Spatial variability in the abundance of the corallivorous gastropod Drupella cornus

The corallivorous gastropod Drupella has been responsible for extensive coral mortality on a number of reefs in the Indo-West Pacific region. Seasonal and spatial variability in the abundance of juvenile ( 2.0 cm) Drupella cornus along the Ningaloo Reef, Western Australia, were documented during 1990/1991. Numbers of D. cornus were found to vary significantly between the different sites and reef habitats sampled, with the highest numbers recorded at a backreef edge site at the southern end of the reef. There was no evidence that the densities of D. cornus varied seasonally, although size-frequency distributions suggest that there may have been a recruitment peak in January/February 1991 following a major spawning event in November/December 1990. Drupella cornus were found predominantly on Acropora species with a caespitose/corymbose growth form; however the abundance of these corals at different sites did not explain the observed distribution patterns of the gastropod. Drupella cornus recruits (