I am a Research Ecologist with the USGS Forest and Rangeland Ecosystem Science Center in Corvallis, Oregon. My research focuses on the interactions among ecological processes, contaminant bioaccumulation, and effects on wild populations.
My work specifically focuses on (1) the ecological factors regulating contaminant bioaccumulation and trophic transfer, with an emphasis on food web processes and contaminant cycling, (2) land use practices and ecosystem restoration effects on contaminant cycling through food webs, and (3) the sublethal effects of contaminants on individuals and contaminant-induced impairment to reproduction in the wild. My research is broadly applied across taxa - primarily fish and waterbirds, and habitat types - including lakes, freshwater wetlands, agricultural fields, and estuarine habitats.
Professional Experience
2010-present: Supervisory Research Ecologist, USGS Forest and Rangeland Ecosystem Science Center, Corvallis, OR
2007-2010: Wildlife Biologist, USGS Western Ecological Research Center, Davis, CA
2003-2007: Biologist, U.S. Fish and Wildlife Service, Sacramento, CA
Education and Certifications
Ph.D., Ecology, University of California, Davis, CA (2006)
B.S., Environmental Resource Sciences - Magna Cum Laude, University of California, Davis, CA (2000)
Science and Products
Contaminant Ecology Research Team (FRESC)
Ecologically-Driven Exposure Pathways Science Team
Scientists Provide an Understanding of Anticoagulant Rodenticide Exposure in Non-Target Bird Species
Nationwide Occurrence
Bioaccumulation of Mercury in Fish Varied by Species and Location in the Chesapeake Bay Watershed—Summary of Existing Data and a Roadmap for Integrated Monitoring
Dragonfly Larvae are Effective Bioindicators of Mercury Exposure in Fish and Amphibians—Results of Citizen Science in 100 National Parks and Protected Places
Roadmap to Understanding Factors Influencing Mercury Exposure and Adverse Health Effects
Scientists Identify Processes that Affect Fish Mercury Concentrations in Estuarine Wetlands
Ecosystem Effects of Increased Coal Transport Across the Pacific Northwest
Contaminant Ecology Research Team (FRESC)
Mercury Cycling and Effects on Ecological Communities
Habitat and Land-Use Influences on Contaminant Bioaccumulation
Contaminant Bioaccumulation through Food Webs
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
Mercury and biogeochemical parameters in surface water and sediment from U.S. National Parks, 2014-2015
Total mercury and methylmercury in biota from Cottage Grove Reservoir and the Coast Fork Willamette River, Oregon, 2021
Survival, growth, behavior and mercury concentrations of mayflies exposed to elevated dietary methylmercury and aqueous selenium
Anticoagulant rodenticide concentrations in blood and tissue of California condors and turkey vultures
Biomass and methylmercury concentrations in biweekly biological samples from Brownlee and Oxbow Reservoir outflows, Snake River Hells Canyon Complex (Idaho-Oregon), 2018-2019
Total Mercury Concentrations in Dragonfly Larvae from U.S. National Parks (ver. 8.0, December 2022)
Mercury Concentrations and Stable Isotopes in Riparian Songbirds and Invertebrates from the Willamette River, Oregon, 2013
Mercury Concentrations and Mercury Isotopes in Salmonid fishes from the Snake River and tributaries in Idaho and Oregon, 2015 and 2019 (ver. 2.0, February 2021)
Mercury Bioaccumulation in US National Parks Using Dragonfly Larvae as Biosentinels, 2009-2018
Total Mercury Concentrations in Smallmouth Bass from Chesapeake Bay Tributaries, USA Dataset, 2013-2017
Fish tissue mercury and selenium concentrations in Upper Colorado River Basin: 1962-2011
Trask River Watershed Study Area Forestry Bioaccumulation Dataset, 2011-2015
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
The influence of short-term temporal variability on the efficacy of dragonfly larvae as mercury biosentinels
In-reservoir physical processes modulate aqueous and biological methylmercury export from a seasonally anoxic reservoir
Collateral damage: Anticoagulant rodenticides pose threats to California condors
Using carbon, nitrogen, and mercury isotope values to distinguish mercury sources to Alaskan lake trout
Mercury exposure of tidal marsh songbirds in the northeastern United States and its association with nest survival
Lethal impacts of selenium counterbalance the potential reduction in mercury bioaccumulation for freshwater organisms☆
Small mammal shooting as a conduit for lead exposure in avian scavengers
Metal accumulation varies with life history, size, and development of larval amphibians
Differential reliance on aquatic prey subsidies influences mercury exposure in riparian arachnids and songbirds
Demethylation of methylmercury in bird, fish, and earthworm
Isotope fractionation from In Vivo methylmercury detoxification in waterbirds
Examining historical mercury sources in the Saint Louis River estuary: How legacy contamination influences biological mercury levels in Great Lakes coastal regions
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Mercury Condition Index Tool
To request an interview, contact fresc_outreach@usgs.gov or call (541) 750-1030.
Science and Products
- Science
Contaminant Ecology Research Team (FRESC)
The FRESC Contaminant Ecology research program evaluates the distribution, movement, and ecological effects of environmental contaminants across the landscape and strives to provide relevant science in support of natural resource conservation, management, and decision making.Filter Total Items: 18Ecologically-Driven Exposure Pathways Science Team
The Ecologically-Driven Exposure pathways team identifies internal and external pathways and processes that can alter exposure and toxicity of contaminants and pathogens to wildlife the environment. That information is used to distinguish actual health risks to fish and wildlife. If actual risks are identified this project will inform how to economically and effectively minimize risk by providing...Scientists Provide an Understanding of Anticoagulant Rodenticide Exposure in Non-Target Bird Species
U.S. Geological Survey scientists and their partners utilize laboratory and field studies and existing information to improve understanding of anticoagulant rodenticide exposure and effects to wild birds.Nationwide Occurrence
A National-scale approach is used to examine and analyze per- and polyfluoroalkyl substances (PFAS) prevalence and magnitude in watersheds and aquifers. As an initial step to fill known science gaps in the understanding of human and wildlife exposure, the team will provide a snapshot of PFAS in drinking water paired with bioaccumulation in fish and wildlife near known or suspected sources of...Bioaccumulation of Mercury in Fish Varied by Species and Location in the Chesapeake Bay Watershed—Summary of Existing Data and a Roadmap for Integrated Monitoring
Fish mercury data from State monitoring programs and research studies within the Chesapeake Bay were compiled and summarized to provide a comprehensive overview of the variation in fish mercury concentrations among species and habitats within the watershed. These data are put into context with existing health benchmarks for humans, birds, and fish. Scientists also provide a roadmap for an...Dragonfly Larvae are Effective Bioindicators of Mercury Exposure in Fish and Amphibians—Results of Citizen Science in 100 National Parks and Protected Places
Mercury concentrations were measured in dragonfly larvae across more than 450 sites in 100 national parks and protected places as part of a partnership among Federal agencies, academic researchers, and more than 4,000 citizen scientists. Mercury concentrations in dragonfly larvae were positively correlated with mercury concentrations in fish and amphibians living in the same aquatic environments...Roadmap to Understanding Factors Influencing Mercury Exposure and Adverse Health Effects
In a comprehensive overview, scientists explain that human and wildlife exposure and toxicological responses to mercury are dependent on factors that operate across global, individual, and molecular scales. They provide a roadmap for unified research to facilitate a better understanding of human and wildlife health risks from mercury exposure.Scientists Identify Processes that Affect Fish Mercury Concentrations in Estuarine Wetlands
In a study designed to help resource managers when considering mercury exposure risk, scientists determined that sulfur cycling—a process closely related to mercury methylation rates—and ecological conditions that influence exposure are important factors affecting fish mercury concentrations in estuarine wetlands.Ecosystem Effects of Increased Coal Transport Across the Pacific Northwest
Proposed new coal export terminals in Washington and Oregon could increase rail traffic through the Northwest and potentially increase unintended release of coal dust to the environment.Contaminant Ecology Research Team (FRESC)
The FRESC Contaminant Ecology research program evaluates the distribution, movement, and ecological effects of environmental contaminants across the landscape and strives to provide relevant science in support of natural resource conservation, management, and decision making.Mercury Cycling and Effects on Ecological Communities
Mercury contamination is a serious issue that impacts both ecosystem and human health on a global scale. In its organic (methylmercury) form, mercury is highly bioaccumulative and is among the most toxic compounds commonly found in the environment. Mercury is a relatively distinctive contaminant in the sense that the risk of deleterious environmental effects is more strongly related to ecological...Habitat and Land-Use Influences on Contaminant Bioaccumulation
The distribution and occurrence of contaminants and the associated biological exposure in ecological systems are driven by complex interactions between contaminant sources and mobilization pathways that are overlaid upon the habitat requirements of at-risk organisms. Moreover, landscape structure and land uses can strongly influence the driving processes of contaminant cycling, as well as the...Contaminant Bioaccumulation through Food Webs
This is a broad theme representing the largest component of the Contaminant Ecology Research Program, acting as a bridge between the “Habitat and Land Use Influences” and “Ecological Effects” themes. “Contaminant Bioaccumulation” focuses on quantifying the transfer or movement of contaminants through food webs, and identifying the primary landscape factors and ecological mechanisms that are... - Data
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
Filter Total Items: 18Mercury and biogeochemical parameters in surface water and sediment from U.S. National Parks, 2014-2015
Comma-separated values (.csv) file containing data related to mercury and biogeochemical parameters in surface water and aquatic sediment collected from U.S. National Parks in 2014-2015.Total mercury and methylmercury in biota from Cottage Grove Reservoir and the Coast Fork Willamette River, Oregon, 2021
Comma-separated values (.csv) file containing data related to mercury in biota from Cottage Grove Reservoir, and the rivers upstream of Cottage Grove Reservoir, Oregon.Survival, growth, behavior and mercury concentrations of mayflies exposed to elevated dietary methylmercury and aqueous selenium
Survival and size of mayflies at each life stage, as well as MeHg concentrations in diatoms and mayflies exposed to low and high MeHg concentrations and a range of selenomethione (SeMet) concentrations.Anticoagulant rodenticide concentrations in blood and tissue of California condors and turkey vultures
The dataset includes specifics on liver tissue and blood plasma anticoagulant rodenticide concentrations measured using high-performance liquid chromatography-tandem mass spectrometry.Biomass and methylmercury concentrations in biweekly biological samples from Brownlee and Oxbow Reservoir outflows, Snake River Hells Canyon Complex (Idaho-Oregon), 2018-2019
This dataset describes biomass and methylmercury concentrations in zooplankton, other invertebrates, fish, and coarse and fine detritus samples collected at the outflow locations of Brownlee and Oxbow Reservoirs in the Snake River Hells Canyon Complex. Based on the sampling locations, the sampled materials were presumed to have flowed through the dam turbines or over the spillway, thereby represenTotal Mercury Concentrations in Dragonfly Larvae from U.S. National Parks (ver. 8.0, December 2022)
Comma-separated values (.csv) file containing data related to mercury concentrations in dragonfly samples from U.S. National Parks collected as part of the Dragonfly Mercury Project (DMP)Mercury Concentrations and Stable Isotopes in Riparian Songbirds and Invertebrates from the Willamette River, Oregon, 2013
This dataset includes bird species, invertebrate order and family, sample identification codes, collection date, latitude, longitude, site name, bird age, invertebrate life stage, invertebrate trophic group, carbon and nitrogen stable isotopes in birds and invertebrates, total mercury concentrations in bird blood, and methylmercury concentrations in composite invertebrates.Mercury Concentrations and Mercury Isotopes in Salmonid fishes from the Snake River and tributaries in Idaho and Oregon, 2015 and 2019 (ver. 2.0, February 2021)
Comma-separated values (.csv) file containing data related to mercury in Salmonid fishes collected from the Snake River and tributaries, Idaho and Oregon.Mercury Bioaccumulation in US National Parks Using Dragonfly Larvae as Biosentinels, 2009-2018
Comma-separated values (.csv) files containing data related to a National-scale assessment of mercury bioaccumulation in the US National Parks using dragonfly larvae as biosentinels through a citizen science framework.Total Mercury Concentrations in Smallmouth Bass from Chesapeake Bay Tributaries, USA Dataset, 2013-2017
This dataset includes fish scientific name, fish common name, site identification codes, latitude, longitude, site name, sample identification codes, collection date, tissue type, percent moisture content in fish samples, and wet and dry total mercury concentrations in fish tissues.Fish tissue mercury and selenium concentrations in Upper Colorado River Basin: 1962-2011
These data were compiled to study mercury and selenium concentrations in fish species and assemblages in lotic waterbodies across the Upper Colorado River Basin. Data were compiled from State and Federal agencies. This data table contains raw concentration data, as well as standardized concentrations corrected for differences based on sample type (i.e., tissue type), species-specific bioaccumulatiTrask River Watershed Study Area Forestry Bioaccumulation Dataset, 2011-2015
This dataset includes timber harvest treatments; mercury concentrations in aquatic macroinvertebrates, salamanders, and riparian songbirds; carbon and nitrogen stable isotopes in aquatic macroinvertebrates and salamanders; and Bayesian estimates of food web length, basal resource diversity, and isotopic niche size for individual feeding guilds. - Multimedia
- Publications
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
Filter Total Items: 122The influence of short-term temporal variability on the efficacy of dragonfly larvae as mercury biosentinels
Mercury (Hg) exposure to fish, wildlife, and humans is widespread and of global concern, thus stimulating efforts to reduce emissions. Because the relationships between rates of inorganic Hg loading, methylmercury (MeHg) production, and bioaccumulation are extremely complex and challenging to predict, there is a need for reliable biosentinels to understand the distribution of Hg in the environmentIn-reservoir physical processes modulate aqueous and biological methylmercury export from a seasonally anoxic reservoir
Anoxic conditions within reservoirs related to thermal stratification and oxygen depletion lead to methylmercury (MeHg) production, a key process governing the uptake of mercury in aquatic food webs. Once formed within a reservoir, the timing and magnitude of the biological uptake of MeHg and the relative importance of MeHg export in water versus biological compartments remain poorly understood. WCollateral damage: Anticoagulant rodenticides pose threats to California condors
Anticoagulant rodenticides (ARs) are widespread environmental contaminants that pose risks to scavenging birds because they routinely occur within their prey and can cause secondary poisoning. However, little is known about AR exposure in one of the rarest avian scavengers in the world, the California condor (Gymnogyps californianus). We assessed AR exposure in California condors and surrogate turUsing carbon, nitrogen, and mercury isotope values to distinguish mercury sources to Alaskan lake trout
Lake trout (Salvelinus namaycush), collected from 13 remote lakes located in southwestern Alaska, were analyzed for carbon, nitrogen, and mercury (Hg) stable isotope values to assess the importance of migrating oceanic salmon, volcanic activity, and atmospheric deposition to fish Hg burden. Methylmercury (MeHg) bioaccumulation in phytoplankton (5.0–6.9 kg L–1) was also measured to quantify the basMercury exposure of tidal marsh songbirds in the northeastern United States and its association with nest survival
The biogeochemistry of tidal marsh sediments facilitates the transformation of mercury (Hg) into the biologically available form methylmercury (MeHg), resulting in elevated Hg exposures to tidal marsh wildlife. Saltmarsh and Acadian Nelson’s sparrows (Ammospiza caudacutua and A. nelsoni subvirgatus, respectively) exclusively inhabit tidal marshes, potentially experiencing elevated risk to Hg exposLethal impacts of selenium counterbalance the potential reduction in mercury bioaccumulation for freshwater organisms☆
Mercury (Hg), a potent neurotoxic element, can biomagnify through food webs once converted into methylmercury (MeHg). Some studies have found that selenium (Se) exposure may reduce MeHg bioaccumulation and toxicity, though this pattern is not universal. Se itself can also be toxic at elevated levels. We experimentally manipulated the relative concentrations of dietary MeHg and Se (as selenomethionSmall mammal shooting as a conduit for lead exposure in avian scavengers
Lead (Pb) exposure is a widespread wildlife conservation threat. Although commonly associated with Pb-based ammunition from big-game hunting, small mammals (e.g., ground squirrels) shot for recreational or pest-management purposes represent a potentially important Pb vector in agricultural regions. We measured the responses of avian scavengers to pest-shooting events and examined their Pb exposureMetal accumulation varies with life history, size, and development of larval amphibians
Amphibian larvae are commonly used as indicators of aquatic ecosystem health because they are susceptible to contaminants. However, there is limited information on how species characteristics and trophic position influence contaminant loads in larval amphibians. Importantly, there remains a need to understand whether grazers (frogs and toads [anurans]) and predators (salamanders) provide comparablDifferential reliance on aquatic prey subsidies influences mercury exposure in riparian arachnids and songbirds
Cross-ecosystem subsidies move substantial amounts of nutrients between ecosystems. Emergent aquatic insects are a particularly important prey source for riparian songbirds but may also move aquatic contaminants, such as mercury (Hg), to riparian food webs. While many studies focus on species that eat primarily emergent aquatic insects, we instead study riparian songbirds with flexible foraging stDemethylation of methylmercury in bird, fish, and earthworm
Toxicity of methylmercury (MeHg) to wildlife and humans results from its binding to cysteine residues of proteins, forming MeHg-cysteinate (MeHgCys) complexes that hinder biological functions. MeHgCys complexes can be detoxified in vivo, yet how this occurs is unknown. We report that MeHgCys complexes are transformed into selenocysteinate (Hg(Sec)4) complexes in multiple animals from two phyla (aIsotope fractionation from In Vivo methylmercury detoxification in waterbirds
The robust application of stable mercury (Hg) isotopes for mercury source apportionment and risk assessment necessitates the understanding of mass-dependent fractionation (MDF) due to internal transformations within organisms. Here, we used high energy-resolution XANES spectroscopy and isotope ratios of total mercury (δ202THg) and methylmercury (δ202MeHg) to elucidate the chemical speciation of HgExamining historical mercury sources in the Saint Louis River estuary: How legacy contamination influences biological mercury levels in Great Lakes coastal regions
Industrial chemical contamination within coastal regions of the Great Lakes can pose serious risks to wetland habitat and offshore fisheries, often resulting in fish consumption advisories that directly affect human and wildlife health. Mercury (Hg) is a contaminant of concern in many of these highly urbanized and industrialized coastal regions, one of which is the Saint Louis River estuary (SLRE)Non-USGS Publications**
Suchanek, T.H., Cooke, J., Keller, K., Richerson, P.J., Eagles-Smith, C.A., Harner, E.J., Adam, D.P., 2009, A mass balance mercury budget for a mine-dominated lake - Clear Lake, California: Water, Air, & Soil Pollution, v. 196, p. 51-73.Richerson, P.J., Suchanek, T.H., Zierenberg, R.A., Osleger, D.A., Heyvaert, A.C., Slotton, D.G., Eagles-Smith, C.A., Vaughn, C.E., 2008, Anthropogenic stressors and changes in the Clear Lake ecosystem as recorded in sediment cores: Ecological Applications, v. 18, no. 8, p. A257-A283.Suchanek, T.H., Eagles-Smith, C.A., Harner, E.J., 2008, Is Clear Lake methylmercury distribution decoupled from bulk mercury loading?: Ecological Applications, v. 18, no. 8, p. A107-A127.Suchanek, T.H., Eagles-Smith, C.A., Slotton, D.G., Harner, E.J., Adam, D.P., 2008, Mercury in abiotic matrices of Clear Lake, California- Human health and ecotoxicological implications: Ecological Applications, v. 18, no. 8, p. A128-A157.Anderson, D.W., Suchanek, T.H., Eagles-Smith, C.A., Cahill, Jr., T.M., 2008, Mercury residues and productivity in osprey and grebes from a mine-dominated ecosystem: Ecological Applications, v. 18, no. 8, p. A227-A238.Suchanek, T.H., Eagles-Smith, C.A., Slotton, D.G., Harner, E.J., Adam, D.P., Colwell, A.E., Anderson, N.L., Woodward, D.L., 2008, Mine-derived mercury- Effects on lower trophic species in Clear Lake, California: Ecological Applications, v. 18, no. 8, p. A158-A176.Suchanek, T.H., Eagles-Smith, C.A., Slotton, D.G., Harner, E.J., Colwell, A.E., Anderson, N.L., Mullen, L.H., Flanders, J.R., Adam, D.P., McElroy, K.J., 2008, Spatiotemporal trends in fish mercury from a mine-dominated ecosystem- Clear Lake, California: Ecological Applications, v. 18, no. 8, p. A177-A195.McEachern, M.B., Eagles-Smith, C.A., Efferson, C.M., Van Vuren, D.H., 2006, Evidence for local specialization in a generalist mammalian herbivore, Neotoma fuscipes: Oikos, v. 113, p. 440-448.**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
- Software
Mercury Condition Index Tool
The Mercury Condition Index Tool uses existing data of mercury concentrations in invertebrates, fish, and birds within national parks to estimate a park level Condition Index (and associated uncertainty) for mercury, based on its potential risk to fish and wildlife health. The tool employs a series of logic steps to convert provided data into standardized units, based upon both basic stoichiometr - News
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