Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 7, 1401-1412, 2010
https://doi.org/10.5194/bg-7-1401-2010
© Author(s) 2010. This work is distributed under
the Creative Commons Attribution 3.0 License.
 
05 May 2010
Individual and interacting effects of pCO2 and temperature on Emiliania huxleyi calcification: study of the calcite production, the coccolith morphology and the coccosphere size
C. De Bodt1, N. Van Oostende2, J. Harlay1,*, K. Sabbe2, and L. Chou1 1Laboratoire d'Océanographie Chimique et Géochimie des Eaux, Université Libre de Bruxelles (ULB), Bruxelles, Belgium
2Protistology & Aquatic Ecology, Gent University (UGent), Gent, Belgium
*now at: AGO, Unité d'Océanographie Chimique, Université de Liège (ULg), Liège, Belgium
Abstract. The impact of ocean acidification and increased water temperature on marine ecosystems, in particular those involving calcifying organisms, has been gradually recognised. We examined the individual and combined effects of increased pCO2 (180 ppmV CO2, 380 ppmV CO2 and 750 ppmV CO2 corresponding to past, present and future CO2 conditions, respectively) and temperature (13 °C and 18 °C) during the exponential growth phase of the coccolithophore E. huxleyi using batch culture experiments. We showed that cellular production rate of Particulate Organic Carbon (POC) increased from the present to the future CO2 treatments at 13 °C. A significant effect of pCO2 and of temperature on calcification was found, manifesting itself in a lower cellular production rate of Particulate Inorganic Carbon (PIC) as well as a lower PIC:POC ratio at future CO2 levels and at 18 °C. Coccosphere-sized particles showed a size reduction with both increasing temperature and CO2 concentration. The influence of the different treatments on coccolith morphology was studied by categorizing SEM coccolith micrographs. The number of well-formed coccoliths decreased with increasing pCO2 while temperature did not have a significant impact on coccolith morphology. No interacting effects of pCO2 and temperature were observed on calcite production, coccolith morphology or on coccosphere size. Finally, our results suggest that ocean acidification might have a larger adverse impact on coccolithophorid calcification than surface water warming.

Citation: De Bodt, C., Van Oostende, N., Harlay, J., Sabbe, K., and Chou, L.: Individual and interacting effects of pCO2 and temperature on Emiliania huxleyi calcification: study of the calcite production, the coccolith morphology and the coccosphere size, Biogeosciences, 7, 1401-1412, https://doi.org/10.5194/bg-7-1401-2010, 2010.
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