Short-term effects of elevated CO2 on periphyton community in an artificially constructed channel

Background: Direct impact of inorganic carbon (i.e., carbon dioxide (CO2)) 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 CO2 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 CO2 concentrations (790 ppm) were evaluated in comparison with the control (395 ppm CO2) 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 CO2, significant decreases of pH, NH3-N, and PO4-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 CO2 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. Background Carbon dioxide (CO2) is a major greenhouse gas with the greatest potential to influence global climate change since the industrial revolution, while the CO2 emission into the atmosphere has been increasing, and its concentration will reportedly double in the next 50–100 years (Houghton et al. 2001). Atmospheric CO2 concentrations have risen from 295 parts per million (ppm) to 380 ppm over the last 100 years and have contributed substantially to global warming, climate change, and resultant biological extinctions (Lewis and Nocera 2006; Battisti and Naylor 2008). CO2 emissions vary with seasonal photosynthesis, respiration of plants, and the amount of fossil fuels consumed (IPCC 2007). * Correspondence: [email protected]; [email protected] Department of Life Science, Hanyang University, Seoul 04763, Republic of Korea Department of Environmental Science, Konkuk University, Seoul 05029, Republic of Korea Full list of author information is available at the end of the article © The Author(s). 2016 Open Access This artic International License (http://creativecommons reproduction in any medium, provided you g the Creative Commons license, and indicate if (http://creativecommons.org/publicdomain/ze In particular, the atmospheric CO2 concentration during the winter season typically increases due to the reduction of photosynthesis of plants and an increase in active consumption of fossil fuels (Lewis and Nocera 2006; Sayre 2010). Low water temperature during the winter increases CO2 solubility (Tortell et al. 2008), which may be expected to affect aquatic ecosystems. CO2 gas dissociates into HCO3 , CO3 , and H ions in water and may enhance algal growth and production. In general, benthic and planktonic algae use bicarbonate (HCO3 ) and carbonate (CO3 ) as carbon sources (Falkowski and Raven 2007; Giordano et al. 2005). Almost all studies on algal biomass variations with increased CO2 have been conducted in marine water in response to a volcanic eruption (Hall-Spencer et al. 2008; Johnson et al. 2011). In contrast, few studies have been performed regarding the impact of increased CO2 on periphyton structure and function in freshwater ecosystems. One exception is a study that assessed these le is distributed under the terms of the Creative Commons Attribution 4.0 .org/licenses/by/4.0/), which permits unrestricted use, distribution, and ive appropriate credit to the original author(s) and the source, provide a link to changes were made. The Creative Commons Public Domain Dedication waiver ro/1.0/) applies to the data made available in this article, unless otherwise stated. Park et al. Journal of Ecology and Environment (2016) 40:3 Page 2 of 8 variables on the fish community (Ross et al. 2001). In the freshwater system, the amount of organic carbon supply frequently exceeds inorganic carbon, particularly at high altitudes, because streams receive carbon as particulate organic matter such as dead leaves. These leaves are processed by fungi, bacteria, and benthic macroinvertebrates (Biggs et al. 1998; Tuchman et al. 2002). Studies considering the direct impact of inorganic carbon (i.e., CO2) on the periphyton community are important to understand how and to what extent atmospheric conditions can affect the structure and dynamics of these communities. Particularly, in a flowing water system, the periphyton community relies on various physicochemical factors as well as other aquatic organisms. Thus, even a small disturbance in CO2 can considerably affect the abundance and species composition of periphyton (Hillebrand and Sommer 2000; Villeneuve et al. 2010). The present study aimed to elucidate the impact of elevated CO2 concentrations on biomass and species composition of periphyton in an aquatic environment with low temperature, high solubility of CO2, and low photosynthesis.