Species Diversity of Decapods Associated with Living and Dead Reef Coral Pocillopora meandrina

The decapod communities associated with live and dead specimens of the reef coral Pocillopora meandrina Dana in Hawaii were investigated. Species composition of decapods shifted gradually from dominance by large sized symbiotic species to minute, facultatively associated nonsymbionts as host corals died from an environmental disturbance. Species diversities of nonsymbiont communities were substantially greater than diversities of symbiont communities on live corals. Statistically significant linear relationships were found between live coral surface area and numbers of species and individuals of symbiotic decapods. Similar relationships were recorded between nonsymbionts and dead coral surface area. The compositions and sizes of the respective communities are determined by the space and nature of their habitats. The symbiont community is a highly predictable association finely turned to its habitat principally by trophic requirements. By contrast, the composition of the more diverse nonsymbiont community appears to be determined by random colonization from the general reef environment, filling to capacity the habitat space provided by the dead coral. The contrasting characteristics of the two decapod communities are discussed in terms of various theories of coral reef diversity.