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2020 (English)In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 26, no 10, p. 5705-5715Article in journal (Refereed) Published
Abstract [en]
Eutrophication of fresh waters results in increased CO2 uptake by primary production, but at the same time increased emissions of CH4 to the atmosphere. Given the contrasting effects of CO2 uptake and CH4 release, the net effect of eutrophication on the CO2-equivalent balance of fresh waters is not clear. We measured carbon fluxes (CO2 and CH4 diffusion, CH4 ebullition) and CH4 oxidation in 20 freshwater mesocosms with 10 different nutrient concentrations (total phosphorus range: mesotrophic 39 µg/L until hypereutrophic 939 µg/L) and planktivorous fish in half of them. We found that the CO2-equivalent balance had a U-shaped relationship with productivity, up to a threshold in hypereutrophic systems. CO2-equivalent sinks were confined to a narrow range of net ecosystem production (NEP) between 5 and 19 mmol O2 m?3 day?1. Our findings indicate that eutrophication can shift fresh waters from sources to sinks of CO2-equivalents due to enhanced CO2 uptake, but continued eutrophication enhances CH4 emission and transforms freshwater ecosystems to net sources of CO2-equivalents to the atmosphere. Nutrient enrichment but also planktivorous fish presence increased productivity, thereby regulating the resulting CO2-equivalent balance. Increasing planktivorous fish abundance, often concomitant with eutrophication, will consequently likely affect the CO2-equivalent balance of fresh waters.
Place, publisher, year, edition, pages
John Wiley & Sons, Ltd, 2020
Keywords
carbon dioxide, eutrophication, food web structure, greenhouse gas, methane, oxidation
National Category
Biological Sciences
Identifiers
urn:nbn:se:uu:diva-427666 (URN)10.1111/gcb.15284 (DOI)000557072200001 ()
Funder
Swedish Research Council, 2018‐04524Swedish Research Council, 2017‐00635Knut and Alice Wallenberg Foundation, 2013.0091EU, European Research Council, 336642
2020-12-092020-12-092021-01-29Bibliographically approved