How does rising atmospheric CO2 affect marine organisms?

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Life in a Cold and Dark Place: Can It Long Be Maintained in a Warming World?
McMinn, A. and Martin, A. 2013. Dark survival in a warming world. Proceedings of the Royal Society B 280: 10.1098/rspb.2012.2909.

The authors write that "most algae regularly experience periods of darkness ranging from a few hours to a few days," during which time they say "they are unable to photosynthesize, and so must consume stored energy products." However, they note that "some organisms such as polar algae and some microalgal cysts and spores are exposed to darkness for months to years, and these must use alternative strategies to survive."

What was done
Focusing on microalgae, McMinn and Martin review the scientific literature pertaining to this intriguing subject.

What was learned
The two Australian researchers - who work at the University of Tasmania's Institute for Marine and Antarctic Studies - report that "some taxa, such as dinoflagellates, form cysts and become dormant," while "others use physiological methods or adopt mixotrophy," noting that "the longest documented survival of more than a century was for dinoflagellates buried in sediments in a Norwegian fjord." In the future, however, they say polar microalgae will have to survive "the same period of seasonal darkness but at higher temperatures, and this will require a greater drawdown of stored energy." So the sixty-four thousand dollar question is: can they do it?

Fortunately, McMinn and Martin report that "recent experimental work has shown that both Arctic [Martin et al., 2012] and Antarctic [Reeves et al., 2011] phytoplankton are able to survive increases of up to 6°C in the dark."

What it means
The experimental results they discuss all suggest, as they put it, that "both Arctic and Antarctic phytoplankton are resilient when grown in the dark at temperatures up to 6°C greater than natural." And they say that such a temperature increase is "unlikely to be experienced in a few centuries as a result of climate change," which pretty much assures that polar microalgae will survive for a long, long time to come.

Martin, A., McMinn, A., Heath, M., Hegseth, E.N. and Ryan, K.G. 2012. The physiological response to increased temperature in over-wintering sea-ice algae and phytoplankton in McMurdo Sound, Antarctica and Tromso, Norway. Journal of Experimental Marine Biology and Ecology 428: 57-66.

Reeves, S., McMinn, A. and Martin, A. 2011. The effect of prolonged darkness on the growth, recovery and survival of Antarctic sea ice diatoms. Polar Biology 34: 1019-1032.

Reviewed 3 July 2013