Coral reef fish communities of Mayotte (western Indian Ocean) two years after the impact of the 1998 bleaching event

This study, conducted during the Coral Reef Observatory programme in 2000, was carried out at 9 localities: 4 on fringing reefs (0 and 3 m depth), 2 on inner reefs (0 and -3 m) and 3 on outer barrier reefs (3 and 6 m). Quantitative data were collected by visual census techniques along 50 m x 5 m transects. The ichthyofauna is separated into fringing inner-reef communities and outer barrier-reef communities. Species richness and abundance were always higher at the deeper sites. These indices were also lower on fringing reef flats and higher on the outer barrier reefs. In terms of individual numbers, browsers of sessile invertebrates (mainly Chaetodontidae) are poorly represented in the fish community at all sites (3%). Planktivores are the dominant trophic category on the deeper sites (mean 63%) and herbivores on the shallower sites (mean 40%, mainly Acanthuridae). The high abundance of herbivores and the low abundance of browsers of sessile invertebrates could be due to altered benthic communities resulting from the 1998 bleaching event.