EGU21-15327
https://doi.org/10.5194/egusphere-egu21-15327
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

The role of methane transport from the active layer in sustaining methane emissions and food chains in subarctic ponds

Carolina Olid1,2, Alberto Zannella3,4, and Danny C.P. Lau1,3
Carolina Olid et al.
  • 1Climate Impacts Research Centre, Department of Ecology and Environmental Science, Umeå University, 98107 Abisko, Sweden.
  • 2Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
  • 3Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, 75007 Uppsala, Sweden
  • 4DISAT, University of Milano-Bicocca, Piazza della Scienza, 1, 20216 Milano, Italy.

Shallow groundwater flow from the seasonally thawed active layer is increasingly recognized as an important pathway for delivering methane (CH4) into Arctic lakes and streams, but its contribution to CH4 emissions from thaw ponds has not been evaluated. Furthermore, the potential influence of the shallow groundwater-derived CH4 on the trophic support and nutritional quality of thaw pond food chains remains unexplored. In this study, we used a radon-mass balance approach to quantify the CH4 transport from the active layer into thaw ponds in a sub-Arctic catchment. We analysed stable isotopes and fatty acids of pond macroinvertebrates to evaluate the potential effects of CH4 inputs through active layer groundwater flows on the aquatic food chains. Our results indicate that CH4 fluxes from the active layer can sustain CH4 emissions from the ponds. Consumers in ponds receiving greater CH4 inputs from the active layer had lower stable carbon isotope signatures that indicates a greater trophic reliance on methane oxidizing bacteria (MOB), and they had lower nutritional quality as indicated by their lower tissue concentrations of polyunsaturated fatty acids. Accurate predictions of CH4 release from small thaw ponds will thus require improved knowledge of the contributions from various processes including internal production, flow paths of active layer groundwater, and MOB-consumer interactions.

How to cite: Olid, C., Zannella, A., and Lau, D. C. P.: The role of methane transport from the active layer in sustaining methane emissions and food chains in subarctic ponds, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15327, https://doi.org/10.5194/egusphere-egu21-15327, 2021.

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