Long-term effects of destruction of hermatypic corals by Acanthaster plana infestation on reef fish communities at Iriomote Island, Japan

Abstract

Long-term changes in structure of fish communities on coral reefs infested by the coralfeeding starfish Acanthasterplanci were determined using 20 mZ visual transects.We censused a living coral reef consisting mainly of staghorn Acropora spp. at Saluyama Bay and a dead coral reef with low structural complexlty of coral branches (about 2 yr after A. planci infestation) at Amitori Bay, Iriomote Island (Ryukyu Islands, Japan) in September 1984.Two yr later, we recensused the dead coral reef, which had changed into a flat plain of unstructured coral rubble ('rubble reef').Mean numbers of species and individuals per transect severely decreased in the following order of reef types: (1) living reef (1984).( 2) dead reef (1984), and (3) rubble reef (1986).Correlated with these decreases in numbers were several patterns: (1) coral-polyp feeders completely &sappeared on both dead and rubble reefs, probably due to absence of food; (2) numbers of resident species and individuals decreased on the dead reef, perhaps due to decrease in living space or shelter associated with the reduction in structural complexity of coral branches; and (3) numbers of species and individuals of both resident and visitor fishes declined on the unstructured rubble reef, likely due to shortage of living space and food.