Environmental controls on modern scleractinian coral and reef-scale calcification.

Abstract

Modern reef-building corals sustain a wide range of ecosystem services because of their ability to build calcium carbonate reef systems. The influence of environmental variables on coral calcification rates has been extensively studied, but our understanding of their relative importance is limited by the absence of in situ observations and the ability to decouple the interactions between different properties. We show that temperature is the primary driver of coral colony (<i>Porites astreoides</i> and <i>Diploria labyrinthiformis</i>) and reef-scale calcification rates over a 2-year monitoring period from the Bermuda coral reef. On the basis of multimodel climate simulations (Coupled Model Intercomparison Project Phase 5) and assuming sufficient coral nutrition, our results suggest that <i>P. astreoides</i> and <i>D. labyrinthiformis</i> coral calcification rates in Bermuda could increase throughout the 21st century as a result of gradual warming predicted under a minimum CO₂ emissions pathway [representative concentration pathway (RCP) 2.6] with positive 21st-century calcification rates potentially maintained under a reduced CO₂ emissions pathway (RCP 4.5). These results highlight the potential benefits of rapid reductions in global anthropogenic CO₂ emissions for 21st-century Bermuda coral reefs and the ecosystem services they provide.