Warming Increases the Proportion of Primary Production Emitted as Methane from Freshwater Mesocosms

Gabriel Yvon-Durocher (1) , Jose Maria Montoya (2) , Guy Woodward (3) , Iwan John Jones (1) , Mark Trimmer (4)

1 School of Biological and Chemical Sciences
2 ICM - Institute of Marine Sciences / Institut de Ciències del Mar [Barcelona]
3 School of Biological and Chemical Sciences
4 School of Biological and Chemical Sciences

Methane and carbon dioxide are the dominant gaseous end products of the remineralisation of organic carbon and also the two largest contributors to the anthropogenic greenhouse effect. We investigated whether warming altered the balance of methane efflux relative to primary production and ecosystem respiration in a freshwater mesocosm experiment. Whole ecosystem CH4 efflux was strongly related to temperature with an apparent activation energy of 0.85eV. Furthermore, CH4 efflux increased faster than ecosystem respiration or primary production with temperature, with all three processes having sequentially lower activation energies. Warming of 4°C increased the fraction of primary production effluxing as methane by 20% and the fraction of ecosystem respiration as methane by 9%, inline with the offset in their respective activation energies. Because methane 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.

Mots clés: Life Sciences

Gabriel Yvon-Durocher, Jose Maria Montoya, Guy Woodward, Iwan John Jones, Mark Trimmer. Warming Increases the Proportion of Primary Production Emitted as Methane from Freshwater Mesocosms. Global Change Biology, 2010, 17 (2), pp.1225. ⟨10.1111/j.1365-2486.2010.02289.x⟩. ⟨hal-00599522⟩