How does rising atmospheric CO2 affect marine organisms?

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Responses of 18 Benthic Marine Calcifiers to Atmospheric CO2 Enrichment
Ries, J.B., Cohen, A.L. and McCorkle, D.C. 2009. Marine calcifiers exhibit mixed responses to CO2-induced ocean acidification. Geology 37: 1131-1134.

The authors write that "there is mounting concern over the impact that future CO2-induced reductions in the CaCO3 saturation state of seawater will have on marine organisms that construct their shells and skeletons from this mineral."

What was done
Ries et al. "reared 18 calcifying species for 60 days in isothermal (25C) experimental seawaters equilibrated with average [atmospheric] CO2 values of 409, 606, 903 and 2856 ppm, corresponding to modern CO2, and ~2, 3 and 10 times pre-industrial levels (~280 ppm), respectively, and yielding average seawater saturation states of 2.5, 2.0, 1.5 and 0.7 with respect to aragonite," after which "the organisms net rates of calcification (total calcification minus total dissolution) under the various CO2 treatments were estimated from changes in their buoyant weight and verified with dry weight measurements after harvesting."

What was learned
The three Woods Hole Oceanographic Institution (USA) researchers report that "in ten of the 18 species (temperate corals, pencil urchins, hard clams, conchs, serpulid worms, periwinkles, bay scallops, oysters, whelks, soft clams), net calcification decreased with increasing CO2," and that "in six of the ten negatively impacted species (pencil urchins, hard clams, conchs, periwinkles, whelks, soft clams) [they] observed net dissolution of the shell in the highest CO2 treatment." However, as they continue, "in four of the 18 species (limpets, purple urchins, coralline red algae, calcareous green algae), net calcification increased relative to the control under intermediate CO2 levels (605 and 903 ppm), and then declined at the highest CO2 level (2856 ppm)." Last of all, they say that "in three species (crabs, lobsters, and shrimps), net calcification was greatest under the highest level of CO2 (2856 ppm)," and that "one species, the blue mussel, exhibited no response to elevated CO2.

What it means
In light of their many diverse findings, Ries et al. concluded that "the impact of elevated atmospheric CO2 on marine calcification is more varied than previously thought," and so it is, with responses ranging from negative to neutral to positive. Hence, all is not "doom and gloom," as is typically claimed by the world's climate alarmists. What is more, there is a large and accumulating volume of research that demonstrates that extremely rapid micro-evolutionary processes operate in almost all of earth's life forms, and that these phenomena enable them to successfully cope with significant environmental changes at rates that correspond to those environmental changes (Balanya et al., 2006; Jump et al., 2006; Franks et al., 2007; Rae et al., 2007; Skelly et al., 2007; Van Doorslaer et al., 2007; Franks and Weis, 2008; Jump et al., 2008; Purcell et al., 2008; Alford et al., 2009; Bell and Gonzalez, 2009; Onoda et al., 2009; Van Doorslaer et al., 2009). This research thus suggests that those species that responded negatively to the dramatic step increases in the air's CO2 content employed in Ries et al.'s study will likely be able to gradually adjust to, and successfully cope with, the restrained and slower rate at which the atmospheric CO2 concentration of the real world will rise in the future.

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Reviewed 6 January 2010