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.
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 bioaccumulation in estuarine fishes: Novel insights from sulfur stable isotopes
Reservoirs and water management influence fish mercury concentrations in the western United States and Canada
Assessing potential health risks to fish and humans using mercury concentrations in inland fish from across western Canada and the United States
Mercury risk to avian piscivores across western United States and Canada
Mercury in western North America: A synthesis of environmental contamination, fluxes, bioaccumulation, and risk to fish and wildlife
Spatial and temporal patterns of mercury concentrations in freshwater fish across the Western United States and Canada
Dragonfly Mercury Project—A citizen science driven approach to linking surface-water chemistry and landscape characteristics to biosentinels on a national scale
From tails to toes: developing nonlethal tissue indicators of mercury exposure in five amphibian species
Mercury in birds of San Francisco Bay-Delta, California: trophic pathways, bioaccumulation, and ecotoxicological risk to avian reproduction
Invasive crayfish as vectors of mercury in freshwater food webs of the Pacific Northwest
Mercury in fishes from Wrangell-St. Elias National Park and Preserve, Alaska
Mercury in fishes from 21 national parks in the Western United States: inter- and intra-park variation in concentrations and ecological risk
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.
Science and Products
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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.
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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: 24Mercury 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 San FrancAuthorsJames J. Willacker, Collin A. Eagles-Smith, Joshua T. AckermanReservoirs and water management influence fish mercury concentrations in the western United States and Canada
Anthropogenic manipulation of aquatic habitats can profoundly alter mercury (Hg) cycling and bioaccumulation. The impoundment of fluvial systems is among the most common habitat manipulations and is known to increase fish Hg concentrations immediately following impoundment. However, it is not well understood how Hg concentrations differ between reservoirs and lakes at large spatial and temporal scAuthorsJames J. Willacker, Collin A. Eagles-Smith, Michelle A. Lutz, Michael T. Tate, Jesse M. Lepak, Joshua T. AckermanAssessing potential health risks to fish and humans using mercury concentrations in inland fish from across western Canada and the United States
Fish represent high quality protein and nutrient sources, but Hg contamination is ubiquitous in aquatic ecosystems and can pose health risks to fish and their consumers. Potential health risks posed to fish and humans by Hg contamination in fish were assessed in western Canada and the United States. A large compilation of inland fish Hg concentrations was evaluated in terms of potential health risAuthorsJesse M. Lepak, Mevin Hooten, Collin A. Eagles-Smith, Michael T. Tate, Michelle A. Lutz, Joshua T. Ackerman, James J. Willacker, Allyson K. Jackson, David C. Evers, James G. Wiener, Colleen Flanagan Pritz, Jay DavisMercury risk to avian piscivores across western United States and Canada
The widespread distribution of mercury (Hg) threatens wildlife health, particularly piscivorous birds. Western North America is a diverse region that provides critical habitat to many piscivorous bird species, and also has a well-documented history of mercury contamination from legacy mining and atmospheric deposition. The diversity of landscapes in the west limits the distribution of avian piscivAuthorsAllyson K. Jackson, David C. Evers, Collin A. Eagles-Smith, Joshua T. Ackerman, James J. Willacker, John E. Elliott, Jesse M. Lepak, Stacy S. Vander Pol, Colleen E. BryanMercury in western North America: A synthesis of environmental contamination, fluxes, bioaccumulation, and risk to fish and wildlife
Western North America is a region defined by extreme gradients in geomorphology and climate, which support a diverse array of ecological communities and natural resources. The region also has extreme gradients in mercury (Hg) contamination due to a broad distribution of inorganic Hg sources. These diverse Hg sources and a varied landscape create a unique and complex mosaic of ecological risk fromAuthorsCollin A. Eagles-Smith, James G. Wiener, Chris S. Eckley, James J. Willacker, David C. Evers, Mark C. Marvin-DiPasquale, Daniel Obrist, Jacob Fleck, George R. Aiken, Jesse M. Lepak, Allyson K. Jackson, Jackson Webster, A. Robin Stewart, Jay Davis, Charles N. Alpers, Joshua T. AckermanSpatial and temporal patterns of mercury concentrations in freshwater fish across the Western United States and Canada
Methylmercury contamination of fish is a global threat to environmental health. Mercury (Hg) monitoring programs are valuable for generating data that can be compiled for spatially broad syntheses to identify emergent ecosystem properties that influence fish Hg bioaccumulation. Fish total Hg (THg) concentrations were evaluated across the Western United States (US) and Canada, a region defined by eAuthorsCollin A. Eagles-Smith, Joshua T. Ackerman, James J. Willacker, Michael T. Tate, Michelle A. Lutz, Jacob Fleck, A. Robin Stewart, James G. Wiener, David C. Evers, Jesse M. Lepak, Jay A. Davis, Colleen Flanagan PritzDragonfly Mercury Project—A citizen science driven approach to linking surface-water chemistry and landscape characteristics to biosentinels on a national scale
Mercury is a globally distributed pollutant that threatens human and ecosystem health. Even protected areas, such as national parks, are subjected to mercury contamination because it is delivered through atmospheric deposition, often after long-range transport. In aquatic ecosystems, certain environmental conditions can promote microbial processes that convert inorganic mercury to an organic formAuthorsCollin A. Eagles-Smith, Sarah J. Nelson, James J. Willacker,, Colleen M. Flanagan Pritz, David P. KrabbenhoftFrom tails to toes: developing nonlethal tissue indicators of mercury exposure in five amphibian species
Exposure to environmental contaminants has been implicated as a factor in global amphibian decline. Mercury (Hg) is a particularly widespread contaminant that biomagnifies in amphibians and can cause a suite of deleterious effects. However, monitoring contaminant exposure in amphibian tissues may conflict with conservation goals if lethal take is required. Thus, there is a need to develop non-lethAuthorsAdam Z. Pfleeger, Collin A. Eagles-Smith, Brandon M. Kowalski, Garth Herring, James J. Willacker, Allyson K. Jackson, John PierceMercury in birds of San Francisco Bay-Delta, California: trophic pathways, bioaccumulation, and ecotoxicological risk to avian reproduction
San Francisco Bay Estuary in northern California has a legacy of mercury contamination, which could reduce the health and reproductive success of waterbirds in the estuary. The goal of this study was to use an integrated field and laboratory approach to evaluate the risks of mercury exposure to birds in the estuary. We examined mercury bioaccumulation, and other contaminants of concern, in five waAuthorsJoshua T. Ackerman, Collin A. Eagles-Smith, Gary Heinz, Susan E.W. De La Cruz, John Y. Takekawa, A. Keith Miles, Terrence L. Adelsbach, Mark P. Herzog, Jill D. Bluso-Demers, Scott A. Demers, Garth Herring, David J. Hoffman, Christopher A. Hartman, James J. Willacker, Thomas H. Suchanek, Steven E. Schwarzbach, Thomas C. MaurerInvasive crayfish as vectors of mercury in freshwater food webs of the Pacific Northwest
Invasive species are important drivers of environmental change in aquatic ecosystems and can alter habitat characteristics, community composition, and ecosystem energetics. Such changes have important implications for many ecosystem processes, including the bioaccumulation and biomagnification of contaminants through food webs. Mercury concentrations were measured in 2 nonnative and 1 native crayfAuthorsBranden L. Johnson, James J. Willacker, Collin A. Eagles-Smith, Christopher A. Pearl, M. J. AdamsMercury in fishes from Wrangell-St. Elias National Park and Preserve, Alaska
In this study, mercury (Hg) concentrations were examined in fishes from Wrangell-St. Elias National Park and Preserve, Alaska, the largest and one of the most remote units in the national park system. The goals of the study were to (1) examine the distribution of Hg in select lakes of Wrangell-St. Elias National Park and Preserve; (2) evaluate the differences in Hg concentrations among fish specieAuthorsBrandon M. Kowalski, James J. Willacker, Christian E. Zimmerman, Collin A. Eagles-SmithMercury in fishes from 21 national parks in the Western United States: inter- and intra-park variation in concentrations and ecological risk
Mercury (Hg) is a global contaminant and human activities have increased atmospheric Hg concentrations 3- to 5-fold during the past 150 years. This increased release into the atmosphere has resulted in elevated loadings to aquatic habitats where biogeochemical processes promote the microbial conversion of inorganic Hg to methylmercury, the bioavailable form of Hg. The physicochemical properties ofAuthorsCollin A. Eagles-Smith, James J. Willacker, Colleen M. Flanagan PritzNon-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.
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