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Thursday, June 7, 2007 - 9:15 AM
353
The Importance of Methane to Benthic Macroinvertebrates in Four Reservoirs in the Cape Fear River Basin
Elizabeth M. Wade and Anne E. Hershey. Biology, University of North Carolina-Greensboro, 312 Eberhart Building, Greensboro, NC 27402
The biogenic production and subsequent oxidation of methane in aquatic sediments are important microbial processes that contribute to the global carbon cycle and play a significant role in the natural flux of methane to the atmosphere. The importance of biogenic methane as a carbon source to benthic food webs in lakes, reservoirs and streams can be substantial. We are studying the importance of biogenic methane to benthic macroinvertebrates and the amount of methane produced and oxidized in four reservoirs within the Cape Fear River Basin. Results from the summer of 2006 suggest benthic macroinvertebrates are obtaining much of their carbon from biogenically produced methane based on their low δ13C values as compared to those of seston (avg. shift in δ13C = -5.69‰). It also appears that there is no significant correlation between the δ13C values of chironomids and the δ13C values of seston, further strengthening this concept. Core incubation experiments using methyl fluoride (CH3F) to inhibit methane oxidation showed methane flux from reservoir sediments with an average methane concentration of 70.27ppm after 24 hrs. This research may have applications in future research on the importance of biogenic methane and the flux of methane from reservoirs.