Crown-of-thorns starfish (Acanthaster planci) and coral cover surveys of the reefs of Vanuatu

The distribution and abundance of the crown-of-thorns starfish (Acanthaster planci) and the cover of living and dead coral were investigated at 29 sites around 13 islands of Vanuatu using spot dives, manta tows and belt transects in 1988.

Survey sites were located in the vicinity of the following islands and reefs: Aneityum, Tanna, Erromango, Efate, Cook's Reef, Pentecost, Gaua, Ureparapara, Reef Islands, Espiritu Santo, Malakula and Epi.

Rapid macroscale surveys of the upper reef slopes (<10m depth) and lagoon reef patches were undertaken using semiqualitative 20 minute spot dives or 2 minute manta tows. In the more detailed mesoscale surveys on Malakula, observations were made along 50m x 5m belt transects.

At each site, the number of Acanthaster planci observed was recorded. The percentage cover of living and dead scleractinian corals was visually estimated, and depth, aspect and coral diversity noted. Particular note was made of any extensive areas of dead standing tabulate and staghorn Acropora spp. on reef slopes as these indicated possible outbreaks of Acanthaster planci in the recent past.

Additional details of Acanthaster planci activity on Efate reefs were obtained from questionnaires and interviews with tourist operators and divers.