The Prey Selection Drupella sp. on Different Coral Type in Pemuteran Waters, Bali

Coral reefs has changed over time that are strongly influenced by environmental conditions and human activities. One of the natural damage to coral reefs is corallivorous gastropod such as Drupella sp. The excessive numbers of Drupella sp. cause the coral reef destruction as the average of predation may reach 1.806 cm2 per coral tissues per night per individual. The marine tourism of Pemuteran waters on northern part of Bali Island is rapidly developing. Thus any compromised health of coral reefs could negatively affect this sector such as 2.374 individuals of Drupella sp. found during 2008-2009 according to the Bio-Rock Center. However, this report was not clearly mentioned the method and detail location. Therefore, this study aimed to determine the densitiy of Drupella sp. and prey preferences of Drupella sp. on coral species in Pemuteran waters. There were four observation sites that parallel to the shoreline at similar depths (5-6 m). The densities of Drupella sp. and prey preference were measured 2 x 20 m belt transect by using SCUBA. Live coral covers were counted in LIT (Line Intercept Transect) method. The significant difference of Drupella sp. densities among sites was analysed by using one-way ANOVA, while the feeding preference among corals species was identified by using Bonferroni test. The result showed that the highest density of Drupella sp. found at station 1 and the lowest at station 2. It is suggested that related to percentage of live coral cover as the highest was at station 1 and the lowest was at station 2. Studies revealed that Drupella sp. feeding particulary on living coral. Furthermore, our observations indicated that Drupella sp. more attracted to coral Porites and Pocillopora. This feeding preferences are thought to be due to the highest abundance of these corals at all study sites.