How does rising atmospheric CO2 affect marine organisms?

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Coccolithophorid Responses to Ocean Warming and Acidification
Sett, S., Bach, L.T., Schulz, K.G., Koch-Klavsen, S., Lebrato, M. and Riebesell, U. 2014. Temperature modulates coccolithophorid sensitivity of growth, photosynthesis and calcification to increasing seawater pCO2. PLOS ONE 9: e88308.

The authors write that "increasing atmospheric CO2 concentrations are expected to impact pelagic ecosystem functioning in the near future by driving ocean warming and acidification." And while they note that "numerous studies have investigated impacts of rising temperature and seawater acidification on planktonic organisms separately," they say that "little is presently known of their combined effects."

What was done
To test for the possibility of synergistic effects of ocean acidification and warming when the two phenomena occur in unison, Sett et al. exposed two coccolithophore species, Emiliania huxleyi and Gephyrocapsa oceanica, to a CO2 gradient ranging from approximately 20 to 6000 ľatm pCO2 at three different temperatures: 10, 15 and 20°C for E. huxleyi and 15, 20 and 25°C for G. oceanica.

What was learned
The six scientists determined that increased temperature generally (1) enhanced the growth and production rates of both species and (2) modified the responses of their primary metabolic processes (photosynthesis, growth and calcification) to increasing CO2, such that the optima of the three processes occurred at higher CO2 concentrations as temperatures rose from intermediate to high values.

What it means
The double whammy of atmospheric CO2 enrichment envisioned by the world's climate alarmists (global warming and ocean acidification) would actually appear to be a double blessing to the world's two most important bloom-forming coccolithophore species. And who knows but what a number of other calcifying species may respond similarly?

Reviewed 30 April 2014