How does rising atmospheric CO2 affect marine organisms?

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The Outlook for Atlantic Cod in a CO2 Enriched and Warmer World

Paper Reviewed
Kreiss, C.M., Michael, K., Lucassen, M., Jutfelt, F., Motyka, R., Dupont, S. and Portner, H.-O. 2015. Ocean warming and acidification modulate energy budget and gill ion regulatory mechanisms in Atlantic cod (Gadus morhua). Journal of Comparative Physiology B 185: 767-781.

Kreiss et al. (2015) introduce their recent study by stating it has been claimed by the IPCC that "anthropogenic climate change has profound impacts on marine ecosystems as the oceans become warmer and are acidified by the uptake of atmospheric carbon dioxide," which assertion they associate with the IPCC report of Portner et al. (2014), as well as the claim that in the case of marine animals, "acidification is thought to enhance ion regulatory costs and thereby baseline energy demand, while elevated temperature also increases baseline metabolic rate." But is this really the case?

Determined to find out for themselves, the four German and three Swedish researchers describe how they "investigated standard metabolic rates and plasma parameters of Atlantic cod (Gadus morhua) after 3-4 weeks of exposure to ambient and future pCO2 levels (550, 1200 and 2200 µatm) and at two temperatures (10, 18°C)," while "in vivo branchial ion regulatory costs were studied in isolated, perfused gill preparations."

This work revealed, as they discovered, that (1) "whole animal standard metabolic rates of Atlantic cod incubated for 3 weeks were independent of temperature (10, 18°C)," which finding confirmed previous findings that (2) "southern cod populations can acclimate and compensate for temperature, within limits marginally reached at 18°C," and that (3) "with respect to the different CO2 concentrations applied (550, 1200 and 2200 µatm), these data also provide an evidence that near-term projected future pCO2 levels per se will have [only] a small effect on standard metabolic rates."

Portner, H.O., Karl, D.M., Boyd, P.W., Cheung,W.L., Lluch-Cota, S.E., Nojiri, Y., Schmidt, D.N. and Zavialov, P.O. 2014. Ocean systems. In: Climate Change 2014: Impacts, Adaptation and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. In: Field, C.B., Barros, V.R., Dokken, D.J., Mach, K.J., Mastrandrea, M.D., Bilir, T.E., Chatterjee, M., Ebi, K.L., Estrada, Y.O., Genova, R.C., Girma, B., Kissel, E.S., Levy, A.N., MacCracken, S., Mastrandrea, P.R. and White, L.L. (Eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Posted 15 January 2016