Managing resilience to reverse phase shifts in coral reefs

Both coral-dominated and degraded reef ecosystems can be resistant to change. Typically, research and manage- ment have focused on maintaining coral dominance and avoiding phase shifts to other species compositions, rather than on weakening the resilience of already degraded reefs to re-establish coral dominance. Reversing degraded coral-reef states will involve reducing local chronic drivers like fishing pressure and poor water quality.

Reversals will also require management of key ecological processes – such as those performed by different func- tional groups of marine herbivores – that both weaken the resilience of the degraded state and strengthen the coral-dominated state. If detrimental human impacts are reduced and key ecological processes are enhanced, pulse disturbances, such as extreme weather events, and ecological variability may provide opportunities for a return to a coral-dominated state. Critically, achieving these outcomes will necessitate a diverse range of integrated approaches to alter human interactions with reef ecosystems.