Ocean Science

Acid Test

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Science  08 Jun 2012:
Vol. 336, Issue 6086, pp. 1211
DOI: 10.1126/science.336.6086.1211-a

Fossil fuel use increases the concentration of carbon dioxide in the atmosphere and thence the oceans, lowering ocean pH. The resulting equilibria diminish the available carbonate that calcifying organisms precipitate as the calcium salt, a problem that has led to a general assumption that calcifying organisms accordingly will decrease in abundance. However, recent research has shown that not all types will be affected equally, or even in the same way. Smith et al. studied how the coccolithophore species Emiliania huxleyi responds to seasonal changes in the Bay of Biscay. By collecting abundance data and making concurrent measurements of carbonate chemistry over the course of a year, they showed that the more heavily calcified morphotype is most abundant in winter, when the ocean there is most acidic, opposite from what one might predict on the basis of pH changes. Although they cannot attribute this variability to pH-related effects, their work illustrates just how difficult it is to project precisely how specific calcifying processes will respond to an acidifying ocean.

Proc. Natl. Acad. Sci. U.S.A. 109, 10.1073/pnas.1117508109 (2012).

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