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Thea M Edwards, PhD

Dr. Thea Edwards is a Supervisory Research Biologist at the Columbia Environmental Research Center.

Meet Thea Edwards

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CERC Biochemistry & Physiology Branch

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Her current research investigates the effects of environmental stressors on aquatic animals. She has particular expertise in endocrine disruption and nitrate-related ecotoxicology. Before joining USGS, Dr. Edwards represented the United States as a Fulbright Scholar in the Okavango Delta in Botswana.

As a group, CERC’s Biochemistry and Physiology Branch conducts diverse biological studies to understand how environmental stressors and water quality affect the health of fishes, amphibians, and freshwater mussels. Current projects investigate hypoxia, contaminants, and nutrient deficiencies. The group is especially interested in how stressors change gene expression and physiology to induce disease, inflammation, infertility, or other negative health outcomes in aquatic wildlife.

Additionally, Branch environmental DNA (eDNA) projects provide powerful information for resource managers as they address invasive and endangered species challenges. With eDNA technology, our scientists can detect the presence of a species by taking a water sample. This makes detection, monitoring, and management of both endangered and invasive species less expensive and more effective.  

To accomplish our mission, we collaborate broadly with other USGS scientists, academic partners, and private companies on mutually beneficial research and development needs. The work of our dedicated and experienced staff is supported by the world class aquaculture and laboratory facilities at CERC. We share and disseminate our findings through scientific publication and public outreach, and, working with USGS data release protocols, we are making all our data universally accessible to current and future stakeholders.

Professional Experience

  • 2018 – present: Branch Chief, Biochemistry and Physiology, USGS Columbia Environmental Research Center, Columbia, MO

  • 2014 – 2018: Research Assistant Professor, Biology, University of the South, Sewanee, TN

  • 2016: Fulbright Scholar, U.S. Department of State and the University of Botswana Okavango Research Institute, Maun, Botswana

  • 2011 – 2014: Assistant Professor, Biological Sciences, Louisiana Tech University, Ruston, LA

  • 2009 – 2011: Research Assistant Professor, Ecology and Evolutionary Biology and Pharmacology, Tulane University, New Orleans, LA

Education and Certifications

  • Ph.D. Biology, University of Florida 2005

  • M.S., Botany, University of Florida, 1997

  • M.S., Environmental Horticulture, University of Florida, 1994

  • B.S., Horticulture, Virginia Tech, 1991

Science and Products

link
Iowa stream

Costs and Benefits of Nitrapyrin

In December 2020, our research group (as part of the Food Integrated Science Team) published a review of nitrapyrin costs and benefits in the journal Environmental Science & Technology.
By
Columbia Environmental Research Center
link

Costs and Benefits of Nitrapyrin

In December 2020, our research group (as part of the Food Integrated Science Team) published a review of nitrapyrin costs and benefits in the journal Environmental Science & Technology.
Learn More
link
Scientist holding a brook trout with gloved hands

Fishing and Hunting Integrated Science Team

The Fishing and Hunting integrated science team focuses on contaminant and pathogen exposures in the environment that could impact the presence and vitality of fish and wildlife populations that drive commercial, recreational and subsistence activities such as hunting and fishing. If actual risks are identified this project will inform how to economically and effectively minimize risk by providing...
By
Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology
link

Fishing and Hunting Integrated Science Team

The Fishing and Hunting integrated science team focuses on contaminant and pathogen exposures in the environment that could impact the presence and vitality of fish and wildlife populations that drive commercial, recreational and subsistence activities such as hunting and fishing. If actual risks are identified this project will inform how to economically and effectively minimize risk by providing...
Learn More

Water chemistry and molecular eDNA data observed in experimental laboratory mesocosms exposed to different nitrogen amendments in the presence or absence of a nitrifier enriched microbial community

Data describe the results of a controlled laboratory mesocosm experiment evaluating the influence of a nitrifier enriched microbial community on silver carp (Hypophthalmichthys molitrix) milt eDNA degradation. Parameters described include the concentration results, limit of detection, and limit of quantification of two silver carp specific quantitative PCR assays and water chemistry results of exp
By
Columbia Environmental Research Center

Water chemistry and fish health effects for fathead minnow embryos exposed to sodium nitrate and matched conductivity controls for 21 days post fertilization

This data set describes developmental and physiological effects observed in fathead minnow embryos that were exposed to sodium nitrate or conductivity-matched controls. Exposures were conducted in the laboratory from fertilization through 21 days post-fertilization (dpf). Nitrate doses were 0, 2, 5, 10, 25, or 100 milligrams per liter nitrate-nitrogen; conductivity controls were matched to the 10
By
Columbia Environmental Research Center

A nitrifier-enriched microbial community contributes to the degradation of environmental DNA

Environmental DNA (eDNA) surveys are a promising alternative to traditional monitoring of invasive species, rare species, and biodiversity. Detecting organism-specific eDNA reduces the need to collect physical specimens for population estimates, and the high sensitivity of eDNA assays may improve detection of rare or cryptic species. However, correlating estimated concentrations of eDNA with speci
Authors
Rachelle Elaine Beattie, Caren C. Helbing, Jacob J. Imbery, Katy E. Klymus, Jonathan Lopez Duran, Catherine A. Richter, Anita A. Thambirajah, Nathan Thompson, Thea Margaret Edwards
By
Ecosystems Mission Area, Columbia Environmental Research Center

Effects of nitrate and conductivity on embryo-larval fathead minnows

Nitrate concentrations have been rising in surface waters over the last century and now frequently exceed drinking water standards and environmental safety benchmarks globally. Health-wise, these trends are concerning because nitrate has been shown to disrupt endocrine function and developmental outcomes. The present study investigated potential sublethal effects of nitrate on developing fathead m
Authors
Thea Margaret Edwards, Daniel J. Lamm, Joel J. Harvey
By
Ecosystems Mission Area, Columbia Environmental Research Center

Widespread use of the nitrification inhibitor nitrapyrin: Assessing benefits and costs to agriculture, ecosystems, and environmental health

Agricultural production and associated applications of nitrogen (N) fertilizers have increased dramatically in the last century, and current projections to 2050 show that demands will continue to increase as the human population grows. Applied in both organic and inorganic fertilizer forms, N is an essential nutrient in crop productivity. Increased fertilizer applications, however, create the pote
Authors
Emily Woodward, Thea Margaret Edwards, Carrie E Givens, Dana W. Kolpin, Michelle Hladik
By
Ecosystems Mission Area, Water Resources Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, California Water Science Center, Pennsylvania Water Science Center

Low oxygen: A (tough) way of life for Okavango fishes

Botswana’s Okavango Delta is a World Heritage Site and biodiverse wilderness. In 2016–2018, following arrival of the annual flood of rainwater from Angola’s highlands, and using continuous oxygen logging, we documented profound aquatic hypoxia that persisted for 3.5 to 5 months in the river channel. Within these periods, dissolved oxygen rarely exceeded 3 mg/L and dropped below 0.5 mg/L for up to
Authors
Thea Margaret Edwards, Ineelo J. Mosie, Brandon C. Moore, Guy Lobjoit, Kelsie Schiavone, Robert E. Bachman, Mike Murray-Hudson
By
Ecosystems Mission Area, Columbia Environmental Research Center

Non-USGS Publications**

Bartsch, P.W., Edwards, T.M., and Brock, J.W., 2019, Prevalence of eight phthalate monoesters in water from the Okavango Delta, Northern Botswana: Bulletin of Environmental Contamination and Toxicology.
Edwards, T.M., and Hamlin, H.J., 2018, Reproductive endocrinology of environmental nitrate: General and Comparative Endocrinology, v. 265, p. 31-40.
Edwards, T.M., Morgan, H.E., Balasca, C., Chalasani, N.K., Yam, L., and Roark, A.M., 2018, Detecting estrogenic ligands in personal care products using a yeast estrogen screen optimized for the undergraduate teaching laboratory: JoVE: Journal of Visualized Experiments, no. 131, p. e55754.
Lambert, M.R., and Edwards, T.M., 2017, Hormonally active phytochemicals and vertebrate evolution: Evolutionary Applications, v. 10, no. 5, p. 419-432.
Hamlin, H.J., Edwards, T.M., McCoy, J., Cruze, L., and Guillette, L.J., 2016, Environmentally relevant concentrations of nitrate increase plasma testosterone concentrations in female American alligators (Alligator mississippiensis): General and Comparative Endocrinology, v. 238, p. 55-60.
McCoy, K.A., Roark, A.M., Boggs, A.S.P., Bowden, J.A., Cruze, L., Edwards, T.M., Hamlin, H.J., Cantu, T.M., McCoy, J.A., McNabb, N.A., Wenzel, A.G., Williams, C.E., and Kohno, S., 2016, Integrative and comparative reproductive biology: From alligators to xenobiotics: General and Comparative Endocrinology, v. 238, p. 23-31.
Samuni-Blank, M., Izhaki, I., Gerchman, Y., Dearing, M.D., Karasov, W.H., Trabelcy, B., Edwards, T.M., and Arad, Z., 2014, Taste and physiological responses to glucosinolates: Seed predator versus seed disperser: PLOS ONE, v. 9, no. 11, p. e112505.
Morgan, H.E., Dillaway, D., and Edwards, T.M., 2014, Estrogenicity of soybeans (Glycine max) varies by plant organ and developmental stage: Endocrine Disruptors, v. 2, no. 1, p. e28490.
Edwards, T.M., 2013, Estrogens and plants: Integrative and Comparative Biology, v. 53, no. Suppl. 1, p. e61.
Edwards, T.M., Miller, H.D., Toft, G., and Guillette, L.J., Jr., 2013, Seasonal reproduction of male Gambusia holbrooki (eastern mosquitofish) from two Florida lakes: Fish Physiology and Biochemistry, v. 39, no. 5, p. 1165-1180.
Schug, T.T., Abagyan, R., Blumberg, B., Collins, T.J., Crews, D., DeFur, P.L., Dickerson, S.M., Edwards, T.M., Gore, A.C., Guillette, L.J., Hayes, T., Heindel, J.J., Moores, A., Patisaul, H.B., Tal, T.L., Thayer, K.A., Vandenberg, L.N., Warner, J.C., Watson, C.S., vom Saal, F.S., Zoeller, R.T., O'Brien, K.P., and Myers, J.P., 2013, Designing endocrine disruption out of the next generation of chemicals: Green Chemistry, v. 15, no. 1, p. 181-198.
Hinther, A., Edwards, T., Guillette, L., and Helbing, C., 2012, Influence of nitrate and nitrite on thyroid hormone responsive and stress-associated gene expression in cultured rana catesbeiana tadpole tail fin tissue: Frontiers in Genetics, v. 3, no. 51.
Roark, A.M., Smith, B.K., Germain-Aubrey, C.C., Cox, C.E., Watts, D.L., Hamlin, H.J., Guillette, L.J., Jr., Bybee, S.M., and Edwards, T.M., 2011, Group-advantaged training of research (GATOR): A metamorphosis of mentorship: BioScience, v. 61, no. 4, p. 301-311.
Edwards, T.M., Toft, G., and Guillette, L.J., 2010, Seasonal reproductive patterns of female Gambusia holbrooki from two Florida lakes: Science of The Total Environment, v. 408, no. 7, p. 1569-1576.
Edwards, T.M., Iguchi, T., and Guillette, L.J., Jr., 2010, Genes to ecosystems: Viviparous fishes and endocrine disruption, in: Uribe, M.C., and Grier, H.J., eds., Viviparous Fishes and Endocrine Disruption: Homestead, Florida, New Life Publications, p. 13-30.
Crain, D.A., Janssen, S.J., Edwards, T.M., Heindel, J., Ho, S.-m., Hunt, P., Iguchi, T., Juul, A., McLachlan, J.A., Schwartz, J., Skakkebaek, N., Soto, A.M., Swan, S., Walker, C., Woodruff, T.K., Woodruff, T.J., Giudice, L.C., and Guillette, L.J., 2008, Female reproductive disorders: the roles of endocrine-disrupting compounds and developmental timing: Fertility and Sterility, v. 90, no. 4, p. 911-940.
Hamlin, H.J., Moore, B.C., Edwards, T.M., Larkin, I.L.V., Boggs, A., High, W.J., Main, K.L., and Guillette, L.J., 2008, Nitrate-induced elevations in circulating sex steroid concentrations in female Siberian sturgeon (Acipenser baeri) in commercial aquaculture: Aquaculture, v. 281, no. 1, p. 118-125.
Guillette, L.J., and Edwards, T.M., 2008, Environmental influences on fertility: Can we learn lessons from studies of wildlife?: Fertility and Sterility, v. 89, no. 2, Supplement, p. e21-e24.
Edwards, T.M., and Myers, J.P., 2007, Environmental exposures and gene regulation in disease etiology: Environmental Health Perspectives, v. 115, no. 9, p. 1264-1270.
Edwards, T.M., and Guillette, L.J., 2007, Reproductive characteristics of male mosquitofish (Gambusia holbrooki) from nitrate-contaminated springs in Florida: Aquatic Toxicology, v. 85, no. 1, p. 40-47.
Kristensen, T., Edwards, T.M., Kohno, S., Baatrup, E., and Guillette, L.J., 2007, Fecundity, 17β-estradiol concentrations and expression of vitellogenin and estrogen receptor genes throughout the ovarian cycle in female Eastern mosquitofish from three lakes in Florida: Aquatic Toxicology, v. 81, no. 3, p. 245-255.
Guillette, L.J., Jr., Edwards, T.M., and Moore, B.C., 2007, Alligators, contaminants and steroid hormones: Environmental sciences: An International Journal of Environmental Physiology and Toxicology, v. 14, no. 6, p. 331-347.
Hamlin, H.J., Edwards, T.M., Moore, B.C., Main, K.L., and Guillette, L.J., 2007, Stress and its relation to endocrine function in captive female Siberian sturgeon (Acipenser baeri): Environmental sciences: An International Journal of Environmental Physiology and Toxicology, v. 14, no. 3, p. 129-139.
Edwards, T.M., McCoy, K.A., Barbeau, T., McCoy, M.W., Thro, J.M., and Guillette, L.J., 2006, Environmental context determines nitrate toxicity in Southern toad (Bufo terrestris) tadpoles: Aquatic Toxicology, v. 78, no. 1, p. 50-58.
Edwards, T.M., Miller, H.D., and Guillette, L.J., 2006, Water quality influences reproduction in female mosquitofish (Gambusia holbrooki) from eight Florida springs: Environmental Health Perspectives, v. 114, no. Suppl 1, p. 69-75.
Edwards, T.M., Moore, B.C., and Guillette, L.J., Jr., 2006, Reproductive dysgenesis in wildlife: A comparative view: International Journal of Andrology, v. 29, no. 1, p. 109-121.
Edwards, T.M., and Guillette, L.J., 2006, Seasonal reproductive variation in Gambusia holbrooki (Eastern mosquitofish) from two Florida lakes: Journal of Experimental Zoology Part A: Comparative Experimental Biology, v. 305A, no. 2.
Milnes, M.R., Bermudez, D.S., Bryan, T.A., Edwards, T.M., Gunderson, M.P., Larkin, I.L.V., Moore, B.C., and Guillette, L.J., 2006, Contaminant-induced feminization and demasculinization of nonmammalian vertebrate males in aquatic environments: Environmental Research, v. 100, no. 1, p. 3-17.
Edwards, T.M., Moore, B.C., and Guillette, L.J., 2005, Metamorphic sex change: Evolutionary insight for endocrine disruption studies: Integrative and Comparative Biology, v. 45, no. Suppl. - Annual Meeting of the Society for Integrative and Comparative Biology.
Guillette, L.J., Jr., and Edwards, T.M., 2005, Is nitrate an ecologically relevant endocrine disruptor in vertebrates?: Integrative and Comparative Biology, v. 45, no. 1, p. 19-27.
Orlando, E.F., Davis, W.P., Edwards, T.M., Sulkowski, D.F., Toft, G., and Guillette, L.J., 2005, Mosquitofish as sentinels of exposure to environmental androgens and estrogens, in: Uribe, M.C., and Grier, H.J., eds., Viviparous Fishes I: Homestead, Florida, New Life Publications, p. 435 – 453.
Gunderson, M.P., Bermudez, D.S., Bryan, T.A., Degala, S., Edwards, T.M., Kools, S.A.E., Milnes, M.R., Woodward, A.R., and Guillette, L.J., 2004, Variation in sex steroids and phallus size in juvenile American alligators (Alligator mississippiensis) collected from 3 sites within the Kissimmee-Everglades drainage in Florida (USA): Chemosphere, v. 56, no. 4, p. 335-345.
Edwards, T.M., Gunderson, M.P., Milnes, M.R., and Guillette, L.J., 2004, Gonadotropin-induced testosterone response in peripubertal male alligators: General and Comparative Endocrinology, v. 135, no. 3, p. 372-380.
Heath, J.A., Frederick, P.C., Edwards, T.M., and Guillette, L.J., 2003, Reproductive physiology of free-living White Ibises (Eudocimus albus) in the Florida Everglades: General and Comparative Endocrinology, v. 133, no. 1, p. 118-131.
Toft, G., Edwards, T.M., Baatrup, E., and Guillette, L.J., Jr., 2003, Disturbed sexual characteristics in male mosquitofish (Gambusia holbrooki) from a lake contaminated with endocrine disruptors: Environmental Health Perspectives, v. 111, no. 5, p. 695-701.
Edwards, T., Benson, N., Thro, M., Toft, G., and Guillette, L., 2002, Reduced sperm quality and seasonal reproductive variation in male Gambusia holbrooki (Eastern Mosquitofish) collected from contaminated versus reference lakes in Florida: Integrative and Comparative Biology, v. 42, p. 1224-1224.
Gunderson, M.P., Bermudez, D.S., Bryan, T.A., Crain, D.A., Degala, S., Edwards, T.M., Kools, S.A.E., Milnes, M.R., and Guillette Jr, L.J., 2002, Temporal and spatial variation in plasma thyroxine (T4) concentrations in juvenile alligators collected from lake Okeechobee and the northern Everglades, Florida, USA: Environmental Toxicology and Chemistry, v. 21, no. 5, p. 914-921.
Guillette, L.J., Orlando, E.F., Gunderson, M., Milnes, M.R., and Edwards, T.M., 2000, Aquatic wildlife as sentinels for endocrine disruption: An update, in: De Guise, S., ed., Endocrine Disruptors in the Marine Environment: Impacts on Marine Wildlife and Human Health: Bar Harbor, ME, The Jackson Laboratory and the Marine Environmental Research Institute of the University of Connecticut.

**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

  • Science
    link
    Iowa stream

    Costs and Benefits of Nitrapyrin

    In December 2020, our research group (as part of the Food Integrated Science Team) published a review of nitrapyrin costs and benefits in the journal Environmental Science & Technology.
    By
    Columbia Environmental Research Center
    link

    Costs and Benefits of Nitrapyrin

    In December 2020, our research group (as part of the Food Integrated Science Team) published a review of nitrapyrin costs and benefits in the journal Environmental Science & Technology.
    Learn More
    link
    Scientist holding a brook trout with gloved hands

    Fishing and Hunting Integrated Science Team

    The Fishing and Hunting integrated science team focuses on contaminant and pathogen exposures in the environment that could impact the presence and vitality of fish and wildlife populations that drive commercial, recreational and subsistence activities such as hunting and fishing. If actual risks are identified this project will inform how to economically and effectively minimize risk by providing...
    By
    Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology
    link

    Fishing and Hunting Integrated Science Team

    The Fishing and Hunting integrated science team focuses on contaminant and pathogen exposures in the environment that could impact the presence and vitality of fish and wildlife populations that drive commercial, recreational and subsistence activities such as hunting and fishing. If actual risks are identified this project will inform how to economically and effectively minimize risk by providing...
    Learn More
  • Data

    Water chemistry and molecular eDNA data observed in experimental laboratory mesocosms exposed to different nitrogen amendments in the presence or absence of a nitrifier enriched microbial community

    Data describe the results of a controlled laboratory mesocosm experiment evaluating the influence of a nitrifier enriched microbial community on silver carp (Hypophthalmichthys molitrix) milt eDNA degradation. Parameters described include the concentration results, limit of detection, and limit of quantification of two silver carp specific quantitative PCR assays and water chemistry results of exp
    By
    Columbia Environmental Research Center

    Water chemistry and fish health effects for fathead minnow embryos exposed to sodium nitrate and matched conductivity controls for 21 days post fertilization

    This data set describes developmental and physiological effects observed in fathead minnow embryos that were exposed to sodium nitrate or conductivity-matched controls. Exposures were conducted in the laboratory from fertilization through 21 days post-fertilization (dpf). Nitrate doses were 0, 2, 5, 10, 25, or 100 milligrams per liter nitrate-nitrogen; conductivity controls were matched to the 10
    By
    Columbia Environmental Research Center
  • Publications

    A nitrifier-enriched microbial community contributes to the degradation of environmental DNA

    Environmental DNA (eDNA) surveys are a promising alternative to traditional monitoring of invasive species, rare species, and biodiversity. Detecting organism-specific eDNA reduces the need to collect physical specimens for population estimates, and the high sensitivity of eDNA assays may improve detection of rare or cryptic species. However, correlating estimated concentrations of eDNA with speci
    Authors
    Rachelle Elaine Beattie, Caren C. Helbing, Jacob J. Imbery, Katy E. Klymus, Jonathan Lopez Duran, Catherine A. Richter, Anita A. Thambirajah, Nathan Thompson, Thea Margaret Edwards
    By
    Ecosystems Mission Area, Columbia Environmental Research Center

    Effects of nitrate and conductivity on embryo-larval fathead minnows

    Nitrate concentrations have been rising in surface waters over the last century and now frequently exceed drinking water standards and environmental safety benchmarks globally. Health-wise, these trends are concerning because nitrate has been shown to disrupt endocrine function and developmental outcomes. The present study investigated potential sublethal effects of nitrate on developing fathead m
    Authors
    Thea Margaret Edwards, Daniel J. Lamm, Joel J. Harvey
    By
    Ecosystems Mission Area, Columbia Environmental Research Center

    Widespread use of the nitrification inhibitor nitrapyrin: Assessing benefits and costs to agriculture, ecosystems, and environmental health

    Agricultural production and associated applications of nitrogen (N) fertilizers have increased dramatically in the last century, and current projections to 2050 show that demands will continue to increase as the human population grows. Applied in both organic and inorganic fertilizer forms, N is an essential nutrient in crop productivity. Increased fertilizer applications, however, create the pote
    Authors
    Emily Woodward, Thea Margaret Edwards, Carrie E Givens, Dana W. Kolpin, Michelle Hladik
    By
    Ecosystems Mission Area, Water Resources Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, California Water Science Center, Pennsylvania Water Science Center

    Low oxygen: A (tough) way of life for Okavango fishes

    Botswana’s Okavango Delta is a World Heritage Site and biodiverse wilderness. In 2016–2018, following arrival of the annual flood of rainwater from Angola’s highlands, and using continuous oxygen logging, we documented profound aquatic hypoxia that persisted for 3.5 to 5 months in the river channel. Within these periods, dissolved oxygen rarely exceeded 3 mg/L and dropped below 0.5 mg/L for up to
    Authors
    Thea Margaret Edwards, Ineelo J. Mosie, Brandon C. Moore, Guy Lobjoit, Kelsie Schiavone, Robert E. Bachman, Mike Murray-Hudson
    By
    Ecosystems Mission Area, Columbia Environmental Research Center

    Non-USGS Publications**

    Bartsch, P.W., Edwards, T.M., and Brock, J.W., 2019, Prevalence of eight phthalate monoesters in water from the Okavango Delta, Northern Botswana: Bulletin of Environmental Contamination and Toxicology.
    Edwards, T.M., and Hamlin, H.J., 2018, Reproductive endocrinology of environmental nitrate: General and Comparative Endocrinology, v. 265, p. 31-40.
    Edwards, T.M., Morgan, H.E., Balasca, C., Chalasani, N.K., Yam, L., and Roark, A.M., 2018, Detecting estrogenic ligands in personal care products using a yeast estrogen screen optimized for the undergraduate teaching laboratory: JoVE: Journal of Visualized Experiments, no. 131, p. e55754.
    Lambert, M.R., and Edwards, T.M., 2017, Hormonally active phytochemicals and vertebrate evolution: Evolutionary Applications, v. 10, no. 5, p. 419-432.
    Hamlin, H.J., Edwards, T.M., McCoy, J., Cruze, L., and Guillette, L.J., 2016, Environmentally relevant concentrations of nitrate increase plasma testosterone concentrations in female American alligators (Alligator mississippiensis): General and Comparative Endocrinology, v. 238, p. 55-60.
    McCoy, K.A., Roark, A.M., Boggs, A.S.P., Bowden, J.A., Cruze, L., Edwards, T.M., Hamlin, H.J., Cantu, T.M., McCoy, J.A., McNabb, N.A., Wenzel, A.G., Williams, C.E., and Kohno, S., 2016, Integrative and comparative reproductive biology: From alligators to xenobiotics: General and Comparative Endocrinology, v. 238, p. 23-31.
    Samuni-Blank, M., Izhaki, I., Gerchman, Y., Dearing, M.D., Karasov, W.H., Trabelcy, B., Edwards, T.M., and Arad, Z., 2014, Taste and physiological responses to glucosinolates: Seed predator versus seed disperser: PLOS ONE, v. 9, no. 11, p. e112505.
    Morgan, H.E., Dillaway, D., and Edwards, T.M., 2014, Estrogenicity of soybeans (Glycine max) varies by plant organ and developmental stage: Endocrine Disruptors, v. 2, no. 1, p. e28490.
    Edwards, T.M., 2013, Estrogens and plants: Integrative and Comparative Biology, v. 53, no. Suppl. 1, p. e61.
    Edwards, T.M., Miller, H.D., Toft, G., and Guillette, L.J., Jr., 2013, Seasonal reproduction of male Gambusia holbrooki (eastern mosquitofish) from two Florida lakes: Fish Physiology and Biochemistry, v. 39, no. 5, p. 1165-1180.
    Schug, T.T., Abagyan, R., Blumberg, B., Collins, T.J., Crews, D., DeFur, P.L., Dickerson, S.M., Edwards, T.M., Gore, A.C., Guillette, L.J., Hayes, T., Heindel, J.J., Moores, A., Patisaul, H.B., Tal, T.L., Thayer, K.A., Vandenberg, L.N., Warner, J.C., Watson, C.S., vom Saal, F.S., Zoeller, R.T., O'Brien, K.P., and Myers, J.P., 2013, Designing endocrine disruption out of the next generation of chemicals: Green Chemistry, v. 15, no. 1, p. 181-198.
    Hinther, A., Edwards, T., Guillette, L., and Helbing, C., 2012, Influence of nitrate and nitrite on thyroid hormone responsive and stress-associated gene expression in cultured rana catesbeiana tadpole tail fin tissue: Frontiers in Genetics, v. 3, no. 51.
    Roark, A.M., Smith, B.K., Germain-Aubrey, C.C., Cox, C.E., Watts, D.L., Hamlin, H.J., Guillette, L.J., Jr., Bybee, S.M., and Edwards, T.M., 2011, Group-advantaged training of research (GATOR): A metamorphosis of mentorship: BioScience, v. 61, no. 4, p. 301-311.
    Edwards, T.M., Toft, G., and Guillette, L.J., 2010, Seasonal reproductive patterns of female Gambusia holbrooki from two Florida lakes: Science of The Total Environment, v. 408, no. 7, p. 1569-1576.
    Edwards, T.M., Iguchi, T., and Guillette, L.J., Jr., 2010, Genes to ecosystems: Viviparous fishes and endocrine disruption, in: Uribe, M.C., and Grier, H.J., eds., Viviparous Fishes and Endocrine Disruption: Homestead, Florida, New Life Publications, p. 13-30.
    Crain, D.A., Janssen, S.J., Edwards, T.M., Heindel, J., Ho, S.-m., Hunt, P., Iguchi, T., Juul, A., McLachlan, J.A., Schwartz, J., Skakkebaek, N., Soto, A.M., Swan, S., Walker, C., Woodruff, T.K., Woodruff, T.J., Giudice, L.C., and Guillette, L.J., 2008, Female reproductive disorders: the roles of endocrine-disrupting compounds and developmental timing: Fertility and Sterility, v. 90, no. 4, p. 911-940.
    Hamlin, H.J., Moore, B.C., Edwards, T.M., Larkin, I.L.V., Boggs, A., High, W.J., Main, K.L., and Guillette, L.J., 2008, Nitrate-induced elevations in circulating sex steroid concentrations in female Siberian sturgeon (Acipenser baeri) in commercial aquaculture: Aquaculture, v. 281, no. 1, p. 118-125.
    Guillette, L.J., and Edwards, T.M., 2008, Environmental influences on fertility: Can we learn lessons from studies of wildlife?: Fertility and Sterility, v. 89, no. 2, Supplement, p. e21-e24.
    Edwards, T.M., and Myers, J.P., 2007, Environmental exposures and gene regulation in disease etiology: Environmental Health Perspectives, v. 115, no. 9, p. 1264-1270.
    Edwards, T.M., and Guillette, L.J., 2007, Reproductive characteristics of male mosquitofish (Gambusia holbrooki) from nitrate-contaminated springs in Florida: Aquatic Toxicology, v. 85, no. 1, p. 40-47.
    Kristensen, T., Edwards, T.M., Kohno, S., Baatrup, E., and Guillette, L.J., 2007, Fecundity, 17β-estradiol concentrations and expression of vitellogenin and estrogen receptor genes throughout the ovarian cycle in female Eastern mosquitofish from three lakes in Florida: Aquatic Toxicology, v. 81, no. 3, p. 245-255.
    Guillette, L.J., Jr., Edwards, T.M., and Moore, B.C., 2007, Alligators, contaminants and steroid hormones: Environmental sciences: An International Journal of Environmental Physiology and Toxicology, v. 14, no. 6, p. 331-347.
    Hamlin, H.J., Edwards, T.M., Moore, B.C., Main, K.L., and Guillette, L.J., 2007, Stress and its relation to endocrine function in captive female Siberian sturgeon (Acipenser baeri): Environmental sciences: An International Journal of Environmental Physiology and Toxicology, v. 14, no. 3, p. 129-139.
    Edwards, T.M., McCoy, K.A., Barbeau, T., McCoy, M.W., Thro, J.M., and Guillette, L.J., 2006, Environmental context determines nitrate toxicity in Southern toad (Bufo terrestris) tadpoles: Aquatic Toxicology, v. 78, no. 1, p. 50-58.
    Edwards, T.M., Miller, H.D., and Guillette, L.J., 2006, Water quality influences reproduction in female mosquitofish (Gambusia holbrooki) from eight Florida springs: Environmental Health Perspectives, v. 114, no. Suppl 1, p. 69-75.
    Edwards, T.M., Moore, B.C., and Guillette, L.J., Jr., 2006, Reproductive dysgenesis in wildlife: A comparative view: International Journal of Andrology, v. 29, no. 1, p. 109-121.
    Edwards, T.M., and Guillette, L.J., 2006, Seasonal reproductive variation in Gambusia holbrooki (Eastern mosquitofish) from two Florida lakes: Journal of Experimental Zoology Part A: Comparative Experimental Biology, v. 305A, no. 2.
    Milnes, M.R., Bermudez, D.S., Bryan, T.A., Edwards, T.M., Gunderson, M.P., Larkin, I.L.V., Moore, B.C., and Guillette, L.J., 2006, Contaminant-induced feminization and demasculinization of nonmammalian vertebrate males in aquatic environments: Environmental Research, v. 100, no. 1, p. 3-17.
    Edwards, T.M., Moore, B.C., and Guillette, L.J., 2005, Metamorphic sex change: Evolutionary insight for endocrine disruption studies: Integrative and Comparative Biology, v. 45, no. Suppl. - Annual Meeting of the Society for Integrative and Comparative Biology.
    Guillette, L.J., Jr., and Edwards, T.M., 2005, Is nitrate an ecologically relevant endocrine disruptor in vertebrates?: Integrative and Comparative Biology, v. 45, no. 1, p. 19-27.
    Orlando, E.F., Davis, W.P., Edwards, T.M., Sulkowski, D.F., Toft, G., and Guillette, L.J., 2005, Mosquitofish as sentinels of exposure to environmental androgens and estrogens, in: Uribe, M.C., and Grier, H.J., eds., Viviparous Fishes I: Homestead, Florida, New Life Publications, p. 435 – 453.
    Gunderson, M.P., Bermudez, D.S., Bryan, T.A., Degala, S., Edwards, T.M., Kools, S.A.E., Milnes, M.R., Woodward, A.R., and Guillette, L.J., 2004, Variation in sex steroids and phallus size in juvenile American alligators (Alligator mississippiensis) collected from 3 sites within the Kissimmee-Everglades drainage in Florida (USA): Chemosphere, v. 56, no. 4, p. 335-345.
    Edwards, T.M., Gunderson, M.P., Milnes, M.R., and Guillette, L.J., 2004, Gonadotropin-induced testosterone response in peripubertal male alligators: General and Comparative Endocrinology, v. 135, no. 3, p. 372-380.
    Heath, J.A., Frederick, P.C., Edwards, T.M., and Guillette, L.J., 2003, Reproductive physiology of free-living White Ibises (Eudocimus albus) in the Florida Everglades: General and Comparative Endocrinology, v. 133, no. 1, p. 118-131.
    Toft, G., Edwards, T.M., Baatrup, E., and Guillette, L.J., Jr., 2003, Disturbed sexual characteristics in male mosquitofish (Gambusia holbrooki) from a lake contaminated with endocrine disruptors: Environmental Health Perspectives, v. 111, no. 5, p. 695-701.
    Edwards, T., Benson, N., Thro, M., Toft, G., and Guillette, L., 2002, Reduced sperm quality and seasonal reproductive variation in male Gambusia holbrooki (Eastern Mosquitofish) collected from contaminated versus reference lakes in Florida: Integrative and Comparative Biology, v. 42, p. 1224-1224.
    Gunderson, M.P., Bermudez, D.S., Bryan, T.A., Crain, D.A., Degala, S., Edwards, T.M., Kools, S.A.E., Milnes, M.R., and Guillette Jr, L.J., 2002, Temporal and spatial variation in plasma thyroxine (T4) concentrations in juvenile alligators collected from lake Okeechobee and the northern Everglades, Florida, USA: Environmental Toxicology and Chemistry, v. 21, no. 5, p. 914-921.
    Guillette, L.J., Orlando, E.F., Gunderson, M., Milnes, M.R., and Edwards, T.M., 2000, Aquatic wildlife as sentinels for endocrine disruption: An update, in: De Guise, S., ed., Endocrine Disruptors in the Marine Environment: Impacts on Marine Wildlife and Human Health: Bar Harbor, ME, The Jackson Laboratory and the Marine Environmental Research Institute of the University of Connecticut.

    **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.