How does rising atmospheric CO2 affect marine organisms?

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Planktonic Marine Microbes
Teira, E., Fernandez, A., Alvarez-Salgado, X.A., Garcia-Martin, E.E., Serret, P. and Sobrino, C. 2012. Response of two marine bacterial isolates to high CO2 concentration. Marine Ecology Progress Series 453: 27-36.

What was done
As the authors describe it, they "tested the direct effect of an elevated CO2 concentration (1,000 ppm) on the biomass and metabolic rates (leucine incorporation, CO2 fixation and respiration) of two isolates belonging to two relevant marine bacterial families, Rhodobacteraceae (strain MED165) and Flavobacteriaceae (strain MED217)," the former of which they refer to as simply Roseobacter and the latter of which they designate Cytophaga.

What was learned
"Contrary to some expectations," in the words of the six Spanish scientists, they state that "lowering pH did not negatively affect bacterial growth." In fact, they indicate that it actually increased growth efficiency in the case of Cytophaga. And they write that "in both cases, the bacterial activity under high CO2 would increase the buffering capacity of seawater."

What it means
Teira et al.'s final words on the implications of their findings are that the responses of both marine bacterial families "would tend to increase the pH of seawater, acting as a negative feedback between elevated atmospheric CO2 concentrations and ocean acidification." And, of course, they also reveal the identities of two more sets of marine organisms that are in no way threatened by the seawater pH changes induced by the historical and still-ongoing rise in the atmosphere's CO2 concentration.

Reviewed 30 January 2013