How does rising atmospheric CO2 affect marine organisms?

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Elevated Atmospheric CO2 Enhances the Healthiness of Lake Water

Paper Reviewed
Yu, L., Kong, F., Shi, X., Yang, Z., Zhang, M. and Yu, Y. 2015. Effects of elevated CO2 on dynamics of microcystin-producing and non-microcystin-producing strains during Microcystis blooms. Journal of Environmental Sciences 27: 251-258.

Yu et al. (2015) begin their intriguing paper by noting that microcystins are a class of toxins produced by certain freshwater cyanobacteria that pose a health risk for humans and animals alike, citing the work of Chorus and Bartram (1999) and Carmichael (2001). They also note that cyanobacterial blooms in freshwater lakes commonly consist of both mycrocystin-producing (MC-producing) and non-MC-producing strains. And, therefore, they decided to conduct an in situ mesocosm CO2-enrichment experiment that utilized a real-time polymerase chain reaction (PCR) technique to quantify the relative abundances of both MC strains in the water of Lake Taihu -- the third largest freshwater lake in China -- which is the primary source of drinking water for 30 million people in the lake basin and the city of Shanghai.

Working with three replications each of three different atmospheric CO2 concentrations -- pre-industrial (270 ppm), current (380 ppm) and future (750 ppm) -- the six Chinese scientists found that in the pre-industrial and current CO2 treatments, the MC-producing strain could outcompete the non-MC-producing strain, while the reverse was found to be the case in the future CO2 treatment. And these findings led them to conclude that "rising atmospheric CO2 concentrations cause non-MC-producing strains to outcompete MC-producing strains, thereby reducing MC concentrations," which clearly bodes well for the health of not only the 30 million people that obtain their drinking water from Lake Taihu, but for all people -- and animals -- everywhere.

Carmichael, W.W. 2001. Health effects of toxin-producing cyanobacteria: "The CyanoHABs." Human and Ecological Risk Assessment 7: 1393-1407.

Chorus, I. and Bartram, J. 1999. Toxic Cyanobacteria in Water: A Guide to Their Public Health Consequences, Monitoring and Management. E&FN Spon, London, United Kingdom.

Posted 27 May 2015