Short-term effects of elevated CO 2 on periphyton community in an artificially constructed channel

Background Direct impact of inorganic carbon (i.e., carbon dioxide (CO 2 )) on the periphyton community is important to understand how and to what extent atmospheric conditions can affect the structure and dynamics of these communities in lotic systems. We investigated the influence of elevated CO 2 concentration on the periphyton community in the artificially constructed channels during the winter period. The channels made of acrylic paneling were continuously supplied with surface water discharged from a small reservoir, which was supported with ground water, at a flow rate of 5 L/min, and water temperature ranging 4–5 °C. The effects of elevated CO 2 concentrations (790 ppm) were evaluated in comparison with the control (395 ppm CO 2 ) by analyzing pH, water carbon content and nutrients in water, periphyton composition and biomass, chlorophyll- a , ash-free dry-matter at 2-day intervals for 10 days. Results After the addition of CO 2 , significant decreases of pH, NH 3 -N, and PO 4 -P ( p < 0.05) and increases of chlorophyll- a , ash-free dry-matter, and the cell density of periphyton ( p < 0.01) were observed, whereas the species composition of periphyton and water carbon content did not change. Conclusions These results suggest that elevated CO 2 in flowing water system with low temperature could facilitate the growth of periphyton resulting in biomass increase, which could further influence water quality and the consumers throughout the food web.