Tracking Overwintering Areas of Fish-Eating Birds to Identify Mercury Exposure

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• 作者：Raphael A. Lavoie ; T. Kurt Kyser ; Vicki L. Friesen ; Linda M. Campbell
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：January 20, 2015
• 年：2015
• 卷：49
• 期：2
• 页码：863-872
• 全文大小：476K
• ISSN：1520-5851

文摘

Migration patterns are believed to greatly influence concentrations of contaminants in birds due to accumulation in spatially and temporally distinct ecosystems. Two species of fish-eating birds, the Double-crested Cormorant (Phalacrocorax auritus) and the Caspian Tern (Hydroprogne caspia) breeding in Lake Ontario were chosen to measure the impact of overwintering location on mercury concentrations ([Hg]). We characterized (1) overwintering areas using stable isotopes of hydrogen (未²H) and band recoveries, and (2) overwintering habitats by combining information from stable isotopes of sulfur (未³⁴S), carbon (未¹³C), nitrogen (未¹⁵N), and 未²H in feathers grown during the winter. Overall, overwintering location had a significant effect on [Hg]. Both species showed high [Hg] in ¹³C-rich habitats. In situ production of Hg (e.g., through sulfate reducing bacteria in sediments) and allochthonous import could explain high [Hg] in birds visiting ¹³C-rich habitats. Higher [Hg] were found in birds with high 未²H, suggesting that Hg is more bioavailable in southern overwintering locations. Hotspot maps informed that higher [Hg] in birds were found at the limit of their southeastern overwintering range. Mercury concentrations in winter feathers were positively related to predicted spatial pattern of [Hg] in fish using the National Descriptive Model of Mercury in Fish (NDMMF) based on bird spatial assignment (using 未²H). This study indicates that the overwintering location greatly influences [Hg].