Linking methane concentration and stable isotope distribution to methane derived carbon in food webs in North Carolina Piedmont streams

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Joshua S. Brigham (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
Anne Hershey

Abstract: In streams, a portion of methane produced by methanogens can be oxidized by MOB. When consumers eat these bacteria, MDC is routed into the aquatic food web. The goal of this study was to determine the distribution and stable isotope signature of methane, and determine the influence of MDC on the diets of Corbicula fluminea and hydropsychid caddisflies in North Carolina piedmont streams. Sampling of twelve streams occurred during summer 2014, winter 2015, and summer 2015. Analysis of methane concentrations found that porewater concentrations (3.19 to 761.72 umol/l) were significantly higher than streamwater concentrations (0.37 to 6.41 umol/l) during all seasons, with porewater methane being highest during summer 2014. Analysis of [lowercase delta]13C-CH4 found that streamwater samples (-34.04 to -63.33 ppt) were higher in [lowercase delta]13C-CH4 than porewater samples(-34.4 to -74.84 ppt). Porewater samples were not significantly different between seasons, but streamwater samples were significantly higher in [lowercase delta]13C-CH4 during winter 2015. Examination of spatial relationships between stream and porewater, and consumer [lowercase delta]13C values suggested that methane concentration was not a good predictor of consumer [lowercase delta]13C. Stable isotope analysis demonstrated that hydropsychids were significantly lower in [lowercase delta]13C than seston during summer 2014 (1ppt difference), winter 2015 (3.5ppt difference), and summer 2015 (1.5ppt difference). Corbicula [lowercase delta]13C values were significantly lower than their diet sources during both summer seasons but were not significantly different from them during the winter, with Corbicula having a value of -30 ppt for summer 2014 and -29.5 ppt for summer 2015. Comparisons of the [lowercase delta]13C of two genera of hydropsychids demonstrated that Hydropsyche were significantly depleted than seston (approximately 1.5ppt). Mixing model analysis demonstrated usage of MOB in the range of 4-11% of diet by consumers, although differences between genera and seasonal differences were found. Analysis demonstrated that hydropsychids were utilizing MOB to a greater extent than Corbicula during the winter. The researched streams have higher concentrations of methane in porewaters that are also lower in [lowercase delta]13C-CH4. The study also demonstrated that both consumers are utilizing MOB as part of their diet. [This abstract has been edited to remove characters that will not display in this system. Please see the PDF for the full abstract.]

Additional Information

Language: English
Date: 2018
Carbon, Methane, Stable Isotopes, Stream
Rivers $z North Carolina
Food chains (Ecology) $z North Carolina
Stable isotopes
Corbicula fluminea

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