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Biogeosciences Discuss., 6, 3771-3802, 2009
www.biogeosciences-discuss.net/6/3771/2009/ doi:10.5194/bgd-6-3771-2009 © Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License. |
Impact of seawater pCO2 changes on calcification and on Mg/Ca and Sr/Ca in benthic foraminifera calcite (Ammonia tepida): results from culturing experiments
1Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
2Faculty of Geosciences, Utrecht University, The Netherlands
Abstract. Evidence is accumulating of increasing concentrations of dissolved carbon dioxide in the ocean and associated acidification impacts on calcifying organisms. Among these organisms, benthic and planktonic foraminifera are responsible for a large amount of the globally precipitated calcium carbonate. Therefore, their response to an acidifying ocean may have important consequences for future inorganic carbon cycling. To assess the sensitivity of benthic foraminifera to changing carbon dioxide levels and subsequent alteration in seawater carbonate chemistry, we cultured specimens of the shallow water species Ammonia tepida at two concentrations of atmospheric CO2 (120 and 2000 ppm) and two temperatures (10°C and 15°C). Shell weights and elemental compositions were determined. Results indicate that shell weights decrease with decreasing [CO32−], and increase with decreasing temperature. Changes in [CO32−] or total dissolved inorganic carbon do not affect the Mg partition coefficient. On the contrary, Sr incorporation is enhanced under increasing [CO32−]. Implications of these results for the paleoceanographic application of foraminifera are also discussed.
Citation: Dissard, D., Nehrke, G., Reichart, G. J., and Bijma, J.: Impact of seawater pCO2 changes on calcification and on Mg/Ca and Sr/Ca in benthic foraminifera calcite (Ammonia tepida): results from culturing experiments, Biogeosciences Discuss., 6, 3771-3802, doi:10.5194/bgd-6-3771-2009, 2009.