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

We assessed the relative abundance of reef fishes and its relation with physical parameters and habitat at four sites in Culebra Bay, a human disturbed area in Gulf of Papagayo, Costa Rica (eastern Pacific) from March to October 1997. Based on 64 visual counts, we recorded 75 species of 28 families of reef fishes. Four pomacentrids, two labrids and one haemulid comprised the top seven most abundant species, ranked as follows: Chromis atrilobata, Thalassoma lucasanum, Abudefduf troschelii, Haemulon steindachneri, Halichoeres dispilus, Stegastes acapulcoensis, and Stegastes flavilatus. Densities of many of the species varied significantly with variable site depth. Our results reflect higher Beta diversity than other studies, altough only 22% of the species were found at all the study sites. The type of substrate, the complexity, and the exposure of the reef may have a strong influence on 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 patterns were stronger than seasonal trends. The shallowest site was characterized by Ophioblennius steindachneri, Microspathodon bairdii, M. dorsalis and Abudefduf troschelii. An intermediate site with a more heterogeneous substrate, was composed by S. acapulcoensis, Canthigaster punctatissima, H. nicholsi, H. chierchiae, T. lucasanum, Sufflamen verres and Serranus psittacinus. A slightly deeper site than the previous was represented by H. dispilus, Johnrandallia nigrirostris, Pomacanthus zonipectus, Holacanthus passer, and S. flavilatus. Finally the deepest site habitat, had a distinctive assemblage composed by C. atrilobata, Chaetodon