The blue starfishLinckia laevigatagrazes 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 byAcanthaster planci, L. laevigatawas confined to algae covered reef tops and rubble banks. On reefs affected byA. planci, L. laevigatahad extended its range and was feeding on and among the coralline algae covered dead hard coral skeletons on the reef perimeter. Coral regrowth, followingattack byA. planci, was found to be slower on reefs with populations ofL. laevigataliving on the reef perimeter than on reefs where they were absent from this region. It is suggested that grazing byL. laevigatadestroys 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.