How does rising atmospheric CO2 affect marine organisms?

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Rising Temperature and OA Effects on Coral Organic Carbon Fluxes

Paper Reviewed
Levas, S., Grottoli, A.G., Warner, M.E., Cai, W.-J., Bauer, J., Schoepf, V., Baumann, J.H., Matsui, Y., Gearing, C., Melman, T.F., Hoadley, K.D., Pettay, D.T., Hu, X., Li, Q, Xu, H. and Wang, Y. 2015. Organic carbon fluxes mediated by corals at elevated pCO2 and temperature. Marine Ecology Progress Series 519: 153-164.

Although climate alarmists have long decried the speculative negative effects of Earth's rising atmospheric CO2 concentration -- to which they attribute ocean acidification (OA) and global warming (prior to the past two decades of thermal stasis, that is) -- Levas et al. (2015) write that "research to date has largely neglected the individual and combined effects of OA and seawater temperature on coral-mediated organic carbon (OC) fluxes," noting that this void of knowledge "is of particular concern as dissolved and particulate OC (DOC and POC, respectively) represent large pools of fixed OC on coral reefs."

In an attempt to reduce this knowledge void, the sixteen scientists assessed coral-mediated POC and DOC, as well as total OC (TOC = DOC + POC), plus the relative contributions of each of them to coral metabolic demand for two species of coral, Acropora millepora and Turbinaria reniformis, at two different levels of pCO2 (382 and 741 µatm) and seawater temperatures (26.5 and 31.0°C). And what did they thereby learn?

Levas et al. report that "independent of temperature, DOC fluxes decreased significantly with increases in pCO2 in both species, resulting in more DOC being retained by the corals and only representing between 19 and 6% of TOC fluxes for A. millepora and T. reniformis," while at the same time POC fluxes were unaffected by elevated temperature and/or pCO2. And, thus, they were able to conclude that "these findings add to a growing body of evidence that certain species of coral may be less at risk to the impacts of OA and temperature than previously thought."

Posted 9 June 2015