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Visualizing Methane-Cycling Microbial Dynamics in Coastal Wetlands
Published on: January 31, 2025
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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.
Plos One
|November 1, 2014
Summary
Methane (CH4) is an energy source in freshwater webs, but its concentration did not affect carbon isotope values in chironomid larvae from stream impoundments. This suggests CH4 has limited impact on these benthic food webs.
Area of Science:
- Ecology
- Biogeochemistry
- Aquatic Ecosystems
Background:
- Methane (CH4) serves as a carbon and energy source in freshwater food webs.
- Methane oxidizing bacteria (MOB) convert CH4, which is then utilized by chironomid larvae, potentially lowering their carbon isotope (δ(13)C) values.
- Previous studies show this in lakes and streams, but the link in stream impoundments remains unclear.
Purpose of the Study:
- To investigate the relationship between methane concentrations and the carbon isotope (δ(13)C) values of chironomid larvae in stream impoundments.
- To determine if methane influences the benthic food web in these specific aquatic environments.
Main Methods:
- Methane concentrations were measured in eleven stream impoundments in the Queich River catchment, Germany.
- Carbon isotope (δ(13)C) values of Chironomini and Tanypodinae larvae were analyzed.
- Larval δ(13)C values were statistically correlated with measured CH4 concentrations.
Main Results:
- Chironomini larvae exhibited lower mean δ(13)C values (-29.2 to -25.5 ‰) compared to Tanypodinae larvae (-26.9 to -25.3 ‰).
- No significant correlation was found between CH4 concentrations and the δ(13)C values of either chironomid subfamily (p > 0.05).
- Mean δ(13)C values of chironomid larvae were comparable to sedimentary organic matter and tree leaf litter.
Conclusions:
- Methane concentration appears to have a limited influence on the benthic food web structure within the studied stream impoundments.
- The carbon isotope signatures of chironomid larvae in these systems are likely derived from sources other than methane.
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