How does rising atmospheric CO2 affect marine organisms?

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Three Responses of a Reef-Building Coral to Ocean Acidification

Paper Reviewed
Zhou, G., Yuan, T., Cai, L., Zhang, W., Tian, R., Tong, H., Jiang, L., Yuan, X., Liu, S., Qian, P. and Huang, H. 2016. Changes in microbial communities, photosynthesis and calcification of the coral Acropora gemmifera in response to ocean acidification. Nature Scientific Reports: DOI: 10.1038/srep35971.

Noting that the effects of ocean acidification (OA) on coral physiology and associated microbes remain largely unknown, Zhou et al. (2016) collected samples of a fast-growing tropical coral (Acropora gemmifera) from a reef flat in the South China Sea, which they later exposed under laboratory conditions to three partial pressures of carbon dioxide (pCO2: 421, 923 and 2070 µatm) for a period of four weeks.

This work revealed, as they report, that "the microbial community associated with A. gemmifera was highly diverse at the genus level." And, more importantly, they report that "the microbial community structure remained rather stable under the different pCO2 treatments." In addition, the 11 Chinese researchers determined that both photosynthesis and calcification in A. gemmifera were significantly impaired only at the high pCO2 µatm (2070 µatm).

And so it was that in light of these several observations, Zhou et al. were led to conclude that "some reef-building corals may be more tolerant to OA in pH/pCO2 fluctuating environments and have a high degree of host-symbiont fidelity, despite the observed impairment of host physiological processes in response to high CO2 stress," such as those observed in their study at 2070 µatm pCO2, which finding is an extremely welcome bit of very good news.

Posted 6 March 2017