Coral reefs are increasingly threatened by various types of disturbances, and their recovery is challenged by accelerating, human-induced environmental changes. Recurrent disturbances reduce the pool of mature adult colonies of reef-building corals and undermine post-disturbance recovery from newly settled recruits. Using a long-term interannual data set, we show that coral assemblages on the reef slope of Moorea, French Polynesia, have maintained a high capacity to recover despite a unique frequency of large-scale disturbances which, since the 1990s, have caused catastrophic declines in coral cover and abundance. In 2014, only four years after one of the most extreme cases of coral decline documented, abundance of juvenile and adult colonies had regained or exceeded pre-disturbance levels, and no phase-shift to macroalgal dominance was recorded. This rapid recovery has been achieved despite constantly low coral recruitment rates, suggesting a high post-disturbance survivorship of recruits. However, taxonomic differences in coral susceptibility to disturbances and contrasting recovery trajectories have resulted in changes in the relative composition of species. In the present context of global coral reef decline, our study establishes a new benchmark for the capacity of certain benthic reef communities to sustain and recover their coral cover from repeated, intense disturbances.

This paper presents the first temperature-growth performance curves for a coral reef fish. Thermal tolerance and growth for the juvenile spiny damselfish Acantho chromis polyacanthus were measured at a range of temperatures from 15℃ to 38℃. A. polyacanthus juveniles showed a critical thermal minimum at 15.5℃±0.1 and a critical thermal maximum at 38℃±0.12. Maximal growth (based on changes in length) occurred at 28-31℃, whereas weight gain was maximised at 28℃, which cor responds closely with the annual mean temperature cur rently experienced by these fishes in their natural en vironment. At temperatures ＞31℃ the growth rate de creas ed mark edly in length and weight up to 34℃, where fishes had negligible growth and died within 8-15 days. Sustained increases in ambient temperature (due to climate change) are expected to have significant adverse effects on these fishes. However, any effects of increasing temperature may also be offset by changing the timing of reproduction; by breeding in early spring or late summer, these fishes may still be able to exploit narrow windows of thermal optima, whereas fishes breeding in the height of summer will expose offspring to potentially lethal tem pera tures at critical stages during their development. Keywords Global

Coral reefs across the globe are facing threats from a variety of anthropogenic disturbances. Consequently, the proportional representation of live scleractinian corals in the benthic community has declined substantially in many regions. In contrast, parts of the reef ecosystem around Mo’orea (French Polynesia) have displayed remarkable rebound potential. Nevertheless, detailed studies of when, where, and to what extent reefs have been disturbed and subsequently recovered in the different reef habitats are lacking. Using long-term monitoring data (2004-2018), we reveal that the spatiotemporal dynamics of benthic communities differ markedly between the contiguous inner (fringing and barrier) and outer (fore) reefs. Coral communities on inner reefs vary spatially but were remarkably stable over 15 yr, exhibiting consistent levels of coral and algal cover, with no evidence for disturbance-driven regimes or community transitions. In contrast, the outer reefs showed marked declines in coral cover following consecutive acute disturbances, but coral recovered rapidly thereafter. Nevertheless, community composition changed significantly, with Pocillopora replacing Acropora as the dominant genus at several sites, indicating a more subtle but potentially critical transition into an alternative state defined by the prevalence of a single, fast-growing genus. Inner reef stability and outer reef recovery provide evidence that the effects of environmental disturbances and chronic anthropogenic stressors can manifest in fundamentally different ways, depending on prevailing conditions. Our results suggest important ecological and physical links between inner and outer reef systems that influence the observed dynamics, emphasizing that reef ecosystem management and conservation strategies need to consider all habitats.