Identifying climate change resilience factors for a coral reef in Sri Lanka

Coral cover and physical parameters at Kayankerni reef in eastern Sri Lanka were monitored to identify resistance and resilience factors related to coral bleaching. Rapid surveys in 2015 indicated bleaching of corals in... [ view full abstract ]

Coral cover and physical parameters at Kayankerni reef in eastern Sri Lanka were monitored to identify resistance and resilience factors related to coral bleaching. Rapid surveys in 2015 indicated bleaching of corals in shallow water with no significant mortality, and transect surveys in 2016 and 2017 recorded a live coral cover of approximately 38% dominated by the genera Acropora, Echinopora, Montipora and Porites. While 57% of corals showed signs of bleaching during the 2016 coral bleaching event, almost all corals appeared to have recovered by late June. Water temperature data indicated daily and weekly temperature fluctuations of approximately 1^oC - 2.5^oC throughout the calm season, suggesting natural variations in water temperature. Resilience may be enhanced by the presence of Montipora aequituberculata and Porites rus that are known to be more resistant to coral bleaching. Some of these corals have also colonized old dead Acropora stands, possibly as a result of a phase shift following a previous mortality event. Water temperature tends to reach a high around late May when seas are at their calmest. However, the onset of strong localized winds by mid June results in rougher conditions with lower temperatures and UV radiation. Survey results and general observations indicate that resilience to coral bleaching at Kayankerni reef is influenced by the time of onset of bleaching, local wind conditions, coral community structure, adaptation to regular temperature variations, and possible community phase shifts towards more resilient coral species.