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Effects of Mercury on Fish-eating and Aquatic Birds Nesting along the Mid-to-Lower Carson River and Willamette River Headwaters
Completed
During the Comstock mining era of the late 1800s, liquid mercury was used to process gold and silver ore mined from Virginia City, Nevada and nearby areas. Along with the waste rock, known as tailings, 7,500 tons of mercury are believed to have been released into the Carson River watershed. Over the years, the mercury has washed downstream into the middle and lower reaches of the Carson River, Lahontan Reservoir, and the wetlands in Lahontan Valley at the terminus of the system. Lahontan Reservoir and Lahontan Valley wetlands provide important habitat to a wide variety of birds, including many migratory species. In the 1970s and 1980s, researchers at the Nevada Division of Environmental Protection, University of Nevada at Reno, U.S. Fish and Wildlife Service, and U.S. Geological Survey began to identify the nature, extent, and impact of the contamination. The Carson River Mercury Site was listed as a Federal Superfund Site on EPAs National Priorities List in August 1990. The site includes mercury-contaminated soils and sediments associated with historical milling activities. Mercury-contaminated tailings are known to have been discharged adjacent to or into Gold Canyon, Seven Mile Canyon, Six Mile Canyon, and a several-mile-long reach of the Carson River downstream of New Empire, Nevada. Contaminated areas are known to include the mill sites, the creeks and rivers adjacent to the mill sites into which mercury-contaminated tailings were discharged, and downstream waterways into which the creeks now flow or in the past have flowed (e.g., the Carson River floodplain). The Lahontan Dam, completed in 1915 as part of the Newlands Irrigation Project, now limits the downstream areas. The vast network of canals, laterals, and drains of the Newlands Irrigation Project has widely distributed mercury-contaminated sediment throughout the Lahontan Valley. The mercury-contaminated area currently extends from New Empire to the Carson Playa and includes portions of Lyon and Churchill Counties. We developed a similar study in the headwaters of the Willamette River. The Willamette River has public health fish advisories posted due to elevated mercury levels. The American Dipper nests in the headwaters and is a logical candidate species to evaluate possible adverse effects of mercury on avian species. Prey species (mayflies, caddisflies, and stoneflies) will be collected and analyzed for methylmercury and total mercury. Of special concern is the accumulation of mercury in dipper eggs and nestling feathers and possible effects on reproduction at the two principal Willamette River tributaries with mining activities.
PROGRAM: Contaminant Biology 5-YEAR GOAL (goals 2,3; objectives 2A,2D,2F,3B; strategies 2A-5,2D-2,2F-1,3B-4A,3B-5D)
The objective is to evaluate the ecological risk posed by mercury. The study will evaluate possible effects of mercury on the reproductive success of several bird species by evaluating the relationship between mercury concentrations in one sample egg collected from each nest and the success or failure of the remaining eggs incubated in the nest. The sample egg technique often is used in bird ecotoxicology studies. In addition, mercury levels in the diet of the young birds will be measured because mercury may affect post-hatch survival. The study will also include efforts to identify sub-lethal effects. Information on nesting success and mercury concentrations in bird eggs and nestling feathers will be determined.
Young waterbirds from the Carson River and reference site(s) will be evaluated for deformities and abnormalities, and blood and tissues will be collected and analyzed for biochemical indicators and histological lesions associated with mercury exposure. The current study design includes measurement of bird reproductive success at locations with varying amounts of mercury contamination so that dose-response relationships can be examined. In addition, statistical comparisons between the two locations will be possible, and a minimum acceptable sample size for each location has been calculated so meaningful pair-wise comparisons can be made. The design of the study for assessing mercury exposure and effects on American Dippers in headwaters of the Willamette River calls for collection of dipper eggs, nestling feathers and macroinvertebrate samples and an evaluation of the reproductive success of dippers in relation to mercury residues in dipper and macroinvertebrate tissues along three principal tributaries of the upper Willamette River (one polluted with a cinnabar mine, one with elevated mercury levels from gold mining operations, and a reference tributary with no mercury or gold mines).
Hill, E.F., Henny, C.J., Grove, R.A., 2008, Mercury and drought along the lower Carson River, Nevada- II. Snowy egret and black-crowned night-heron reproduction on Lahontan Reservoir, 1997-2006: Ecotoxicology, v. 17, p. 117-131. [Highlight] [Abs] [FullText] Catalog No: 1892 Henny, C.J., Hill, E.F., Grove, R.A., Kaiser, J.L., 2007, Mercury and drought along the lower Carson River, Nevada- I. Snowy egret and black-crowned night-heron annual exposure to mercury, 1997-2006: Archives of Environmental Contamination and Toxicology, v. 53, p. 269-280. [Highlight] [FullText] Catalog No: 1636 Henny, C.J., Kaiser, J.L., Packard, H.A., Grove, R.A., Taft, M.R., 2005, Assessing mercury exposure and effects to American dippers in headwater streams near mining sites: Ecotoxicology, v. 14, p. 709-725. [Highlight] [FullText] Catalog No: 1413 Henny, C.J., Hill, E.F., Hoffman, D.J., Spalding, M.G., Grove, R.A., 2002, Nineteenth century mercury- Hazard to wading birds and cormorants of the Carson River, Nevada: Ecotoxicology, v. 11, no. 4, p. 213-231. [Highlight] [Abs] [FullText] Catalog No: 1127 Henny, C.J., Hoffman, D.J., Keith, J.O., Spalding, M., Hill, E.F., 1998, Progress Report- Effects of mercury on fish-eating birds nesting along the Carson River drainage, Nevada: U.S. Environmental Protection Agency, Region 9 Interagency Agreement No DW-14955335-01-01, p. 38. [FullText] Catalog No: 296 Henny, C.J., 1997, DDE still high in white-faced ibis eggs from Carson Lake, Nevada.: Colonial Waterbirds, v. 20, no. 3, p. 478-484. [FullText] Catalog No: 151
Henny, Charles J. - Research Zoologist
Phone: 541-757-4840
Email: charles_j_henny@usgs.gov
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