Predictability of fish assemblages on coral patch reefs

Fish associated with the common patch-forming coral, Porites rus, were surveyed in lagoons of Moorea, French Polynesia, to examine the degree to which attributes of the coral predicted aspects of the fish assemblage. Physical characteristics of the colonies such as size, morphology, and degree of isolation from other patch reefs varied greatly, as did species richness, total abundance and composition of the fish assemblage. Multiple-regression analyses revealed that variation in potential living space (live surface area; number of holes; amount of interior empty space) accounted for over half of the variation in species richness and total abundance of fish on a coral. In contrast, species composition appeared to be influenced more by the physical setting within the lagoon (water depth; distance to deep water; degree of isolation). Relationships derived from the initial analyses predicted 65-78% of the variation in species richness among a different set of corals. Together, the results indicate that physical attributes of the corals can help account for spatial variation in fish assemblage structure and provide a starting point for studies of the underlying mechanisms.