IS THE CROWN-OF-THORNS STARFISH A THREAT TO THE REEFS OF LORD-HOWE-ISLAND

1. Lord Howe Island, a World Heritage Area which lies in the southern Pacific Ocean, has the most southern true coral reefs in the world. 2. In the past decade, populations of Acanthaster planci, the crown-of-thorns starfish, have significantly reduced coral cover at Elizabeth and Middleton Reefs, approximately 200 km to the north of Lord Howe Island, and a small population has been reported from Lord Howe Island. 3. The abundance and distribution of A. planci was evaluated using surveys by the local recreational diving industry and video-transects, and the potential rate of recovery of the coral community following predation was assessed by analysing coral recruitment patterns. 4. The starfish population at Lord Howe Island remained relatively small and localized between 1984 and 1993. 5. Coral recruitment was dominated by the juveniles of brooding corals, and these same species dominated the established coral community. There was limited recruitment of broadcast-spawning coral species during the study period, suggesting that southern dispersal of coral larvae from more northern sites may be a rare or sporadic event. 6. The results indicate that there is only a small probability that the present starfish population will result in a major starfish outbreak. However, the recovery of the coral community from a major outbreak would be slow because of the apparently low rate of input of coral larvae from sources external to the reef. 7. Management agencies need to consider whether the present small and localized starfish population should be removed, given the likely ramifications of an infestation and the economic importance of the reef to tourism.