Wetland water-management may influence mercury bioaccumulation in songbirds and ducks at a mercury hotspot
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Wetland water-management may influence mercury bioaccumulation in songbirds and ducks at a mercury hotspot Virginia L. Winder1 Michael J. Anteau2 Mark R. Fisher3 Mary Kate Wilcox4 Lawrence D. Igl2 Joshua T. Ackerman5 ●
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Accepted: 25 November 2019 © This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply 2020
Abstract Mercury is a persistent, biomagnifying contaminant that can cause negative behavioral, immunological, and reproductive effects in wildlife and human populations. We examined the role of wetland water-management on mercury bioaccumulation in songbirds and ducks at Kellys Slough National Wildlife Refuge Complex, near Grand Forks, North Dakota USA. We assessed mercury concentrations in blood of wetland-foraging songbirds (80 common yellowthroats [Geothlypis trichas] and 14 Nelson’s sparrows [Ammospiza nelsoni]) and eggs of upland-nesting ducks (28 gadwall [Mareca strepera], 19 bluewinged teal [Spatula discors], and 13 northern shoveler [S. clypeta]) across four wetland water-management classifications. Nelson’s sparrow blood mercury concentrations were elevated (mean: 1.00 µg/g ww; 95% CL: 0.76–1.31) and similar to those reported 6 years previously. Mercury in songbird blood and duck eggs varied among wetland water-management classifications. Songbirds and ducks had 67% and 49% lower mercury concentrations, respectively, when occupying wetlands that were drawn down with water flow compared to individuals occupying isolated-depressional wetlands with no outflow. Additionally, songbirds within impounded and partially drawn-down wetland units with water flow had mercury concentrations that were 26–28% lower, respectively, than individuals within isolated-depressional wetlands with no outflow. Our results confirm that mercury concentrations in songbirds at Kellys Slough continue to be elevated and suggest that water-management could be an important tool for wetland managers to reduce bioaccumulation of mercury in birds. Keywords Blood mercury Common yellowthroat Egg mercury Impounded wetland Nelson’s sparrow Waterfowl ●
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Introduction The methylated or organic form of mercury biomagnifies and can pose toxicity risks, linked to negative behavioral,
* Virginia L. Winder [email protected] 1
Department of Biology, Benedictine College, Atchison, KS 66002, USA
2
Northern Prairie Wildlife Research Center, U.S. Geological Survey, 8711 37th St SE, Jamestown, ND 58401, USA
3
Devils Lake Wetland Management District, U.S. Fish and Wildlife Service, Devils Lake, ND 58301, USA
4
Division of Biology, Kansas State University, Manhattan, KS 66502, USA
5
Western Ecological Research Center, Dixon Field Station, U.S. Geological Survey, 800 Business Park Drive, Suite D, Dixon, CA 95620, USA
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immunological, and reproductive effects in wildlife and humans (Wolfe et al. 1998; Clarkson and Magos 2006; Evers et al. 2008; Jackson et al. 2011; Ackerman et al. 2016a). Wetland ecosystems are of particular concern fo
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