A preliminary study of the biology and ecology of the blue starfish Linckia laevigata (L.) on the Australian Great Barrier Reef and an interpretation of its role in the coral reef ecosystem

The blue starfish Linckia laevigata grazes coralline algae. The starfish populations studied were composed entirely of adults. Spawning takes place in October at the southern end of the Great Barrier Reef. On reefs which were unaffected by Acanthaster planci, L. laevigata was confined to algae covered reef tops and rubble banks. On reefs affected by A. planci, L. laevigata had extended its range and was feeding on and among the coralline algae covered dead hard coral skeletons on the reef perimeter. Coral regrowth, followingattack by A. planci , was found to be slower on reefs with populations of L. laevigata living on the reef perimeter than on reefs where they were absent from this region. It is suggested that grazing by L. laevigata destroys small coral colonies and newly settled larvae thus slowing down the rate of coral regeneration. The consequences of this reduced rate of recolonisation is also discussed.