How does rising atmospheric CO2 affect marine organisms?

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How Rapidly Can Diatoms Evolve to Deal with Ocean Acidification?

Paper Reviewed
Scheinin, M., Riebesell, U., Rynearson, T.A., Lohbeck, K.T. and Collins S. 2015. Experimental evolution gone wild. Journal of the Royal Society Interface 12: 10.1098/rsif.2015.0056.

Introducing their dual-purpose study (to learn something about evolution and to learn it fast), Scheinin et al. (2015) write that "because of their large population sizes and rapid cell division rates, marine microbes have, or can generate, ample variation to fuel evolution over a few weeks or months, and subsequently have the potential to evolve in response to global change." And as a third important feat, they simultaneously demonstrate how pertinent studies can be conducted in real-world environments rather than in a laboratory, by demonstrating that "marine mesocosms can be used for microbial evolution experiments by measuring evolution in a marine diatom in CO2-enriched marine mesocosms." This the five researchers did by deploying ten mesocosms in the Gullmar Fjord on the west coast of Sweden, five of which were kept untreated as controls, while the carbonate chemistry in the remaining five mesocosms was manipulated in such a way as to establish elevated pCO2 at an initial level of 1100 µatm - see Riebesell et al. (2012) for details - within which enclosures they measured the progression of evolution in the marine diatom Skeletonema marinoi over a period of 107 days. And what were the results of their efforts?

Scheinin et al. report that they detected "a large evolutionary response to CO2 enrichment in the focal marine diatom, where population growth rate increased by 1.3-fold in high CO2-evolved lineages," which finding, as they describe it, "opens an exciting new possibility of carrying out in situ evolution experiments to understand how marine microbial communities evolve in response to environmental change." And in light of the findings of this first experiment, it would appear that evolution can operate much more rapidly in marine diatoms than many might have expected.

Riebesell, U, Czerny, J., Von, K., Ockel, B., Boxhammer, T. and Udenbender, J. 2012. Technical note: a mobile sea-going mesocosm system; new opportunities for ocean change research. Biogeosciences Discussions 9: 12,985-13,017.

Posted 10 August 2015