www.biogeosciences.net/7/289/2010/ © Author(s) 2010. This work is distributed under the Creative Commons Attribution 3.0 License.

• Main Authors: R. Rodolfo-metalpa, S. Martin, J. -p. Gattuso
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2009
• Subjects: Ocean acidification
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.461.2672; http://www.biogeosciences.net/7/289/2010/bg-7-289-2010.pdf

Abstract. Atmospheric CO2 partial pressure (pCO2) is ex-pected to increase to 700 µatm 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 () of the seawater. Elevated pCO2 was shown to dras-tically decrease calcification rates in tropical zooxanthellate corals. Here we show, using the Mediterranean zooxanthel-late coral Cladocora caespitosa, that an increase in pCO2, in the range predicted for 2100, does not reduce its calcifi-cation rate. Therefore, the conventional belief that calcifica-tion rates will be affected by ocean acidification may not be widespread in temperate corals. Seasonal change in temper-ature is the predominant factor controlling photosynthesis, respiration, calcification and symbiont density. An increase in pCO2, alone or in combination with elevated temperature, had no significant effect on photosynthesis, photosynthetic efficiency and calcification. The lack of sensitivity C. cae-spitosa to elevated pCO2 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 pro-jected for the end of the century.