Responses of Buluan Island turbid fringing reefs, southern Philippines to the 2016 thermal anomaly

Abstract

Coral beaching due to increasing sea surface temperature causes a decline of global reef ecosystems. Turbidity and sedimentation are localized threats that may contribute to and exacerbate the impacts of coral bleaching. Some reports show coral communities thriving in turbid conditions are resilient to bleaching-related mortality events. In the Philippines, information on the effects of turbidity and elevated levels of light attenuation on bleaching in coral assemblages is generally lacking. This study describes the response to coral bleaching of a turbid reef in Buluan Island Marine Sanctuary (BIMS), southern Philippines. Coral cover and diversity showed no changes after the bleaching event. Coral community composition and abundance in some genera were affected but the majority showed either no significant change or recovery to pre-bleaching state even with high bleaching index values. The dominance and presence of bleaching-susceptible genera even after the 2016 global bleaching event suggest that turbidity experienced in BIMS might have reduced the impact of intense irradiance on the reef. Findings from this study indicate the potential existence of turbid resilient reefs across the Philippines and recommend that they be immediately identified and protected.