Estimating Mercury Exposure of Piscivorous Birds and Sport Fish Using Prey Fish Monitoring

Ackerman, Joshua T.; Hartman, C. Alex; Eagles‐Smith, Collin A.; Herzog, Mark P.; Davis, Jay A; Ichikawa, G.; Bonnema, A.

doi:10.1021/acs.est.5b02691

Cited by 21 publications

(35 citation statements)

References 37 publications

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“…Back-transformed standard errors were estimated using the delta method (Seber 1982). In order to standardize the relative risk estimates, the least squares mean prey fish THg concentration in each grid was converted to the equivalent avian blood THg concentrations using the global equation from Ackerman et al (2015), which synthesized seven different study’s equations (Eq. 3).…”

Section: 0 Materials and Methodsmentioning

confidence: 99%

“…(Ackerman et al, 2015)

ln false(italicBird italicBlood T H g_{ww} false) = 1.788 + 0.6182 * ln false(normalPr e y italicFish T H g_{ww} false)

…”

Section: 0 Materials and Methodsmentioning

confidence: 99%

“…Loons and Osprey are known to focus on fish prey, but Bald Eagles often consume carrion or terrestrial prey not related to fish. Grebes and Kingfishers will eat a variety of invertebrates in addition to small fish (Kelly et al, 2009; Storer and Nuechterlien, 1992; LaPorte et al, 2013), but prey fish THg concentrations are very highly correlated to grebe blood THg concentrations (Ackerman et al 2015). Third, it was assumed that birds were eating the same fish species that were included within the fish Hg database.…”

Section: 0 Materials and Methodsmentioning

confidence: 99%

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Mercury risk to avian piscivores across western United States and Canada

Jackson

Evers

Eagles‐Smith

et al. 2016

Science of The Total Environment

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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 limit 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=36 cm, Osprey=30 cm, Common and Yellow-billed Loon=15 cm, Western and Clark’s Grebe=6 cm, and Belted Kingfisher=5 cm) 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 (<0.5 μg/g), low (0.5 – 1 μg/g), moderate (1 – 2 μg/g), high (2 – 3 μg/g), and extra high (>3 μg/g). These risk categories were used to estimate potential mercury risk to avian piscivores across the west at a 1 degree-by-1 degree grid cell resolution. Avian piscivores foraging on larger-sized fish generally were at higher relative risk to Hg. Habitats with 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.

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Section: 0 Materials and Methodsmentioning

confidence: 99%

“…(Ackerman et al, 2015)

ln false(italicBird italicBlood T H g_{ww} false) = 1.788 + 0.6182 * ln false(normalPr e y italicFish T H g_{ww} false)

…”

Section: 0 Materials and Methodsmentioning

confidence: 99%

Section: 0 Materials and Methodsmentioning

confidence: 99%

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Mercury risk to avian piscivores across western United States and Canada

Jackson

Evers

Eagles‐Smith

et al. 2016

Science of The Total Environment

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“…Therefore, a percent moisture of 79% (see Eagles-Smith et al, 2008) was assumed to convert μg/g dw to μg/g ww. (eq 3)

ln (Female Bird Blood {italicTHg}_{\frac{normalμ g}{g} w w}) = 1.0734 \times ln (Egg {italicTHg}_{\frac{normalμ g}{g} fww}) + 0.8149

(R 2 = 0.95; Ackerman et al, 2016a) (eq 4)

ln (Female Bird Blood {italicTHg}_{\frac{normalμ g}{g} w w}) = 0.6182 \times ln (Preg Fish {italicTHg}_{\frac{normalμ g}{g} fww}) + 1.788

(Ackerman et al, 2015) (eq 5)

ln (Blood {italicTHg}_{\frac{normalμ g}{g} w w}) = 1.080 \times ln (Bird Muscle {italicTHg}_{\frac{normalμ g}{g} d w}) - 1.024

(R 2 = 0.90; Eagles-Smith et al, 2008) c Moisture content from the study was used if reported. If it was not reported, a moisture content of 67% in liver, 75% in eggs, 70% in muscle, and 79% in blood was used (Eagles-Smith et al, 2008).…”

Section: Figurementioning

confidence: 99%

“…(eq 4)

ln (Female Bird Blood {italicTHg}_{\frac{normalμ g}{g} w w}) = 0.6182 \times ln (Preg Fish {italicTHg}_{\frac{normalμ g}{g} fww}) + 1.788

(Ackerman et al, 2015)…”

Section: Figurementioning

confidence: 99%

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

Ackerman

Eagles‐Smith

Herzog

et al. 2016

Science of The Total Environment

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198

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Methylmercury contamination of the environment is an important issue globally and birds are useful bioindicators for mercury monitoring programs. The available data on mercury contamination of birds in western North America were synthesized. Original data from multiple databases were obtained and a literature review was conducted to obtain additional mercury concentrations. In total, 29219 original bird mercury concentrations from 225 species were compiled, and an additional 1712 mean mercury concentrations, representing 19998 individuals and 176 species, from 200 publications were obtained. To make mercury data comparable across bird tissues, published equations of tissue mercury correlations were used 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. Bird mercury concentrations were above toxicity benchmarks in many areas throughout western North America, and multiple hotspots were identified. Additionally, published toxicity benchmarks established in multiple tissues were summarized and translated into a common blood-equivalent mercury concentration. Overall, 66% of birds sampled in western North American exceeded a blood-equivalent mercury concentration of 0.2 μg/g wet weight (ww; above background levels), which is the lowest-observed effect level, 28% exceeded 1.0 μg/g ww (moderate risk), 8% exceeded 3.0 μg/g ww (high risk), and 4% exceeded 4.0 μg/g ww (severe risk). Mercury monitoring programs should sample bird tissues, such as adult blood and eggs, that are most-easily translated into tissues with well-developed toxicity benchmarks and that are directly relevant to bird reproduction. Results indicate that mercury contamination of birds is prevalent in many areas throughout western North America, and large-scale ecological attributes are important factors influencing bird mercury concentrations.

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Spatial patterns of mercury contamination and associated risk to piscivorous wading birds of the south central United States

Gerstle

Drenner

Chumchal

2018

Enviro Toxic and Chemistry

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Piscivorous birds are top predators in aquatic ecosystems and are vulnerable to mercury (Hg) exposure and associated adverse health effects. In some areas of North America, the health risk posed to piscivorous birds by Hg contamination has not been characterized because concentrations of Hg in bird tissues have not been extensively monitored. When data on Hg in tissues of piscivorous birds are not available, the concentration of Hg in the blood of piscivorous birds can be estimated from the concentration of Hg in prey fish. We used concentrations of Hg in different lengths of a proxy prey fish, bluegill (Lepomis macrochirus), to estimate the concentration of Hg in the blood of 4 species of adult piscivorous wading birds (little blue herons [Egretta caerulea], green herons [Butorides virescens], great egrets [Ardea albus], and great blue herons [Ardea herodias]) in 14 ecoregions of the south central United States. The 4 species of birds consume different sizes of fish with different concentrations of Hg and were predicted to have different concentrations of Hg in their blood, with little blue herons < green herons < great egrets < great blue herons. For each species of bird, there were significant differences in average estimated concentrations of Hg in blood between ecoregions, with estimated concentrations of Hg in blood increasing with Hg deposition. The level of predicted risk varied with ecoregion and bird species and was highest for great blue herons. We recommend that future studies of Hg contamination of piscivorous wading birds of the southern United States focus on great blue herons in water bodies within ecoregions that have high Hg deposition. Environ Toxicol Chem 2019;38:160–166. © 2018 SETAC

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Estimating Mercury Exposure of Piscivorous Birds and Sport Fish Using Prey Fish Monitoring

Cited by 21 publications

References 37 publications

Mercury risk to avian piscivores across western United States and Canada

Mercury risk to avian piscivores across western United States and Canada

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

Spatial patterns of mercury contamination and associated risk to piscivorous wading birds of the south central United States

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