Written by DIVE Magazine Tuesday, 22 January 2013 13:45
Dive guides from the centre have collected more than 60,000 of the coral eating gastropod in the last two years and have been helping with research into the threat they pose.
A study of the corallivorous snail reveals that after severe coral bleaching in 2010 the snail has moved onto eating more coral species.
This week an article about the research has been published in the scientific journal Coral Reefs – Dietary shift in corallivorous Drupella snails following a major bleaching event at Koh Tao, Gulf of Thailand (Hoeskema et al., 2013). (download from SpringerLink)
Twenty species of mushroom corals were surveyed during the bleaching in 2010 and after the bleaching in 2011 and they were found to have been invaded by the snails after the bleaching.
Previously these gastropods mainly consumed branching corals and hardly any mushroom corals. The snails were found preying on four fungiid species, three of which were susceptible to bleaching. The dietary shift became apparent after populations of the preferred prey species (Acroporidae and Pocilloporidae) had died during the bleaching event.
Drupella snails are a small mucirid gastropod found throughout the Indo Pacific Ocean. They have been found in large aggregations or outbreak populations in areas such as Kenya, Australia, Hong Kong, the Red Sea, and the Gulf of Thailand.
These outbreaks or overpopulations have led to dramatic loss in living coral tissue, reduced reef resilience and recovery, population regime shifts, and possibly increased disease occurrence. Current theories point to the loss of predators through fishing and decreased water quality due to other anthropogenic activities as the cause of these outbreaks which have only been observed within the last 30 years.