How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Coccolithophores: Are They Genetically Prepared for Ocean Acidification?
Volume 13, Number 11: 17 March 2010

Writing in the Journal Club section of Nature, Stoll (2009) restates the climate-alarmist mantra that "ocean acidification in response to excess carbon dioxide in the atmosphere could become a problem for marine organisms, especially those that make skeletons or shells out of calcium carbonate," including "the coccolithophorids -- microscopic algae that are, by volume, the most important shell producers." She, however, has a much more optimistic view of the subject, thanks in large part to the recent research of Langer et al. (2009).

The latter scientists -- hailing from France, Germany, Spain and the Netherlands -- grew four different strains of the coccolithophore Emiliania huxleyi in dilute batch cultures of seawater with carbonate chemistries characteristic of those expected to prevail beneath an atmosphere of four different CO2 concentrations ranging from approximately 200 to 1200 ppm, while they measured particulate organic carbon content, particulate inorganic carbon content, and organic and inorganic carbon production. In doing so, they found the four strains "did not show a uniform response to carbonate chemistry changes in any of the analyzed parameters and none of the four strains displayed a response pattern previously described for this species."

In light of these findings -- plus other aspects of their earlier studies (Langer et al., 2006, 2007) and the diverse findings of others (all of whom had used still different strains of the species) -- the five scientists concluded that "the sensitivity of different strains of E. huxleyi to acidification differs substantially and that this likely has a genetic basis." Stoll agrees with this assessment, stating that Langer et al. "argue convincingly" in this regard; and she adds that the work of those who foresee disastrous consequences typically "precludes the kind of natural selection and adaptation that might occur over decades and centuries in the ocean."

In further discussing the subject, Langer et al. (2009) write that "shifts in dominance between species and/or between clones within a species might therefore be expected," as the air's CO2 content continues to rise; but they say that far too often "the possibility of adaptation is not taken into account." This ought not be, for the great genetic diversity that exists, both among and within species, in the words of Stoll, "is good insurance in a changing ocean." Indeed, we interpret it as evidence that earth's coccolithophorids are well prepared for whatever the future may thrust at them in this regard, for as Langer et al. (2006) have more boldly and explicitly stated, "genetic diversity, both between and within species, may allow calcifying organisms to prevail in a high CO2 ocean."

Sherwood, Keith and Craig Idso

Langer, G. and Geisen, M., Baumann, K.-H., Klas, J. , Riebesell, U., Thoms, S. and Young, J.R. 2006. Species-specific responses of calcifying algae to changing seawater carbonate chemistry. Geochemistry, Geophysics, Geosystems 7: 10.1029/2005GC001227.

Langer, G., Gussone, N., Nehrke, G., Riebesell, U., Eisenhauer, A. and Thoms, S. 2007. Calcium isotope fractionation during coccolith formation in Emiliania huxleyi: Independence of growth and calcification rate. Geochemistry, Geophysics, Geosystems 8: 10.1029/2006GC001422.

Langer, G., Nehrke, G., Probert, I., Ly, J. and Ziveri, P. 2009. Strain-specific responses of Emiliania huxleyi to changing seawater carbonate chemistry. Biogeosciences Discussions 6: 4361-4383.

Stoll, H. 2009. A biogeochemist sees the value of diversity in a changing ocean. Nature 460: 935.