title: Mercury risk to avian piscivores across western United States and Canada.
abstract: The widespread distribution of mercury (Hg) threatens wildlife health, particularly piscivorous birds. Western North America is a diverse region that provides critical habitat to many piscivorous bird species, and also has a well-documented history of mercury contamination from legacy mining and atmospheric deposition. The diversity of landscapes in the west limits the distribution of avian piscivore species, complicating broad comparisons across the region. Mercury risk to avian piscivores was evaluated across the western United States and Canada using a suite of avian piscivore species representing a variety of foraging strategies that together occur broadly across the region. Prey fish Hg concentrations were size-adjusted to the preferred size class of the diet for each avian piscivore (Bald Eagle=36cm, Osprey=30cm, Common and Yellow-billed Loon=15cm, Western and Clark's Grebe=6cm, and Belted Kingfisher=5cm) across each species breeding range. Using a combination of field and lab-based studies on Hg effect in a variety of species, wet weight blood estimates were grouped into five relative risk categories including: background (<0.5μg/g), low (0.5-1μg/g), moderate (1-2μg/g), high (2-3μg/g), and extra high (>3μg/g). These risk categories were used to estimate potential mercury risk to avian piscivores across the west at a 1degree-by-1degree grid cell resolution. Avian piscivores foraging on larger-sized fish generally were at a higher relative risk to Hg. Habitats with a relatively high risk included wetland complexes (e.g., prairie pothole in Saskatchewan), river deltas (e.g., San Francisco Bay, Puget Sound, Columbia River), and arid lands (Great Basin and central Arizona). These results indicate that more intensive avian piscivore sampling is needed across Western North America to generate a more robust assessment of exposure risk.
authors.affiliation: Oregon State University, Department of Fisheries and Wildlife, 104 Nash Hall, Corvallis, OR 97331, USA. Electronic address: allyson.jackson@oregonstate.edu.
authors.forename: Allyson
authors.initials: A
authors.lastname: Jackson
authors.affiliation: Biodiversity Research Institute, 276 Canco Road, Portland, ME 04103, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Evers
authors.affiliation: U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, OR 97331, USA.
authors.forename: Collin A
authors.initials: CA
authors.lastname: Eagles-Smith
authors.affiliation: U.S. Geological Survey, Western Ecological Research Center, Dixon Field Station, 800 Business Park Drive, Suite D, Dixon, CA 95620, USA.
authors.forename: Joshua T
authors.initials: JT
authors.lastname: Ackerman
authors.affiliation: U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, OR 97331, USA.
authors.forename: James J
authors.initials: JJ
authors.lastname: Willacker
authors.affiliation: Environment Canada Science and Technology Branch, Pacific Wildlife Research Centre, Delta, British Columbia V4K 3N2, Canada.
authors.forename: John E
authors.initials: JE
authors.lastname: Elliott
authors.affiliation: Colorado Parks and Wildlife, 317 West Prospect Rd., Fort Collins, CO 80526, USA.
authors.forename: Jesse M
authors.initials: JM
authors.lastname: Lepak
authors.affiliation: National Institute of Standards and Technology, Chemical Sciences Division, Hollings Marine Laboratory, 331 Fort Johnson Road, Charleston, SC 29412, USA.
authors.forename: Stacy S
authors.initials: SS
authors.lastname: Vander Pol
authors.affiliation: National Institute of Standards and Technology, Chemical Sciences Division, Hollings Marine Laboratory, 331 Fort Johnson Road, Charleston, SC 29412, USA.
authors.forename: Colleen E
authors.initials: CE
authors.lastname: Bryan
mesh_terms: D000818:Animals; D001717:Birds / Q000097:blood* / Q000254:growth & development; D002170:Canada; D016208:Databases, Factual; D004781:Environmental Exposure / Q000032:analysis* / Q000517:prevention & control; D004784:Environmental Monitoring; D005399:Fishes / Q000097:blood* / Q000254:growth & development; D020387:Food Chain; D008099:Liver / Q000737:chemistry; D008628:Mercury / Q000032:analysis* / Q000097:blood; D015205:Northwestern United States; D010063:Ovum / Q000737:chemistry; D018570:Risk Assessment; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000097:blood
chemical_list: D014874:Water Pollutants, Chemical; D008628:Mercury
keywords: Bioindicator; Fish; Methylmercury; Risk assessment