Biodiversity patterns in Chagos reef fishes

New data are presented on reef fish community structures on outer reef slopes at ten sites in the northern Chagos Archipelago. Data were gathered by a single observer using a fixed point visual census technique. Results show relatively high and consistent levels of diversity across sites. Species packing is lower than in comparative studies on fringing reef communities in the northern Seychelles. The twenty most abundant species are heavily dominated by planktivores, notably caesionids, anthiids and pomacentrids. Rare species make up an important part of the total diversity and are evenly distributed across sites. Despite variation in distribution of individual species between sites, comparisons made between sites at the level of wider communities suggest a high level of homogeneity between communities over meso-scales (1-150km). This finding is in marked contrast to previous studies which have shown significant variation in biodiversity patterns in reefs over meso-scales. Such homogeneity is probably related both to relatively constant environmental conditions across the Chagos Archipelago, combined with the high degree of connectivity between sites.
Spalding Mark .
fish, reef fish, abundance, diversity, underwater visual census