How does rising atmospheric CO2 affect marine organisms?

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The Response of Juvenile King Scallops to Ocean Acidification
Sanders, M.B., Bean, T.P., Hutchinson, T.H. and Le Quesne, W.J.F. 2013. Juvenile king scallop, Pecten maximus, is potentially tolerant to low levels of ocean acidification when food is unrestricted. PLOS ONE 8: e74118.

The authors note that the decline in ocean water pH and changes in carbonate saturation states caused by anthropogenically-mediated increases in atmospheric CO2 levels "may pose a hazard to marine organisms" that "may be particularly acute for those species reliant on calcareous structures like shells and exoskeletons." And they say that "this is of particular concern in the case of valuable commercially exploited species such as the king scallop, Pecten maximus."

What was done
To explore this possibility Sanders et al. "investigated the effects on oxygen consumption, clearance rates and cellular turnover in juvenile P. maximus following three months' laboratory exposure to four pCO2 treatments (290, 380, 750 and 1140 ppm)."

What was learned
The four researchers determined that "none of the exposure levels were found to have significant effects on the clearance rates, respiration rates, condition index or cellular turnover (RNA: DNA) of individuals." And they further note that these findings are compatible with those of Anderson et al. (2013), who also studied the growth, development and survival of the initial larval stages of P. maximus and who only found them to be susceptible to the deleterious effects of ocean acidification at pCO2 levels of 1600 ppm and above.

What it means
Simply put, Sanders et al. indicate that the results of their study suggest that "where food is in abundance, bivalves like juvenile P. maximus may display a tolerance to limited changes in seawater chemistry."

Andersen, S., Grefsrud, E.S. and Harboe, T. 2013. Effect of increased pCO2 on early shell development in great scallop (Pecten maximus Lamark) larvae. Biogeosciences Discussions 10: 3281-3310.

Reviewed 8 January 2014