The effect of CO2 and temperature change on phytoplankton and benthic algae – a mesocosm study

By the end of this century, the expected atmospheric CO2 concentration will reach 800~1000 ppm. Phytoplankton and benthic algae are the primary production in the ocean, but the effects of CO2 and temperature on the algae is inconclusive. In this study, we examined the effects of CO2 and temperature on growth and community assemblages of phytoplankton and benthic algae. The experiments were conducted with two CO2 treatments (400 ppm and 800 ppm) and three temperatures (28, 25 and 22 degrees Celsius) in the mesocosms. The results indicated that at 28 degrees Celsius, elevated CO2 enhanced the growth of phytoplankton but the species diversity decreased. Elevated CO2 increased the benthic algal growth, especially for diatom but not cyanobacteria or dinoflagellates. Lower temperature benefited the growth of benthic algae, with the highest chl a concentrations and abundances found at 22 degrees Celsius. When temperature decreased from 28 to 22 degrees Celsius, the relative abundance of cyanobacteria increased while the diatom decreased. CO2 and temperature alter algal community assemblages, a result that might affect marine primary production and nutrient cycle in the future.

Siao Y.-J., 2014. The effect of CO2 and temperature change on phytoplankton and benthic algae – a mesocosm study. MSc thesis, National Sun Yat-sen University, 81 pp. Thesis.


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