Warming increases the proportion of primary production emitted as methane from freshwater mesocosms |
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Authors: | GABRIEL YVON‐DUROCHER JOSÉ M. MONTOYA GUY WOODWARD J. IWAN JONES MARK TRIMMER |
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Affiliation: | 1. School of Biological & Chemical Sciences, Queen Mary University of London, London E1 4NS, UK;2. Institute of Marine Sciences (ICM‐CSIC) Pg. Marítim de la Barceloneta, 37‐49 E‐08003 Barcelona, Spain;3. Centre for Ecology and Hydrology, MacLean Building, Benson Lane, Crowmarsh Gifford, Wallingford OX10 8BB, UK |
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Abstract: | Methane (CH4) and carbon dioxide (CO2) are the dominant gaseous end products of the remineralization of organic carbon and also the two largest contributors to the anthropogenic greenhouse effect. We investigated whether warming altered the balance of CH4 efflux relative to gross primary production (GPP) and ecosystem respiration (ER) in a freshwater mesocosm experiment. Whole ecosystem CH4 efflux was strongly related to temperature with an apparent activation energy of 0.85 eV. Furthermore, CH4 efflux increased faster than ER or GPP with temperature, with all three processes having sequentially lower activation energies. Warming of 4 °C increased the fraction of GPP effluxing as CH4 by 20% and the fraction of ER as CH4 by 9%, in line with the offset in their respective activation energies. Because CH4 is 21 times more potent as a greenhouse gas, relative to CO2, these results suggest freshwater ecosystems could drive a previously unknown positive feedback between warming and the carbon cycle. |
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Keywords: | carbon cycle ecosystem respiration global warming metabolic theory methane primary production |
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