How does rising atmospheric CO2 affect marine organisms?

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No Response of a Toxic Algae to Ocean Acidification and Warming

Paper Reviewed
Li, P.F., Yang, G.P., Liu, C.Y. 2020. Combined effects of elevated temperature and pCO2 on the production of DMSP and DMS in the culture of Amphidinium carterae. Journal of Applied Phycology

Introducing their work, Li et al. (2020) say that Amphidinium carterae is "a known toxic marine dinoflagellate [phytoplankton] to cause red tides and is listed as harmful toxic microalga by the Intergovernmental Oceanographic Commission and United Nations Educational, Scientific and Cultural Organization." Consequently, as a toxin, it would not be a good outcome if this species was found to respond positively to predicted future changes in seawater pH and temperature, either alone or in combination. And so the team of three Chinese researchers set out to ascertain what may be in store for this phytoplankton species.

To accomplish their objective, Li et al. grew samples of A. carterae in semicontinuous cultures under controlled laboratory conditions over a period of ten days. A full-factorial design of two temperatures (ambient at 20°C or elevated at 23°C) and two seawater pCO2 (400 or 1000 µatm) treatments was applied, resulting in four experimental treatments: (1) ambient CO2 and ambient temperature), (2) elevated CO2 and ambient temperature, (3) ambient CO2 and elevated temperature, and (4) elevated CO2 and elevated temperature.

With respect to the impact of CO2 and temperature on microalgae growth, the researchers report (1) "no temperature-induced effects were observed at both CO2 levels in this study," (2) "no CO2-induced effect on the growth of A. carterae was found in this study," and (3) "neither temperature nor CO2 [combined] had any effect on the growth of A. carterae." Consequently, Li et al. conclude "no additive or synergistic effects of elevated CO2 and temperature on A. carterae were observed, indicating that A. carterae [is] insensitive to elevated CO2 and temperature."

The above findings represent good news given the toxic nature of this species and its ability to cause red tides. But you probably won't find any acidification alarmists publicizing or rejoicing at it!

Posted 15 June 2020