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Updated: Apr 21, 2026

Visualizing Methane-Cycling Microbial Dynamics in Coastal Wetlands
Published on: January 31, 2025
Methane-derived carbon in the benthic food web in stream impoundments
John Gichimu Mbaka1, Celia Somlai1, Denis Köpfer1
1Institute for Environmental Sciences, University of Koblenz-Landau, Landau, Rhineland-Palatinate State, Germany.
Abstract:
Methane gas (CH4) has been identified as an important alternative source of carbon and energy in some freshwater food webs. CH4 is oxidized by methane oxidizing bacteria (MOB), and subsequently utilized by chironomid larvae, which may exhibit low δ(13)C values. This has been shown for chironomid larvae collected from lakes, streams and backwater pools. However, the relationship between CH4 concentrations and δ(13)C values of chironomid larvae for in-stream impoundments is unknown. CH4 concentrations were measured in eleven in-stream impoundments located in the Queich River catchment area, South-western Germany. Furthermore, the δ(13)C values of two subfamilies of chironomid larvae (i.e. Chironomini and Tanypodinae) were determined and correlated with CH4 concentrations. Chironomini larvae had lower mean δ(13)C values (-29.2 to -25.5 ‰), than Tanypodinae larvae (-26.9 to -25.3 ‰). No significant relationships were established between CH4 concentrations and δ(13)C values of chironomids (p>0.05). Mean δ(13)C values of chironomid larvae (mean: -26.8‰, range: -29.2‰ to -25.3‰) were similar to those of sedimentary organic matter (SOM) (mean: -28.4‰, range: -29.3‰ to -27.1‰) and tree leaf litter (mean: -29.8 ‰, range: -30.5‰ to -29.1‰). We suggest that CH4 concentration has limited influence on the benthic food web in stream impoundments.
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