COMMUNITY STRUCTURE OF EASTERN PACIFIC REEF FISHES (GULF OF PAPAGAYO, COSTA RICA)

We assessed the relative abundance of reef fishes and ita relation with physical parameters and habitat at four sites in Culebra Bay, a human disturbed arca in Gulf of Papagayo, Costa Rica (eastem Pacific) from March to October 1997. Based on 64 visual counts, we recorded 75 species of 28 families of reef fishes. Four pomacentrids, Iwo labrids and one haemulid comprised the top seven most abundant species, ranked as foliows: Chromis agrilobata, Thalassoma lucasanum, Abudefduf troschelii, Haemulon steindaclineri, Halichoeres dispilus, Stegastes acapulcoensis, and Stegastesflavilazus. Densities of many of the species varied significantly with variable site depth. Our resulta reflect higher Beta diversity than other studies, altough only 22% of the species were found at alI the study sites. The type of substrate, the complexity, and the exposure of the reef may have a strong influence en the distribution of many of the species of reef fishes in the Gulf of Papagayo. Four possible groups of fish species were observed suggesting that spatial pattems were stronger iban seasonal trends. The shallowest site was characterized by Ophioblennius steindachneri, Microspathodon bairdii, M dorsalis and Abudefduf lroschelii. An intennediate site with a more heterogeneous substrate, was composed by S. acapulcoensis, Canihigaster punc:atissima, H. nicholsi, H chierchiae, 7'. lucasanum, Sufflamen yerres and Serranus psittacinus. A slightly deeper site than the previous was represented by Ji dispilus, Johnrandallia nigrirostris, Pomacanthus zonipectus, Holacanthus passer, and S. flavilatus. Finally the deepest site habitat, had a distinctive assemblage composed by C. atrilobata, Chaetodon humeralis, Diodon holocanthus, H. steindachneri, and H. maculicauda. In terms of trophic groups, our resulis shows trends have more affinities to ternperate regions were planktívores and invertebrates feeders are the most abundant than herbivores.