James J Willacker, Jr.
I am an Ecologist specializing in aquatic and trophic ecology at the USGS Forest and Rangeland Ecosystem Science Center in Corvallis, OR
I am broadly interested in aquatic ecology and in particular the application of trophic ecology to questions of ecotoxicology, evolution, physiology, and conservation biology. My current research focuses on understanding the interplay among ecological, biogeochemical, and physiological processes that govern contaminant accumulation in biota, particularly fishes and other aquatic taxa. My work is also aimed at quantifying ecological risk and toxicological impacts associated with contaminants, particularly mercury.
Professional Experience
2013 - Present: Ecologist, USGS Forest and Rangeland Ecosystem Science Center, Corvallis, OR
2009 - 2013: Doctoral Researcher, University of Alaska Fairbanks, Fairbanks, AK
2009 - 2012: Instructor, Alaska Community Action on Toxics, Anchorage, AK
2007 - 2009: Aquatic Ecologist, Environmental and Natural Resource Institute, Anchorage, AK
Education and Certifications
Ph.D., Biological Sciences, University of Alaska, Fairbanks, AK (2013)
M.S., Biological Sciences, University of Alaska, Anchorage, AK (2009)
B.S., Environmental and Forest Biology- Summa cum laude, State University of New York College of Environmental Science and Forestry (2006)
Honors and Awards
Outstanding Graduate Researcher Award, Environment and Natural Resources Institute, University of Alaska, Anchorage, AK. (2011)
Valedictorian, SUNY ESF (2007)
University Scholar, SUNY (2007)
Faculty Honors, Department of Environmental and Forest Biology, SUNY ESF (2007)
Robin Hood Oak Award, SUNY ESF (2006)
Science and Products
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: 14
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...
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.
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: 29
Fish habitat use and food web structure following pond and plug restoration of a Montane Meadow in the Sierra Nevada, California
Montane meadows are areas of high biodiversity and provide many important ecosystem services; however, degradation of 40–60% of these habitats in the Sierra Nevada region of California has left many of these areas impaired. The “pond-and-plug” meadow-restoration technique is 1 type of treatment implemented to restore montane meadows. The objectives of this technique are to re-water the...
Authors
Lora B. Tennant, Collin Eagles-Smith, James Willacker, Matthew S. Johnson
A national-scale assessment of mercury bioaccumulation in United States National Parks using dragonfly larvae as biosentinels through a citizen-science framework
We conducted a national-scale assessment of mercury (Hg) bioaccumulation in aquatic ecosystems using dragonfly larvae as biosentinels, by developing a citizen science network to facilitate biological sampling. Implementing a carefully designed sampling methodology for citizen scientists, we developed an effective framework for landscape-level inquiry that might otherwise be resource...
Authors
Collin Eagles-Smith, James Willacker, Sarah J. Nelson, Colleen M Flanagan Pritz, David Krabbenhoft, Celia Y. Chen, Josh T. Ackerman, Evan H. Campbell Grant, David Pilliod
Mercury bioaccumulation in freshwater fishes of the Chesapeake Bay watershed
Chemical contaminants are a threat to the Chesapeake Bay watershed, with mercury (Hg) among the most prevalent causes of impairment. Despite this, large-scale patterns of Hg concentrations, and the potential risks to fish, wildlife, and humans across the watershed, are poorly understood. We compiled fish Hg data from state monitoring programs and recent research efforts to address this...
Authors
James Willacker, Collin Eagles-Smith, Vicki S. Blazer
Mercury 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...
Authors
Natalie K. Day, Travis Schmidt, James Roberts, Barbara Campbell Osmundson, James Willacker, Collin Eagles-Smith
Timber harvest alters mercury bioaccumulation and food web structure in headwater streams
Timber harvest has many effects on aquatic ecosystems, including changes in hydrological, biogeochemical, and ecological processes that can influence mercury (Hg) cycling. Although timber harvest’s influence on aqueous Hg transformation and transport are well studied, the effects on Hg bioaccumulation are not. We evaluated Hg bioaccumulation, biomagnification, and food web structure in...
Authors
James Willacker, Collin Eagles-Smith, Brandon M. Kowalski, Robert J. Danehy, Allyson K. Jackson, Evan Adams, David C. Evers, Chris S. Eckley, Michael Tate, David Krabbenhoft
Mercury bioaccumulation in estuarine fishes: Novel insights from sulfur stable isotopes
Estuaries are transitional habitats characterized by complex biogeochemical and ecological gradients that result in substantial variation in fish total mercury concentrations (THg). We leveraged these gradients and used carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) stable isotopes to examine the ecological and biogeochemical processes underlying THg bioaccumulation in fishes from the...
Authors
James J. Willacker, Collin Eagles-Smith, Josh T. Ackerman
Non-USGS Publications**
Willacker Jr., J.J., Sobczak, W.V., Colburn, E.A., 2009, Stream macroinvertebrate communities in paired hemlock and deciduous watersheds: Northeastern Naturalist, v. 16, no. 1, p. 101-112, https://doi.org/10.1656/045.016.0108.
Willacker Jr., J.J., von Hippel, F.A., Wilton, P.R., Walton, K.M., 2010, Classification of threespine stickleback along the benthic–limnetic axis: Biological Journal of the Linnean Society, v. 101, p. 595-608, https://doi.org/10.1111/j.1095-8312.2010.01531.x.
Kenney, L.A., von Hippel, F.A., Willacker Jr., J.J., O'Hara, T.M., 2012, Mercury concentrations of a resident freshwater forage fish at Adak Island, Aleutian Archipelago, Alaska: Environmental Toxicology and Chemistry, v. 31, no. 11, p. 2647-2652, https://doi.org/10.1002/etc.1990.
Walton, K.M., Spalinger, D.E., Harris, N.R., Collins, W.B., Willacker Jr., J.J., 2013, High spatial resolution vegetation mapping for assessment of wildlife habitat: Wildlife Society Bulletin, v. 37, no. 4, p. 906-915, https://doi.org/10.1002/wsb.344.
Willacker Jr., J.J., von Hippel, F.A., Ackerly, K.L., O'Hara, T.M., 2013, Habitat-specific foraging and sex determine mercury concentrations in sympatric benthic and limnetic ecotypes of threespine stickleback: Environmental Toxicology and Chemistry, v. 32, no. 7, p. 1623-1630, https://doi.org/10.1002/etc.2213.
Shedd, K.R., F.A. von Hippel, J.J. Willacker, T.R. Hamon, O.L. Schlei, J.K. Wenburg, J.L. Miller, and S.A. Pavey. 2015. Ecological release leads to novel ontogenetic diet shift in kokanee (Oncorhynchus nerka). Canadian Journal of Fisheries and Aquatic Sciences 72: 1718-1730.
Willacker, J.J. 2013. Ecological drivers of mercury accumulation in Threespine Stickleback fish. Doctor of Philosophy, University of Alaska Fairbanks, Fairbanks, AK, USA.
Willacker, J.J. 2009. Geometric morphometrics of Threespine Stickleback in the Cook Inlet Basin, Alaska. Master of Science, University of Alaska Anchorage, Anchorage, AK, USA.
Willacker, J.J., D. Rinella, and D. Bogan. 2008. Aquatic macroinvertebrate and diatom surveys in Tetlin National Wildlife Refuge, AK. Environmental and Natural Resources Institute Annual Progress Report to the U.S. Fish and Wildlife Service.
Willacker, J.J., D. Rinella, and D. Bogan. 2007. Macroinvertebrate abundance in the Eklutna River, AK: an estimate of food supply for rearing salmonids. Environmental and Natural Resources Institute Final Report to the Eklutna River Restoration Project, U.S. Army Corps of Engineers.
**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.
Science and Products
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: 14
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...
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.
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: 29
Fish habitat use and food web structure following pond and plug restoration of a Montane Meadow in the Sierra Nevada, California
Montane meadows are areas of high biodiversity and provide many important ecosystem services; however, degradation of 40–60% of these habitats in the Sierra Nevada region of California has left many of these areas impaired. The “pond-and-plug” meadow-restoration technique is 1 type of treatment implemented to restore montane meadows. The objectives of this technique are to re-water the...
Authors
Lora B. Tennant, Collin Eagles-Smith, James Willacker, Matthew S. Johnson
A national-scale assessment of mercury bioaccumulation in United States National Parks using dragonfly larvae as biosentinels through a citizen-science framework
We conducted a national-scale assessment of mercury (Hg) bioaccumulation in aquatic ecosystems using dragonfly larvae as biosentinels, by developing a citizen science network to facilitate biological sampling. Implementing a carefully designed sampling methodology for citizen scientists, we developed an effective framework for landscape-level inquiry that might otherwise be resource...
Authors
Collin Eagles-Smith, James Willacker, Sarah J. Nelson, Colleen M Flanagan Pritz, David Krabbenhoft, Celia Y. Chen, Josh T. Ackerman, Evan H. Campbell Grant, David Pilliod
Mercury bioaccumulation in freshwater fishes of the Chesapeake Bay watershed
Chemical contaminants are a threat to the Chesapeake Bay watershed, with mercury (Hg) among the most prevalent causes of impairment. Despite this, large-scale patterns of Hg concentrations, and the potential risks to fish, wildlife, and humans across the watershed, are poorly understood. We compiled fish Hg data from state monitoring programs and recent research efforts to address this...
Authors
James Willacker, Collin Eagles-Smith, Vicki S. Blazer
Mercury 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...
Authors
Natalie K. Day, Travis Schmidt, James Roberts, Barbara Campbell Osmundson, James Willacker, Collin Eagles-Smith
Timber harvest alters mercury bioaccumulation and food web structure in headwater streams
Timber harvest has many effects on aquatic ecosystems, including changes in hydrological, biogeochemical, and ecological processes that can influence mercury (Hg) cycling. Although timber harvest’s influence on aqueous Hg transformation and transport are well studied, the effects on Hg bioaccumulation are not. We evaluated Hg bioaccumulation, biomagnification, and food web structure in...
Authors
James Willacker, Collin Eagles-Smith, Brandon M. Kowalski, Robert J. Danehy, Allyson K. Jackson, Evan Adams, David C. Evers, Chris S. Eckley, Michael Tate, David Krabbenhoft
Mercury bioaccumulation in estuarine fishes: Novel insights from sulfur stable isotopes
Estuaries are transitional habitats characterized by complex biogeochemical and ecological gradients that result in substantial variation in fish total mercury concentrations (THg). We leveraged these gradients and used carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) stable isotopes to examine the ecological and biogeochemical processes underlying THg bioaccumulation in fishes from the...
Authors
James J. Willacker, Collin Eagles-Smith, Josh T. Ackerman
Non-USGS Publications**
Willacker Jr., J.J., Sobczak, W.V., Colburn, E.A., 2009, Stream macroinvertebrate communities in paired hemlock and deciduous watersheds: Northeastern Naturalist, v. 16, no. 1, p. 101-112, https://doi.org/10.1656/045.016.0108.
Willacker Jr., J.J., von Hippel, F.A., Wilton, P.R., Walton, K.M., 2010, Classification of threespine stickleback along the benthic–limnetic axis: Biological Journal of the Linnean Society, v. 101, p. 595-608, https://doi.org/10.1111/j.1095-8312.2010.01531.x.
Kenney, L.A., von Hippel, F.A., Willacker Jr., J.J., O'Hara, T.M., 2012, Mercury concentrations of a resident freshwater forage fish at Adak Island, Aleutian Archipelago, Alaska: Environmental Toxicology and Chemistry, v. 31, no. 11, p. 2647-2652, https://doi.org/10.1002/etc.1990.
Walton, K.M., Spalinger, D.E., Harris, N.R., Collins, W.B., Willacker Jr., J.J., 2013, High spatial resolution vegetation mapping for assessment of wildlife habitat: Wildlife Society Bulletin, v. 37, no. 4, p. 906-915, https://doi.org/10.1002/wsb.344.
Willacker Jr., J.J., von Hippel, F.A., Ackerly, K.L., O'Hara, T.M., 2013, Habitat-specific foraging and sex determine mercury concentrations in sympatric benthic and limnetic ecotypes of threespine stickleback: Environmental Toxicology and Chemistry, v. 32, no. 7, p. 1623-1630, https://doi.org/10.1002/etc.2213.
Shedd, K.R., F.A. von Hippel, J.J. Willacker, T.R. Hamon, O.L. Schlei, J.K. Wenburg, J.L. Miller, and S.A. Pavey. 2015. Ecological release leads to novel ontogenetic diet shift in kokanee (Oncorhynchus nerka). Canadian Journal of Fisheries and Aquatic Sciences 72: 1718-1730.
Willacker, J.J. 2013. Ecological drivers of mercury accumulation in Threespine Stickleback fish. Doctor of Philosophy, University of Alaska Fairbanks, Fairbanks, AK, USA.
Willacker, J.J. 2009. Geometric morphometrics of Threespine Stickleback in the Cook Inlet Basin, Alaska. Master of Science, University of Alaska Anchorage, Anchorage, AK, USA.
Willacker, J.J., D. Rinella, and D. Bogan. 2008. Aquatic macroinvertebrate and diatom surveys in Tetlin National Wildlife Refuge, AK. Environmental and Natural Resources Institute Annual Progress Report to the U.S. Fish and Wildlife Service.
Willacker, J.J., D. Rinella, and D. Bogan. 2007. Macroinvertebrate abundance in the Eklutna River, AK: an estimate of food supply for rearing salmonids. Environmental and Natural Resources Institute Final Report to the Eklutna River Restoration Project, U.S. Army Corps of Engineers.
**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.