Rev. Siol. Trop., 44(2): 643-651,1996

Distribution and community structure of the reef corals of Ensenada de Utría, Pacitic coast of Colombia

Bernardo Vargas-Angel Division of Marine Siology & Fisheries, Rosenstiel School of Marine & Atmospheric Science, 4600 RiCkenbacker Causeway, Miami, Fl, 33149. U.S.A.

(Rec. 14-VII-1994. Rev. 8-11-1995. Accep. 22-V-1995)

Abstract: Two types of coral communities occur in the Ensenada de Utría National Park (Pacific of Colombia) reefs, which develop in shallow sheltered water, and smaller non-reefal communities along wave exposed basaItic blocks. Chola reef, the largest coral comínunity (approx. 10.5 ha), is characterized by relative high coral cover (32.4%) and dominated by Pocillopora damicornis. Smaller in size (approx. 1.5 ha), Diego reef is mainly covered by dead Pocil/opo"ra damicornis and live Psammocora (S.) stel/ata (2%). The other non-reefal communities are characterized by isolated coral colonies and patches of Pavona clavus, Pavona gigantea and Porites [obata. Coral community deteri­ oration at Utría is evident, specially in the reefs, where both natural and antropogenic disturbances (e.g. phytoplankton blooms, human induced siltation, dynamite fishing and probably El Niño 1982-83 warming event) seem to influence the community structure.

Key words: Utría, Colombian Pacific, coral reefs, community structure, reef deterioration.

Three main areas along the Pacific coast of northern Colombian Pacific coast results of the Colombia have coral reef development (Prahl Velero III, IV and T.E. Vega expeditions Iist & Erhardt 1985). These are: Gorgona Island, coral species and describe subtidal pro files for Malpelo Island and the northern end of the certain localities (Durham & Barnard 1952). coast from Cabo Corrientes (5° 28'N) to Punta Recent works only provide a succint descrip­ Ardita (8°12' N). From these, Gorgona Island tion of the coral communities of Ensenada de reefs are not only the best developed but also Vtría (Prahl & Erhardt 1985, Prahl 1986 c, the most studied. Crossland (1927) was the first Vargas-Angel 1988). to report Pocilloporid corals for the island; Coral reefs along the northern Colombian however it was only until Prahl et al. (1979) Pacific are meager if compared to those of when sorne aspects of the reef distribution and Gorgona Island. Development of coral reefs composition were described. Other works like along this coast may be limited by lack of proper those of Glynn et al. (1982), Cantera (1983), substrata, water turbidity and upwelling influ­ Prahl & Erhadrt (1985), Prahl (1986 a, b) and ence from the Gulf of Panamá. This work pre­ Prahl et al. (1988) have certainly added to the sents a first attempt to quantitatively describe the general knowledge of the ecology and commu­ distribution and community structure of the nity structure of these formationS. main coral communities at Ensenada de Vtría. By contrast, the two other zones have been briefly studied, perhaps due to the les ser coral MATERIAL AND METHODS development and inaccessibility of the sites. Despite the biogeographical importance of Study area: Ensenada de Vtría (6°4'N; Malpelo Island, no further research has been 77°23'W) is located on the northern half of the conducted after Birkeland et al. (1975). For the Pacific coast of Colombia (Fig. 1). This region 644 REVISTA DE BIOLOGIA TROPICAL owes its fractured relief to the coastal moun­ season (INDERENA and Fundación Natura tainous range, Serranía del Baudó, which runs unpublished data). south from Gulf of San Miguel in Panamá Methodoiogy: The coral communüies of (8°20'N) to Cabo Corrientes in Colombia Ensenada de Utría were located using previous (5°23'N). GeologicalIy, Ensenada de Utría is a works (Prahl & Erhardt 1985) and with the help fault, forrned during the late Cretaceous, asso­ of local fishermem. AH sites were carefully ciated with active tectonism as the coastal inspected in order to obtain a qualitative picture Serranía was uplifted (Galvis 1980). The main of species distribution and abundance; only a part of this mountainous range is composed of quantitative study was conducted at Chola reef metamorphosed sediments of Mesozoic age, as (Fig. 1), the largest coral reef at Utría. well as upper Miocene and Eocene igneous for­ Survey of coral communities took place mations (Gansser 1950, Oppenheim 1952). from May1988 to January 1989. At Chola reef a total of l36-1O m transects were mn along three stations, at fixed 5 m intervals from the coast to the reef base. Number of species and Uve coral cover were recorded using a ten-meter long chain (1.1 cm link; see Porter 1972) laid on the reef, following the bottom contour and parallel to the shore. Survey of non-reefal communities was conducted in a more qualitative basis. A station was set where high concentration of scleractinians occurred. Similar to Chola reef, transects were run at fixed 5 m intervals, starting from the shore. Species of Pocillopora were identified according to Cantera el al. (1989). Species diversity and evenness were ca1culated accord­ ing to Shannon & Weaver (1948) and Pielou (1966), based on coral cover data, as in Loya t (1972) and Porter (1972). Non parametric N & I Kurskal-Wallís Analyses of Variance (Sokal Rohlf 1969) were used to compare coral cover and species diversity between stations and reef

o 1.0 2.0 6" zones (no transformation allowed data to com­ � ply with homogeneity of variances).

RESULTS Fig. l. Localization of Ensenada de Utría in the Pacific coast of Colombia. Coral reefs are denoted by dark trian­ General description of coral communi­ gles, non-reefal communities by empty triangles. A = Hes: Mainly five sites where reef corals Malpelo Island, B = Gorgona Island. develop were identified at Utría, all dominated by Pocillopora (Fig. 1). The only two reefs, The climate at Ensenada de Utría is closely occur in calmed shelterd waters. The other linked to the North-South oscillation of the three communities referred as non-reefal, con­ Inter Tropical Convergence Zone (!TCZ) sist of sparse coral patches and small build-ups (Wirtky 1965, Glynn et al. 1982). The dry sea­ over basaltic boulders. son occurs from January to April and the rainy Chola reef is the largest coral reef (approx ,eason from May to December (Murphy 1939, 10.5 has) in Ensenada de Utría. It lies about West 1957). Annual rainfall is between 5000 150 m off the coast, separated by a shallow mm and 7000 mm (West 1957); air temperature channel (3-4 m depth) that receives substantial ranges from 21°C to 31°C with a mean of terrigenous run-off from La Aguara stream. 25°C, and relative humidity varies from 40% Three main features can be distingushed: the during dry season to 80-100% during the rainy reef fIat (approx 1.0 - 2.0 m deep) which is VARGAS-ANGEL: The Utria reef corals, Colombian Pacific 645 subject to periodic low tide exposures, the reef to P. damicomis, Pavona varians (Verrill), slope (approx 2.0 - 5.0 m) and the reef base Pavona clavus (Dana) and Porites lobata (approx. 5.0-7.0 m). Chola reef is mainly built (Dana). by Pocillopora damicomis (Linnaeus). Reef corals at Cocalito (Fig. 1) grow over a Diego reef (Fig. l), was probably erroneosly submerged spur-like rocky ridge of about 200m positioned from aerial pliotographs by Prahl long running off the beach. P.. capit ata and P. and Erhardt (1985), referring to it as Playa damicomis were abundant, while only a few Blanca reef. Diego reef is small (approx 1.5 colonies of P. lobata, Pavona gigantea ha); the reef flat starts at about 100 m off the (Verrill), Pocillopora elegans (Dana) and P. beach and extends for approximately 100 m stellata were observed. at a depth of 2.0 - 2.5 m. The reef slope is Live coral cover was highest (18%) at steep and falls to approximately 6.0 to 8.0 m Punta Diego (Fig. l). This site appeared to be deep. Diego reef is covered mainly by coral the best developed (both in live coral cover rubble and crustose coraline algae. Live and richness) of the non-reefal formations. As corals: Psammocora (S.) stellata (Verrill) in Playa Blanca and Cocalito, there were and P. damicornis, comprise only 2% of patches of stubby colonies of P. capitata and total reef area. P. damicomis growing on shallow flattened Live coral cover is relatively low (8.9%- rocky blocks subject to continuous wave 18%) along the non-reefal communities. action. Largest colonies of massive P. clavus Coral colonies at these sites grow between 1 (1.5 - 3.0 m) were observed at Punta Diego. m and 5 m deep, with other subtidal sessile Other reef corals: P. varians, P. gigantea, P. invertebrates such as octocorals, barnacles elegans and P. stellata also occurred at Punta and hydroids. Among these formations, Playa Diego. The only colony (1.0 m diameter) of Blanca (Fig. 1) is the most deteriorated, prob­ Gardineroseris planulata (Dana) was ably due to tourism and coral collecting. observed at Punta Diego. Live coral cover Colonies of Pocillopora capitata (Verrill) and species abundance for these non-reefal were relatively more abundant in comparison communities is shown in Table l.

TABLE I

Percent of live coral cover for the non-reefal communities at Utría estimated using chain-transects; np = species not sampled under transect at that site

Species Percent Live Coral Cover

Playa Blanca Punta Diego Cocalito

Pocillopora damicornis 0.93 1.93 2.12

Pocillopora capitata 8.77 8.12 14.12

Pocillopora eydouxi 0.43 np np

Pavona clavus 0.19 1.83 np

Pavona gigantea np 0.17 0.54

Pavona varians np 0.32 np

Porites lobata 0.97 np 1.09

Psammocora (S) stellata 0.11 0.06 0.13

Total 11.40 12.43 18.01 646 REVISTA DE BIOLOGIA TROPICAL

Community structure at Chola reef: Surveyed stations at Chola reef collected information on number Of species and live coral cover at the north, center and south of the reef. For the purposes of this study, each sta­ tion was divided into three zones: leeward (1.5 m- 3.0 m), reef flat (0.5 m-l.5 m) and seaward (1.5 m-4.0m) (Fig. 2).

N f

_1 _2 1llllllmI3 80 Station 3 Fig. 2. Schematic distribution of coral cover a10ng Olola reef . Transect stations are indicated by SI, S2, S3. Legend: 60 c:::J Pocillopora damicornis 1- Mono-stands of Pocillopora; mean cover -=50-90%. 2- _ Psammocora stellata Mixed zone of Pocillopora and Psammocora; mean cover =20- III!III Pocillopora capitata 30%. 3- Psammocoraand coralrubble; mean cover -=5- 10%. 40

20

High cover of P. damicornis was found in o Station 1 (Fig.3). In the shallow reef flat and Leeward Flat Seaward leeward zones corals grow over a mixed sand­ Fig. 3. Percent cover of coral species by zone at Chola reef. rock substrate. P. damicornis grew Standard error of mean and number of coral species present thin-branched colonies, probably due to high indicated above columns. levels of resuspended sediments (see: Veron & Pichon 1976, Prahl & Estupiñán 1990). Psammocora (S.) stellata occurred only in thir­ nis and Psammocora (S.) stellata were present teen of thirty one transects, and always in low on the reef flat. This was the only zone in the abundances. entire reef to contain massive P. gigantea. This Station 2 presented high live cover of P. species occurred only in one of thirty one tran­ damicornis at the leeward zone (approx. 60%). sects, representing less than 1 % of total reef Along the reef flat and seaward zones, P. dami­ live coral cover. Live cover on seaward zone of cornis decreased substantialIy , whilst live station 3 was low as in station 2; in this two cover of Psammocora increased (Fig. 3). stations Psammocora was more abundant than Pavona varians and P. capitata only occured in Pocillopora damicornis(Fig. 3). one and seven transects, respectively, from A total of five scleractinianspecies were found forty-seven sampled in the reef flatzone. These at Chola reef: P. damicomis, P. capitata, P. stel­ two species represented less than 1 % of total lata, P. varians and P. gigantea. From these P. cover. damicomis was dominant; absent only in thirteen The leeward zone in Station 3 was charac­ of one hundred thirty five surveyed transects, and terized by low cover of all species (5-10%) representing 80% of the total reef coral fauna. (Fig. 3). Higher cover of Pocillopora damicor- Spatial distribution of live coral coverage was VARGAS-ANGEL: The Ulría reef coraJ.s, Colombian Pacifíc 647 highly variable dueto a high degree of patchiness. 1.0 1.0 (> Station 1 Al! high coral cover areas 60%) at Chola reef :J occurred at dense mono-stands of P. damicornis, 0.8 [;] 0.8 whereas the low Iive coral cover « 10%) 0.6 0.6 occurred where P. damicornis was less abun­ 2 2 dant or absent. OA OA Total percent of coral cover was higher in 0.2 0.2 Station 1 (45.3%± 5.8) than at stations 2 and 3 2 (26.5% ± 2.7 and 26.8% ± 3.5, respectively), 0.0 0.0 however such differences were not significant (Kruskal-Wallis Anova, P > 0.05). By contrast, 1.0 1.0 percent of cover was significantly different Station 2 between reef zones (Kruskal-Wallis Anova, P < 0.8 4 0.8 0.05); being higher ín the leeward and reef flat � 0.6 0.6 ::3- than at the seaward slope. .?;- '" IJ) '§ ID Species diversity varied inversely lo percent DA DA e � e of ¡ive coral cover. Transects with high coral ID i:5 0.2 > cover at Stations 1 and 2 showed low diversity 0.2 UJ

índices (O - 0.7 Bits/Ind). Highest species 0.0 0.0 diversity values (1.2 - 1.6 BitslInd) were found at stations 2 and 3 where coral cover was lower 1.0 1.0 (10-30%) and coral species occurred in similar Station 3 proportions (Fig. 4). Species diversity between 0.8 0.8 stations did not differ significantly (Kruskal­ Wallis Anova, P> 0.05). However, between 0.6 0.6 reef zones, species díversity on the seaward OA DA sIope (0.32 bits/ind ± 0.1) was Iower, and sig­ nificantly different than on reef flat and lee­ 0.2 0.2 ± ward edge (0.45 bits/ind ± 0.06; 0.62 bits/ind 0.0 0.0 O.05)(Kruskal-Wallis Anova, P< 0.05). Leeward Flat Seaward

Fig. 4. Mean coralspecies diversity (H') (Black) and even- ness (1') (hatched) for reef zones within each transee! at DISCUSSION Chola reef. Standard error of mean and number coral species present indicated above columns. No apparent zonation pattern can be recog­ nized for non-reefal coral communities at Utda. These formations consisted basically of coral aggregations on basaltic boulders. At these sites mental factors have been suggested as strong two species of Pocillopora (P. capitata and P. determinants of particular distribution patterns damicornis) were most abundant. Massive corals (Glynn et al. 1972, Glynn 1976, Wellington were common on shallow waters. Porites lobata, 1982, Guzmán 1988, Guzmán and Cortés 1989). Pavona clavus and P. varians were never found Low coral cover at non-reefal communities in beneath 3.0 m deep. This situation is in contrast Ulría may be the result of low coral recruitment with zonation patterns at other eastern Pacific rates associated to high settlement rates of fouling coral communities like Malpelo, Galápagos and organisms, as observed in the Gulf of Panamá by Cocos Islands , where massive corals account or Birkeland (1977, see also Birkeland 1987). used to account for the deep communities. Coral species zonation at Chola reef is some­ (Bakus 1975, Birkeland et al. 1975, Glynn and what more defined. In general terms mean coral Wellington 1983, Guzmán and Cortés 1989, cover decreased fromnorth to south, whilst species 1992). Shallow and deep zonation of corals diversity and evenness increased. Statistical analy­ along the tropical eastern Pacific reefs are fairly ses however show no significant difference in coral weH understood; predation, aggresivity and cover or species diversity between stations; but species tolerance to different physical environ- suggest the presence of tWQ major reef zones: 1) 648 REVISTA DE BIOLOGIA TROPICAL

the live leeward slope and reef flat,which presents such natural disturbances caused coral mortality a highly variable caver pattem dominated by P. at Utría, it is possible that differential factors or damicomis, ana 2) the dead outer fIat and seaward localized secondary disturbances (e.g. siltation, slope, characterized by low coral cover and. the predation, erosion) a]]owed recovery of coral predomiance of P. stellata. species in the non-reefal and fostered coral Present community structure and zonation death at Diego and Chola reefs. Utría reefs, pattern of Chola reef contrasts with previos likewise most eastern Pacific coral red com­ descriptions by Prahl (1986c ), who visted the munities exhibit highly variable coral cover area in 1981 (Prahl, pers. comm). Translating patterns and low diversity and evenness. These fmm Prahl (1986c, pag 96), we read: "Chola features have been generally associated with reef presents a mature structure, dominated by both biotic and abiotic factors (Glynn 1976, P. damicornis, P. elegans and P. eydouxi as Wellington 1982, Guzmán and Cortés 1989, well as Psammocora (S.) stellata. Massive Glynn 1990). To what extent present coral reef Pavonids and Porites panamensis are also pre­ community structure at UtrÍa is the result of sent in isolated formations entrusting along the natural and/or anthropogenic infiuences, still seaward slope and base, or in clear areas where remains to be determined. Monospecificity is Pocillopora is absent". The present study found another trend that characterizes many easter no live or dead colonies of ramase P. elegans Pacific coral reefs: Porites lobata for example, or P. eydouxi in Chola reef. The only massive is the main reef builder along several reefs off corals present were small colonies (lO - 20 cm the Pacific of Costa Rica (Guzmán and Cortés diameter) of Pavona varians and P. gigantea 1989, Cortés 1990). In Panamá and Gorgona on the reef flat. No dead evidence was found of Island, Colombia, reef frameworks are mainly the other massive corals (Porites panamensis, composed by P. damicomis (Prahl et al. 1979, Pavona clavus) mentioned by Prahl (1986c). Glynn 1982, Glynn et al. 1982). Predominance Althaugh there are no formal descriptions of this species has been attributed to its rapid on Utría non-reefal communities prior to the growth rate and aggresivity (Wellington 1980, present work (only scattered sampling conduct­ 1982, Glynn and Wellington 1983) as well as ed by Barnard and Durham 1952, but see its toleran ce to sedimentation (Marshall and Vargas-Angel 1988, 1989), general colony size Orr 1931). Al Chola red P. damicornis is also and overall species richness suggests that par­ the most abundant coral and perhaps the most ticular conditions have caused selective mortal­ tolerant species to local environmental con di­ ity of reef coral s (specialIy masive corals), tions. Continuous monitoring during the study leading to severe coral richness deterioration period showed that although tive extreme low along Utría reefs in comparison to the non­ tides (-40cm) exposed the reef fiat, coral mor­ reefal communities. Possible linkage with El tality was never observed; in fact bleaching Niño-warming (1982-83) can be suggested never resulted in coral death. Moreover, narrow since this event caused catastrophic mortality belts along the leeward slope which presented of reef coral communities in Panamá, highest leveles of resuspended sediments (see Colombia, Galápagos and Costa Rica (see sum­ Vargas-Angel 1989 for data on sedimentation mary in Glynn 1990). Other natural distur­ rates) showed higher coral cover (60 - 90%) bances such as 1985 red tide which led to than areas of the flat where sedimentation was extense mortality of the red corals in Panamá lower. and Costa Rica (Guzmán et al. 1990), may It is a fact that distribution of main reef have had similar consequences on the builder at Chola reef is highly patchy. Colombian Pacifico Specially along the north Patchiness has been attributed to successional end of the coast, where this type of phytoplank­ processes after disturbances (eonnell and ton blooms are not rare (W.Tavera and M. Slayter 1977, Foster 1980) and also has been Asprilla, pers. comm.) probably due to the recognized as an important preserver of diver­ proximity of the upwellíng infiuenceof the Gulf sity in intertidal and subtidal communities of Panamá. It is very dífficult trying to asses the (Connell 1983). It is among these patches effects of these natural disturbances on coral where most fish fauna tends to congregate at communities at Utría since there are no quanti­ Chola reef; only few corallivores and grazers tative works prior to these events. However if wander aJong the low coverage areas. If associ-· VARGAS-ANGEL: The Utria reef corals, Colombian Pacific 649 ated fauna contributes to control coral cover at reduced, and with the help of a feasible man­ Chola reef is not yet completely clear. agement plan, coral community recovery may However, high cover patches display a great be possible at Dtría. number of territorial damselfish (Stegastes aca­ pulcoensis Fowler) which constantly defended their algal lawns against corallivore and herbi­ ACKNOWLEDGEMENTS vore intruders. Low coverage areas on the other hand, face predatory and foraging activities 1 am grateful to the late H.v. Prahl for his mainly from the tetraodontid, Arothron melea­ inspiratíon, guidance and encouragement while gris (Bloch and Scheneider) and the triggerfish, conducting of this work. Field work would not Pseudobalistes naufragium (Jordan and have been possible withoutthe collaboration of F. Starks). It is possible that this activities have Estupiñán and the logistical support provided by enhanced the development of dense patches Fundación Natura and INDERENA 1 also want and slow the recovery of dead areas. to thank R. Esguerra and G.A. Bravo for their Coral recruitment is also directly correlated cooperation at UtríaNational Park, S. de Lao who with coral distribution; specially Pocillopora helped with statistical analyses, and H.M. where fragmentation seems to constitute the Guzmán, J. Cortés, J. Garzónand two anonymous primary means of reproduction in the Eastern reviewers for their valuable suggestions regarding Pacific (Richmond 1987, but see Glynn et al. this paper. Barracudas Divers Club helped with 1991). Lack of mother colonies and perhaps transportation to the study area. This work was high predation and grazing activities as written while granted with an Exxon Fellowship observed in Galápagos and Panamanian reefs at Smithsonian Tropical Research Institute. after El Niño 1982-83 (Glynn 1988, Glynn Financial support was received from Fundación 1990), may also have been responsible for ero­ Natura (Bogotá, Colombia). sion and low coral cover present in Chola and Diego reefs. Human induced disturbances have also RESUMEN caused coral demise at Utría reefs. Small scale land slides, coastal erosion and thus increased En el Parque Nacional Ensenada de Utría hay dos tipos siltation have been the results of forest clearing de comunidades coralinas existen; los arrecifes de borde que se desarrollan en el interior de la ensenada y las forma­ and soil movements near Chola reef. These ciones en los bancos rocosos en las zonas externas. El type of uncontrolled practices have not only arrecife de la Chola es la formación de mayor tamaño threatened but killed entire reefs along the east­ (aprox. 10.5 ha), con una cobertura coralina promedio rela­ ern Pacific (Prahl et al. 1979, Cortés and tivamente alta (32.4%) dominada por Pocillopora damicor­ Más pequeño en tamaño (aprox. 1.5 ha), el arrecife de Murillo 1985, Cortés 1990). Furthermore, large nis. Diego está compuesto principalmente por algas incrus­ craters (1.0 - 1.5 m diameter) along the outer tantes y una baja cobertura viva de Psammocora (S.) ,¡(ella­ Chola reef flat and seaward slope are the evi­ fa (2%). Las otras comunidades que no forman arrecifes, dence of dynamite blasts implemented several muestran un desarrollo importante de corales masivos years ago as fishing technique. FinalIy, coral como: Pavona e/avus, P. gigantea y Porifes lobata. El deterioro de las comunidades coralinas de Ulría es evi­ communities at Utría have not been immune to dente, especialmente en los arrecifes, donde perturbaciones coral collecting and plundering, specially by severas tanto naturales como antropogénicas (e.g. proba­ handcrafters who seU these items as souvenirs blemente El Niño 1982-83, mareas rojas, sedimentación in nearby villages. inducida por humanos, pesca con dinamita), parecen con­ trolar la estructura y composición de éstas formaciones. Within the north portion of the Pacific coast of Colombia, Utría can be considered as one of the most important coral development sites. It REFERENCES is characterized by high coral species richness (for the eastern Pacific) in a relative small area. Bakus, G.L. 1975. Marine zonation and ecology of Cocos However, present day ecological structure sug­ Island, off Central America. Ato1!. Res. Bull. 179: 1-9. gests that these communities have been severe­ Birkeland, C. 1977. The importance of ¡he rate of biomass ly disturbed. Fortunately, the area was declared accumuJation in early successional stages of benthic as a NationaJ Park in October ] 987. Therefore community survival of coral recruits. Proc. 3rd Int. as long as human deleterious influence is Coral Reef Symp, Miami, Biology: 15-21. 650 REVISTA DE BIOLOGIA TROPICAL

Birkeland, C. 1987. Nutrient availability as a major deter­ Glynn, P.W. 1982. Coral communities and their modifica­ minant of differences among eoastal hard-substratum tions relative to past and prospectiye Central American communities in different regions of the tropics. p 45-98 seaways. Adv. Mar. Biol. 19: 91-132. In C. Birkeland (ed.) Comparison between Atlantic and Pacific tropical marine eoastal ecosystems: community Glynn, P.W. 1988. El Niño warming, coral mortality and structure, eeological processes and productiYity. reef framework destruction by echinoid bíoerosíon in University of the South Pacific, Suya, Fiji, 24-29 the eastern Pacifico Galaxea 7: 129-160 March, 1986. UNESCO. Paris. Glynn, P.W. 1990. Coral mortality and disturbances to J.P. Stames & c.L. Buford. Birkeland, C., D.L. Meyer, coral reefs in the tropical eastern Pacífíc, p.55-I 26. In 1975. Subtidal communities of Malpelo Island. P.W. Glynn (ed.). Global Ecological Consequences of Smithson. Contrib. Zoo1. 176: 55-68. the 1982-1983 El Niño-Southern Oscillatíon. Elseyier. Amsterdam. Cantera, J.R. 1983. Distribution des peuplements de sclérac­ tiniaires sur un récif frangeant de I'ile de Gorgona (Cote Glynn, P.W. & G,W. WeIlington. 1983. Corals and coral Pacifique de Colombie). Tethys 11: 25-31. reefs of the Galápagos lslands. (With an annoted Iist of sc\eractinian corals of the Galápagos by J.W. Cantera, J.R., H.v. Prahl, J.C. Escobar & E. Peña. 1989. Wells). Uniyersity of California, Berkeley. 330 p. Sistemática de los corales del género Pocillopora del Pacífico colombiano utilizando taxonomía numérica. Glynn, P.W., H.v. Prahl & F. Guh!. 1982. Coral reefs of Rev. Biol. Trop. 37: 23-28. Gorgona Island, Colombia, with special reference to corallivores and their influence on community structure ConnelI, J.H. 1983. Disturbance and patch dynamies of and development. An. Inst. Invest. Mar. Punta Betín 12: reef corals. p. 179-189. In J.T. Baker, R.M. Carter, 185-214. P.W. Sammarco & K.P. Stark (eds.). Proc. Inaugural Great Barner Reef Conference. James Cook University. Townsville, Queensland, Australia. Glynn, P.W., Stewart & l.E. McCosker. 1972. Pacific coral reefs of Panamá: structure distribution and predation. ConnelI, J.H. & R.O. Slayter. 1977. Mechanisms of sucees­ Geo\. Rundusch. 61: 483-519. sion in natural communities and their role in communi­ ty stability and organization. Amer. Natur. 1 I 1: 1119- Glynn, P.W., NJ. Gassman, C.M. Eakin, J. Cmtés, D.B. 1144. Smith & H.M. Guzmán. 1991. Reef coral reproduction in the eastern Pacific: Costa Rica, Panamá and Cortés, J. 1990. The coral reefs of Golfo Dulce, Costa Galápagos Islands (Ecuador). 1. Pocilloporidae. Mar. Rica: distribution and eommunity structure. Atol!. Res. Biol. 109: 355-368. Bul\. 344: 1-37. Guzmán, H.M. 1988. Distribución y abundancia de organ­ Cortés, 1. & M.M. Murillo. 1985. Comunidades coralinas y ismos coralívoros en la Isla del Caño, Costa Rica. Rey. arrecifes del Pacífico de Costa Rica. Rey. Bio\. Trop. Bio\. Trop. 36: 191-207. 33: 197-202. Guzmán, H.M. 1991. Restoration of coral reefs in Pacific Crossland, C. 1927. The expedition to the south Pacific of Costa Rica. Conservo Biol. 5: 189-195. S.Y.St. George. Marine ecology and coral formationsin the Panamá region, the Galápagos and Marquesas Guzmán, H.M. & J. Cortés. 1989. Coral reef community islands and the atoll of Napuke. Trans. Roy. Soco Edim. stucture at Caño Island, Pacifico Costa Rica. P.S.Z.N.I: SS, p. 2: 531-554. Mar. Ecol. 10: 23-41. Durham, J.W. & J.L. Barnard. 1952. Stony coral s of the eastern Pacific collected by the Velero III and Velero Guzmán, H.M. & J. Cortés. 1992. Cocos Island (Pacific of IV. Allan Hancock Pacific Expeditions 16: 1-110. Costa Rica) coral reefs after the 1982-83 El Niño dis­ turbance. Rey. Biol Trop. 40: 309-324. Foster, R.B. 1980. Heterogeneity and disturbance in tropi­ cal vegetation. 1/1 Conservation bíology, an evolution­ Guzmán, H.M., 1. Cortés, P.W. Glynn & R.H. Richmond. ary ecological perspectiye. M. E. Soulé (ed.). Sinauer, 1990. Coral mortality associated with dinoflagellate Massachusetts. blooms in the eastern Pacific (Costa Rica and Panamá). Galvis, J. 1980. Un arco de islas terciarias en el occidente Mar. Eco!. Prog. Ser. 60: 299-303. colombiano. Geol. Col. 11: 7-43. Loya, Y. 1972. Community structure and species diyersity Gansser, A. 1950. Geological and petrographical notes on of hermatypic corals at Eilat, Red Sea. Mar. Biol. 13: Gorgona in relation to north-western South America. 100-123. Scheiz. Min. Petr. Mitt. 30: 219-237. Marshall, S.M. & A.P. Orr. 1931. Sedimention on Low Glynn, P.W. 1976. Sorne physical and biological determi­ Isles and its relation to coral growth. Scientific Report nants of coral community structure in the eastern of the Grea! Barrier Reef Expedition 1928-29, Br. Mus. PacificoEco!. Monogr. 46: 431-456. Nat. His. 1: 93-133. VARGAS-ANGEL: The Utria reef coral s, Colombian Pacific 651

Murphy, R.C. 1939. The litoral of Pacific Colombia and reproduction in the reef coral Pocil/opora damicornis. Ecuador. Geo. Rev. 29: 1-33. Bull. Mar. Sci. 4: 594-604.

Oppenheim. V. 1952. The structure of Colombia. Trans. Shannon, C.E. & W. Weaver. 1948. The mathematical tho­ Amer. Geophys. Union 30: 739-748. ery of communication. University of lIIinois, Urbana, lIIinois. 117 p. Pielou, E.G. 1966. The rnesurement of diversity in different types of bio10gical collections. J. Theor. Biol. 13: 131-144 . Sokal, R. & F. Rohlf. 1969. Biometry. W.H. Freeman, San Francisco. 766 p. Porter, J.W. 1972. Patterns of species diversity in Caribbean reef corals. Ecology 53: 745-748. Vargas-Angel, B. 1988. Contribución al conocimiento de Prahl, H.V. 1986a: Corales y arrecifes coralinos en la isla las formaciones coralinas del litoral Pacífico colom­ biano. Mem. VI Semin. Nal. Cienc. Mar, Bogotá, de Gorgona, p. 59-87. In H.V. Prahl & M. Alberico (eds.). Gorgona. Banco Popular. Bogotá. Comiso Colom. Oceanog. p.562-570.

Prahl, H.V. 1986b. Crecimiento del coral Pocil/opora dam­ Varga�-Angel, B. 1989. Contribuciónal conocimiento de la icornis durante y después del fenómeno de El Niño en dinámica y distribución de las formaciones coralinas de la isla de Gorgona. Bol. Erfen. 18: 11-13. la Ensenada de Utría, Chocó, Colombia. Tesis de Grado Universidad del Valle, Cali, Colombia. 89 p. Prahl, H. V. 1986c. Crustáceos decápodos asociados a difer­ entes hábitats de la Ensenada de Utría. Actualidades Veron, lE.N. & M. Pichon l976. Scleractinia of the Estern Biológicas 15: 95-99. Australia, part 1. Families Thamna�teriidae, Astroceniidae and Pocilloporidae. Australian Institute of Marine Prahl, H.V. & H. Erhardt. 1985. Colombia: corales y Science. Monograph series. Vol 1. 86 p. arrecifes coralinos. Presencia, Bogotá. 295 p. Wellington, G.M. 1980. Reversal of digestive interactions Prahl, H.V. & F. Estupiñán. 1990 Estudio sobre las ecoforma� between Pacific corals: mediation by sweeper tentacles. coralina� del género Pocillopora en la Ensenada de Utría. Oecologia 47: 340-343. Pacífico colombiano. Rev. Ciencia� Univ. Valle 2: 45-54. Wellington, G.M. 1982. Deep zonation of corals in the Prahl, H.V., J.C. Escobar & EJ. Peña. 1988. Diversidad de Gu1f of Panama: control and facilitation by resident especies de un arrecife de coral de la Isla Gorgona, reef fishes.Ecol. Monogr. 53: 223-241. Pacífico colombiano. Memorias VI Seminario de Ciencias del Mar, Bogotá: 57 1-577. West, R.C. 1957. The Pacific lowlands of Colombia; a negroid area of the American tropics. Louisiana State Prahl, H.V., F. Gühl & M. Grogl. 1979. Gorgona. Futura, Universiy , Baton Rouge. 278 p. Bogotá. 272 p.

Richmond, R.H. 1987. Energetic relationships and biogeo­ Wirtky, K. 1965. Surface currents of the ea�terntropical Pacific graphical differences among fecundity, growth and ocean.Inter -Amer. Trop. Tuna Comm. Bull. 9: 271-304.