Kim, Tawin. 2013. Determining the Abundance, Density, Population Structure, and Feeding Preference of Drupella Snails on Koh Tao, Thailand. Mahidol University International College, Mahidol Univeristy, Thailand.
Coral reefs around the world are threatened with a wide range and anthropogenic and natural stresses, and over-predation by corallivores is one of them. On Koh Tao, Thailand, Drupella snails were observed in two locations: Chalok Ban Kao and Ta Cha. The aim of our study was to look at 1) whether or not Drupella were still feeding on Fungiid corals, 2) Drupella aggregation abundance, 3) feeding preferences, and 4) severity of infestation at the two sites. We found that Drupella were still preying on Fungiid corals, a shift in diet which started after the 2010 bleaching event. Our surveys suggest that Drupella aggregations appear to be localised in one area or depth, and are few and far between in other areas. Drupella were mostly found on hard corals, with 3 genera of coral being infected: Fungia, Acropora, and Pocillopora. Acropora and Pocillopora are long known as preferred preys while preying on Fungia was not commonly observed. Lastly the surveys suggest that the density of Drupella in Chalok and Ta Cha are 1.175 and 1.167 m-2 respectively, which is not classified as an outbreak. However, larger scale studies are required to adequately determine the severity of Drupella infestations because the ‘outbreak’ may be at an unsurveyed location.
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