The effect of atmospheric carbon dioxide elevation on plant growth in freshwater ecosystems

The authors developed a dynamic model to investigate the effect of atmospheric carbon dioxide (CO2) increase on plant growth in freshwater ecosystems. Steady-state simulations were performed to analyze the response of phytoplankton and submerged macrophytes to atmospheric CO2 elevation from 350 to 700 ppm. The authors studied various conditions that may affect this response, such as alkalinity, the air–water exchange rate of CO2, the community respiration rate, and the phosphorus (P) supply rateWe developed a dynamic model to investigate the effect of atmospheric carbon dioxide (CO2) increase on plant growth in freshwater ecosystems. Steady-state simulations were performed to analyze the response of phytoplankton and submerged macrophytes to atmospheric CO2 elevation from 350 to 700 ppm. We studied various conditions that may affect this response, such as alkalinity, the air-water exchange rate of CO2, the community respiration rate, and the phosphorus (P) supply rate. The increase in atmospheric CO2 could affect submerged plant growth only under relatively eutrophic conditions and at a low community respiration rate. Alkalinity had little effect on the response of the different species. When the air-water exchange was low, the proportional effect of the CO2 increase on plant growth was higher. Under eutrophic conditions, algae and macrophytes using CO2 and HCO3- may double their growth rate due to atmospheric CO2 elevation, while the growth of macrophytes restricted to CO2 assimilation may be threefold. The differences in response of the species under various conditions indicate that the elevation of atmospheric CO2 may induce drastic changes in the productivity and species dominance in freshwater systems