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Coccolithophores and calcite saturation state in the Baltic and Black Seas
1School of Ocean & Earth Science, National Oceanography Centre, Southampton, European Way, Southampton SO14 3ZH, UK
2Institut für Ostseeforschung Warnemünde, Seestrasse 15, 18119 Rostock, Germany
3Leibniz-Institute of Marine Sciences, IFM-GEOMAR, Duesternbrooker Weg 20, 24105 Kiel, Germany
Abstract. The Baltic and Black Seas are both brackish, that is to say both have salinities intermediate between freshwater and seawater. The coccolithophore Emiliania huxleyi is abundant in one, the Black Sea, but absent from the other, the Baltic Sea. Here we present summertime coccolithophore measurements confirming this difference, as well as data on the calcium carbonate saturation state of the Baltic Sea. We find that the Baltic Sea becomes undersaturated (or nearly so) in winter, with respect to both the aragonite and calcite mineral forms of CaCO3. Data for the Black Sea are more limited, but it appears to remain strongly supersaturated year-round. The absence of E. huxleyi from the Baltic Sea could therefore potentially be explained by dissolution of their coccoliths in winter, suggesting that minimum annual (wintertime) saturation states could be most important in determining future ocean acidification impacts. In addition to this potential importance of winter saturation state, alternative explanations are also possible, either related to differences in salinity or else to differences in silicate concentrations.
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Citation: Tyrrell, T., Schneider, B., Charalampopoulou, A., and Riebesell, U.: Coccolithophores and calcite saturation state in the Baltic and Black Seas, Biogeosciences Discuss., 4, 3581-3605, 2007. Bibtex EndNote Reference Manager
