Thermal-Stress Response of Coral Communities to Climate Change

With the current rapid rate of climate change, coral communities are being repeatedly subjected to anomalously high thermal-stress events. Most global models predict that within the next 100 years, few reef corals will survive in tropical oceans. Yet thermal stresses have long been spatially and temporally variable across the oceans, and coral communities in different geographic regions are likely to be inherently different in their capacity to tolerate thermal stress. Using a spatially explicit Bayesian approach, we examined the response of coral communities to the hazards of climate-change associated thermal stress. We used the rates of change in sea-surface temperatures and the maximum sea-surface temperatures from 1980 to 2012 as predictive covariates of global records of coral bleaching over the same time period. There were negative relationships between the rates of change in sea-surface temperatures and coral bleaching, although the results were misleading because the highest rates of change in sea-surface temperatures were recorded at high latitudes, where average sea-surface temperatures are characteristically cooler than at low latitudes. Also, the results suggested that the most hazardous localities for corals, which experienced the highest maximum sea-surface temperatures, were in the northern hemisphere, particularly in the northern and western Indian Ocean, and along the rim of the eastern and western Pacific Ocean. Coral populations in these localities have suffered the greatest mortality. When a capacity to adapt to thermal stress was considered in the model, several localities responded positively, particularly corals in the Hawaiian Islands, the northern Marshall Islands, Micronesia, the Line Islands, the Cook Islands, the southern Great Barrier Reef, and along the coast of Brazil.