The effects of climate, habitat, and trophic position on methylmercury bioavailability for breeding New York songbirds
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The effects of climate, habitat, and trophic position on methylmercury bioavailability for breeding New York songbirds Evan M. Adams
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Amy K. Sauer1 Oksana Lane1 Kevin Regan1 David C. Evers1 ●
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Accepted: 6 December 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Mercury (Hg) is a global pollutant that affects songbird populations across a variety of ecosystems following conversion to methylmercury (MeHg)—a form of Hg with high potential for bioaccumulation and bioavailability. The amount of bioavailable MeHg in an ecosystem is a function of the amount of total Hg present as well as Hg methylation rates, which vary across the landscape in space and time, and trophic transfer. Using songbirds as an indicator of MeHg bioavailability in terrestrial ecosystems, we evaluated the role of habitat, climate, and trophic level in dictating MeHg exposure risk across a variety of ecosystems. To achieve this objective, 2243 blood Hg samples were collected from 81 passerine and nearpasserine species in New York State, USA, spanning 10 different sampling regions from Long Island to western New York. Using a general linear mixed modeling framework that accounted for regional variation in sampling species composition, we found that wetland habitat area within 100 m of capture location, 50-year average of summer maximum temperatures, and trophic position inferred using stable isotope analysis were all correlated with songbird blood Hg concentrations statewide. Moreover, these patterns had a large degree of spatial variability suggesting that the drivers of MeHg bioavailability differed significantly across the state. Mercury deposition, land cover, and climate are all expected to change throughout the northeastern United States in the coming decades. Terrestrial MeHg bioavailability will likely respond to these changes. Focused research and monitoring efforts will be critical to understand how exposure risk responds to global environmental change across the landscape. Keywords Mercury Methylmercury Songbirds Stable isotopes Climate Wetlands ●
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Introduction Mercury (Hg) is a pollutant that is globally distributed, but locally variable in its availability for biomagnification and bioaccumulation (Evers and Clair 2005; Driscoll et al. 2013). After being emitted to the atmosphere from natural (e.g., volcanoes) and anthropogenic sources (e.g., coal-fired power plants, municipal incinerators), Hg can be transported globally and deposited in habitats far from the original sources (VanArsdale et al. 2005; Driscoll et al. 2007). Additionally, Hg can enter habitats from local sources through atmospheric deposition (e.g., Evers et al. 2007) or via soil and/or water contamination from human activities (e.g., artisanal gold
* Evan M. Adams [email protected] 1
Biodiversity Research Institute, 276 Canco Rd., Portland, ME 04103, USA
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mining Telmer and Veiga 2009; Gibb and O’Leary 2014; industrial sites; Reis et al. 2009; Davis et al. 2012; Amos et al. 20
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