Effects of elevated CO₂ on phytoplankton during a mesocosm experiment in the southern eutrophicated coastal water of China.

ABSTRACT: There is a growing consensus that the ongoing increase in atmospheric CO₂ level will lead to a variety of effects on marine phytoplankton and ecosystems. However, the effects of CO₂ enrichment on eutrophic coastal waters are still unclear, as are the complex mechanisms coupled to the development of eutrophication. Here, we report the first mesocosm CO₂ perturbation study in a eutrophic subtropical bay during summer by investigating the effect of rising CO₂ on a model artificial community consisting of well-characterized cultured diatoms (Phaeodactylum tricornutum and Thalassiosira weissflogii) and prymnesiophytes (Emiliania huxleyi and Gephyrocapsa oceanica). These species were inoculated into triplicate 4?m³ enclosures with equivalent chlorophyll a (Chl-a) under present and higher partial pressures of atmospheric CO₂ (pCO₂?=?400 and 1000?ppmv). Diatom bloom events were observed in all enclosures, with enhanced organic carbon production and Chl-a concentrations under high CO₂ treatments. Relative to the low CO₂ treatments, the consumption of the dissolved inorganic nitrogen and uptake ratios of N/P and N/Si increased significantly during the bloom. These observed responses suggest more extensive and complex effects of higher CO₂ concentrations on phytoplankton communities in coastal eutrophic environments.

SUBMITTER: Liu X 

PROVIDER: S-EPMC5537254 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature