How does rising atmospheric CO2 affect marine organisms?

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The Potential for Polychaetes to Cope with Ocean Acidification
Calosi, P., Rastrick, S.P.S., Lombardi, C., de Guzman, H.J., Davidson, L., Jahnke, M., Giangrande, A., Hardege, J.D., Schulze, A., Spicer, J.I. and Ganbi, M.-C. 2014. Adaptation and acclimatization to ocean acidification in marine ectotherms: an in situ transplant experiment with polychaetes at a shallow CO2 vent system. Philosophical Transactions of the Royal Society B 368: 10.1098/rstb.2012.0444.

The authors begin by stating that "metabolic rate determines the physiological and life-history performances of ectotherms [animals whose regulation of body temperature depends on external sources]," and, therefore, they add that "the extent to which such rates are sensitive and plastic to environmental perturbation is central to an organism's ability to function in a changing environment." Unfortunately, they also note that "little is known of long-term metabolic plasticity and potential for metabolic adaptation in marine ectotherms exposed to elevated pCO2."

What was done
"To define the potential for metabolic acclimatization and adaptation that allows colonization of elevated pCO2 areas," Calosi et al. "carried out a series of in situ transplant and mutual transplant experiments populated with polychaetes [a polyphyletic class of annelid worms] living around the shallow-water CO2 vents system off Ischia [Naples, Italy]." In the first of these experiments, they say they "characterized metabolic rates and responses of the polychaetes," which allowed them "to infer the potential for metabolic adaptation in tolerant versus sensitive species, as well as between populations of tolerant species found both inside and outside the vent areas."

What was learned
Noting that previous studies have shown that "unicellular organisms can adapt to elevated pCO2," citing Lohbeck et al. (2012), Benner et al. (2013) and Tatters et al. (2013), the eleven scientists say their study (1) "provides evidence that a marine ectotherm (Platynereis dumerilii) has been able to genetically and physiologically adapt to chronic and elevated levels of pCO2," and that it (2) "supports those studies that have indicated the potential of marine metazoans [animals with differentiated tissues, including nerves and muscles] to adapt to elevated pCO2," citing the work of Pespeni et al. (2013), Pistevos et al. (2011), Sunday et al. (2011), Foo et al. (2012), Schlegel et al. (2012), Padilla-Gamiño et al. (2013) and Kelly et al. (2013).

What it means
"Ultimately," in the words of Calosi et al., "the ability of marine organisms to persist in a rapidly changing ocean is largely dependent on the taxa's ability for rapid physiological adaption, which could potentially occur, via genetic assimilation of emerging phenotypes," as demonstrated by the studies of Ghalambor et al. (2007), Reznick and Ghalambor (2001), Waddington (1942), Torres Dowdall et al. (2012) and Pigliucci et al. (2006), while in reference to their own study, they say "it appears that both plasticity and adaptation may be key to prevent species' risk for extinction in the face of ongoing ocean acidification." And so it would also appear that the potential for polychaetes and many other marine life forms to successfully cope with ocean acidification is indeed rather good.

Benner, I., Diner, R.E., Lefebvre, S.C., Li, D., Komada, T., Carpenter, E.J. and Stillman, J.H. 2013. Emiliania huxleyi increases calcification but not expression of calcification-related genes in long-term exposure to elevated temperature and pCO2. Philosophical Transactions of the Royal Society B 368: 10.1098/rstb.2013.0049.

Foo, S.A., Dworjanyn, S.A., Poore, A.G.B. and Byrne, M. 2012. Adaptive capacity of the habitat modifying sea urchin Centrostephanus rodgersii to ocean warming and ocean acidification: performance of early embryos. PLOS ONE 7: e42497.

Ghalambor, C.K., McKay, J.K., Carroll, S.P. and Reznick, D.N. 2007. Adaptive versus non-adaptive phenotypic plasticity and the potential for contemporary adaptation in new environments. Functional Ecology 21: 394-407.

Kelly, M.W., Padilla-Gamiño, J.L. and Hofmann, G.E. 2013. Natural variation and the capacity to adapt to ocean acidification in the keystone sea urchin Strongylocentrotus purpuratus. Global Change Biology 19: 2536-2546.

Lohbeck, K.I., Riebesell, U. and Reusch, T.B.H. 2012. Adaptive evolution of a key phytoplankton species to ocean acidification. Nature Geoscience 5: 346-351.

Padilla-Gamiño, J.L., Kelly, M.W., Evans, T.G. and Hofmann, G.E. 2013. Temperature and CO2 additively regulate physiology, morphology and genomic responses of larval sea urchins, Strongylocentrotus purpuratus. Proceedings of the Royal Society B 280: 10.1098/rspb.2013.0155.

Pespeni, M.H., Sanford, E., Gaylord, B., Hill, T.M., Hosfelt, J.D., Jaris, H.K., LaVigne, M., Lenz, E.A., Russell, A.D., Young, M.K. and Palumbi, S.R. 2013. Evolutionary change during experimental ocean acidification. Proceedings of the National Academy of Sciences USA 110: 6937-6942.

Pigliucci, M., Murren, C.J. and Schlichting, C.D. 2006. Phenotypic plasticity and evolution by genetic assimilation. Journal of Experimental Biology 209: 2362-2367.

Pistevos, J.C.A., Calosi, P., Widdicombe, S. and Bishop, J.D.D. 2011. Will variation among genetic individuals influence species responses to global climate change? Oikos 120: 675-689.

Reznick, D.N. and Ghalambor, C.K. 2001. The population ecology of contemporary adaptations: what empirical studies reveal about the conditions that promote adaptive evolution. Genetica 112-113: 183-198.

Schlegel, P., Havenhand, J.N., Gillings, M.R. and Williamson, J.E. 2012. Individual variability in reproductive success determines winners and losers under ocean acidification: a case study with sea urchins. PLOS ONE 7: e53118.

Sunday, J.M., Crim, R.N., Harley, C.D.G. and Hart, M.W. 2011. Quantifying rates of evolutionary adaptation in response to ocean acidification. PLOS ONE 6: e22881.

Tatters , A.O., Roleda, M.Y., Schnetzer, A., Fu, F., Hurd, C.L., Boyd, P.W., Caron, D.A., Lie, A.A.Y., Hoffmann, L.J. and Hutchins, D.A. 2013. Short- and long-term conditioning of a temperate marine diatom community to acidification and warming. Philosophical Transactions of the Royal Society B 368: 10.1098/rstb.2012.0437.

Torres Dowdall, J., Handelsman, C.A., Ruell, E.W., Auer, S.K., Reznick, D.N. and Ghalambor, C.K. 2012. Fine-scale local adaptation in life histories along a continuous environmental gradient in Trinidadian guppies. Functional Ecology 26: 616-627.

Waddington, C.H. 1942. Canalization of development and the inheritance of acquired characters. Nature 150: 563-565.

Reviewed 30 April 2014