Fish and benthic communities in an offshore and well-managed coral reef after bleaching disturbance in the Philippines

Abstract

Abstract Climate change is perhaps the greatest threat to coral reefs worldwide. However, there is spatial variation in the extent and severity of this disturbance, with offshore and well-managed reefs presumed to minimize the consequences. In this study, fish and benthic communities at the offshore and well-managed reefs of Apo Reef Natural Park, Philippines was examined during (2016), 2 years (2018) and 3 years (2019) after bleaching disturbance. Fish and benthic surveys were conducted on scuba at 5 sites at depths of 8-10m. Results showed that benthic communities varied more strongly with year attributed to changes in the benthic cover of coral. These changes were also influenced by site, with some sites experiencing coral loss of 41–48%, while at other sites there were minimal changes. These site differences were associated with the cover of coral pre-bleaching, with higher cover prior to the disturbance contributing to larger losses. Fish communities varied more with sites associated with differences in the predominant benthos among sites. The stability of fish communities with year despite coral loss may be attributed to the variable loss of coral cover among sites. For sites that experienced high losses of coral cover, the presence of alternative and/or deeper habitats may have provided shelter and food for fishes maintaining taxonomic composition within sites. This study shows that bleaching disturbance circumvents localized protection, but impacts are variable even at small (≤ 3km) spatial scales. Community composition pre-bleaching and alternative habitats seem to buffer against the consequences of bleaching disturbance.