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Article 4
Chaoborus spp. transport CH from the sediments to the surface waters of a eutrophic reservoir, but their contribution to water column CH concentrations and diffusive efflux is minor 4
Cayelan C. Carey, Ryan P. McClure, Jonathan P. Doubek, Mary E. Lofton, Nicole K. Ward, and Durelle Scott Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.7b04384 • Publication Date (Web): 20 Dec 2017 Downloaded from http://pubs.acs.org on January 3, 2018
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Environmental Science & Technology
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Chaoborus spp. transport CH4 from the sediments to the surface waters of a eutrophic reservoir,
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but their contribution to water column CH4 concentrations and diffusive efflux is minor
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Cayelan C. Carey1*, Ryan P. McClure1, Jonathan P. Doubek1, Mary E. Lofton1, Nicole K.
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Ward1, Durelle T. Scott2
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Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
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Department of Biological Systems Engineering, Virginia Tech, Blacksburg, Virginia, USA
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*Corresponding author. Email:
[email protected]; Phone: +1-540-231-8938
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Authorship Contributions: CCC conceived the original idea for the manuscript. All authors
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collected field data; CCC led the Chaoborus incubations; RPM led GHG analyses; JPD
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conducted the zooplankton microscopy; and all authors contributed to data analysis and
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interpretation. CCC led the writing of the manuscript, and all authors provided feedback and
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approved the final version.
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Submitted as a Research Article to ES&T
ACS Paragon Plus Environment
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Environmental Science & Technology
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Abstract:
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Chaoborus spp. (midge larvae) live in the anoxic sediments and hypolimnia of freshwater
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lakes and reservoirs during the day and migrate to the surface waters at night to feed on plankton.
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It has recently been proposed that Chaoborus take up methane (CH4) from the sediments in their
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tracheal gas sacs, use this acquired buoyancy to ascend into the surface waters, and then release
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the CH4, thereby serving as a CH4 “pump” to the atmosphere. We tested this hypothesis using
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diel surveys and seasonal monitoring, as well as incubations of Chaoborus to measure CH4
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transport in their gas sacs at different depths and times in a eutrophic reservoir. We found that
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Chaoborus transported CH4 from the hypolimnion to the lower epilimnion at dusk, but the
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overall rate of CH4 transport was minor, and incubations revealed substantial variability in CH4
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transport over space and time. We calculated that Chaoborus transport ~0.1 mmol CH4 m-2 yr-1 to
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the epilimnion in our study reservoir, a very low proportion (
