Mercury in swamp sparrows (Melospiza georgiana) from wetland habitats in Wisconsin

Strom, Sean M.; Brady, Ryan S.

doi:10.1007/s10646-011-0734-x

Cited by 6 publications

(3 citation statements)

References 30 publications

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“…However, global increases in circulating mercury have resulted in elevated mercury levels in some vulnerable ecosystems which then accumulates in birds living in these ecosystems. In particular, birds living in bogs, estuaries, and other wetlands are at elevated risk, and average blood mercury levels of 0.05 – 0.9 ppm ww have been reported depending on species and season [7], [12], [13]. Birds living in temperate and tropical high elevation forests may have a moderate risk of mercury accumulation with average blood mercury levels of 0.06 – 0.5 ppm ww [11], [14].…”

Section: Introductionmentioning

confidence: 99%

Mercury Reduces Avian Reproductive Success and Imposes Selection: An Experimental Study with Adult- or Lifetime-Exposure in Zebra Finch

2014

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Mercury is a global pollutant that biomagnifies in food webs, placing wildlife at risk of reduced reproductive fitness and survival. Songbirds are the most diverse branch of the avian evolutionary tree; many are suffering persistent and serious population declines and we know that songbirds are frequently exposed to mercury pollution. Our objective was to determine the effects of environmentally relevant doses of mercury on reproductive success of songbirds exposed throughout their lives or only as adults. The two modes of exposure simulated philopatric species versus dispersive species, and are particularly relevant because of the heightened mercury-sensitivity of developing nervous systems. We performed a dosing study with dietary methylmercury in a model songbird species, the zebra finch (Taeniopygia guttata), at doses from 0.3 – 2.4 parts per million. Birds were exposed to mercury either as adults only or throughout their lives. All doses of mercury reduced reproductive success, with the lowest dose reducing the number of independent offspring produced in one year by 16% and the highest dose, representing approximately half the lethal dose for this species, causing a 50% reduction. While mercury did not affect clutch size or survivorship, it had the most consistent effect on the proportion of chicks that fledged from the nest, regardless of mode of exposure. Among birds exposed as adults, mercury caused a steep increase in the latency to re-nest after loss of a clutch. Birds exposed for their entire lifetimes, which were necessarily the offspring of dosed parents, had up to 50% lower reproductive success than adult-exposed birds at low doses of methylmercury, but increased reproductive success at high doses, suggesting selection for mercury tolerance at the highest level of exposure. Our results indicate that mercury levels in prey items at contaminated sites pose a significant threat to populations of songbirds through reduced reproductive success.

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Section: Introductionmentioning

confidence: 99%

Mercury Reduces Avian Reproductive Success and Imposes Selection: An Experimental Study with Adult- or Lifetime-Exposure in Zebra Finch

2014

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“…Hotspots appeared to be related to the presence of reservoirs (northeastern Minnesota) and lakes with low pH and high sulfate and total organic carbon (northeastern Minnesota), low alkalinity (northwest Illinois and the Upper Peninsula of Michigan), legacy contamination (Upper Peninsula of Michigan), low alkalinity and low pH (Ontario), and low dissolved organic carbon, pH, and acid neutralizing capacity (New York). Strom and Brady (2011) compared Hg accumulation in wetlands between northern and southern Wisconsin using the swamp sparrow (Melospiza georgiana) as a representative, high trophic level biosentinel. Mean blood Hg concentrations were 0.14 ± 0.06 lg/g in northern Wisconsin wetlands and 0.19 ± 0.11 lg/g in southern ones did not differ significantly.…”

Section: Spatial Patterns and Mercury Accumulation In Fish And Wildlifementioning

confidence: 99%

“…Yet the bioaccumulation and ecotoxicological significance of methylmercury in terrestrial invertivores has received little study in the Great Lakes region. A single species of sparrow, the swamp sparrow (Melospiza georgiana), was examined in Wisconsin by Strom and Brady (2011). However, it is known that different-even closely related-species of songbirds often accumulate methylmercury at very different rates Evers et al 2011c;Lane et al 2011).…”

Section: The Great Lakes Region Is An Internationally Significantmentioning

confidence: 99%

Mercury in the Great Lakes region: bioaccumulation, spatiotemporal patterns, ecological risks, and policy

et al. 2011

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This special issue examines bioaccumulation and risks of methylmercury in food webs, fish and wildlife in the Laurentian Great Lakes region of North America, and explores mercury policy in the region and elsewhere in the United States and Canada. A total of 35 papers emanated from a bi-national synthesis of multi-media data from monitoring programs and research investigations on mercury in aquatic and terrestrial biota, a 3-year effort involving more than 170 scientists and decision-makers from 55 different universities, non-governmental organizations, and governmental agencies. Over 290,000 fish mercury data points were compiled from monitoring programs and research investigations. The findings from this scientific synthesis indicate that (1) mercury remains a pollutant of major concern in the Great Lakes region, (2) that the scope and intensity of the problem is greater than previously recognized and (3) that after decades of declining mercury levels in fish and wildlife concentrations are now increasing in some species and areas. While the reasons behind these shifting trends require further study, they also underscore the need to identify information gaps and expand monitoring efforts to better track progress. This will be particularly important as new pollution prevention measures are implemented, as global sources increase, and as the region faces changing environmental conditions.

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Impact of flow diversion by run‐of‐river dams on American dipper diet and mercury exposure

Silverthorn

Bishop

Jardine

et al. 2017

Enviro Toxic and Chemistry

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Run-of-river dams produce lower greenhouse gas emissions than large hydropower projects, but there is a paucity of research on their potential ecotoxicological impacts through disruption of natural flow regimes. We used stable isotopes (δ C, δ N, δ S) to reconstruct diet and trace methylmercury in a predatory river-resident passerine, the American dipper (Cinclus mexicanus), at 7 regulated and 6 free-flowing mountain streams in coastal British Columbia, Canada. Assimilated diets were comparable among regulated and unregulated streams, dominated by benthic macroinvertebrates and resident freshwater fish, with negligible contributions from anadromous Pacific salmon. Although invertebrates at unregulated streams were isotopically similar along their gradient, dippers and invertebrates sampled below dams on regulated streams had S-depleted tissues, suggesting increased activity of sulfate-reducing bacteria and more Hg methylation below the dams. Mercury concentrations in dipper blood (417.6 ± 74.1 standard error [SE] ng/g wet wt at regulated streams, 340.7 ± 42.7 SE ng/g wet wt at unregulated streams) and feathers (1564 .6 ± 367.2 SE ng/g dry wt regulated, 1149.0 ± 152.1 SE ng/g dry wt unregulated), however, were not significantly different between stream types. Relative to other passerines across western North America, dippers in these densely forested mountain streams experienced high mercury exposure; and one recently regulated stream supported dippers with mercury concentrations of potential toxicity concern (up to 8459.5 ng/g dry wt in feathers and 1824.6 ng/g wet wt in whole blood). Elevated mercury in dippers is likely attributable to the birds' relatively high trophic position and high regional inorganic mercury deposition; however, biogeochemical conditions in reservoirs of some regulated streams may be contributing to methylmercury production. Environ Toxicol Chem 2018;37:411-426. © 2017 SETAC.

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Mercury in swamp sparrows (Melospiza georgiana) from wetland habitats in Wisconsin

Cited by 6 publications

References 30 publications

Mercury Reduces Avian Reproductive Success and Imposes Selection: An Experimental Study with Adult- or Lifetime-Exposure in Zebra Finch

Mercury Reduces Avian Reproductive Success and Imposes Selection: An Experimental Study with Adult- or Lifetime-Exposure in Zebra Finch

Mercury in the Great Lakes region: bioaccumulation, spatiotemporal patterns, ecological risks, and policy

Impact of flow diversion by run‐of‐river dams on American dipper diet and mercury exposure

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