Drupella, Thiele, 1925

Scott, C. M., Mehrotra, R., Hein, M. Y., Moerland, M. S. & Hoeksema, B. W., 2017, Population dynamics of corallivores (Drupella and Acanthaster) on coral reefs of Koh Tao, a diving destination in the Gulf of Thailand, Raffles Bulletin of Zoology 65, pp. 68-79 : 72-74

Drupella and Acanthaster abundance relative to reef threats. Drupella abundance showed no correlation with diving pressure (R 2 =0.001, p=0.943) according to the results of Weterings (2011) and there was also no significant correlation between Acanthaster populations and diving pressure (R 2 =0.071, p=0.402). When coral predator abundance was compared to the combined stress model of Weterings (2011) there was no significant correlation for both Drupella (R 2 =0.123, p=0.355) and Acanthaster (R 2 =0.123, p=0.355). Drupella populations also showed no significant (R 2 =0.404, p=0.175) correlation with lower reef health as recorded by Lamb et al. (2014) and neither did Acanthaster abundance (R 2 =0.258, p=0.304).

When compared by site use categories developed by Lamb et al. (2014), no significant differences were found. Drupella snails showed scores of 0.95 ± 0.34 in high-use sites and 0.81 ± 0.19 in low-use sites, respectively ( Fig. 5a ; ANOVA Df=1, p=0.723). Mean Acanthaster abundance was 10.3 ± 4.2 indiv. ha-1 at low-use sites and 5.8 ± 1.9 indiv. ha-1 at high-use sites ( Fig. 5b ; ANOVA Df=1, p=0.406). Similarly, when compared with sites’ protective status developed by Hein et al. (2015), Drupella snails seemed to be more abundant in MPA sites (0.95 ± 0.34 compared with 0.67 ± 0.26 at non-MPA sites) ( Fig. 5c ; ANOVA Df=1, p=0.549), and Acanthaster more abundant in non-MPA sites (7.2 ± 1.4 indiv. ha-1 compared with 3.0 ± 1.0 indiv. ha-1 at MPA sites) ( Fig. 5d ; ANOVA Df=1, p=0.087). Nevertheless, none of these differences were statistically significant.

Figures

Fig. 5. Coral predator abundance compared to previously published results on Koh Tao’s reefs; differences are not significant. Drupella (a) and Acanthaster (b) abundance in low- and high-use sites as designated by Lamb et al. (2014). Similar for the designations as MPA or non-MPA sites used by Hein et al. (2014) concerning Drupella (c) and Acanthaster (d).