Coral-eating snail Drupella cornus population increases in Kenyan coral reef lagoons

Data from a study of corallivorous snails in 8 Kenyan coral-reef lagoons sampled at 3 time intervals over a 6 yr period suggest that Drupella cornus populations have increased on Kenyan reefs. This increase was greatest in heavily fished reefs and a transition reef (converted to a park in about 1990) but less pronounced in the unfished parks and a reserve (restricted fishing). The abundance of corallivorous snails was better predicted by the abundance of their predators than the abundance of their coral food. The 2 most abundant species, Coralhophjla violacaea and D. cornus, were associated with the coral genus Porites although D. cornus was found on a wider variety of coral genera than C. violacea. D. cornus was most abundant on fished reefs with the exception of l reef where C. violacea was dominant and persisted at high population densities over the study period. Observed population increases in Kenya and western Australia may be due to oceanic conditions which improved D. cornus recruitment success during the late 1980s.