widely-separated, dominantly outbreeding colonies presently known, one each at Champion and Espafiola Islands, the persistence of this species within the archipelago is problematical. Coral communities monitored at all remaining Gal~ipagos sites, from centrally located (sites 8-15) to the most northern islands (sites 16 and 17), all revealed severe declines in live coral cover after 1982-83 with mostly minimal, if any, recovery. Some sites are now
Fig. 8. ErodedPocilloporaframeworkresultingfromcoraldeath and bioerosionfollowingthe 1982-83E1Nifio event. Severallarge (5-6 cm test diameter) Eucidarisgalapagensis, scrapingalgae from the dead corals, are visible in the foreground (Onslow Island, off northeastern coast of Floreana Island, site 3, Fig. 3, Gal~pagos Islands, 1.5 m depth, 29 October 1987).
Coralcommunitiesand coralreefs of Ecuador
463
wholly devoid of corals. For example, all pocilloporid corals have disappeared from the Punta Espinosa lava pools. Notable exceptions include the coral community at Urvina Bay (site 11), Marchena Island (site 14) and Wolf Island (site 16), where regeneration of surviving patches of large massive colonies and recruitment of new colonies by sexual means, have occurred. Some inter-island distributions of coral-associated biota that conform with SST zones are noteworthy. For example, the northern islands (sites 16 and 17), located within the warmest region of the archipelago, harbor two coral species (Leptoseris scabra and Pavona maldivensis) and the crown-of-thorns sea star Acanthasterplanci (Linnaeus), not found in the southern islands. It is likely that A. planci is in very low abundance, present as only a few individuals. Also, such tropical fishes as Zanclus cornutus (Linnaeus), Sufflamen verres (Gilbert & Starks), Johnrandallia nigrirostris (Gill) and Thalassoma lucasanum (Gill) occur in highest abundance in coral communities in the north-central (sites 13-15) and northern islands (sites 16 and 17). Curiously, the Blunthead Triggerfish Pseudobalistes naufragium, so common and influential as a bioturbator in coastal coral communities, is uncommon to rare in the Gal/tpagos Islands (Jennings et al. 1994). Large numbers of another triggerfish, Balistes polylepis Steindachner, appeared in Elizabeth Bay (ca. 35 km southeast of Urvina, site 11) after the 1982-83 ENSO event (G.M. Wellington per. com.). 4.3. Coral Reefs
The number of coral reefs in Ecuador with moderate coral cover, potentially capable of accretion, is now greatly reduced compared with the 1970s. Following are brief descriptions of mainland and Gal/lpagos coral reefs, emphasizing their present condition, but also noting pre-ENSO condition in some better known examples. 4.3.1. Mainland
Of the mainland coral reefs, the fringing reef in the lee of Sucre Island at Machalilla, Ecuador is probably the best known. This reef was discovered in 1975 (Glynn and Wellington 1983), and at that time contained populations of seven species of zooxanthellate corals. The predominant frame-building species were Pocillopora damicornis and Pocillopora elegans, which constructed a rigid framework covering over 1 ha of bottom. From the surface inspection of eroded pits and collapsed sides of the reef, it appeared that the pocilloporid framework had a minimum thickness of 3 to 4 meters. When surveyed in 1991 only two species of living corals were observed on the Machalilla reef, namely, highly dispersed colonies of P. damicornis and P. elegans. Broken skeletons of large massive species (Pavona clavus and Pavona gigantea) present in 1975 were scattered along the beach. The reef flat was subject to severe erosion by large aggregations of the black-spined sea urchin Diadema mexicanum. Several 50-cm deep depressions in the pocilloporid framework, with 20 to 50 actively grazing sea urchins, were present on the reef flat. By May 1998, modest coral recovery had occurred with an increase in colony abundances and species richness. New recruits ofPocillopora spp., P. clavus and P. gigantea were present, all affixed to dead and eroded as yet persistent frameworks. While pocilloporid corals displayed normal (brown) pigmentation, colonies of all massive species were bleached with dead surfaces, a result of the 1997-98 ENSO that severely affected the Ecuadorean coast. The long-term in.acts of this latest ENSO event are still unknown. PociUoporid flinging reefs, 3-4 m vertical buildups, also occur a few km south of Machalilla, off Cabuya beach near Los Frailes (Fig. 2). These reefs were also dead in 1991, in a similar state of erosion and dis-
464
P. W. Glynn
Fig. 9. Pavona clavus colony exhibiting bleaching during the 1997-98 El Niflo event. Bleached live tissues are predominantly on the sides of the colony with normally pigmented tissues on the summits. Colony about 80 cm across, El Soplador, La Plata Island, off coastal Ecuador, 8 m depth, 21 May 1998.
Fig. 10. Lava rock basin filled with pocilloporid corals, near Punta Espinosa, Femandina Island (October 1974, courtesy G.M. Wellington).
Coral communitiesand coralreefs of Ecuador
465
integration to reefs in the Galfipagos and elsewhere in the equatorial eastem Pacific (Colombia, Panarmi, Costa Rica) following the 1982-83 ENSO disturbance (Glynn 1990, 1994). Numerous D. mexicanum were congregated around the dead reef frameworks. Small fringing reefs of 200-400 m 2 occur on the northeastern, leeward side of La Plata Island, built dominantly by massive colonies ofPavona clavus and Pavona gigantea. One of these reefs situated less than 1 km north of Drake Bay (Punta Faro) has a vertical coral buildup of about 5-6 rn, and two to the east of the bay entrance are about 3-4 m (El Soplador) and 2-3 m (Punta Palo Santo) in vertical relief. A total of ten coral species are present at these sites, including several colonies of Gardineroseris planulata, which is now rare in the Gahipagos Islands. One very large colony ofPavona clavus measuring about 5 m high and 8 m in diameter contributes importantly to the framework of the Punta Faro reef. Coral bleaching and mortality were commonplace and severe when these reefs were surveyed in May 1998, comparable to that observed in coral communities along the mainland coast (Fig. 9).
4.3.2. Gal~pagos
Before the 1982-83 ENSO, at least 17 small patch and fringing coral reefs were known from 10 of the 14 larger Galfipagos Islands (see Fig. 44, Glynn and Wellington 1983). The Champion Island fringing reef (site 5, Fig. 3), built dominantly by Pavona clavus, had a maximum vertical thickness of 10 meters. The Onslow Island pocilloporid patch reef(site 3), while only 0.6 m thick, was a special attraction for snorkelers because of its high biotic diversity and majestic setting in an extinct crater (Fig. 4). A very high proportion (97100%) of the corals suffered bleaching and mortality in 1983, leaving all of these reefs virtually devoid of live coral cover. Surface bioeroders, such as Eucidaris galapagensis and other echinoids, and internal bioeroders, such as boring bivalves (Lithophaga spp.) and sponges, have caused the disintegration of reef frameworks (Glyrm 1988, 1990, 1994) to such an extent that it is now often impossible to discern the existence of reef structures present only 18 years ago (Fig. 4). No trace of live Pocillopora damicornis can be found now in the once coral-filled lava rock pools at Punta Espinosa, Femandina Island (Fig. 10). The poritid fringing reef at Bartolom6, Santiago Island (site 10) was still largely intact in 1993, but only a few small patches of live coral were present. Reaka-Kudla et al. (1996) demonstrated that Eucidaris galapagensis was by far the most significant eroder of massive corals. Monitoring of the condition of the disturbed reefs, to the present day, reveals essentially no recovery. Lamentably, the coral reefs of the Galfipagos Islands have all but disappeared. Dead coral frameworks, in varying degrees of erosion, now occur at only a few sites, e.g. Onslow Island (site 3), Champion Island (site 5), and Bartolom6 (site 10). 5. NATURAL PERTURBATIONS Because of Ecuador's location within the core zone of E1 Nifio-Southem Oscillation (ENSO) activity, it is little wonder that this sporadic perturbation has had an important effect on corals in this region (Glynn & Colgan 1992; Podest~i & Glynn 1997; Wellington 1997; Glynn & Ault 2000). Elevated and protracted sea temperatures during the 1982-83 ENSO event resulted in severe and widespread coral bleaching and mortality in the Gal/tpagos Islands. The 1997-98 ENSO also severely affected coral communities in the
466
p. Ire'. Glynn
Gal~pagos and on the mainland. The condition of dead coral reefs at several coastal sites after 1982-83 (in 1991), suggest that reefs there also experienced massive mortality during the earlier ENSO disturbance. Surveys conducted in 1991 revealed totally dead and severely bioeroded reef frameworks, similar to those observed at other eastern Pacific localities. Experimental studies have demonstrated that stressful high sea temperatures, often in combination with high irradiance (UV radiation especially), cause a disruption of the coral/zooxanthella partnership (Gleason and Wellington 1993; Brown 1997; Rowan et al. 1997). This response results in a marked reduction in photosymbiont densities and/or pigment concentration, which render the tissues of the coral host transparent, thus revealing the presence of the white ('bleached') calcareous skeleton. If high temperature conditions persist, e.g. for 3-4 weeks or longer, the coral host will die. In addition to the stressful high sea temperatures, large ocean swells from the northwest, contrary to the usual southerly to southeasterly seas, dislodged large massive colonies of Pavona and Porites, and branching Pocillopora spp., depositing them above the high tide line on Floreana and Champion Islands in the Galfipagos (Robinson 1985). Among other known natural disturbances, with largely local effects, may be noted extreme low tidal emersion events, rock slides, tectonism (sudden uplifting of coastal shelves), and volcanism (Glynn and Wellington 1983). Perhaps the greatest biotic disturbance can be effected by large numbers of the cidarid echinoid Eucidaris galapagensis, attaining densities of 30 to 40 inds m 2 in many coral communities. This sea urchin bears a powerful mastigatory organ with sharp calcareous teeth (Aristotle's Lantern), which breaks apart coral skeletons when the urchins feed on algae coating dead corals or on live coral tissues. Acanthasterplanci has been observed feeding on corals in the northern Galfipagos Islands, but since it is rare there, observed on only a few occasions, it does not pose an important threat at this time. 6. ANTHROPOGENIC IMPACTS A current global assessment of the anthropogenic threats to coral reefs does not consider coastal Ecuador, presumably due to the absence of published information on this region (Bryant et al. 1998). Some acute types of human-induced damage observed during recent surveys of mainland coral communities and reefs result from careless anchoring procedures, fishing activities and the harvesting of corals for the curio trade. Grappling-type anchors, and fishing lines and nets have been seen at several sites from Ayangue to La Plata Island, entangled with broken and overturned corals. The wholesale extraction of pocilloporid corals at Ayangue and Salango Island has greatly diminished the local abundances of species in this taxon. A fisherman/diver at Puerto L6pez has informed me that truckloads of live corals had been harvested recently at Salango Island, which lies within the jurisdiction of the Machalilla National Park. Wellington (1997) has noted these same types of anthropogenic disturbances in the Gal~pagos Islands. Additionally, in 1995 an estimated 8-12 million sea cucumbers [Stichopus fuscus (Ludwig)] had been harvested by 850-900 divers. While the careless extraction of these sea cucumbers can cause considerable damage to corals, the main fisheries is centered in the upwelling areas of the western Gal~ipagos Islands where coral abundance is low (Hickman 1998). Lobster fishing also had an impact, in the 1970s and
Coral communities and coral reefs of Ecuador
467
1980s, but is now relatively unimportant as this resource has been severely over-exploited. Probably of greater impact to corals, although often more difficult to assess, are the chronic effects of sedimentation and eutrophication resulting from deforestation and poor land-use management. This has caused extensive coral reef damage in the Revillagigedo Islands, M6xico (Ochoa L6pez et al. 1998), Costa Rica (Cort6s 1990) and Colombia (Vargas Angel 1996). Toward the end of the 1997-98 ENSO event, muddy waters were prevalent around coral communities along coastal Ecuador. While lateral visibility at 5-10 m depth was frequently less than 30 crn, most corals observed under these conditions exhibited some degree of bleaching, yet were still alive. The condition of near-shore coral communities has not been assessed since May 1998, therefore, the effects of this massive runoff are not known. Since high turbidity is generally uncommon and transitory in the Gal~pagos Islands, lasting only a few days, sedimentation and eutrophication stresses do not appear to pose a serious threat to corals there. 7. CONSERVATION AND MANAGEMENT A recent listing of existing eastern tropical Pacific marine protected areas with living coral communities and/or coral reefs reveals two in Ecuador, namely the Machalilla National Park situated along the central mainland coast, and the Gal~ipagos Marine Resources Reserve (Kelleher et al. 1995). The Machalilla National Park, established in 1979, is subdivided into three sections, totaling 46,683 ha. La Plata and Salango Islands are included in the park boundaries, and their shorelines to 2 nautical miles (3.7 km) seaward. La Plata Island supports a diverse marine vertebrate fauna, including three species of boobies, the waved albatross, frigate and tropic birds, a small pod of sea lions, numerous shore fishes, sea turtles, and dolphins and whales in its surrounding waters. For this and other similarities, La Plata Island is often referred to as "la Gal~ipagos de los pobres", that is "poor man's Gal~ipagos". There is a management plan for the Machalilla park, but it does not contain any provisions for the protection of the coral fauna or other benthic marine biota (L. Arriaga pers. comm.). The reason for this is probably because the marine resources in this part of Ecuador, exclusive of marine vertebrates, are virtually unknown. An inventory of all marine biota is urgently needed. Considering the accessibility of the Machalilla park, if adequately protected and managed it could offer considerable enjoyment to visitors unable to travel to the Galhpagos Islands. The Gal~pagos reserve, comprising 13 major islands and over 115 smaller islands and rocks covering 70,000 km2, is the largest protected area in the eastern Pacific region. With an increasing awareness of the geological and biological uniqueness of the Gal~pagos, in 1934 the Ecuadorean government moved to protect the islands from commercial and scientific over-exploitation by providing for the establishment of reserves and a national park. To assist in this effort, in 1957 Ecuador requested and received help from the United Nations Education, Science, and Culture Organization (UNESCO) and the International Union for the Conservation of Nature and Natural Resources (IUCN). Since the founding of the Charles Darwin Foundation in 1959, several important developments have occurred that have helped to strengthen a commitment toward protection and conservation: 1964 inauguration of the Charles Darwin Research Station (CDRS); 1968 -establishment of the Gakipagos National Park Service (GNPS); 1975 - formulation of the first marine protection
468
P. w. Glynn
plan (Wellington 1984); 1979 - Gal~pagos designated a World Heritage Site; 1984 accepted as an internationally recognized Biosphere Reserve under the Man and Biosphere Program administered by UNESCO; 1986 - establishment of the Gal~ipagos Marine Resources Reserve, which provides for the protection of all wildlife in the archipelago's inner seas and surrounding waters; 1992 - approval of a comprehensive management plan. Thus, the protection and management of the Gal~ipagos biota, including all terrestrial and marine species, are now sanctioned by national law and, additionally, by prestigious international conservation organizations (see Wellington 1997 for a review of these developments). Unfortunately, several anthropogenically-related pressures still threaten much of the unique Gal~ipagos environment and its biota. With the growing visitation rate of tourists (projected at 75,000 to 100,000 per year in the year 2000) and a rapidly expanding resident population (about 20,000 souls islandwide by the year 2000), numerous new threats are imminent (Rodriguez 1993). Increasing levels of marine resource exploitation are occurring, the introduction of exotic species, and sundry kinds of pollution associated with wastes and sewage disposal that inevitably accompany urbanization. The first large-scale pollution event occurred in Academy Bay, Santa Cruz Island, in 1988 with the spillage of 190,000 liters of diesel oil being delivered at Puerto Ayora (Whelan 1989). Additionally, the necessary resources to support enforcement measures for safeguarding the environment and its biota are generally lacking (Izurieta 1992). If the marine environments of Machalilla and the Gal~ipagos Islands can be effectively protected this would help sustain the visitation rate of international and domestic, eco-minded tourists, which would in turn benefit local, caretaker populations. Thanks to the outreach efforts of the CDRS and the GNPS, many island residents are now aware of the importance of safeguarding this unique natural resource. ACKNOWLEDGMENTS I am especially grateful for the sustained field support offered by Lenin Cruz, Ren6 Espinosa, Joshua S. Feingold, Femando Rivera and the occasional assistance of many others, including Ecuadorean student volunteers. I also thank Luis Arriaga for kindly supplying information on the Machalilla Park. Mitchell W. Colgan, Joshua S. Feingold and Gerard M. Wellington offered helpful comments on the manuscript, and Donald B. Olson reviewed the section on ocean currents. The original findings reported in this contribution were obtained from research support by the Smithsonian Institution and the U.S. National Science Foundation, Biological Oceanography Program (grams OCE-9314798 and OCE9711529). TAME (Transportes A6reos Militates Ecuatorianos) kindly subsidized national air travel. For allowing permission to study corals in Ecuador and for logistical and facility support, I thank the Gal~ipagos National Park Service and the Charles Darwin Research Station of the Charles Darwin Foundation for the Gal~pagos Islands. REFERENCES Agassiz, A. 1892. Reports on the dredging operations offthe west coast of Central America to the Gal~pagos, to the west coast of Mexico, and in the Gulf of California, in charge of Alexander Agassiz, carried on by the U.S. Fish Commission Steamer"Albatross," Lieut.
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Commander Z.L. Tanner, U.S.N., Commanding. II. General sketch of the Expedition of the "Albatross," from February to May 1891. Bull. Mus. Comp. Zool., Harvard College 23(1): 1-89, 22 pls. Allen, G.R. & D.R. Robertson. 1994. Fishes of the tropical eastern Pacific. Crawford House Press, Bathurst. Brown, B.E. 1997. Coral bleaching: causes and consequences. Coral Reefs 16 (suppl.): 129-138. Bryant, D., L. Burke, J. McManus & M. Spalding. 1998. Reefs at risk, a map-based indicator of threats to the world's coral reefs. World Resources Institute, Washington, D.C. 56 p. Chavez, F.P. & R.C. Brusca. 1991. The Gal~pagos Islands and their relation to oceanographic processes in the tropical Pacific: 9-33. In" M.J. James (ed.), Gahipagos Marine Invertebrates: Taxonomy, Biogeography, and Evolution in Darwin's Islands. Plenum Press, New York. Colgan, M.W. 1990. E1Nifio and the history of eastern Pacific reef building: 183-232. In: P.W. Glynn (ed.), Global Ecological Consequences of the 1982-83 E1 Nifio-Southern Oscillation. Elsevier Oceanography Series, 52, Amsterdam. Colgan, M.W. 1991. E1Nifio and coral reef development in the Gahipagos Islands" a study of the Urvina Bay uplift: 99-120. In." M.J. James (ed.), Gal~pagos Marine Invertebrates: Taxonomy, Biogeography, and Evolution in Darwin's Islands. Plenum Press, New York. Cort6s, J. 1990. The coral reefs of Golfo Dulce, Costa Rica: distribution and community structure. Atoll Res. Bull. 344: 1-37. Crossland, C. 1927. Marine ecology and coral formations in the Panan~ region, the Gal~pagos and Marquesas Islands, and the Atoll of Napuka. The expedition to the South Pacific of the S.Y. St. George. Trans. Roy. Soc. Edinburgh 55(2): 531-554. Dana, T.F. 1975. Development of contemporary eastern Pacific coral reefs. Mar. Biol. 33: 355-374. Darwin, C. 1889. The structure and distribution of coral reefs. 3rd ed., Smith, Elder, & Co., London. 344 p. Druffel, E.R.M., R.B. Dunbar, G.M. Wellington & S.A. Minnis. 1990. Reef-building corals and identification of ENSO warming episodes: 233-253. In: P.W. Glynn (ed.), Global Ecological Consequences of the 1982-83 E1 Nifio-Southem Oscillation. Elsevier Oceanography Series 52, Amsterdam. Dunbar, R.B., G.M. Wellington, M.W. Colgan & P.W. Glynn. 1994. Eastern Pacific climate variability since 1600 A.D." stable isotopes in Gal~pagos corals. Paleoceanog. 9: 291-315. Duncan, P.M. 1876. Notices of some deep-sea and littoral corals from the Atlantic Ocean, Caribbean, Indian, New-Zealand, Persian Gulf and Japanese, etc., Seas. Proc. Zool. Soc. London for 1876: 428-442. Durham, J.W. 1962. Corals from the Gal~pagos and Cocos Islands. Proc. Calif. Acad. Sci., ser. 4, 32: 41-56. Durham, J.W. 1966. Coelenterates, especially stony corals, from the Gahipagos and Cocos Islands: 123-135. In: R.I. Bowman (ed.), The Gahipagos: Proceedings of the Gahipagos International Scientific Project of 1964. University of California Press, Berkeley. Durham, J.W. & J.L. Bamard. 1952. Stony corals of the eastern Pacific collected by the Velero III and Velero IV. Allan Hancock Pac. Exped. 16: 1-110.
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Feingold, J.S. 1995. Effects of elevated water temperature on coral bleaching and survival during E1 Nifio disturbance events. Ph.D. dissert., Univ. Miami. 236 p. Feingold, J.S. 1996. Coral survivors of the 1982-83 E1 Nifio-Southem Oscillation, Galfipagos Islands, Ecuador. Coral Reefs 15" 108. Fiedler, P.C. 1992. Seasonal climatologies and variability of eastern tropical Pacific surface waters. NOAA Tech. Rpt. NMFS 109: 1-65. Finet, Y. 1991. The marine mollusks of the Galfipagos Islands: 253-280. In: M.J. James (ed.), Gal~pagos Marine Invertebrates: Taxonomy, Biogeography, and Evolution in Darwin's Islands. Plenum Press, New York & London. Gleason, D.F. & G.M. Wellington. 1993. Ultraviolet radiation and coral bleaching. Nature 365: 836-838. Glynn, P.W. 1988. E1 Nifio warming, coral mortality and reef framework destruction by echinoid bioerosion in the eastern Pacific. Galaxea 7: 129-160. Glynn, P.W. 1990. Coral mortality and disturbances to coral reefs in the tropical eastern Pacific: 55-126. In: P.W. Glynn (ed.), Global Ecological Consequences of the 1982-83 E1Nifio-Southem Oscillation. Elsevier Oceanography Series 52, Amsterdam. G1)am, P.W. 1994. State of coral reefs in the Gal~ipagos Islands: natural vs anthropogenic impacts. Mar. Poll. Bull. 29:131-140. Glynn, P.W. 1997. Eastern Pacific reef coral biogeography and faunal flux: Durham's dilemma revisited. Proc. 8th Int. Coral Reef Symp., Panarmi 1" 371-378. Glynn, P.W. & J.S. Ault. 2000. A biogeographic analysis and review of the far eastern Pacific coral reef region. Coral Reefs 19: 1-23. Glynn, P.W. & M.W. Colgan. 1992. Sporadic disturbances in fluctuating coral reef environments: E1Nifio and coral reef development in the eastern Pacific. Amer. Zool. 32:707-718. Glynn, P.W. & J.L. Matr. 1997. Field guide to the Pacific coral reefs ofPanarr~. Proc. 8th Int. Coral Reef Symp., Panarn,5 1" 145-166. Glynn, P.W. & G.M. Wellington. 1983. Corals and coral reefs of the Galhpagos Islands. University of California Press, Berkeley. 330 p. Glynn, P.W., G.M. Wellington & C. Birkeland. 1979. Coral reef growth in the Gal~pagos: limitation by sea urchins. Science 203: 47-49. Glynn, P.W., J. Cortrs, H.M. Guzrn~n & R.H. Richmond. 1988. E1 Nifio (1982-83) associated coral mortality and relationship to sea surface temperature deviations in the tropical eastern Pacific. Proc. 6th Int. Coral Reef Symp., Townsville 3: 237-243. Glynn, P.W., N.J. Gassman, C.M. Eakin, J. Cortrs, D.B. Smith & H.M. Guzrr~n. 1991. Reef coral reproduction in the eastern Pacific: Costa Rica, Panalrfi, and Gal~ipagos Islands (Ecuador). I. Pocilloporidae. Mar. Biol. 109: 355-368. Glynn, P.W., S.B. Colley, C.M. Eakin, D.B. Smith, J. Cortrs, N.J. Gassman, H.M. Guzm~n, J.B. Del Rosario & J.S. Feingold. 1994. Reef coral reproduction, recruitment and recovery in the eastern Pacific" Costa Rica, Panarrfi and Galhpagos Islands (Ecuador). II. Poritidae. Mar. Biol. 118: 191-208. Glynn, P.W., S.B. Colley, N.J. Gassman, K. Black, J. Cortrs & J.L. Matr. 1996. Reef coral reproduction, recruitment and recovery in the eastern Pacific: Costa Rica, Panan~ and Gal~ipagos Islands (Ecuador). III. Agariciidae (Pavona gigantea and Gardineroseris planulata). Mar. Biol. 125: 579-601.
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Glynn, P.W., S.B. CoUey, J.H. Ting, J.L. Mat6 & H.M. Guzn~n. 2000. Reef coral reproduction in the eastern Pacific: Costa Rica, Panan~ and Gal~ipagos Islands (Ecuador). IV. Agariciidae, recruitment and recovery of Pavona varians and Pavona sp. a. Mar. Biol. 136:785-805. Grove, J.S. 1989. E1 Nifio 1982-1983 and new records of Indo-west Pacific fishes at the Gal/Lpagos. Ann. Rept. West. Malacol. Soc. 21" 5 (single page). Guzmhn, H.M. & J. Cort6s. 1993. Arrecifes coralinos del Pacifico oriental tropical: revisi6n y perspectivas. Rev. Biol. Trop. 41: 535-557. Hickman, C.P. Jr. 1998. A field guide to sea stars and other echinoderms of Galhpagos. Sugar Spring Press, Lexington, Virginia. 83 p. Houvenaghel, G.T. 1984. Oceanographic setting of the Gal~pagos Islands: 43-54. In: R. Perry (ed.), Key Environments: Gal/lpagos. Pergamon Press, New York. Izurieta V., A. 1992. La Reserva de Recursos Marinos de Gal/tpagos: una reserva olvidada. Carta Informativa 34:1-2 (a newsletter published by Estaci6n Cientifica Charles Darwin and Servicio Parque Nacional Galitpagos). James, M.J. (Ed.). 1991. Gal~pagos Marine Invertebrates: Taxonomy, Biogeography, and Evolution in Darwin's Islands. Plenum Press, New York & London. 474 p. Jennings, S., A.S. Brierley & J.W. Walker. 1994. The inshore fish assemblages of the Gal/lpagos Archipelago. Biol. Conserv. 70: 49-57. Kay, E.A. 1991. The marine mollusks of the Gal~ipagos: determinants of insular marine faunas: 235-252. In: M.J. James (ed.), Gal/tpagos Marine Invertebrates" Taxonomy, Biogeography, and Evolution in Darwin's Islands. Plenum Press, New York & London. Kelleher, G., C. Bleakley & S. Wells. 1995. A global representative system of marine protected areas. Vol. IV: South Pacific, Northeast Pacific, Northwest Pacific, Southeast Pacific and Australia/New Zealand. The International Bank for Reconstruction and Development/The World Bank, Washington, D.C. 212 p. + map supplement. Lessios, H.A., B.D. Kessing, G.M. Wellington & A. Graybeal. 1996. Indo-Pacific echinoids in the tropical eastern Pacific. Coral Reefs 15: 133-142. Lessios, H.A., B.D. Kessing, D.R. Robertson & G. Paulay. 1999. Phylogeography of the pantropical sea urchin Eucidaris in relation to land barriers and ocean currents. Evolution 53: 806-817. Macintyre, I.G., P.W. Glynn & J. Cort6s. 1993. Holocene reefhistory in the eastern Pacific: mainland Costa Rica, Carlo Island, Cocos Island, and Gal~ipagos Islands. Proc. 7th Int. Coral Reef Symp., Guam 2:1,174-1,187. Malmquist, D.L. 1991. The past as a key to the present: taphonomy and paleoecology of the Urvina Bay uplift: 393-421. In: M.J. James (ed.), Gal~pagos Marine Invertebrates: Taxonomy, Biogeography, and Evolution in Darwin's Islands. Plenum Press, New York. Milne Edwards, H. & J. Haime. 1848. Recherches sur les Polypiers. Premier M6moire. Structure et d6veloppement des polypiers en g6n6ral. Annales des Sciences Naturelles (3)9: 37-89. Milne Edwards, H. & J. Haime. 1857-60. Histoire naturelle des Coralliaires. Paris. Vol. 2: 633 p. (1857); vol. 3:560 p. (1860); Atlas, 31 pls. (1857). Ochoa L6pez, E., H. Reyes Bonilla & J. Ketchum Mejia. 1998. Effects of sedimentation on coral communities of southern Socorro Island, Revillagigedo Archipelago, M6xico. Cienc. Mar. 24: 233-240.
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Podestfi, G.P. & P.W. Glynn. 1997. Sea surface temperature variability in Panamfi and Galapagos: extreme temperature causing coral bleaching. J. Geophys. Res. 102: 15,749-15,759. Pourtal~s, L.F. de. 1875. Corals at the Galfipagos Islands. Amer. J. Sci. Arts, ser.3, 10: 282283. Reyes Bonilla, H. In press. Coral reefs of the Pacific coast of M6xico. In." J. Cort6s (ed.), Latin American Coral Reefs, Elsevier, Amsterdam. Reaka-Kudla, M.L., J.S. Feingold & P.W. Glynn. 1996. Experimental studies of rapid bioerosion of coral reefs in the Gal~pagos Islands. Coral Reefs 15:101-107. Robinson, G. 1985. Influence of the 1982-83 E1Nifio on Gal~pagos marine life: 153-190. In: G. Robinson & E.M. del Pino (eds.), E1Nifio in the Gal~ipagos Islands: The 19821983 Event. Charles Darwin Foundation for the Gal~pagos Islands, Quito, Ecuador. Rodriguez, J. 1993. Las Islas Gal~ipagos: estructura geogr~ifica y propuesta de gesti6n territorial. Ph.D. dissert., Catholic University of Nijmegen, Holland. 276 p. Rowan, R., N. Knowlton, A. Baker & J. Jara. 1997. Landscape ecology of algal symbionts creates variation in episodes of coral bleaching. Nature 388: 265-269. Shen, G.T. & C.L. Sanford. 1990. Trace element indicators of climate variability in reefbuilding corals: 255-283. In: P.W. Glynn (ed.), Global Ecological Consequences of the 1982-83 E1Nifio-Southem Oscillation. Elsevier Oceanography series 52, Amsterdam. Shen, G.T., T.M. Campbell, R.B. Dunbar, G.M. Wellington, M.W. Colgan & P.W. Glynn. 1991. Paleochemistry of manganese in corals from the Gal~ipagos Islands. Coral Reefs 10: 91-101. Shen, G.T., J.E. Cole, D.W. Lea, L.J. Linn, T.A. McConnaughey & R.G. Fairbanks. 1992. Surface ocean variability at Gal~ipagos from 1936-1982: calibration of geochemical tracers in corals. Paleoceanog. 7: 563-588. St'rub, P.T., J.M. Mesias, V. Montecino, J. Rutllant & S. Salinas. 1998. Coastal ocean circulation off western South America: 273-313. In: A.R. Robinson & K.H. Brink (eds.), The Sea, Vol. 11, The Global Coastal Ocean: Regional Studies and Syntheses. Wiley, New York, Chap. 10. UNEP/IUCN. 1988. Coral Reefs of the World. Volume 1: Atlantic and eastern Pacific. UNEP regional seas directories and bibliographies, IUCN, Gland, Switzerland and Cambridge, U.K.KINEP, Nairobi, Kenya. 373 p., 38 maps. Vargas ~ngel, B. 1996. Distribution and community structure of the Utria reef corals, Colombian Pacific. Rev. Biol. Trop. 44: 627-635. Veron, J.E.N. 1995. Corals in Space and Time: The Biogeography and Evolution of the Scleractinia. Comstock/Cornell, Ithaca & London. 321 p. Walker, S.E. 1991. Taphonomy and paleoecology of Villamil fossil megagastropods oflsla Isabela: 423-437. In: M.J. James (ed.), Gal~ipagos Marine Invertebrates: Taxonomy, Biogeography, and Evolution in Darwin's Islands. Plemtm Press, New York & London. Wellington, G.M. 1984. Marine environment and protection: 247-263. In: R. Perry (ed.), Key Environments, Gal~ipagos. Pergamon Press, Oxford. Wellington, G.M. 1997. Field guide to the corals and coral reefs of the Gal~ipagos Islands, Ecuador. Proc. 8th Int. Coral Reef Symp., Panarn,5 1" 185-202. Wellington, G.M., R.B. Dunbar & G. Merlen. 1996. Calibration of stable oxygen isotope signatures in Gal~pagos corals. Paleoceanog. 11" 467-480. Whelan, P. 1989. Oil spill in Galfipagos. Noticias de Gal~pagos 47: 2.
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Reef-building coral communities of Easter Island (Rapa Nui), Chile P e t e r W . G l y n n a, G e r a r d M. W e U i n g t o n b, E v i e A. W i e t e r s c a n d S e r g i o A. N a v a r r e t e c aDivision of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149-1098 USA bDepartment of Biology and Biochemistry, University of Houston, Houston, Texas 77204-5513 USA CDepartamento de Ecologia, Facultad de Ciencias Biol6gicas, Pontificia Universidad Cat61ica de Chile, Santiago, Chile
ABSTRACT: Easter Island (Rapa Nui) and Sala y G6mez Island are Chile's only subtropical marine environments supporting reef-building corals. The depauperate coral communities of Easter Island, one of the world's most isolated marine outposts, form topographically complex and aesthetically appealing subtidal seascapes. Little is known of the coral fauna and coral communities of Sala y G6mez Island. Information on Easter Island's coral fauna has increased slowly, from sporadic taxonomic studies in the early to late 1900s to a comprehensive reconnaissance of subtidal communities published in 1988. Ecological/geological studies from 1998 to 2000 (and continuing) are now adding rapidly to our knowledge of Easter Island coral community structure and reef growth potential. Eleven species of zooxanthellate corals are currently recognized and only two of these, Pocillopora verrucosa and Porites lobata, contribute significantly to live substrate cover. Easter Island's position near the western arm of the South Pacific subtropical gyre explains its moderately warm marine climate, with seasonal mean monthly sea surface temperatures ranging from about 19~ to 25~ Low nutrient concentrations in the euphotic zone dictate low phytoplankton production and generally clear waters with high visibility (-~20-40 meters). Coral communities are prevalent around most island exposures, best developed from about 5 to 50 m depth, except for the southeastern shore which is frequently subject to strong wave assault. Live coral cover is often near 40% and reaches 80 to 90% in some areas. Incipient reef frameworks of P. lobata, 2-5 m in vertical relief, are present at some sites along the northeast coast. While some relatively minor coral mortality has been noted, due to the muricid gastropod Coralliophila and unidentified sources, coral bleaching and mortality resulting from anomalous high sea temperatures in the year 2000 represent the most serious recognized disturbance. Man's current utilization of coral communities at Easter Island is for harvesting organisms for local food consumption or harvesting corals and invertebrates to be sold to tourists. Unfortunately, little information is available for any resource species. Official statistics or estimates of population size, fishing effort or pressure have not been kept at the same pace as on mainland Chile because many of the harvested species are locally consumed and have not been declared fished resources. Corals themselves are either sold as whole bleached colonies or as carved statues, jewelry and parts of other curios. Pocillopora spp. are the primary targets of the curio trade, with Pocillopora verrucosa constituting 90% of coral items for sale in local markets. No permits are required to extract corals and there are no enforced limits on the numbers or sizes of corals or fishes taken. Despite the lack of basic information and formulation of a management plan, the Chilean government has realized the importance of protecting these coral communities that contain a high percentage of endemic species. With
Latin American Coral Reefs, Edited by Jorge Cort6s 9 2003 Elsevier Science B.V. All rights reserved.
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the recent (2000) establishment of Chile's first three submarine parks at Easter Island, this new level of governmentalsanction,with increasedpublic awarenessand support,shouldhelpsustainthe biodiversityand vitalityof the island's unique coral communities.
1. I N T R O D U C T I O N Of the three Pacific island groups of Chile, only the western-most, composed of Easter Island and Sala y G6mez Island, and located in the South Pacific gyre near 27~ is bathed by subtropical waters and supports reef-building coral communities and incipient coral reef formations (Fig. 1). The two island groups lying closer to mainland Chile, in the path of the Perf/Chile Oceanic Current, San Ambrosio/San Frlix Islands (26~ and the Juan Ferrfindez Islands (33~ are influenced by cool waters originating from southern subpolar seas and harbor a marine biota with clear temperate affmities and without reefbuilding corals. Easter Island, also known as Isla de Pascua and Rapa Nui, is one of the world's most isolated islands, located about 3,750 km from the Chilean mainland and 2,250 km east of Pitcairn Island. In terms of human colonization, Easter Island is considered to be the eastern-most island of Polynesia. While there may have been sporadic contact from South America, the weight of diverse evidence -- archeological, botanical, linguistic, oral traditions -- indicates that Easter Island was colonized by humankind from eastern Polynesia, perhaps from the Marquesas Islands (Bahn and Flenley 1992). The small (2.5 km 2 surface area), uninhabited Sala y G6mez Island is located 415 km to the northeast of Easter Island (Fig. 2). Both Easter and Sala y G6mez Islands probably originated from a hot spot volcanic source associated with the fast-spreading mid-ocean ridge of the East Pacific
Fig. 1. location of Easter and Sala y G6mez Islands relativeto the west coast of South Americaand the nearest south Pacific islands. Synopticsurface circulation after National Geographic Societymap of the Pacific Ocean (Mercatorprojection, scale 1:36,432,000).
Reef-building coral communities of Easter Island (RapaNui), Chile
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Fig. 2. EasterIsland and Sala y G6mez Island. Fromchartno. 22451, HydrographicOffice, Washington,D.C., 8th edition, October 1925 (no. 1119),from a Chileangovernmentchart of 1918. Locationof 100 m isobathfrom chart no. 250, Instituto Hidrogr~fico de la Armada de Chile (see Castilla and Oliva, 1987).
Rise (Pilger and Handschumacher 1981). The Easter and Sala y G6mez Islands seamount chain is moving rapidly in an easterly direction on the Nazca Plate. While the ecology of temperate benthic communities along the mainland coast of Chile has been extensively studied over the past two decades (see Castilla and Paine 1987; Santelices 1989, 1990; V/Lsquez and Buschmann 1997; Castilla 1999; FernAndez et al. 2000 for reviews), the shallow-occurring coastal communities of Easter Island have largely been overlooked. The remoteness of the island and absence of in situ research facilities are the main reasons for such neglect, but lack of expertise on the biology and ecology of tropical species within the Chilean scientific community has also played a role hindering the study of this ecosystem. Even less is known of Sala y G6mez Island, and except for a few comments concerning this island, the main focus of this paper is on Easter Island. Besides taxonomic species lists, little is known of the natural history of most invertebrates and fishes that inhabit the island' s reef coral communities. Since the publication of Castilla's (1987) book reviewing our knowledge of the Chilean oceanic islands and the comprehensive description of subtidal commtmities by DiSalvo et aL (1988), we are not aware of any publication by Chilean workers or others concerning reef-coral ecological investigations conducted at Easter Island.
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In this account we offer a sketch of the limited history of coral studies, a brief review of oceanographic conditions, especially with reference to anomalous sea temperatures, a revised species list of zooxanthellate corals, and quantitative descriptions of coral communities, including associated biota. Natural and anthropogenic disturbances also are addressed, particularly in light of coral bleaching events and the harvesting of corals for the curio trade. With recent increased diving activities at Easter Island, and the potential for damage to coral communities from unregulated access and collecting, some steps that are being taken to safeguard them are discussed. 2. HISTORY OF REEF-CORAL STUDIES An excellent general source treating the history of marine invertebrate studies at Easter and Sala y G6mez Islands was compiled by Castilla and Rozbaczylo (1987), but unfortunately this publication has not been widely circulated. More specialized papers tracing the history of crustacean and mollusk studies are those of Holthuis (1972) and Rehder (1980) respectively. The first mention of corals at Easter Island was by T. Wayland Vaughan (1906), who named two species from shore collections made during the Albatross Expedition to the eastern tropical Pacific in 1904 to 1905. These corals were Pocillopora diomedeae and Porites paschalensis, the latter now recognized as a junior synonym of a previously described species (see Table 1). Three additional coral species were collected during the Downwind Expedition of the Scripps Institution of Oceanography (University of California), as part of the International Geophysical Year cruise to the southeast Pacific in 1957. Although these corals were from deep water collections offLa P6rouse Bay (40-100 meters) and Poike Peninsula (132-174 meters) at least a few had been alive when dredged. The Downwind specimens, plus small collections obtained by I.E. Efford in 1965 and H.G. Richards in 1968 were studied by J.W. Wells, resulting in the publication of a systematic account that included six species (Table 1). The corals collected in 1965 were from the Canadian Medical Expedition (University of British Columbia), with Efford serving as the leader. A new species was named by Wells (1972), the agariciid Leptoseris paschalensis. The holotype specimen was part ofEfford's collection, which was obtained from a "Father Richardo" (sic) who said it was snagged while fishing in 150 meters. No locality was given. A seventh species (Psammocora superficialis) was added to the Easter Island coral list by Wells in 1983 (see Table 23 in Glynn and Wellington 1983). While not directly related to corals, Kohn's work (Kohn and Lloyd 1973; Kohn 1978a, b) dealing with the ecology and biogeography of shallow-living marine mollusks and polychaete worms of Easter Island, is noted for its thoroughness and ecological perspective. The first ecologically conducted coral study, by researchers at the Universidad del Norte (Coquimbo, Chile), arose from an island-wide bleaching event in 1980 (Cea Egafia and DiSalvo 1982). Chilean workers were summoned to investigate this disturbance since it was feared that corals of commercial value might be dying due to recent human development activities. Alfredo Cea followed the bleaching event from late 1980 to its full recovery in early 1981, by means of underwater observations and photographic documentation. Cognizant of the abundant coral formations and other subtidal biota, Louis H. DiSalvo and co-workers teamed up to perform the first comprehensive submarine surveys of Easter
477
Reef-building coral communities o f Easter Island (Rapa NuO, Chile TABLE 1 Zooxanthellate coral records from Easter Island.
Wells (1972)
Wells (1983)
DiSalvo et al. (1988)
This study
Pocillopora damicornis (Linnaeus)
+
+
+
+
Pocillopora danae Verrill i
+
+
+
+
.
+
Pocillopora verrucosa (Ellis & Solander)
+
+
Pocillopora eydouxi (M. Edwards & Haime)
+
+
+
+
+
+
+
+
+
-
+
+
-
+
+
+
-
+
6
7
8
11
Species
Pocillopora diomedeae Vaughan
Vaughan (1906)
+
Pocillopora meandrina Dana Porites paschalensis Vaughan 2 +
Porites lobata Dana
+
Leptastrea purpurea (Dana) Psammocora superficialis (Gardiner) +
Leptoseris paschalensis Wells 3 Leptoseris solida (Quelch) Leptoseris tubulifera (Vaughan) 4 Leptoseris scabra Vaughan Cycloseris vaughani (Boschma) 5 Totals
2
1 -Pocillopora danae of Wells (1972, 1983) is recognized as a junior synonym ofPocillopora verrucosa by DiSalvo et al. (1988) and this study. 2 - Wells (1972, 1983) concluded that Poritespaschalensis is a junior synonym ofPorites lobata. 3 - Wells (1983) concluded that Leptoseris paschalensis is a synonym ofLeptoseris solida (Quelch). 4 - Veron and Pichon (1979) noted that Leptoseris tubulifera has been widely confused with Leptoseris scabra Vaughan. 5 - This deep-living coral, dredged as dead specimens (Wells 1972), was not seen in our surveys but is acknowledged as occurring at Easter Island.
Island. This work, executed in 1985 and 1986, was supported by the National Geographic Society and the Englehard Foundation. Numerous new records and species were reported for the Foraminifera, Porifera, Anthozoa, Polychaeta, Crustacea, Mollusca, Echinodenmta and Pisces (DiSalvo et al. 1988). These workers also offered hypotheses concerning biotic processes shaping benthic community structure and the role of various physical and biotic influences. As late as 1995, the paucity of information on Easter Island corals led Veron to state, "The corals of Easter Island, despite ease of access, are largely unknown." In light of work
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performed by Dennis Hubbard in 1998 and 1999, and our investigations in 1999 and 2000, the coral fauna is now well described, at least to 60 m depth. Hubbard's study, supported by the Explorers' Club, the Science Museum of Long Island, the U.S. National Park Service and (indirectly) by their Chilean counterpart, was concerned with an evaluation of the character and condition of coral formations around the island in relation to physical oceanographic and geological/geographic constraints.Our study, with Gerard M. Wellington as principal investigator, was supported by the National Geographic Society, and is concerned with a biogeographic analysis of reef corals in the south-central and southeastern Pacific. 3. O C E A N O G R A P H I C SETTING In constrast to Chile's other oceanic islands, nearer the mainland coast and influenced by the cool equatorward flowing Peril-Chile (Humboldt) Oceanic Current, Easter and Sala y G6mez Islands are located within the South Pacific subtropical gyre, an anticyclonic current system characterized by relatively warm and stable thermal conditions (Fig. 1). This major gyre, centered between 20 ~ to 50~ is driven largely by the eastward-flowing West Wind Drift at high latitudes and the westward-flowing South Equatorial Current in tropical latitudes. The surface waters in its northern sector are warmed as they flow towards the west. At Easter Island's position, the E-SE trades persist over six months of the year, N-NW winds for 4 months, and variable to calm conditions during April-May and July-August. Sea state is generally relatively calm on the N, NW and W shores, whereas the SE coast is often subject to strong wave assault. In addition to the SE trades, the SE shore is exposed to storm-generated swell trains originating from major storm centers located between 40 ~ to 55~ off Antarctica (Snodgrass et al. 1966). Average annual rainfall is 1,126 mm and is usually evenly distributed throughout the year. A period of higher rainfall sometimes occurs from March to May with a combined mean total of 339 mm, based on a 7 year record (1965-1971). The maximum 24 hr precipitation during this period was 150 nma, occurring in December (Hajek and Espinosa 1987). Another high daily record, 97.6 mm ofprecipitation on 16 June 1980, was assumed to have caused massive coral bleaching due to heavy runoff and osmotic stress (Cea Egafia and DiSalvo 1982). Because of the low frequency of ship traffic in the southern ocean, particularly in the vicinity of Easter Island, historical sea surface temperature (SST) data are limited. The most reliable SSTs available for coastal waters are from 1982 to the present. From a 19 years IGOSS (Integrated Global Ocean Services System) SST data set (Reynolds and Smith 1994), representing blended observations from several sources, including advanced veryhigh-resolution radiometer (AVHRR), ship XBTs and other instrumental sources, mean annual SST was 22.0~ (Fig. 3A). Between 1982-1999, mean monthly maximum SST was 25. I~ (range, 18.5 ~ to 26. I~ The mean monthly warm season temperature was 25.1 ~ (range, 23.4 ~ to 26.1~ and mean minimum cool season was 19.5~ (range, 18.5 ~ to 20.3~ The warmest period occurs during February to March and the coolest from August to September. Absolute SSTs and SST anomalies (Fig. 3B) reveal that during E1 NifioSouthern Oscillation events water temperatures in the vicinity of Easter Island tend to be considerably cooler, by as much as 1.7~ Similar seasonal and inter-annual trends in
Reef-building coral communities iof Easter Island (Rapa Nui), Chile
479
28-
A. .~
Easter Island (28.5~
26-
!
24 '!22
~
20
1981 2
ENSO
ENSO
18-
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991 1 9 9 2 1 9 9 3 1994
ENSO 1995
1996
1997
1998
1999
2000
2001
g.
t~
r~
E 1981
1982
1 9 8 3 1984
1985
1986
1 9 8 7 1988
1 9 8 9 1990
1991 1 9 9 2 1 9 9 3 1994
1995
1996
1997
1998
1999
2000
2001
Fig. 3. Sea surface temperature (SST) conditions at Easter Island. A - IGOSS (Integrated Global Ocean Services System Products Bulletin) monthly SST data from January 1982 to March 2000. B - Monthly SST anomalies over the same period. Data based on 1 x 1 degree of latitude and longitude centered at 28.5~ and 109~ IGOSS is blended from ship data, buoy and bias-corrected satellite data.
surface water temperature are observed in the 21 year long (1974-1995) database of the Chilean Oceanographic and Hydrographic Service (SHOA 1996), which represents measurements taken directly from the shore at Hanga Roa. The average difference in monthly mean SSTs in the two data sets (IGOSS and SHOA), from 1981-1999, was only + 0.2~ In comparison with the maximum mean monthly SST from SHOA's database, our own data show that an extraordinarily warm water event occurred during year 2000, as maximum SST reached over 27~ This is considerably warmer (greater than 1.5~ than past warming events, such as that which occurred in 1980. Our surveys in March 2000 revealed mass coral bleaching. In a follow-up study in April 2001, we observed extensive coral mortality, particularly among colonies of Pocillopora spp. at shallow depths. Zooxanthellae densities in live but severely bleached corals ranged from 1.4 x 103 to 5.9 x 104 cells c m "2 with an overall average of 3.5 x 103 cells c m -2. These values were several orders of magnitude below the normal complement of algal cells of 1 to 20 x 106 cells cm2. Such colonies would not be expected to survive. As predicted, the majority of the corals that bleached in 2000 were later found dead in 2001 surveys (Wellington et al. 2001, in prep.).
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Easter Island lies in a region of extremely low primary productivity. Remotely sensed satellite data (CZCS, Coastal Zone Color Scanner) of chlorophyll a and phaeophytin are available for this region (McClain et al. 1993). Primary productivity derived from these data, collected from November 1978 through June 1986, shows year-round values ranging from 0.05 to 0.1 mgC rn-2 day ~. These values range among the lowest in the world's oceans and are consistent with our observations of high water clarity of up to 50 m or more. 4. THE CORAL FAUNA Veron (1995) tentatively included the zooxanthellate coral fauna of Easter Island with the Southeast Pacific region, but emphasized that this area is not sufficiently well known to offer a reliable assignment. In Wells' (1972) systematic analysis, which included a reexamination of the first coral collection reported by Vaughan (1906), and three later collections made in the 1950s and 1960s, six species of corals were recognized (Table 1). This list was modified slightly about 10 years later by Wells (Table 23, in Glynn and Wellington 1983) to include 7 species. With the later study ofDiSalvo et al. (1988), which Ilit~IUUUTU LIU UTU7l l ~ W I I~UUI U8 i~llU [ i ~ X l J l l l J l l f i ~ UIII~7110/IIU)IIL~, IAI~LI ~ l . ) ~ k , l ~ t.,UtiXtt i ~GLK#II%.,U t,vl~iil,.
Our analysis, recognizing one new record, raises the coral fauna to 11 species. At least two azooxantheUate coral species occur at Easter Island, but these are generally inconspicuous, i.e. small and confmed to cryptic habitats or vertical rock faces, often below 20 m depth. These species are Madracis pharensis (Heller), observed at 60 m and Culicia rubeola (Quay & Gaimard), found between 5-55 m (DiSalvo et al. 1988). Of the 11 currently recognized zooxanthellate coral species, only two are preeminent in coral communities, namely Pocillopora verrucosa and Porites lobata (Fig. 4). These two species make up over 95% of the live coral cover island-wide and are present to at least 60 m.The growth form of P. verrucosa is branching and spreading, exhibiting little intraspecific variation. Colonies reach 20 cm in diameter and 12 to 14 cm in height. P. lobata occurs as massive hemispherical mounds, erect blades, plates, and cones as vertical outgrowths of plates (Figs. 4-8). These different colony morphologies, often occurring side by side, contribute toward the structural diversity and complexity of Easter Island coral communities. Hemispherical Porites colonies commonly reach 2 to 3 rn in diameter, and a few rare colonies attain 12 m in diameter and stand 10 m above the bottom. These remarkably large colonies are very old. Three 1-2 m diameter colonies core-drilled at Easter Island in March 2000 demonstrated mean annual vertical growth rates that ranged from 0.89 to 1.17 cm (n = 20 and 15 density band measurements per colony respectively). Equating these growthrate measurements to a 10 m high colony reveals an estimated age ranging from 860 to 1,120 years. Accordingly, Easter Island's oldest living organisms were constructing limestone edifices at about the same time the earliest monumental platforms (ahu) were being erected. Pocillopora damicornis is found most commonly on vertical and partially shaded substrates, to at least 60 rn depth, not in direct competition with Pocillopora verrucosa. Pocillopora eydouxi typically has thick branches and attains the largest size of all Pocillopora species, some colonies up to 0.5 rn in diameter (Fig. 9). This species is relatively easy to recognize, but now rarely seen. When compared with other Pocillopora spp., our sampling revealed an abundance of about 1 in 10,000 colonies or less. The remaining two pocilloporid species, Pocillopora diomedeae and Pocillopora meandrina, are relatively uncommon, occasionally found interspersed among colonies ofP. verrucosa.
Reef-building coral communities of Easter Island (Rapa Nui), Chile
481
Fig. 4. Mixed assemblage of partially bleached Pocillopora verrucosa and Porites lobata. A sea urchin, Diadema paucispinum, is visible at left-center of field (Anakena, 10 m, 22 March 2000).
Fig. 5. Varied growth forms of bleached Porites lobata (Hanga Roa, 25 m, 19 March 2000).
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P. W. Glynn et al.
Fig. 6. A platey-digitate colony of Porites lobata, partially bleached (Hanga Roa, 10 m, 20 March 2000).
Fig. 7. Columnar growth form of Porites lobata (Colorado, near Cook Point, 41 m, 17 March 1999).
Reef-building coral communities of Easter Island (Rapa Nui), Chile
Fig. 8. Conical growth form of a bleached colony of Porites lobata (Hanga Roa, 9 m, 19 March 2000).
Fig. 9. Pocilloporid community consisting of several colonies of Pocillopora verrucosa surrounding a thickly-branched colony of Pocillopora eydouxi (Motu Iti, 18 m, 15 March 1999).
483
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As a precautionary measure, we retain the species P. diomedeae because the live colonies we examined do not belong to P. eydouxi as surmised by Wells (in DiSalvo et al. 1988). P. meandrina represents a new record for Easter Island. Leptastrea purpurea, first reported at Easter Island by DiSalvo et al. (1988), was observed between 6 to 10 m at several sites, but always as one or, at most, a few clustered colonies. It was generally found encrusting fiat, exposed rock substrates subject to sand scour. Parts of some colonies were covered with sand and their full extent was not evident until they were swept clean. The recumbent colonies of L. purpurea ranged in size from about 0.1 to 0.25 m 2. Psammocora superficialis is also an uncommon species, added to the Easter Island coral fauna by Wells in 1983 (Table 23, in Glyrm and Wellington 1983). This is a small, nodular (toothlike), subramose species, 5 to 10 cm in diameter, interspersed among larger corals and macrophytic algae at 6-12 rn depth. Usually fewer than 10 colonies could be found at any given site. It now appears that two species of Leptoseris have been collected at Easter Island, namely L. solida and L. scabra. The first of these was mistakingly classified as a new species by Wells (L. paschalensis) and the second was confused withL, tubulifera. Because these corals begin to appear in relatively deep water, at 40 to 60 rn, our knowledge of their depth range, abundance and distribution is fragmentary. The few colonies of both species examined in this study (collected by H. and M. Garcia) were found at 60-65 rn, and L. solida may occur as deep as 150 m (Wells 1972). Although our specimens were small, the longest colony dimensions were less than 10 crn, the L. solida colony examined by Wells measured 25 by 33 cm. Live colonies are attached to rocks and dead fragments may be dredged from soft substrates. Both species have been found at Motu Nui and Motu Iti, and L. solida has been collected off La Perouse Bay. Cycloseris vaughani is also a deep-water coral, living on sandy bottoms. The only specimens known from Easter Island were dredged dead from 132 to 174 m depths offthe Poike Peninsula (Wells 1972). In Hawaii, this species is usually found at depths greater than 15 m and contains zooxanthellae (Maragos 1977). The only corals presently known from Sala y G6mez Island are Pocillopora damicornis and Porites lobata, both contained in the collections of the U.S. National Museum of Natural History, Smithsonian Institution. Since the two most recent systematic studies at Easter Island are based on extensive scuba surveys, in all subtidal habitats to 60 m depth, it is likely that the present coral inventory is definitive or nearly so. Curiously, although Veron (and J.W. Wells) helped to document the authenticity of the three new records reported by DiSalvo et al. (1988), these were not mentioned in Veron's 1995 biogeographic treatment of Easter Island. Reexamination of Wells' (1983) compilation of eastern Pacific and nearest eastcentral Pacific zooxanthellate coral records reveals a strong affinity between Easter Island and French Polynesia. Eight of the 11 presently recognized Easter Island coral species also occur at various localities in French Polynesia (Pichon 1985). A close connection with the coral fauna of Hawaii and the Line Islands is also evident with six species shared among each of these areas. 5. CORAL C O M M U N I T I E S Mirroring the depauperate coral fauna of Easter Island, nearly all other taxa associated with coral assemblages are also species poor. Macroalgal communities, however, are
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exceptionally well developed and diverse compared with the flora of other small islands in the central Pacific. The flora, comprising 166 taxa, shares a general affmity with the western Pacific, and demonstrates only 14% endemism (Santelices 1987; Santelices and Abbott 1987). At relatively shallow depths (1-10 m) around the island, three species of brown algae -- Zonaria stipitata Tanaka & Nozawa, Sargassum skottsbergii Sj6stedt and Lobophora variegata (Lamour.) Wom. -- often occupy a large share of available substrates. Depending upon the species, these algae may attain 0.2 to 1.0 m in height, form a thick cover, and appear to be in direct competition with corals for space and light. DiSalvo et al. (1988) remarked on the "barren grounds" present in many areas with high abundances of the grazing sea urchin Diadema, and suggested a cause and effect relationship between high coral cover, high densities of herbivorous echinoids and sparse algal development. Sea urchin grazing on algae can indirectly favor coral growth. Additionally, on western Pacific reefs sea urchin feeding excavations may facilitate coral recruitment by offering young corals habitat niches relatively unfavorable to algae (Birkeland and Randall 1982). Supporting this hypothesis was an extensive coral recruitment event on sea urchin barrens observed at Easter Island in 1986 (DiSalvo et al. 1988). Herbivorous fishes that often limit algal growth in coral communities elsewhere are not presently abundant at Easter Island (see sections 6 and 7 below). Their numbers were low in 1985 and 1986, and also in 1999 and 2000. Some potentially important schooling herbivores include the acanthurids Acanthurus leucopareius (Jenkins) and Acanthurus triostegus (Linnaeus), the scarid Leptoscarus vaigiensis (Quoy & Gaimard), and the two kyphosids Girellops nebulosus (Kendall and Radcliffe) and Kyphosus bigibbus Lacep~de (see Randall and Cea Egafia 1984; Sepfilveda 1987). Coral communities dominate rock substrates from about 10 to 40 rn along the western and northern coasts of Easter Island, and the islets Motu Iti and Motu Nui off the island's southwestern tip. DiSalvo et al. (1988) attributed the sparse coral cover on the southeastern coast to frequent exposure to heavy wave action there. They noted that algal turfs and foliaceous calcareous red algae, common in crevices and under overhangs, contributed predominantly to the epibenthic cover in environments exposed to high wave assault. Live coral cover is high in well developed coral communities, often ranging from 40 to 100%. Mixed species assemblages of Porites lobata and Pocillopora verrucosa are common, as well as nearly pure stands of one or the other species. At Hanga Roa, Porites lobata was the most abundant species sampled (Fig. 10). Most colonies adhere directly to basalt substrates, but occasionally where coral densities are high they build upwards on old dead skeletons, thus forming incipient coral reef frameworks (Fig. 8). The initial stages of reef building have been observed at a few sites off the west coast, e.g. at Hanga Roa and Hanga Piko, and along the northeast coast at Ovahi and La Perouse Bay (Fig. 2). Surface inspection has revealed that the vertical coral buildups in these areas range from 2 m to a maximum of about 5 m, and are limited to only a few hundreds of square meters in extent. A 7 m thick Porites patch occurs off the north shore of Easter Island, west of Cape O'Higgins (D. Hubbard, per. com.). In the Hanga Roa Porites community, other sessile taxa with mean abundances of less than 10%, were Pocillopora verrucosa, macroalgae, crustose coralline algae and sponges. Zonaria stipitata contributed most to the plant cover, but Sargassum skottsbergii was also present, and the calcareous green alga Halimeda renschii Hauck. Crustose coralline algae and sponges were present as well. Species belonging to the red coralline algal crusts
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A
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R/S rock, sand PL Porites l o b a t a ]VIA macroalgae PV PocUloporav e r r u c o s a CA crustose coralline algae SP sponges
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SP echinoids gastropods holothurians bivalves ophiuroids hermit crabs
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Fig. 10. Mean abundances of macroscopic epibenthos at Hanga Roa, 18-20 March 2000, 8-9 m depth, from 43 randomly located 0.25 m2quadrats. Vertical lines denote standard errors of means. A- Visual estimates of percent cover of 6 categories. B - Numbers of six classes of organisms per mz of bottom sampled.
Lithothamnion, Lithophyllum, Melobesia, Neogoniolithon and Porolithon can be abundant locally (Santelices 1987; Santelices and Abbott 1987). At least 11 sponge genera have been observed at Easter Island, and are abundant in certain areas (DiSalvo et al. 1988). Red Tedania sp. and the black Asteropus sp. are especially abundant on some coral community substrates. A m o n g the more abundant vagile taxa were echinoids, gastropods and holothurians, each with mean densities of around 3 ind m 2 at Hanga Roa (Fig. 10). Diadema paucispinum A. Agassiz, a dominantly Hawaiian species that occurs across the Indo-Pacific region to the east African coast, is the most abundant sea urchin associated
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with corals. Aggregations of this species offAnakena numbered up to 20 ind m "2 in March 1999 and 2000. Another more sedentary sea urchin that bores into dead coral skeletons and basalt is Echinostrephus aciculatus (A. Agassiz). The most abundant gastropod sampled in the Porites community was Coralliophila violacea (Kiener), which lives onPorites lobata. This gastropod is a corallivore and is typically found in fissures, fimaly attached to colony surfaces adjacent to live coral tissues on which it feeds. Large Porites colonies may harbor hundreds of these gastropods, but do not reveal obvious signs of tissue loss because the feeding activities of C. violacea are confined to areas immediately around their attachment sites. Holothurians were also commonly encountered, especially on substrates with light to moderate amounts of sand cover. The two holothurians most frequently seen during the day were Holothuria (Microthele) nobilis (Selenka), a large (20-25 cm) black species, and Holothuria (Semperothuria) cinerascens (Brandt), a smaller (10-15 cm) black species. Both are deposit feeders, ingesting sand from which they extract organic matter. Other cryptic holothurian species emerge at night also to forage over the substrate (DiSalvo et al. 1988). Commonly present, but at lower densities, are bivalves, ophiuroids (brittle stars) and hermit crabs (Fig.10). The jewel box bivalve, Chama iostoma Conrad, is found among corals firmly attached to the substrate. At Anakena, where grazing Diadema are abundant, the bases of these bivalves are heavily bioeroded, allowing easy dislodgment. It is highly likely that the few ophiuroids and hermit crabs sampled during the day increase greatly in numbers at night. Other vagile species emerging at night include polychaete worms, gastropods, crustaceans and sea cucumbers. And other cryptobionts nestled under and within eroded coral skeletons are foraminiferans, flatworms, nematodes, ribbon worms (nemerteans), bryozoans, a variety of crustacean taxa, pycnogonids, tunicates and hemichordates (DiSalvo et al. 1988). Typically associated with corals at Easter Island are the wrasse Thalassoma lutescens (Lay and Bennett), the butterflyfish Forcipigerflavissimus Jordan & McGregor and the damselfishes Chromis randalli Greenfield and Hensley, Chrysiperta rapanui Greenfield and Hensley and Stegastesfasciolatus (Ogilby). These fishes can be seen feeding on various invertebrates. The butterflyfish, in addition to eating a variety of small invertebrates and their appendages, also feeds on coral polyps. Other corallivores that bite off both live coral tissues and associated skeletons are the puffer Arothron meleagris (Bloch & Schneider) and Cantherines dumerilii (HoUard), a filefish. Knicked skeletons of Porites and tnmcated Pocillopora branches are often a result of the feeding activities of these fishes. Stegastes fasciolatus establishes algal gardens at the base of coral colonies causing localized damage to coral tissues, but because of the low productivity of surrounding waters and low fish densities their impact on coral growth is low relative to such eastern Pacific sites as Panarn,~i and the Gakipagos Islands (Wellington 1982; Glynn and Wellington 1983). Although two species of carcharhinid sharks are listed as occurring at Easter Island (Sepfilveda 1987), none was observed by DiSalvo's group in February 1985 and 1986 nor byus in March 1999 and 2000. Carcharhinus galapagensis (Snodgrass & Heller), however, was abundant at Sala y G6mez (DiSalvo et al. 1988). 6. NATURAL DISTURBANCES Compared with many areas supporting abundant coral growth, relatively little damage was reported at Easter Island until the coral bleaching and mortality event that occurred
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during the first quarter of 2000. Coral bleaching, the loss of symbiotic zooxanthellae and/or their photosynthetic pigments from coral host tissues, is often caused by elevated SSTs. Since SSTs in February and March were 1-2~ (26-27~ above the long term seasonal maxima, it is highly likely that the bleaching event was a stress response to anomalous sea warming. All coral species to 30 m depth were bleached to varying degrees (Figs. 4-6, 8). Recently dead colonies indicated that over one-half of all surveyed pocilloporid corals succumbed during the initial stages of this disturbance. The extent of recovery, in terms of tissue regeneration and colony recruitment, is presently unknown. An earlier coral bleaching event occurred in June 1980, and was attributed to heavy rains with 97.6 mm recorded in 24 hours (Cea Egafia and DiSalvo 1982). The high rainfall in 1980 caused extensive soil erosion and runoff, which was thought to have lowered salinity, resulting in osmotic stress and the loss of zooxantheUae. This bleaching event probably had no longlasting effects because corals regained their normal coloration after 2-3 months. Whether Easter Island will continue to experience bleaching episodes - multiple bleaching disturbances due to elevated SSTs are now occurring in several coral reef areas (Wilkinson 1998; Hoegh-Guldberg 1999)- is also unknown. Violent tropical storms are unknown at Easter Island. Despite brief periods of severe wave assault from anomalous quarters, even the largest coral colonies that are vulnerable to toppling appear to be well adjusted to local conditions. The absence of coral skeletal debris from the strand line is also an indication of long-term colony stability. However, DiSalvo et al. (1988) hypothesized that low coral abundance along the southeast coast may be due to nearly constant exposure to large waves originating from frequent storms in the southern subpolar seas. One class of biotic disturbance that can affect coral community structure stems from herbivore activity. It is often difficult to determine, however, whether changes in herbivore abundances are due to natural causes or to anthropogenic influences, such as overfishing. At Easter Island, extensive algal turfs interspersed with macroalgae often predominate where D i a d e m a is scarce (DiSalvo et al. 1988). Conversely, "barren grounds" devoid of algal turfs and with occasional patches of herbivore-resistant macroalgae are found where D i a d e m a is abundant. Studies on coral reefs elsewhere have demonstrated that moderate levels ofherbivory can prevent algae from monopolizing available surfaces, thus allowing corals to settle, recruit and compete successfully with diverse epibenthic taxa (Glynn 1990). Possibly intense fishing pressure for certain fish herbivores at Easter Island has resulted in marked reductions in abundances (see section 7 below). 7. HUMAN IMPACT, CONSERVATION AND MANAGEMENT Easter Island has a long history of human habitation, probably first settled before the fourth century AD from somewhere in eastern Polynesia (Bahn and Flenley 1992; McCall 1995; Seelendfreund 1997). Humankind's historical influence on the environment of the island is famous and wrought with accounts of ecological devastation. Once a rich, heavily forested, subtropical landscape with dense cover of palm trees [related to the still-surviving Chilean giant palm, J u b a e a chilensis (Molina) Baillon], woody bushes, and thick undercover of diverse shrubs, fems, herbs, and grasses, now the landscape above water is largely barren (Bahn and Flenley 1992; Clark 1998). As human populations grew the forest was cleared to plant gardens (banana trees, taro root, sugar cane, yams, gourds, and sweet
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/
potato brought by the settlers), to provide firewood, construct large seagoing canoes, and to build and move the giant stone statues (moai). As early as 800 AD the island's human population was somewhere between 7,000-20,000 and the destruction of forests was well under way (Seelenfreund 1997; Clark 1998). Most tree species were driven to extinction, including the palms and the unique Toromiro that now exists only in a Swedish botanical garden. All attempts to re-introduce the Toromiro tree have failed (Maunder 1997). Every species of land bird became extinct (Steadman 1992). Man's historical influence on marine organisms is less well documented. Archaeological evidence shows that early on (900-1300 AD), one-third of the aborigine's diet consisted of porpoises harpooned far offshore and about one-quarter consisted of fishes (Steadman 1992). People also feasted on some of the 25 plus bird species that once nested on the island, including albatross, boobies, frigate birds, fulmars, petrels, prions, shearwaters, storm petrels, terns, and tropic birds (Steadman 1992). They also seem to have included seals in their diet. Once the native forests were gone (not long after 1400 AD), the aborigines were no longer able to construct seagoing canoes to harpoon porpoises, which must have increased the pressure on nearshore resources, such as crustaceans and mollusks. As food became scarce, islanders turned to cannibalism. Famine became widespread, war broke out, and by 1700 AD the human population began to crash, reaching numbers between one-quarter and one-tenth of its maximum size (McCall 1995). There is some evidence of early over-exploitation of shellfish, as the islanders appear to have settled for small sea snails instead of the larger cowries (Seelenfreund 1997). It is also possible that intense human exploitation led to the local extinction of more than half of the seabird species breeding on the island or its offshore islets (Steadman 1992). The evidence is circumstantial, however. It has recently been discovered that the islanders were using pieces of the coral Porites lobata to make the eyes of the volcanic-stone carved moais. Apparently, they collected pieces of coral and carved them into an oval shape that would fit snuggly into the eye sockets of the moais. It is not clear what impact this activity could have had on the coral population or what was the overall impact of human fishing on coral communities before the arrival and colonization by Europeans and South American mainland settlers during the 18th and 19th centuries. In recent years, Easter Island's resident population has been increasing; the 1992 census disclosed a population of 2,770 (McCall 1995). Of the over 200 terrestrial species of plants, invertebrates, birds and mammals found on the island presently, three quarters have been introduced by humans. These include two dozen varieties of eucalyptus and many grasses, as well as sheep, horses, cattle, pigeons, quail, hawks and ducks among others (McCall 1995). There are no records of species introductions in the sea. Maritime shipping has always been limited and most tourism to the island is by air transport, which probably diminishes the potential for exotic introductions. Known or suspected anthropogenic disturbances include an oil spill, harvesting of corals for the curio trade and overfishing. An island-wide oil spill resulted from the grounding of the cargo ship Regent Oak in mid1983, although details of the scope of the contamination and effects on marine communities are sketchy (DiSalvo et al. 1988). According to the islanders, the disappearance of Lobophora variegata, an important food species, and severe declines of Sargassum skottsbergi were caused by this spill. The main aspect of man's current utilization of coral communities at Easter Island is for harvesting organisms for local food consumption or harvesting corals, as well as
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Fig. 11. Pocilloporidcorals collectedby RapaNui diversfor the curio trade, HangaRoa dock(18 March 1999, courtesy Simone Wellington). invertebrates to be sold to tourists. Present sport diving activities are uncommon and unlikely to have an in~ortant effect on corals. The exploitation of sea urchins, lobsters and fishes, many utilizing corals as a habitat, is now and probably has been intense over the past few decades. Lobster, particularly Panuliruspascuensis Reed, but also Parribacusperlatus Holthuis and Scyllarides roggeveeni Holthuis, have traditionally been captured by islanders and are of great commercial interest. Over 13 years ago, Castilla (1987) warned about the potential exploitation of these species, and the current situation does not inspire optimism. These species are now essentially absent from shallow waters and, despite their high value, they are not found in the local market or restaurants. Corals are either sold as whole bleached colonies or as carved statues, jewelry and parts of other curios (Fig. 11). Corals were for sale by 41% of 79 vendors surveyed in March 2000 in local craft markets, and 100% of larger stores (8 surveyed). Of 115 colonies identified, 104 (90%) were Pocillopora verrucosa, while the remaining 10% were Pocillopora meandrina, Pocillopora eydouxi, Porites lobata, and even Acropora and Fungia. The latter two genera are not found at Easter Island and likely have been imported from other Indo-Pacific localities. Harvesting pressure is highly selective for P. eydouxi, which is a rare species. When extracting coral colonies, collectors also extract the assemblages of associated species (by-catch). Porites lobata is the primary species used to form the eyes of small recreations of stone moai statues (39 of 46 carved pieces sampled). Besides corals, islanders also collect mollusk shells, mostly Cypraea caputdraconis Melvill, Conus miliaris pascuensis Rehder and Nerita sp., to create native art and jewelry, such as necklaces.
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Local fishers catch a variety of fish species in coastal waters. The main consumption is tuna and "nanue" (Kyphosidae). Islanders also enjoy sea urchins. Because all fishes are consumed locally, there are no statistics for landings readily available and there is no enforcement of fishing regulations. Official statistics or estimates of population size, fishing effort or pressure have not been kept at the same pace as on mainland Chile because many of the harvested species have not been declared fished resources. One report from IFOP (Chilean Instituto de Fomento Pesquero) in 1974 recommends study and enforcement of size limits of lobsters, but we saw no evidence of any enforcement of such regulations. In reality, no permits are required to extract corals and there is no enforced limits on the numbers or sizes of fishes or corals taken. Despite the lack of basic information and formulation of a management plan, the Chilean government has realized the importance of protecting coral communities. Though depauperate relative to other subtropical locations, there is a very high level of endemism (ca. 25%) of most marine taxa due to the isolation from other source populations. This fact alone, and the splendor of the underwater seascape, justifies all efforts to preserve these truly unique communities. Regrettably, the more than 4,200 km of coastline on the Chilean mainland does not contain a single marine park (Castilla 1986, 1996). The well studied marine reserve of Pontificia Universidad Cattlica de Chile at Las Cruces (central Chile) does not have any formal protection according to Chilean legislation (Castilla 1996). Therefore, it was symbolic when in April 2000 the Subsecretaria de Marina (Marine Secretary) of the Chilean Defense Ministry, created the country's first National Marine Parks, all of which lie in the subtropical waters of Easter Island (Diario Oficial, 5 April, 2000, Chile). These areas are protected by government law as a sanctuary for marine flora and fauna with the objective of securing biodiversity. The parks correspond to three small areas in shallow waters near the shore, but none of them has a coastal border. One park is called Coral Nui Nui (Giant Coral), and encompasses approximately 24 km2 in area, including the 10 meter high, approximately 1,000 year old colony of Porites lobata located near Cook Point (Fig. 2). Another park located on the west coast is Motu Tautara, approximately 0.1 km2 in area, which includes a heterogeneous rocky substrate supporting numerous pocilloporid corals with 10 m deep submarine caves. The third park is Hanga Oteo, located on the northeast coast close to Anakena beach and coveting an area of 24.1 km2. This park provides refuge for many fish species, including beautiful butterfly fish (Chaetodontidae). Along with the goal of preserving these sites, there is hope that their unique attractions will promote tourism. Regulations and limitations within these parks are not yet clear, however, and it remains to be seen whether the areas would effectively protect the local biota. ACKNOWLEDGMENTS This study benefitted from species identifications kindly provided by Diane and Mark Littler (algae), Michel Pichon and Bernard Riegel (corals), Jose Leal (mollusks), Haris A. Lessios (echinoids), and David L. Pawson (sea cucumbers). We thank H. Reyes Bonilla for sharing information on coral identifications in the collections of the U.S. National Museum. Special thanks are due Henri and Michel Garcia for their help in the field. We are also grateful for the many kindnesses offered by our hosts, Dofia Ana Paoa Rangitopa and Don Jorge Edmunds Rapahango. Dennis Hubbard generously shared information with us from
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his Easter Island studies. Support for this work was provided by National Geographic Society grant 6047-97. REFERENCES
Bahn, P. & J. Flenley. 1992. Easter Island, earth island. Thames and Hudson, London. 240 p. Birkeland, C. & R.H. Randall. 1982. Facilitation of coral recruitment by echinoid excavations. Proc. 4 th Int. Coral Reef Symp., Manila 1: 695-698. Castilla, J.C. 1986. /,Sigue existiendo la necesidad de establecer parques y reservas maritimas en Chile? Ambiente y DesaroUo 2: 53-63. Castilla, J.C. (Ed.) 1987. Islas Oce/lnicas Chilenas: conocimiento cientifico y necesidades de investigaciones. Ediciones Universidad Cat61ica de Chile, Santiago. 353 p. Castilla, J.C. 1996. La futura Red Chilena de Parques y Reservas Marinas y los conceptos de conservaci6n, preservaci6n y manejo en la legislaci6n nacional. Rev. Chil. Hist. Nat. 69: 253-270. Castilla, J.C. 1999. Coastal marine communities: trends and perspective from humanexclusion experiments. Trends Ecol. Evol. 14" 280-283. Castilla, J.C. & D. Oliva. 1987. Islas oce~nicas Chilenas: aspectos descriptivos y potencialidades: 15-35. In: J.C. Castilla (ed.), Islas Oce/tnicas Chilenas: conocimiento cientifico y necesidades de investigaciones. Ediciones Universidad Cat61ica de Chile, Santiago. Castilla, J.C. & R.T. Paine. 1987. Predation and community organization on eastem Pacific, temperate zone, rocky intertidal shores. Rev. Chil. Hist. Nat. 60:131-151. Castilla, J.C. & N. Rozbaczylo. 1987. Invertebrados marinos de Isla de Pascua y Sala y G6mez: 191-215. In J.C. Castilla (ed.). Islas Oce/lnicas Chilenas: conocimiento cientifico y necesidades de investigaciones. Ediciones Universidad Cat61ica de Chile, Santiago. Cea Egafia, A. & L.H. DiSalvo. 1982. Mass expulsion of zooxanthellae by Easter Island corals. Pac. Sci. 36: 61-63. Clark, L. 1998. Secrets of Easter Island: First Inhabitants. NOVA Online Adventure. WGBH Science Unit for PBS. www.pbs.org/wgbh/nova/easter. Diario Oficial de la Reptiblica de Chile. 5 April 2000: 1-2. DiSalvo, L.H., J.E. Randall & A. Cea. 1988. Ecological reconnaissance of the Easter Island sublittoral marine environment. Nat. Geogr. Res. 4:451-473. Fernandez, M., E. Jaramillo, P.A. Marquet, C.A. Moreno, S.A. Navarrete, F.P. Ojeda, C. Valdovinos & J. V~squez. 2000. Diversity, ecology and biogeography of nearshore benthic ecosystems: an overview and needs for conservation. Rev. Chil. Hist. Nat.; in press. Glynn, P.W. 1990. Feeding ecology of selected coral-reef macroconsumers: patterns and effects on coral community structure: 365-400. In: Z. Dubinsky (ed.), Ecosystems of the World 25, Coral Reefs. Elsevier, Amsterdam. Glynn, P.W. & G.M. Wellington. 1983. Corals and Coral Reefs of the Gal~pagos Islands. University of California Press, Berkeley, Los Angeles & London. 330 p. Hajek, E. & G.A. Espinosa. 1987. Meteorology, climatology and bioclimatology of the Chilean Oceanic Islands: 55-83. In: J.C. Castilla (ed.). Islas Oce~nicas Chilenas: conocimiento cientifico y necesidades de investigaciones. Ediciones Universidad Cat61ica de Chile, Santiago.
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495
Subject Index AGRRA 69, 182, 184 Algal proliferation 293, 321,437
59, 65, 150, 187,
CARICOMP 69, 95, 112, 205, 208, 210, 215, 217, 219, 285,294, 309 Climate change 64, 182, 186
Anthropogenic impacts 5, 40, 65, 106, 126, 150, 167, 187, 209, 233, 257, 294, 320, 342, 357, 379, 409, 439, 489 -Anchoring 41, 66, 151, 190, 211, 234, 342, 380, 409, 439, 467 -Diving 41, 66, 127, 153, 190, 234, 342, 380, 439, 476 -Fisheries 42, 66, 106, 112, 127, 133, 149, 150, 168, 188, 211, 218, 262, 295, 342, 357, 379, 410, 467, 489 -Fishing with explosives 42, 295 -Military activities 125, 127, 259 -Sedimentation 40, 65, 106, 126, 151, 167, 188, 211, 233, 260, 286, 294, 312, 343, 357, 379, 408, 436, 468 -Ship grounding 43, 150, 295, 321, 409 -Tourism 41, 91, 99, 106, 127, 150, 154, 180, 190, 234, 266, 292, 313, 321,342, 380, 439
Coastal development 41,106, 124, 151, 180, 234, 320
Atolls 22, 25, 27, 28, 33, 34, 43, 139, 175, 177, 180, 183, 280, 283, 317, 318
Currents -Caribbean 206 Brazilian 13 -North Equatorial Countercurrent 376, 456 -Northern Equatorial 79 -Peru 453 -South Equatorial 478 -Equatorial Undercurrent 453 -Yucatan 141
Cold water 311,332, 339, 406 Conservation 5, 42, 68, 106, 128, 154, 168, 191,218, 235, 249, 262, 264, 295, 321,343, 358, 380, 410, 440, 460, 468, 492 Coral diseases 61, 69, 83, 92, 104, 126, 145, 148, 184, 257, 320 Coral extraction 42, 66, 67, 106, 235, 258, 260, 279, 358, 409, 459, 467,491 Coral reproduction 374, 403 Corallivores -Acanthasterplanci 338, 376, 408, 467 -Arothon meleagris 376, 339, 488
-
Bioerosion -Diadema 59, 65, 85, 100, 113, 309, 340, 342, 376, 405,463,488 -Eucidaris 339, 460, 462, 466 -Lithophaga 339, 372, 375, 459, 466 Black corals 18, 68, 116, 230, 234, 292, 356, 366, 379, 460 Bleaching 36, 38, 64, 65, 69, 104, 113, 125, 145, 150, 166, 185, 209, 232, 257, 294, 341,358, 374, 377, 404, 433, 438, 450, 466, 478, 489
Diadema antillarum 59, 65, 85, 100, 113, 126, 147, 164, 184, 225, 232, 256, 294
Dinoflagellate blooms (phytoplankton blooms) 148, 377, 407, 438
496 Earthquakes 166, 225,227, 232, 438 E1 Nifio 38, 64, 150, 232, 257, 340, 352, 358, 367, 374, 377, 393, 400, 404, 433,452, 460, 478 Eutrophication 125, 150, 187, 210, 468 Expeditions -Allan Hancock (Velero) 363, 419, 451 -Arcturus 363 -Beagle 451 -Canadian Medical 476 -Downwind 476 -Hassler 451 -Hopkins-Stanford 363 -New York Zoological Society 363 -Roosevelt Presidential Cruise 363 -St. George 419, 451 -Stanford (Te Vega) 363, 419 -Templeton-Crocker 363 -U.S. Fisheries Commission (Albatross) 243,363,451,476 -Xarifa 451 Fish communities 63, 66, 161 Herbivory 126, 147, 166, 181,213,320, 460, 486 Hurricanes (Cyclones) 61, 64, 105, 125, 146, 148, 154, 162, 166, 178, 183, 186, 205,209, 214, 217, 257, 293, 316, 340 La Nifia 64, 378,407,436 Legislation 42, 68, 106, 128, 154, 191, 194, 218, 262, 321,381,410, 468,492 Little Ice Age 378 Management 42, 65, 68, 106, 126, 133, 153, 154, 168, 181, 189, 191,205, 217, 234, 262, 294, 343, 380, 410, 439, 468, 489
Mangroves 78, 81, 99, 115, 117, 162, 188, 209, 213, 249, 260, 283, 305, 313, 362, 369, Mass mortality 42, 65, 105, 113, 126, 145, 166, 181, 184, 189, 225, 232, 294, 320, 244, 256, 314, 377, -Acropora 105, 149, 184, 286, 434 -Diadema 65, 105, 113, 126, 149, 166, 184, 189, 232, 244, 256, 294, 320 -Gorgonia 225,232, 257, 294 -Fish 150 Oceanic islands 103, 115, 278, 375, 425, 431,474, 478 Octocorals 14, 18, 61, 65, 67, 83, 86, 95, 97, 101, 118, 119, 122, 143, 164, 165, 177, 216, 217, 224, 226, 230, 234, 243, 252, 257, 279, 285, 290, 292, 316, 356, 368, 374, 397, 399 Oil spills 42, 127, 150, 190, 260, 318, 321,358,440, 490 Over-exploitation 42, 66, 106, 150, 155, 188, 235,262, 295, 410, 467 Phytoplankton blooms (dinoflagellate blooms, red tides) 148, 320, 377, 407, 438 Pollution 65, 106, 126, 133, 150, 233, 260, 295,321,358, 468 Protected Areas 42, 69, 78, 93, 101, 128, 143, 154, 168, 191,225, 234, 262, 296, 321,343, 364, 380, 410, 439, 468, 492 Reef growth 33,245,372 Seagrasses 83, 92, 117, 136, 161,165, 188, 209, 213,227, 232, 288, 291,378
497 Sea-level rise 33, 64, 173, 186, 214, 245
Tectonism (earthquakes) 166, 225, 227, 232, 438
Sedimentation 11, 17, 33, 40, 65, 106, 126, 132, 151, 167, 188, 211,224, 233, 260, 286, 290, 294, 312, 320, 337, 343, 357, 379, 408, 436, 468
Tourism 41, 43, 66, 91, 99, 150, 154, 167, 180, 188, 195, 234, 266, 313, 314, 321,380
Sponges 25, 59, 85, 94, 100, 104, 116, 164, 217, 231,256, 279, 290, 292, 310, 316, 487 Storms 17, 30, 44, 105, 146, 183, 210, 340, 378,489 Sub aerial exposure (low tidal exposure) 378, 407, 430, 435
Turtles 62, 67, 162, 167, 209, 211, 316, 468 Upwelling 64, 135, 181,204, 208, 283, 315, 339, 341,378, 389, 406, 422, 438, 454 Vertebrates 62, 468 World Heritage Site 191,375, 467
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