|Dynamics of Drupella cornus populations on Kenyan coral reefs|
McClanahan, T. R. (1997). Dynamics of Drupella cornus populations on Kenyan coral reefs. Proc. 8th Int. Coral Reef Sym. 1: 633-638
In: Proceedings of the 8th International Reef Symposium, more
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In the central Pacific and western Australia the coral-eating snail Drupella cornus has been reported to exhibit large population increases or 'outbreaks' (>10 snails/m2) that result in the loss or devastation of their coral prey. In Kenya, a large population increase of Drupella cornus was recorded from the early 1990's where D. cornus increased from a rare species in the mid 1980's to among the most common prosobranch snail by 1995 (~0.2 snails/m2). Population increases were most commonly observed in a section of reef that had experienced heavy fishing and loss of the durophagous predators such as triggerfish, but still maintained a high abundance of the branching coral Porites nigrescens. In unfished reefs, the population increases of D. cornus were less pronounced despite an abundance of their preferred coral prey - branching Acropora, Montipora, and Pocillopora. In one heavily fish reef, with a high abundance of another coral-eating snail, Coralliophila neritoidea, and low abundance of branching corals, few D. cornus were observed. Consequently, the success of D. cornus appears to be related to a complex interaction between appropriate environmental conditions for settlement success, the existence of branching corals, a low abundance of predators and the lack of other competitors such as C. neritoidea. An alternate hypothesis is that D. cornus settlement is patchy in space and time and the patterns observed in Kenya simply reflect this patchiness.