HABITAT CORRELATES OF THE DISTRIBUTION AND BIOMASS OF SEYCHELLES REEFFISHES

Relationships between quantitative measures of habitat type and the bi omass of Chaetodon, Scarus and Parupeneus species were investigated ac ross 35 reef sites in the Inner Seychelles Group. Multiple regression was used to determine the proportion of variance in biomass between si tes which could be explained by depth, exposure, vertical relief, topo graphic complexity, live coral cover, coral rubble cover, rock cover, sand cover, underlying carbonate substrate, underlying sand substrate, underlying rock substrate and an index of fishing intensity. A signif icant proportion of the variance in biomass was explained by habitat v ariables and the index of fishing intensity for 7 of 12 Chaetodon spec ies (23-52% of variance explained), 3 of 6 Parupeneus species (33-40%) , and 10 of 13 Scarus species (14-46%). Within genera, different group s of habitat variables explained the variance in biomass for different species and, of the variables studied, only the proportion of underly ing sand substrate failed to explain a significant proportion of the v ariance in biomass for any species. Quantitative relationships between the biomass of Chaetodon and habitat were often in accordance with th ose suggested by previous studies of their ecology, life-history and d istribution at other Indo-Pacific locations. However, the habitat asso ciations of the Parupeneus and some Scarus species have not been studi ed at other locations and clearly warrant further investigation. It wa s concluded that habitat was an important determinant of the distribut ion of many Seychelles reef fishes, but that the habitat variables exa mined were rarely the most important determinant of biomass. However, the inclusion of a procedure to collect habitat data provided a useful means by which to reduce the unexplained variance associated with vis ual census biomass estimates and therefore improves the possibility of elucidating the effects of other factors on the biomass of Seychelles reef fishes.