View article

Rapidly rising levels of atmospheric CO₂ are not only causing ocean warming, but also lowering seawater pH hence the carbonate saturation state of the oceans, on which many marine organisms depend to calcify their skeletons^,. Using boron isotope systematics, we show how scleractinian corals up-regulate pH at their site of calcification such that internal changes are approximately one-half of those in ambient seawater. This species-dependent pH-buffering capacity enables aragonitic corals to raise the saturation state of their calcifying medium, thereby increasing calcification rates at little additional energy cost. Using a model of pH regulation combined with abiotic calcification, we show that the enhanced kinetics of calcification owing to higher temperatures has the potential to counter the effects of ocean acidification. Up-regulation of pH, however, is not ubiquitous among calcifying organisms; those lacking …