Structure and Ecology of the Saipan Reefs in Relation to Predation by Acanthaster Planci (Linnaeus)

A survey was made of the structure and ecology of the reefs of Saipan and the probable effects of the crown-of-thorns starfish Acanthaster planci on the present status of the coral communities. The geomorphology of the nearshore platform is briefly discussed, and a glossary applies coral reef terminology to the Saipan reefs. Acanthaster predation is examined as a possible regulating factor in reef community structure. The marked preference of Acanthaster for some species of corals (Acropora, Montipora spp.) and its avoidance of others (Synarea iwayamensis, Pocillopora eydouxi) is of considerable ecological significance because of its selective effect on population structure of coral reefs subject to different levels of predation. The discussion gives information on population, behaviour, and feeding of the starfish; on the relation between their infestations and damage to reefs from various causes (human agencies, storms); and on the predation of reef corals by the cushion starfish Culcita novaeguineae. An unusually abundant living fauna of hermatypic sponges of geological significance was discovered during this survey.