Supporting resilience-based coral reef management using broadscale threshold approaches

Abstract

Managing coral reefs to maintain ecosystem function and maximise resilience requires identification of resilience indicators and clear ecological reference thresholds for reef managers to maintain or aim for. In the absence of local resilience-based targets, reef managers can conduct local-scale resilience assessments by collecting data on resilience indicators and comparing them to recently established broadscale thresholds which have been defined by incorporating large spatial variability. This study documents the application of these broadscale threshold approaches to kick-start resilience-based management at Aldabra Atoll UNESCO Marine World Heritage Site. Aldabra’s seaward coral reefs conformed to the expected resilience of a well-managed and remote marine reserve. All but one reef met or exceeded thresholds for each of the five assessed resilience indicators and fell within the ‘recover’ strategy of the management strategy analysis. Combining the individual indices into a synthetic index of resilience gave an atoll-level estimate of reefs having an 87.5% ‘chance of recovery’ post-disturbance. Reef resilience predictions largely aligned with our data on post-bleaching coral trajectories. We recommend additional broadscale threshold categories that could be defined and included in future assessments, and suggest local factors that need to be considered to fine-tune the assessments at site-level.