Reef fish community structure in four atolls of the San Andres Providenciaarchipelago (southwestern Caribbean)

In 1994 and 1995, 131 visual censuses of reef fishes were made using the st ationary sampling method in Courtown, Albuquerque, Serrana and Roncador, fo ur atolls of the Archipelago of San Andres and Old providence in the Southw estern Caribbean. Fish species and their abundances were recorded in four g eomorphologic zones: lagoon, windward barrier reef, windward terrace and fo rereef terrace. A total of 98 species were censused; the most abundant were Chromis cyanea (14%), Clepticus parra (14%) and Stegastes partitus (10%). The most abundant families were Pomacentridae (37%), Labridae (28%) and Sca ridae (10%). Analysis of similarilies showed that differences between zones were greater than differences between atolls, but lagoon and forereef terr ace were not significantly different. Cluster and ordination analysis confi rmed these results; in addition, the ordination analysis placed the groups according to depth and wave-exposure gradients, suggesting that these two p hysical variables were responsibles for the clustering. Differences in equi tability and species richness appear also due to these variables. Inverse a nalysis showed in each group few characteristic species, then the differenc es between zones were due specially to dominance of some species. The domin ant trophic categories were planktivorous and herbivorous that were signifi cantly different between zones. In shallow zones (shallow lagoonal patch re efs) and high wave-exposed zones (winward barrier reef) dominated herbivoro us fishes, while in deeper zones (tetraces and deep lagoonal patch reefs) p lanktivorous were more abundant.