Ocean acidification and calcified Antarctic seafloor macroorganisms: The perfect storm

An important consequence of anthropogenic production of atmospheric CO2 is the acidification of the worlds oceans. Antarctic seas are perhaps the most vulnerable anywhere due to: 1) an inverse relationship between dissolution rates of calcium carbonate and temperature, and 2) a preponderance of generally weakly calcified macroorganisms due to either the high cost of calcium carbonate production at low temperature and/or a lack of evolutionary selection for robust calcification due to the absence of shell-crushing invertebrate (crabs) or heavily jawed fish predators. Employing shells of the common antarctic bivalves Laternula elliptica and Yoldia eightsi, the limpet Nacella concinna (with and without an encrusting coralline alga), as well as the brachiopod Liothyrella uva, we measured rates of dissolution under conditions of ambient (pH 8.2) and acidified (pH 7.4) seawater (current models predict pH 7.4 in the world’s oceans by the year 2200). Shells were cut lengthwise, weighed, and placed into 1-liter glass beakers with seawater that was aerated with different concentrations of C02 so as to regulate pH. Within 14 days shells in acidified sea water had lost their luster. After 5 weeks the shells and thallus of the coralline alga had suffered significant dissolution when compared to controls. Moroever, one of the shells of the bivalve L. elliptica in acidified seawater became so fragile it fragmented into multiple pieces. Our findings indicate that antarctic calcified seafloor macroorganisms, and the communities they comprise, are likely to be the first to experience the cascading impacts of ocean acidification. Supported by NSF OPP#0442769 to JBM and CDA.

Mcclintock, J. B., Angus, R. A., Mcdonald, M. R., & Amsler, C. D., 2009. Ocean acidification and calcified Antarctic seafloor macroorganisms: The perfect storm. Integrative and Comparative Biology 49: E269-E269. Meeting abstract.

Conference Information
: Annual Meeting of the Society-for-Integrative-and-Comparative-Biology
Boston, MA, January 03-07, 2009

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