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Avian mercury exposure and toxicological risk across western North America: a synthesis

Published

Author(s)

Joshua T. Ackerman, Collin A. Eagles-Smith, Mark P. Herzog, Alex Hartman, Sarah Peterson, David C. Evers, Allyson Jackson, John E. Elliott, Stacy S. Schuur, Colleen E. Bryan Sallee

Abstract

Methylmercury contamination of the environment is an important issue globally and birds are useful bioindicators for mercury monitoring programs. We synthesized all of the available data on mercury contamination of birds in western North America. We obtained original data from multiple databases and conducted a literature review to obtain additional mercury concentrations. In total, we compiled 29,219 original bird mercury concentrations from 225 species, and obtained an additional 1,712 mean mercury concentrations, representing 19,998 individuals, from 200 publications on 176 species. To make the mercury data comparable across bird tissues, we used published nist-equations of tissue mercury correlations to convert all mercury concentrations into blood-equivalent mercury concentrations. Blood-equivalent mercury concentrations differed among species, foraging guilds, habitat types, locations, and ecoregions. Piscivores and carnivores exhibited the greatest mercury concentrations, whereas herbivores and granivores exhibited the lowest mercury concentrations. Bird mercury concentrations were greatest in ocean and salt marsh habitats and lowest in terrestrial habitats. Mercury concentrations of individual birds were above toxicity benchmarks in many areas throughout western North America, and multiple hotspots for bird mercury contamination were identified. We summarized published toxicity benchmarks established in multiple tissues, and translated them into a common blood-equivalent mercury concentration. Overall, 28% of birds sampled in western North American exceeded a blood-equivalent mercury concentration of 1.0 μg/g ww, 15% exceeded 2.0 μg/g ww, 8% exceeded 3.0 μg/g ww, and 4% exceeded 4.0 μg/g ww. We recommend that future mercury monitoring programs sample bird tissues that are most-easily translated into a tissue that has a well-developed toxicity benchmark and that are directly relevant to bird reproduction. High priority sampling tissues include adult blood and egg
Citation
Science of the Total Environment
Volume
568

Keywords

Birds, Mercury, Eggs, Bioaccumulation, Toxicity Benchmarks
Created October 15, 2016, Updated November 10, 2018