How does rising atmospheric CO2 affect marine organisms?

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Effects of Elevated CO2 and Temperature on Coccolithophore Growth and Calcification
Fiorini, S., Middelburg, J.J. and Gattuso, J.-P. 2011. Effects of elevated CO2 partial pressure and temperature on the coccolithophore Syracosphaera pulchra. Aquatic Microbial Ecology 64: 221-232.

The authors write that coccolithophores "are considered to be the most productive calcifying organisms on the planet," and they say "they play a crucial role in the marine carbon cycle through calcification and photosynthetic carbon production (Rost and Riebesell, 2004)," noting that they "contribute significantly to the flux of organic matter from the sea surface to deep waters and sediments (Klaas and Archer, 2002)," and that they are "responsible for about half of the global surface ocean calcification."

What was done
Fiorini et al. examined the effects of the pCO2 and temperature levels projected for the end of this century on photosynthesis, growth and calcification during both life stages (haploid and diploid) of strain AC418 of the coccolithophore Syracosphaera pulchra, via a series of culture studies conducted in the laboratory, where they focused on both particulate inorganic carbon (PIC) and particulate organic carbon (POC).

What was learned
The three researchers report that "neither the rate of calcification (production of particulate inorganic carbon) nor the PIC:POC ratio were significantly affected by elevated pCO2, temperature or their interaction."

What it means
In the words of Fiorini et al., "our results confirm that the expected 3°C increase in the present seawater temperature will not strongly affect the physiology of this eurythermal species," and that "the effect of an elevated pCO2 in seawater will not be significant on calcification or on the PIC:POC ratio in either life stage." And this no real news is definitely real good news for life in the world's oceans.

Klaas, C. and Archer, D.E. 2002. Association of sinking organic matter with various types of mineral ballast in the deep sea: implications for the rain ratio. Global Biogeochemical Cycles 16: 10.1029/2001GB001765.

Rost, B. and Riebesell, U. 2004. Coccolithophores and the biological pump: responses to environmental changes. In: Thierstein, H.R. and Young, J.R. (Eds.). Coccolithophores: From Molecular Processes to Global Impact. Springer, New York, New York, USA, p. 99-125.

Reviewed 8 February 2012