Climate warning and the ocean-scale integrity of coral reef ecosystems

Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution of climate warming to the loss of live coral cover has been well documented across large spatial and temporal scales, the associated effects on fish have not. Such information is important as coral reef fish assemblages are the most species dense vertebrate communities on earth, contribute critical ecosystem functions and provide crucial ecosystem services to the burgeoning human societies in tropical countries. Here we assess the impacts of the 1998 mass bleaching event on coral cover, reef structural complexity, and the functionality and abundance of reef fishes across the Indian Ocean. Using Bayesian meta-analysis we show changes in the size structure, diversity and trophic composition of the reef fish community have followed coral declines. Furthermore, using Bayesian predictive intervals we predict how different components of the fish community will respond to any future changes to coral cover across the region. Although ocean scale integrity of these coral reef ecosystems has been lost, it is positive to see the effects are spatially variable at various scales with impacts and vulnerability affected by geography, oceanography and management regime. Existing no-take marine protected areas still support high biomass of fish, however they had no positive affect on the response of the ecosystem to large-scale disturbance. This suggests that it is imperative that future planning identifies regional refugia from climate change as priorities for protection