2 CONTRASTING EFFECTS OF PREDATION ON SPECIES RICHNESS IN CORAL-REEF HABITATS

Abstract

The species richness of sessile organisms on settlement panels on a coral reef was measured by the slope of a regression of loge number of species against loge area of sample. At a well illuminated site where panels were colonised by algae, the species richness of algae was 19% smaller on surfaces grazed by fishes than on protected surfaces. At a second site in a cave, the species richness of animals on grazed surfaces was 20% greater than on protected surfaces. These results are discussed in the light of differences between the sites. The contrasting effects of predation at the two sites are probably the result of more selective predation at the cave site than at the other site.