How does rising atmospheric CO2 affect marine organisms?

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How Phytoplankton Adapt to Ocean Acidification and Warming

Paper Reviewed
Schluter, L., Lohbeck, K.T., Gutowska, M.A., Groger, J.P., Riebesell, U. and Reusch, T.B.H. 2014. Adaptation of a globally important coccolithophore to ocean warming and acidification. Nature Climate Change 4: 1024-1030.

In a paper published in Nature Climate Change, Schluter et al. (2014) write that "marine phytoplankton, a diverse group of photoautotrophic microbes thriving in the world's oceans, generate about half of the global primary production," citing Thomas et al. (2012). And because of this, they say "they form the basis of marine food webs and play a major role in the Earth's biogeochemical cycles," citing Falkowski et al. (2008), with the result that "observed and projected changes in marine primary productivity associated with surface ocean warming are of deep concern."

Responding to this concern, the six scientists went on to test the ability of the globally-important phytoplankton species Emiliania huxleyi to adapt to ocean warming in combination with ocean acidification. In describing their findings Schluter et al. state that "growth rates were up to 16% higher in populations adapted for one year [roughly 460 asexual generations] to warming when assayed at their upper thermal tolerance limit," while particulate inorganic and organic carbon production was -- as a result of adaptive evolution over a period of three years -- 101% and 55% higher under combined warming (26.3 vs. 15.0°C) and acidification (2200 vs. 400 µatm CO2), respectively, than in non-adapted controls.

In their parting words to us, Schluter et al. thus write that the fact "that even the asexual offspring of a single isolate will considerably change their performance at high temperature within months to years owing to evolution illustrates that evolutionary processes need to be considered when predicting the effects of a warming and acidifying ocean on phytoplankton," while additionally citing in this regard the paper of Collins et al. (2014). And so we see, yet again, that the lifeblood of Earth's oceans -- its phytoplankton -- are well equipped to deal with the dual threat of simultaneous ocean warming and acidification.

Collins, S., Rost, B. and Rynearson, T.A. 2014. Evolutionary potential of marine phytoplankton under ocean acidification. Evolutionary Applications 7: 140-155.

Falkowski, P.G., Fenchel, T. and Delong, E.F. 2008. The microbial engines that drive Earth's biogeochemical cycles. Science 320: 1034-1039.

Thomas, M.K., Kremer, C.T., Klausmeier, C.A. and Litchman, E.A. 2012. A global pattern of thermal adaptation in marine phytoplankton. Science 338: 1085-1088.

Posted 17 March 2015