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 scientific data and understandings about the management practice as well as related environmental transport, fate, and exposure pathways of contaminants and pathogens. Emphasis will be placed on addressing these issues on public and Department of the Interior managed landscapes.
Contaminant and pathogen exposure alone does not necessarily result in adverse health outcomes in fish, wildlife, or humans. There are numerous pathways and processes that can alter the toxicity of naturally occurring and human-made contaminants in the environment.
The team uses their broad scientific expertise in hydrology, geochemistry, biology, and ecotoxicoogy to understand the complexities associated with the movement of toxicants and pathogens through the environment and within individual organisms. That information is used to determine how, where, and when exposure occurrs and if exposure results in health risks to wildlife and humans.
Current Science Questions and Activities
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What are the various ecological factors, such as habitats and foraging strategies, that influence the pathways of contaminant exposure, health risks to fish and wildlife?
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What are the major intrinsic and extrinsic drivers of mercury exposure and risk to humans, fish, and wildlife at a global scale?
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What are the internal physiological determinants such as metababolism, transfer of mercury to offspring, changes in body mass, and molting that influence exposure and health risks in fish and wildlife?
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How do the internal factors differ among species and life stages?
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What are the Influences of landscape alterations, perturbations, and restoration on pathways and movement of contaminants through ecosystems and bioaccumulation into the food web of aquatic biota?
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Do multiple types and chemical mixtures have additive, synergistic, or antagonistic effects that influence the health of fish and wildlife?
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What are the internal and external drivers and regulators of human exposure to mercury?
- What is the risk of pathogen exposure and transmission among wildlife, livestock, and humans?
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What are the key environmental factors that control the viability of avian influenza virus shed by wild birds and what are the key environmental pathways of exposure and transmission of the virus?
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What is the role of soil, water, and vegetation in disease transmission such as Chronic Wasting Disease?
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How do invasive species influence the timing of contaminant uptake and bioaccumulation in fish and wildlife?
USGS science related to this science team’s activities.
Food Web Changes Dampen Expected Reductions in Lake Trout Mercury Levels in Lake Michigan—Invasive Species Play Major Role
Mercury Isotope Ratios used to Determine Sources of Mercury to Fish in Northeast U.S. Streams
Science to Help Understand Exposure and Toxicological Effects of Environmental Mercury to Representative Birds
No Adverse Reproductive Effects Observed in Tree Swallows Exposed to Perfluoroalkyl Substances in Clarks Marsh, Michigan
Roadmap to Understanding Factors Influencing Mercury Exposure and Adverse Health Effects
Systematic Approach to Understanding Tree Swallow Health in the Great Lakes Region—Science to Inform Restoration
Scientists Identify Processes that Affect Fish Mercury Concentrations in Estuarine Wetlands
Simple Ways to Avoid Public Exposures to Infectious Wildlife Diseases Summarized
New Method Can Measure Naturally Occurring Element Exposure in Hummingbirds Without Harm
Body Symmetry in Forster's Terns Related to Mercury Exposure
Efficacy of Eggshell Analyses as a Nonlethal Method to Estimate Mercury Exposure in Bird Embryos
New Method Improves Measurement of Bullet Fragments in Culled Varmints
The following are the data releases from this science team’s research activities.
Total Mercury Concentrations in Smallmouth Bass from Chesapeake Bay Tributaries, USA Dataset, 2013-2017
Trask River Watershed Study Area Forestry Bioaccumulation Dataset, 2011-2015
Incubation Constancy, Number of Incubation Recesses, Recess Duration and Mercury Concentrations for Tree Swallows at the Cosumnes River Preserve 2014
Pore water chemistry of wetlands in Interior and Southcentral Alaska, 2015 and 2016
Mercury concentrations in songbird feathers and tissues
Total Mercury and Methylmercury in Riparian Songbirds and Aquatic Invertebrates from the Willamette Valley, Oregon, 2013-2014
Feather mercury concentrations in North American raptors sampled at migration monitoring stations
Variability of mercury concentrations among whole bird feathers, feather homogenates, and feather components quantified in California in 2017-2018
Polychlorinated biphenyl concentrations in adult walleye from the Fox River (Wisconsin) population, 2014
Fox River walleye mercury isotope data
Annual winter elk movements in the Greater Yellowstone Ecosystem 2001-2015
Geochemistry of shallow sediment including mercury, methylmercury and other constituents in the Cache Creek Settling Basin, Yolo County, California, 2010-16
Below are publications associated with this science team.
Genomically diverse carbapenem resistant Enterobacteriaceae from wild birds provide insight into global patterns of spatiotemporal dissemination
Evidence for continental-scale dispersal of antimicrobial resistant bacteria by landfill-foraging gulls
Contaminant subsidies to riparian food webs in Appalachian streams impacted by mountaintop removal coal mining
Prioritizing water security in the management of vector borne diseases: Lessons from Oaxaca, Mexico
Mercury and selenium concentrations in fishes of the Upper Colorado River Basin, southwestern United States: A retrospective assessment
Synthesis of maternal transfer of mercury in birds: Implications for altered toxicity risk
Isolation of methylmercury using distillation and anion-exchange chromatography for isotopic analyses in natural matrices
The assessment and remediation of mercury contaminated sites: A review of current approaches
Antibiotic resistant bacteria in wildlife: Perspectives on trends, acquisitions and dissemination, data gaps, and future directions
Methylmercury exposure in wildlife: A review of the ecological and physiological processes affecting contaminant concentrations and their interpretation
Wintering in the western subarctic pacific increases mercury contamination of Red-legged Kittiwakes
Mercury source changes and food web shifts alter contamination signatures of predatory fish from Lake Michigan
- Overview
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 scientific data and understandings about the management practice as well as related environmental transport, fate, and exposure pathways of contaminants and pathogens. Emphasis will be placed on addressing these issues on public and Department of the Interior managed landscapes.
Photograph showing white-faced ibis nesting at Bear River Migratory Bird Refuge, Great Salt Lake, Utah. U.S. Geological Survey (USGS) scientists evaluated a nonlethal method to estimate mercury in the embryos of 23 bird species using mercury content in eggshells. This method was effective for a wide range of ages and species.(Credit: Josh T. Ackerman, Western Ecological Research Center. Public domain.) Contaminant and pathogen exposure alone does not necessarily result in adverse health outcomes in fish, wildlife, or humans. There are numerous pathways and processes that can alter the toxicity of naturally occurring and human-made contaminants in the environment.
The team uses their broad scientific expertise in hydrology, geochemistry, biology, and ecotoxicoogy to understand the complexities associated with the movement of toxicants and pathogens through the environment and within individual organisms. That information is used to determine how, where, and when exposure occurrs and if exposure results in health risks to wildlife and humans.
Current Science Questions and Activities
-
What are the various ecological factors, such as habitats and foraging strategies, that influence the pathways of contaminant exposure, health risks to fish and wildlife?
-
What are the major intrinsic and extrinsic drivers of mercury exposure and risk to humans, fish, and wildlife at a global scale?
-
What are the internal physiological determinants such as metababolism, transfer of mercury to offspring, changes in body mass, and molting that influence exposure and health risks in fish and wildlife?
-
How do the internal factors differ among species and life stages?
-
What are the Influences of landscape alterations, perturbations, and restoration on pathways and movement of contaminants through ecosystems and bioaccumulation into the food web of aquatic biota?
-
Do multiple types and chemical mixtures have additive, synergistic, or antagonistic effects that influence the health of fish and wildlife?
-
What are the internal and external drivers and regulators of human exposure to mercury?
- What is the risk of pathogen exposure and transmission among wildlife, livestock, and humans?
-
What are the key environmental factors that control the viability of avian influenza virus shed by wild birds and what are the key environmental pathways of exposure and transmission of the virus?
-
What is the role of soil, water, and vegetation in disease transmission such as Chronic Wasting Disease?
-
How do invasive species influence the timing of contaminant uptake and bioaccumulation in fish and wildlife?
-
- Science
USGS science related to this science team’s activities.
Filter Total Items: 21Food Web Changes Dampen Expected Reductions in Lake Trout Mercury Levels in Lake Michigan—Invasive Species Play Major Role
Combined analyses of mercury, nitrogen, and carbon isotopes in archived lake trout (Salvelinus namaycush) tissues and sediment cores in Lake Michigan from 1978 to 2012 indicated that lake trout mercury concentrations mirrored declines in mercury sources prior to the arrival of invasive species that changed mercury transfer through the food and dampened the expected decreases in mercury...Mercury Isotope Ratios used to Determine Sources of Mercury to Fish in Northeast U.S. Streams
Mercury isotope analyses were used to distinguish different sources of mercury to fish in 23 streams along a forested-rural to urban-industrial land-use gradient in the Northeastern United States. The use of mercury isotope measurements in fish tissue allow for distinguishing different sources of mercury that are bioaccumulating into the food web. Mercury isotope signatures in fish in forested...Science to Help Understand Exposure and Toxicological Effects of Environmental Mercury to Representative Birds
Exposure and toxicity of environmental mercury to birds can be enhanced or lessened due to the available sources and forms of mercury and other species dependent factors such as life stage, migratory patterns, foraging and nesting behaviors, transfer of mercury from mothers to eggs, and sex. For example, mercury exposure can lead to sublethal toxicological effects that can influence parental...No Adverse Reproductive Effects Observed in Tree Swallows Exposed to Perfluoroalkyl Substances in Clarks Marsh, Michigan
Perfluoroalkyl substance (PFAS) concentrations in tree swallows (Tachycineta bicolor) breeding at Clarks Marsh near a decommissioned U.S. Air Force base in Michigan were among the highest concentrations ever documented in birds indicating significant PFAS exposures. In contrast to previous studies where reproductive impairment was documented at lower PFAS exposure, there were no adverse effects on...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.Systematic Approach to Understanding Tree Swallow Health in the Great Lakes Region—Science to Inform Restoration
Four papers by U.S. Geological Survey (USGS) scientists document tree swallow (Tachycineta bicolor) chemical exposure, physiological responses, and reproductive success in the Great Lakes region. These studies were designed to understand if there are health threats to swallows from contaminant exposure, and to provide resource managers with information about the actual as opposed to the perceived...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.Simple Ways to Avoid Public Exposures to Infectious Wildlife Diseases Summarized
The U.S. Geological Survey (USGS), in collaboration with the U.S. Fish and Wildlife Service (USFWS) and other disease specialists, have published reports during the past 12 years with information about the geographic distribution of diseases, specific pathogens, disease ecology, and strategies to avoid human exposure and infection for seven zoonotic diseases.New Method Can Measure Naturally Occurring Element Exposure in Hummingbirds Without Harm
Seventeen naturally occurring trace elements, including those associated with adverse health impacts when birds are exposed to toxic levels (iron, lead, mercury, selenium, zinc, cadmium, and arsenic) were measured in small birds without harm. The nonlethal method was developed for hummingbirds, with Anna's hummingbirds (Calypte anna) as a test species and can be more broadly applied to other...Body Symmetry in Forster's Terns Related to Mercury Exposure
Body symmetry of Forster's terns (Sterna forsteri) in San Francisco Bay was related to blood and feather mercury concentrations. Body asymmetry can affect a bird's fitness by reducing flight efficiency, thus increasing energetic costs (especially during migration) and interrupting normal feeding and breeding behaviors.Efficacy of Eggshell Analyses as a Nonlethal Method to Estimate Mercury Exposure in Bird Embryos
U.S. Geological Survey (USGS) scientists evaluated a nonlethal method to estimate mercury in the embryos of 23 bird species using mercury content in eggshells. This method was effective for a wide range of ages and species.New Method Improves Measurement of Bullet Fragments in Culled Varmints
A creative combination of radiography and techniques borrowed from meat processing and gold prospecting led to a better method for determining the lead content in ground squirrels shot by hunters to evaluate potential exposure risk to avian scavengers such as golden eagles (Aquila chrysaetos). - Data
The following are the data releases from this science team’s research activities.
Filter Total Items: 18Total 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.Trask 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.Incubation Constancy, Number of Incubation Recesses, Recess Duration and Mercury Concentrations for Tree Swallows at the Cosumnes River Preserve 2014
These metadata provide data used to examine tree swallow incubation behavior in relation to egg mercury concentration and maternal blood mercury concentration. These data were collected from tree swallows nesting in artificial wooden nest boxes at the Cosumnes River Preserved in California's Central Valley in 2014. Included are two datasets. One dataset provides daily incubation constancy (the proPore water chemistry of wetlands in Interior and Southcentral Alaska, 2015 and 2016
The pore water of eight wetlands in Interior and Southcentral Alaska were collected in 2015 (17 July - 22 July) and 2016 (12 July - 16 July). Wetlands were selected to span a range in trophic status (e.g., from bog to fen). Using ultraclean trace metal clean protocols, pore waters were sampled from shallow (10-15 cm) and deep (20-35 cm) depths below the water table. Field measurements reported forMercury concentrations in songbird feathers and tissues
This dataset includes the bird species, sex, age, and total mercury concentrations in feathers, muscle, liver, and nail tissues.Total Mercury and Methylmercury in Riparian Songbirds and Aquatic Invertebrates from the Willamette Valley, Oregon, 2013-2014
This dataset includes bird species, invertebrate order and family, sample identification codes, capture date, latitude, longitude, habitat, site name, bird age, total mercury concentrations in bird blood, and methylmercury concentrations in whole body aquatic invertebrates.Feather mercury concentrations in North American raptors sampled at migration monitoring stations
We assessed total mercury concentrations in breast feathers of diurnal North American raptors collected at migration monitoring stations. We sampled raptor feathers from 9 species in the Pacific Flyway and compared species, sex, date, and flyway effects on mercury concentrations. We also explored year effects on 3 species of raptors in the Pacific Flyway during 13-years (2002-2014). Finally, we coVariability of mercury concentrations among whole bird feathers, feather homogenates, and feather components quantified in California in 2017-2018
These data are the raw total mercury (THg) concentrations in whole feathers, feather homogenates, and feather components (i.e., rachis, vane, calamus) that are presented in the Journal Article "Mercury concentrations vary within and among individual bird feathers: A critical evaluation and guidelines for feather use in mercury monitoring programs" in Environmental Toxicology and Chemistry by PeterPolychlorinated biphenyl concentrations in adult walleye from the Fox River (Wisconsin) population, 2014
Adult walleye (10 females and 10 males) were caught in Fox River (Wisconsin) during April 2014. Total length, weight, and age were determined for each of the walleye. Whole-fish homogenates were prepared during 2017. Lipid concentration and polychlorinated biphenyl (PCB) congener concentrations were determined in each of the homogenates during 2017-2018. For each sample, PCB congener concentrationFox River walleye mercury isotope data
Adult walleye were caught in Fox River (Wisconsin) during April 2014. Age-0 walleye were caught in Fox River during October 2014. Total length, weight, age, and proportion of weight represented by water were determined for each of the walleye. Whole-fish homogenates were prepared during 2014-2015 and during 2017. Total mercury (HgT) concentration, methylmercury (MeHg) concentration, and mercury (HAnnual winter elk movements in the Greater Yellowstone Ecosystem 2001-2015
521 unique elk with GPS collars were tracked using telemetry from 2001 to 2015 in the Greater Yellowstone Ecosystem to determine winter-to-winter annual dispersal distance of each individual. All elk were identified and located using telemetry during the months of January and February for two successive years. An individual elk was included at most three times in the data and each year was consideGeochemistry of shallow sediment including mercury, methylmercury and other constituents in the Cache Creek Settling Basin, Yolo County, California, 2010-16
The Cache Creek Settling Basin (CCSB) is a 13.3 km2 leveed basin located at the terminal drainage of the Cache Creek watershed, immediately NE of the town of Woodland (Yolo County), California and approximately 18 km NW of Sacramento, California. The basin was constructed by the U.S. Army Corps of Engineers (completed in 1937 and modified in 1993) for the purpose of trapping suspended sediment tra - Publications
Below are publications associated with this science team.
Filter Total Items: 86Genomically diverse carbapenem resistant Enterobacteriaceae from wild birds provide insight into global patterns of spatiotemporal dissemination
Carbapenem resistant Enterobacteriaceae (CRE) are a threat to public health globally, yet the role of the environment in the epidemiology of CRE remains elusive. Given that wild birds can acquire CRE, likely from foraging in anthropogenically impacted areas, and may aid in the maintenance and dissemination of CRE in the environment, a spatiotemporal comparison of isolates from different regions anEvidence for continental-scale dispersal of antimicrobial resistant bacteria by landfill-foraging gulls
Anthropogenic inputs into the environment may serve as sources of antimicrobial resistant bacteria and alter the ecology and population dynamics of synanthropic wild animals by providing supplemental forage. In this study, we used a combination of phenotypic and genomic approaches to characterize antimicrobial resistant indicator bacteria, animal telemetry to describe host movement patterns, and aContaminant subsidies to riparian food webs in Appalachian streams impacted by mountaintop removal coal mining
Selenium is highly elevated in Appalachian streams and stream organisms that receive alkaline mine drainage from mountaintop removal coal mining compared to unimpacted streams in the region. Adult aquatic insects can be important vectors of waterborne contaminants to riparian food webs, yet pathways of Se transport and exposure of riparian organisms are poorly characterized. We investigated Se conPrioritizing water security in the management of vector borne diseases: Lessons from Oaxaca, Mexico
Changes in human water use, along with temperature and rainfall patterns, are facilitating habitat spread and distribution of Aedes aegypti and Aedes albopictus mosquitoes, the primary vectors for the transmission of Dengue, Chikungunya, and Zika viruses in the Americas. Artificial containers and wetspots provide major sources of mosquito larval habitat in residential areas. Mosquito abatement andMercury and selenium concentrations in fishes of the Upper Colorado River Basin, southwestern United States: A retrospective assessment
Mercury (Hg) and selenium (Se) are contaminants of concern for fish in the Upper Colorado River Basin (UCRB). We explored Hg and Se in fish tissues (2,324 individuals) collected over 50 years (1962–2011) from the UCRB. Samples include native and non-native fish collected from lotic waterbodies spanning 7 major tributaries to the Colorado River. There was little variation of total mercury (THg) inSynthesis of maternal transfer of mercury in birds: Implications for altered toxicity risk
Maternal transfer is the predominant route of methylmercury (MeHg) exposure to offspring. We reviewed and synthesized published and unpublished data on maternal transfer of MeHg in birds. Using paired samples of females’ blood (n=564) and their eggs (n=1814) from 26 bird species in 6 taxonomic orders, we conducted a meta-analysis to evaluate whether maternal transfer of MeHg to eggs differed amoIsolation of methylmercury using distillation and anion-exchange chromatography for isotopic analyses in natural matrices
The development of mercury (Hg) stable isotope measurements has enhanced the study of Hg sources and transformations in the environment. As a result of the mixing of inorganic Hg (iHg) and methylmercury (MeHg) species within organisms of the aquatic food web, understanding species-specific Hg stable isotopic compositions is of significant importance. The lack of MeHg isotope measurements is due toThe assessment and remediation of mercury contaminated sites: A review of current approaches
Remediation of mercury (Hg) contaminated sites has long relied on traditional approaches, such as removal and containment/capping. Here we review contemporary practices in the assessment and remediation of industrial-scale Hg contaminated sites and discuss recent advances. Significant improvements have been made in site assessment, including the use of XRF to rapidly identify the spatial extent ofAntibiotic resistant bacteria in wildlife: Perspectives on trends, acquisitions and dissemination, data gaps, and future directions
The proliferation of antibiotic resistant bacteria in the environment has potential negative economic and health consequences. Thus, previous investigations have targeted wild animals to understand the occurrence of antibiotic resistance in diverse environmental sources. In this critical review and synthesis, we summarize important concepts learned through the sampling of wildlife for antibioticMethylmercury exposure in wildlife: A review of the ecological and physiological processes affecting contaminant concentrations and their interpretation
Exposure to methylmercury (MeHg) can result in detrimental health effects in wildlife. With advances in ecological indicators and analytical techniques for measurement of MeHg in a variety of tissues, numerous processes have been identified that can influence MeHg concentrations in wildlife. This review presents a synthesis of theoretical principals and applied information for measuring MeHg exposWintering in the western subarctic pacific increases mercury contamination of Red-legged Kittiwakes
Marine methylmercury concentrations vary geographically and with depth, exposing organisms to different mercury levels in unique habitats. Red-legged kittiwakes (Rissa brevirostris), a specialist predator, forage on fish and invertebrates from the mesopelagic zone, a part of the ocean with elevated methylmercury concentrations. We used kittiwakes as bioindicators of MeHg concentrations in remoteMercury source changes and food web shifts alter contamination signatures of predatory fish from Lake Michigan
To understand the impact reduced mercury (Hg) loading and invasive species have had on methylmercury bioaccumulation in predator fish of Lake Michigan, we reconstructed bioaccumulation trends from a fish archive (1978 to 2012). By measuring fish Hg stable isotope ratios, we related temporal changes in Hg concentrations to varying Hg sources. Additionally, dietary tracers were necessary to identify