Biogeosciences Discuss., 6, 7103-7131, 2009
www.biogeosciences-discuss.net/6/7103/2009/
doi:10.5194/bgd-6-7103-2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Biogeosciences (BG). Please refer to the corresponding final paper in BG.
Response of the temperate coral Cladocora caespitosa to mid- and long-term exposure to pCO2 and temperature levels projected in 2100
R. Rodolfo-Metalpa1,2, S. Martin3, C. Ferrier-Pagès1, and J.-P. Gattuso3
1Centre Scientifique de Monaco, Monaco (Principality), France
2International Atomic Energy Agency-Marine Environment Laboratories, 4 Quai Antoine Ier, 98000 Principality of Monaco, France
3CNRS, Laboratoire d'océanographie de Villefranche, Villefranche-sur-Mer Cedex, France; Université Pierre et Marie Curie–Paris 6, France

Abstract. Atmospheric CO2 partial pressure (pCO2) is expected to increase to 700 ppm or more by the end of the present century. Anthropogenic CO2 is absorbed by the oceans leading to decreases in pH and the CaCO3 saturation state (Ω) of the seawater. While pCO2 was shown to drastically decrease calcification rates in tropical, fast growing corals, here we show, using the Mediterranean symbiotic coral Cladocora caespitosa, that the conventional belief that an increase in pCO2, in the range predicted to 2100, reduces calcification rates may not be widespread in temperate corals. We found that the seasonal change in temperature was the predominant factor controlling the physiology and growth of C. caespitosa, while an increase in pCO2, alone or in combination with global warming, had no significant effect on photosynthesis, photosynthetic efficiency and calcification. This result differs from that obtained on reef-building corals, which exhibit lower rates of calcification at elevated pCO2. The lack of sensitivity of temperate corals to high-pCO2 levels might be due to its slow growth rates, which seem to be more dependent on temperature than on the saturation state of calcium carbonate in the range predicted for the end of the century.

Citation: Rodolfo-Metalpa, R., Martin, S., Ferrier-Pagès, C., and Gattuso, J.-P.: Response of the temperate coral Cladocora caespitosa to mid- and long-term exposure to pCO2 and temperature levels projected in 2100, Biogeosciences Discuss., 6, 7103-7131, doi:10.5194/bgd-6-7103-2009, 2009.
 
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