Carbonate chemistry co-variation with temperature and oxygen in coastal environments and the design of ecologically relevant ocean acidification experiments

Ocean acidification (OA) is expected to have major impacts on marine ecosystems by directly influencing organismal performance (e.g., growth, development, survival) and indirectly through shifts in food web structure or competitive interactions. Our ability to predict the effects of OA on most species is currently limited but growing, and CO2 exposure experiments are central to efforts to increase understanding.

Typically, experiments include control conditions that attempt to simulate contemporary or preindustrial seawater CO2 concentrations and acidified treatments that correspond to potential future CO2 uptake by the oceans. For studies focused on organisms from low productivity, open-ocean surface waters, researchers can rely on IPCC simulations of future atmospheric CO2 partial pressure (pCO2) to identify potential carbonate chemistry treatments because assumptions of air-sea pCO2 equilibrium are often nearly met (1). In contrast, pCO2 can be far from air-sea equilibrium in many coastal systems, and considerable spatial and temporal variation can exist due to multiple processes, including high rates of primary production and respiration, freshwater inputs, and upwelling (2, 3). To estimate the potential impact of OA on organisms from these regions, control pCO2 levels that reflect contemporary ambient conditions are needed. Recognition of this issue has led researchers to use data from coastal seawater chemistry monitoring programs to inform treatment levels in several recent OA experiments. (…)

Reum J. C. P. & Alin S. R., 2015. Carbonate chemistry co-variation with temperature and oxygen in coastal environments and the design of ecologically relevant ocean acidification experiments. OCB News 8(1):3-7. Article.


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