FACTORS INFLUENCING SPATIAL PATTERNS ON CORAL-REEFS AROUND MOOREA, FRENCH-POLYNESIA

Spatial patterns of 5 components of the macrobenthos (corals, macroalg ae, mollusks, sponges, and echinoderms) at 42 stations on 4 reef types were compared in Moorea. Fifteen abiotic and biotic factors were meas ured and included in Canonical Correspondence Analyses. Macrobenthic c ommunities were dominated by corals and macroalgae, Two major gradient s (along the bays, and from the fringing reef to the outer reef slope) were found for corals, macroalgae, and echinoderms. The gradients wer e realized at a small spatial scale in Moorea (less than 2 km from the fringing reef to the outer reef slope at 35 m depth), while the same type of variation occurs at a large spatial scale (more than 100 km) o n the Great Barrier Reef. Abiotic and biotic factors explained a large amount of the variance in sponge and coral communities, but less for mcllusks and markedly less for macroalgae and echinoderms. Some of the factors identified in this study, such as depth, sand coverage, and a lgal coverage, have been also reported as controlling factors in other coral reefs. In contrast, the high abundance of sea urchins and its i mpact seem to be characteristic of coral reefs around Moorea.