Recovery trajectories of oceanic reef ecosystems following multiple mass coral bleaching events

Climate-induced mass bleaching events are one of the greatest threats to coral reefs, causing widespread loss of coral cover. Drivers of recovery and adaptation for coral reefs in the face of repeated large-scale disturbances are unclear, with marked differences across geographies. Using a monitoring dataset lasting from 2005 to 2018, we documented the response of coral reefs of northwest Mahé in the granitic Seychelles islands following the 1998 and 2016 mass bleaching events. We analysed trends in coral cover, coral community composition and key fish trophic group densities for 24 sites. Coral cover increased almost fourfold from 2005 to 2015 with 42.1% mean coral cover in 2015, highlighting a recovery from the 1998 bleaching event dominated by Acropora growth forms. Impacts of the 2016 bleaching event were less acute than the 1998 one. However, following the 2016 bleaching event, coral cover significantly decreased to 16.1% mean cover in 2017, marked by a sharp decrease of Acropora corals and branching growth forms. Corallivorous, herbivorous and piscivorous fish densities were positively correlated with coral cover from 2005 to 2016. These findings highlight the dominant role of Acropora in recovery from mass coral bleaching events. It also shows the importance of time-series datasets in understanding coral recovery dynamics and their use in an integrated management approach to building reef resilience.