How does rising atmospheric CO2 affect marine organisms?

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Effects of Atmospheric CO2 Enrichment on Calcifying Aquatic Organisms
Volume 10, Number 4: 24 January 2007

Many theoretical analyses and short-term experiments have suggested that the historic (and ongoing) rise in the air's CO2 content has been (and is) detrimental to calcifying aquatic organisms; but real-world observations have tended to refute these contentions (see Calcification in our Subject Index). The study of Langer et al. (2006) lends even more support to this positive view of the subject; and it helps us to better understand the basis for it.

Working with two previously untested coccolithophores, Calcidiscus leptoporus and Coccolithus pelagicus, which they describe as "two of the most productive marine calcifying species," the team of seven scientists from Germany and the United Kingdom conducted batch-culture experiments in which they observed (1) a "deterioration of coccolith production above as well as below [our italics] present-day CO2 concentrations in C. leptoporus," and (2) a "lack of a CO2 sensitivity [our italics] of calcification in C. pelagicus" over an atmospheric CO2 concentration range of 98-915 ppm. Both of these observations, in their words, "refute the notion of a linear relationship of calcification with the carbonate ion concentration and carbonate saturation state," which notion is the mantra repeatedly proclaimed by the world's climate alarmists.

In an apparent negative finding, however, particularly in the case of C. leptoporus, Langer et al. observed that although their experiments revealed that "at 360 ppm CO2 most coccoliths show normal morphology," they found that at both "higher and lower CO2 concentrations the proportion of coccoliths showing incomplete growth and malformation increases notably."

To determine if such was also the case in the real world, the researchers studied coccolith morphologies in six sediment cores extracted along a range of latitudes in the Atlantic Ocean. As they describe it, this work revealed that changes in coccolith morphology similar to those "occurring in response to the abrupt CO2 perturbation applied in [their] experimental treatments are not [our italics] mirrored in the sedimentary record." This finding indicates, as they suggest, that "in the natural environment C. leptoporus has adjusted to the 80 ppm CO2 and 180 ppm CO2 difference between present, preindustrial and glacial times, respectively."

In further discussing these observations, Langer et al. say "it is reasonable to assume that C. leptoporus has adapted its calcification mechanism to the change in carbonate chemistry having occurred since the last glacial maximum," suggesting as a possible explanation for this phenomenon that "the population is genetically diverse, containing strains with diverse physiological and genetic traits, as already demonstrated for E. huxleyi (Brand, 1981, 1982, 1984; Conte et al., 1998; Medlin et al., 1996; Paasche, 2002; Stolte et al., 2000)." They also state that this adaptive ability "is not likely to be confined to C. leptoporus but can be assumed to play a role in other coccolithophore species as well," which leads them to conclude that such populations "may be able to evolve so that the optimal CO2 level for calcification of the species tracks the environmental value [our italics]."

Regarding the future, Langer et al. thus end on an extremely positive note, stating that "genetic diversity, both between and within species, may allow calcifying organisms to prevail in a high CO2 ocean," which has been our position on this subject from day one, and from which we have never backed away. Truly, life has many ways of adjusting to tremendous changes in environmental conditions, ways that are often not well understood - or understood at all - by even the most perceptive of scientists, until it is faced with the challenge (or opportunity) of real-world environmental transformation.

Sherwood, Keith and Craig Idso

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Brand, L.E. 1982. Genetic variability and spatial patterns of genetic differentiation in the reproductive rates of the marine coccolithophores Emiliania huxleyi and Gephyrocapsa oceanica. Limnology and Oceanography 27: 236-245.

Brand, L.E. 1984. The salinity tolerance of forty-six marine phytoplankton isolates. Estuarine and Coastal Shelf Science 18: 543-556.

Conte, M., Thompson, A., Lesley, D. and Harris, R.P. 1998. Genetic and physiological influences on the alkenone/alkenonate versus growth temperature relationship in Emiliania huxleyi and Gephyrocapsa oceanica. Geochimica et Cosmochimica Acta 62: 51-68.

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.

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Paasche, E. 2002. A review of the coccolithophorid Emiliania huxleyi ((Prymnesiophyceae), with particular reference to growth, coccolith formation, and calcification-photosynthesis interactions. Phycologia 40: 503-529.

Stolte, W., Kraay, G.W., Noordeloos, A.A.M. and Riegman, R. 2000. Genetic and physiological variation in pigment composition of Emiliania huxleyi (Prymnesiophyceae) and the potential use of its pigment ratios as a quantitative physiological marker. Journal of Phycology 96: 529-589.