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Mercury correlations among six tissues for four waterbird species breeding in San Francisco Bay, California, USA

Authors

  • Collin A. Eagles-Smith,

    Corresponding author
    1. U.S. Geological Survey, Western Ecological Research Center, Davis Field Station, One Shields Avenue, University of California, Davis, California 95616
    Current affiliation:
    1. The use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government
    • U.S. Geological Survey, Western Ecological Research Center, Davis Field Station, One Shields Avenue, University of California, Davis, California 95616
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  • Joshua T. Ackerman,

    1. U.S. Geological Survey, Western Ecological Research Center, Davis Field Station, One Shields Avenue, University of California, Davis, California 95616
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  • Terrence L. Adelsbach,

    1. U.S. Fish and Wildlife Service, Environmental Contaminants Division, 2800 Cottage Way, Suite W-2605, Sacramento, California 95825
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  • John Y. Takekawa,

    1. U.S. Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, 505 Azuar Drive, Vallejo, California 94592
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  • A. Keith Miles,

    1. U.S. Geological Survey, Western Ecological Research Center, Davis Field Station, One Shields Avenue, University of California, Davis, California 95616
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  • Robin A. Keister

    1. U.S. Geological Survey, Western Ecological Research Center, Davis Field Station, One Shields Avenue, University of California, Davis, California 95616
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  • Published on the Web 4/29/2008.

Abstract

Despite a large body of research concerning mercury (Hg) in birds, no single tissue has been used consistently to assess Hg exposure, and this has hampered comparisons across studies. We evaluated the relationships of Hg concentrations among tissues in four species of waterbirds (American avocets [Recurvirostra americana], black-necked stilts [Himantopus mexicanus], Caspian terns [Hydroprogne caspia; formerly Sterna caspia], and Forster's terns [Sterna forsteri]) and across three life stages (prebreeding adults, breeding adults, and chicks) in San Francisco Bay, California, USA. Across species and life stages, Hg concentrations (least square mean ± standard error) were highest in head feathers (6.45 ± 0.31 μg/g dry wt) and breast feathers (5.76 ± 0.28 μg/g dry wt), followed by kidney (4.54 ± 0.22 μg/g dry wt), liver (4.43 ± 0.21 μg/g dry wt), blood (3.10 ± 0.15 μg/g dry wt), and muscle (1.67 ± 0.08 μg/g dry wt). Relative Hg distribution among tissues, however, differed by species and life stage. Mercury concentrations were highly correlated among internal tissues (r2 ≥ 0.89). Conversely, the relationships between Hg in feathers and internal tissues were substantially weaker (r2 ≤ 0.42). Regression slopes sometimes differed among species and life stages, indicating that care must be used when predicting Hg concentrations in one tissue based on those in another. However, we found good agreement between predictions made using a general tissue-prediction equation and more specific equations developed for each species and life stage. Finally, our results suggest that blood is an excellent, nonlethal predictor of Hg concentrations in internal tissues but that feathers are relatively poor indicators of Hg concentrations in internal tissues.

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