A Comparative Survey of Reef in Caribbean and Pacific Costa Rica
Total Page:16
File Type:pdf, Size:1020Kb
A comparative survey of reef fISh es in Caribbean and Pacific Costa Rica Peter C. Phillips Escuela de Ciencias Biológicas, Universidad Nacional, Heredia, Costa Rica. Mikie 1. Perez-Cruet Associated Colleges of the Midwest (ACM), San José, Costa Rica. Present address: University of South Florida, Tam pa, Florida 33604, U.S.A. (Received fOI publication November 11, 1983) Abstraet: Fishes from five transects in Manuel Antonio National Park (pacific) and seven transects in Cahuita National Park (Caribbean), Costa Rica were censuscd using a rapíd visual technique from February to April 1982. Cahuita, with 49 species, had a higher overaU species diversity, whereas more individuals were usually seen on the Manuel Antonio transects, where 39 species were counted. Transects with similar habitat com plexity showed highest PS values (approximately 60%). Wrasses (Labridae) and damselfish (Pomacentridae) dominated in both the Pacific rock reer and the alribbean coral reef study areas. Individuals up to 7.5 cm usually dominated on transects, but an ¡ncrease in size was observed as the habitat complexity increased. Diversity was low at Cah�ita in relation to other Caribbean reer areas, probably due to the declining state of the coral reer. Thc specics diversity valucs at Manuel Antonio are within the range of values found in Cen tral American Pacific estuarine and tidepool studies. Rock reefs and coral reefs morphologically tional Parks, Cahuita (Caribbean) and Manuel present very similar habitats of considerable Antonio (Pacific) during February, March and niche diversity harboring a great variety of fish April 1982. assemblages. Since the structure of a reef is very irregular and complex, most standard STUDY AREA methods of fish sampling (nets), are inadequate (Alevizon and Brooks, 1975). Other melhods Cahuita National Park is situated 35 km which involve lhe use of rotenone (Srnith, soulh of Limón on the Caribbean coast of 1973) or explosives (Talbott and Goldman, Costa Rica (Fig. 1). Its coral reef extends to 1973) are efficient for collections but are 300 m from lhe shore around Cahuita Point frequently incompatible with the goals of areas and is 4 km long. The nearshore currents in lhe set aside for conservation purposes. In order to area flow from north to south. Risk el al. overcome this problem, various visual census (1980) noted that the reef at Cahuita is in a techniques have been developed which require state of decline probably due to heavy sediment no direct collection of fishes (Brock, 1954; loading in the rivers to lhe north of lhe park Hobson, 1974; Jones and Thompson, 1978; during heavy rains aand contamination from Gladfelter el al. , 1980; Sale, 1980). One visual the port city of Limón. In a study by Wel method places transects over the study areas tington (1974), 34 species of coral were found and by repeatedly taking sightings of the on the Cahuita reer. abundance of fish species a10ng a transect, an Manuel Antonio National Park, on lhe accurate estimation of fish inhabiting the Pacific coast (Fig. 2), is characterized by rock transect area can be determined. ctiffs interspersed by sand beaches. Allhough The present study utllizes a rapid visual there is no extensive living coral reef at Manuel census technique to estimate the number of Antonio there are numerous rack reefs and fish species, their abundance and size distri occasional coral fo nnations. bution in relation to habitat complexity for The transects in bolh study areas were a series of transects at two Costa Rican Na- numbered according to degree of habitat 96 REVISTA DE BIOLOGIA TROPICAL f) Internol eresl PACIFIC OCEAN . �. .. ,. \ . .• .. ... • . .. ... CAR'8B�AN SEA o 500 � m o 500 S � m ! Fig. 1. Transects in Cahuita National Park (Caribbean), Fig. 2. Transects in Manuel Antonio National Park Costa Rica. (pacific), Costa Rica. ....... _". ---. - . F?====. -:i Fig. 3. Overlap in the ichthyofaunal species compo Fig. 4. Overlap in the ichthyofaunal species composi sition for the seven transects in Cahuita. tion fOI the five transects in Manuel Antonio. complexity, Transect I being tbe least complex. Transeet 3: Inside part of tbe intemal crest, Here, habitat complexity refers to an area 'S composed of c1umps of coral up to 1 m in topographical irregularity. height covered by numerous small patches of Figure 1 indicates the seven different hab· vegetation and algae. The most corumon itats which were sampled at Cahuita: coral s were Diploria sp., Porites sp. and Sideras trea sp. Between the coral fo rmations were flat Transeet 1: Located inside the internal reef areas of sand and coral rubble. Deptbs ranged erest, this area was characterized by loose from 0.5 to 1.5 m. dead coral rubble free of vegetation. The bottom was flat witb a depth from 0.5 to 1.5 Transee! 4: Northem part of the reef erest m. loca!ed on tbe poin!. There were large coral fo rmations to 2 m in height. There was also Transect 2: Inside of the reef crest of much vegetation and small patches of the Cahuita point and surrounded by extensive corals; Siderastrea ra dians, MilIepora sp., fields of turtle grass (Thalassia sp.), thls flat Agaricia sp. and Diploria clivosa. This area area was covered by coral formations up to aeted as a buttress against tbe strong incoming 0.75 m in height and small patches ofthe corals current and waves. Mon tastrea sp., Porites spp., and MilIepo ra sp. Transee! S: This small coral reef in tbe PHI LLIPS & PEREZ-CR UE T: Reef fishes of Caribbean and Pacific Costa Rica 97 shallowest part of the lagoon included the of the island and the rack outcrapping, but the following corals� Acropora sp .. Siderastrea sp., rocks in the channel were generally of mediurn Po rites sp., Diploria sp., and Corgonia sp. The - size. This area was exposed to the waves surrounding lagoon was of coral rubble. sand entering the bay and Ihere was usual!y a strang beds of Thalassia sp. and large blocks of coral. current. The water depth was from 0.5 to 6 m. This small reef was from 1 to 2 m in depth. Transect s: lnside part of a rack point in Transect 6: On the outer side of the intemal Manuel Antonio Bay. There was one large crest and composed of fields of branching coral head which, along with Ihe racks, ranged o::: Acropora sp. surraunded by areas of MilIepora in height from 0.5 to 2 m. During low tide Ihis sp., Siderastrea radlans, Montastrea caver area was protected from the incoming waves by nosa, Pon' tes astreoides, Agarióa agaricites, the rock pojnt, which was uoderwater at high Diploria stn'gosa and Mo ntastrea annualus. tide. The water depth was fram 0.5 to 5 m. This area 's irregularity provided a very complex habitat for fishes. The water depth was fram 0.5 to 3 m. MATERIAL AND METHODS Transect 7: This most complex habitat was a Dne huodred foot transects were perma reef located between the internal and externa! nentIy identified with plastic jugs secured by crests. It was made up of large branching eord to the bottom. Fishes were sighted by the Acropora palmata that extended to heights of 4 junior author equipped with snorkeling gear. m. Also there were large heads of Diploria Eight sightings of each lOO foot transect stngosa, Siderastrea radians and Montastrea were taken irrespective of tidal stage and cavernosa and large patches of MilIepora sp., recorded 00 an underwater writing pad. Each Porites astreoides, Dichocoenia stokesii, Col transect included a field 1 m to either side pophyllia sp., Porites porites and Agarida and from Ihe bollom to Ihe surfaee. Photo agaricites. The water depth ranged fram O to 6 graphs of fish species that could not be im m. mediately identified were taken with a Nikonos Figure 2 indica tes the five different habitats 4A underwater camera. An effort was also which were sampled at Manuel Antonio: made to record the fish species that hid in caves or under coral during the day , sinee the visual Transect 1: This plain area was located oear technique is only accurate for diurnal species the beach in Manuel Antonio Bay and was (Broek, 1982). Therefore, the transect data characterized by smal! racks, pebbles and coral reflect relative rather than absolute abundance. rubble which were covered in sorne places by The use of snorkeling gear tends to reduce Ihe algae. The water depth was approximatley 4 m. amount of noise assoeiated wilh SCUBA and also facilitates the fish census in shallower Transect 2: Rock reer also in Manuel Anto waters (Chapman el al., 1974). It was noted nio Bay. The bOllom was of irregular racks that that smaller species seemed to be attracted to measured from a few contimeters to 0.3 m in Ihe bOllom sediment Ihat was raised during height. In between the racks there were sandy sampling. This allraetion of smaller fishes may areas and areas that were sparsely covered by have led to a bias of higher eounts of these low vegetation. smaller individuals. Upon completion of all sightings, eaeh N Transect 3: Roek reef on the calm east side (number of individual sightings per species of a small island in Puerto Escondido Bay. per transect area) was divided by 8 and Ihe Characteristic of this area were the medium respective standard deviation was calculated. sized raeks that ranged in height fram 0.2 Individual fish in each sighting were grouped to 1 m fo rrning nurnerous small caves. The into the following size categories; Graup water depth ranged from 0.5 to 2 m. 1, to 7.5 cm; Group 2, 7.5-20 cm; Group 3, 20.5-28 cm; Group 4, 28.546 cm; and Graup Transect 4: West side of the small island in 5>46 cm.