Travis S Schmidt, Ph.D.
Travis Schmidt is a Research Ecologist for the Wyoming-Montana Water Science Center.
Travis' aims are to better understand how ecosystems respond to natural and human cause disturbances. He researches the effects of metals, pesticides, and other contaminants on aquatic and riparian ecological communities.
Professional Experience
2020 to present, Research Ecologist, Wyoming-Montana Water Science Center, Helena, MT
2009-2020, Research Ecologist, Colorado Water Science Center, Fort Collins, CO
2007-2009, Mendenhall Fellow, Central Mineral and Environmental Science Center, Denver, CO
2003-2007, USDA Fellow, Colorado State University, Fort Collins, CO
2001-2003, Ecotoxicologist, ELM Consulting, Chicago, IL
1999-2001, Research Assistant, Virginia Tech, Blacksburg, VA
1998-1999, Research Assistant, Aquatic Ecology Lab, The Ohio State University, Columbus, OH
1998-1999, Department of Biology, Notre Dame University, South Bend, IN
Education and Certifications
Ph.D. Ecotoxicology, Fish, Wildlife, and Conservation Biology, Colorado State University, 2007
M.S. Aquatic Toxicology, Biology Department, Virginia Tech, 2001
B.S. Ecology, Biology Department, The Pennsylvania State University, 1998
Science and Products
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Larval aquatic insect responses to cadmium and zinc in experimental streams
To evaluate the risks of metal mixture effects to natural stream communities under ecologically relevant conditions, the authors conducted 30-d tests with benthic macroinvertebrates exposed to cadmium (Cd) and zinc (Zn) in experimental streams. The simultaneous exposures were with Cd and Zn singly and with Cd+Zn mixtures at environmentally relevant ratios. The tests produced concentration–response
Authors
Christopher A. Mebane, Travis S. Schmidt, Laurie S. Balistrieri
Bifenthrin causes trophic cascades and alters insect emergence in mesocosms: implication for small streams
Direct and indirect ecological effects of the widely used insecticide bifenthrin on stream ecosystems are largely unknown. To investigate such effects, a manipulative experiment was conducted in stream mesocosms that were colonized by aquatic insect communities and exposed to bifenthrin-contaminated sediment; implications for natural streams were interpreted through comparison of mesocosm results
Authors
Holly Rogers, Travis S. Schmidt, Brittanie L. Dabney, Michelle Hladik, Barbara Mahler, Peter C. Van Metre
Isotopic insights into biological regulation of zinc in contaminated systems
Aquatic organisms use a variety of biogeochemical reactions to regulate essential and non-essential trace metals. Many of these mechanisms can lead to isotopic fractionation, thus measurement of metal isotopes may yield insights into the processes by which organisms respond to metal exposure. We illustrate these concepts with two case studies, one involving an intra- and the other an extra-cellula
Authors
Richard B. Wanty, Laurie S. Balistrieri, Jeff S. Wesner, David Walters, Travis S. Schmidt, Francesca Podda, G. De Giudici, Craig A. Stricker, Johanna M. Kraus, Pierfranco Lattanzi, Ruth E. Wolf, R. Cidu
Aquatic pollution increases use of terrestrial prey subsidies by stream fish
Stream food webs are connected with their riparian zones through cross-ecosystem movements of energy and nutrients. The use and impact of terrestrial subsidies on aquatic consumers is determined in part by in situ biomass of aquatic prey. Thus, stressors such as aquatic pollutants that greatly reduce aquatic secondary production could increase the need for and reliance of stream consumers on terr
Authors
Johanna M. Kraus, Justin F. Pomeranz, Andrew S. Todd, David M. Walters, Travis S. Schmidt, Richard B. Wanty
Expanding metal mixture toxicity models to natural stream and lake invertebrate communities
A modeling approach that was used to predict the toxicity of dissolved single and multiple metals to trout is extended to stream benthic macroinvertebrates, freshwater zooplankton, and Daphnia magna. The approach predicts the accumulation of toxicants (H, Al, Cd, Cu, Ni, Pb, and Zn) in organisms using 3 equilibrium accumulation models that define interactions between dissolved cations and biologic
Authors
Laurie S. Balistrieri, Christopher A. Mebane, Travis S. Schmidt, William (Bill) Keller
Soil disturbance as a driver of increased stream salinity in a semiarid watershed undergoing energy development
Salinization is a global threat to the quality of streams and rivers, but it can have many causes. Oil and gas development were investigated as one of several potential causes of changes in the salinity of Muddy Creek, which drains 2470 km2 of mostly public land in Wyoming, U.S.A. Stream discharge and salinity vary with seasonal snowmelt and define a primary salinity-discharge relationship. Salini
Authors
Carleton R. Bern, Melanie L. Clark, Travis S. Schmidt, JoAnn M. Holloway, Robert Mcdougal
Metamorphosis alters contaminants and chemical tracers in insects: implications for food webs
Insects are integral to most freshwater and terrestrial food webs, but due to their accumulation of environmental pollutants they are also contaminant vectors that threaten reproduction, development, and survival of consumers. Metamorphosis from larvae to adult can cause large chemical changes in insects, altering contaminant concentrations and fractionation of chemical tracers used to establish c
Authors
Johanna M. Kraus, David M. Walters, Jeff S. Wesner, Craig A. Stricker, Travis S. Schmidt, Robert E. Zuellig
Metamorphosis enhances the effects of metal exposure on the mayfly, Centroptilum triangulifer
The response of larval aquatic insects to stressors such as metals is used to assess the ecological condition of streams worldwide. However, nearly all larval insects metamorphose from aquatic larvae to winged adults, and recent surveys indicate that adults may be a more sensitive indicator of stream metal toxicity than larvae. One hypothesis to explain this pattern is that insects exposed to elev
Authors
Jeff S. Wesner, Johanna M. Kraus, Travis S. Schmidt, David M. Walters, William H. Clements
Cross-ecosystem impacts of stream pollution reduce resource and contaminant flux to riparian food webs
The effects of aquatic contaminants are propagated across ecosystem boundaries by aquatic insects that export resources and contaminants to terrestrial food webs; however, the mechanisms driving these effects are poorly understood. We examined how emergence, contaminant concentration, and total contaminant flux by adult aquatic insects changed over a gradient of bioavailable metals in streams and
Authors
Johanna M. Kraus, Travis S. Schmidt, David Walters, Richard B. Wanty, Robert E. Zuellig, Ruth E. Wolf
Emergence flux declines disproportionately to larval density along a stream metals gradient
Effects of contaminants on adult aquatic insect emergence are less well understood than effects on insect larvae. We compared responses of larval density and adult emergence along a metal contamination gradient. Nonlinear threshold responses were generally observed for larvae and emergers. Larval densities decreased significantly at low metal concentrations but precipitously at concentrations of m
Authors
Travis S. Schmidt, Johanna M. Kraus, David M. Walters, Richard B. Wanty
Zinc isotope and transition-element dynamics accompanying hydrozincite biomineralization in the Rio Naracauli, Sardinia, Italy
The Rio Naracauli in SW Sardinia drains part of the Ingurtosu Zn–Pb mining district, and contains extreme concentrations of dissolved Zn at near-neutral pH. In the upper reaches of the stream, pH, alkalinity and Zn concentrations are such that hydrozincite [Zn5(CO3)2(OH)6] precipitates in a biologically mediated process facilitated by a microalga (Chlorella sp.) and a cyanobacterium (Scytonema sp.
Authors
Richard B. Wanty, F. Podda, Giovanni De Giudici, R. Cidu, Pierfranco Lattanzi
Characterizing invertebrate traits in wadeable streams of the contiguous US: differences among ecoregions and land uses
Much is known about invertebrate community traits in basins across Europe, but no comprehensive description of traits exists for the continental US. Little is known about the trait composition of invertebrates in reference or least-disturbed basins of the US, how trait composition varies among ecoregions, or how consistently traits respond to land use. These elements are essential to development o
Authors
Robert E. Zuellig, Travis S. Schmidt
Non-USGS Publications**
Stahl, Ralph G., Kapustka, Lawrence A., Munns, Wayne R., and Bruins, Randall J. F. 2007. Organizing and Integrating the Valuation Process. pp.129–163. DOI: 10.1201/9781420062632.ch6
Church, S.E., R.B. Wanty, T.S. Schmidt, D.L. Fey, B.W. Rockwell, and C.A. San Juan. 2008. Environmental Assessment of Central Colorado-Effects of hydrothermal alteration on water and sediment quality. [abs.]. In: Society of Environmental Toxicology and Chemistry, November 16-20, 2008, Tampa, Florida, USA. Society of Environmental Toxicology and Chemistry. p. 1.
Church, S.E., D.L. Fey, T.L. Klein, T.S. Schmidt, R.B. Wanty, E.H. DeWitt, B.W. Rockwell, and C.A. San Juan. 2008. Environmental effects of hydrothermal alteration and historical mining on water and sediment quality in central Colorado. [pages in] In: The Third Interagency Conference on Research in Watersheds, September 8-11, 2008, Estes Park, Colorado, USA. p. 1.
Van Metre. (2022). Sediment Sources and Sealed-Pavement Area Drive Polycyclic Aromatic Hydrocarbon and Metal Occurrence in Urban Streams. Environmental Science & Technology., 56(3), 1615–1626. https://doi.org/10.1021/acs.est.1c00414
**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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Larval aquatic insect responses to cadmium and zinc in experimental streams
To evaluate the risks of metal mixture effects to natural stream communities under ecologically relevant conditions, the authors conducted 30-d tests with benthic macroinvertebrates exposed to cadmium (Cd) and zinc (Zn) in experimental streams. The simultaneous exposures were with Cd and Zn singly and with Cd+Zn mixtures at environmentally relevant ratios. The tests produced concentration–responseAuthorsChristopher A. Mebane, Travis S. Schmidt, Laurie S. BalistrieriBifenthrin causes trophic cascades and alters insect emergence in mesocosms: implication for small streams
Direct and indirect ecological effects of the widely used insecticide bifenthrin on stream ecosystems are largely unknown. To investigate such effects, a manipulative experiment was conducted in stream mesocosms that were colonized by aquatic insect communities and exposed to bifenthrin-contaminated sediment; implications for natural streams were interpreted through comparison of mesocosm resultsAuthorsHolly Rogers, Travis S. Schmidt, Brittanie L. Dabney, Michelle Hladik, Barbara Mahler, Peter C. Van MetreIsotopic insights into biological regulation of zinc in contaminated systems
Aquatic organisms use a variety of biogeochemical reactions to regulate essential and non-essential trace metals. Many of these mechanisms can lead to isotopic fractionation, thus measurement of metal isotopes may yield insights into the processes by which organisms respond to metal exposure. We illustrate these concepts with two case studies, one involving an intra- and the other an extra-cellulaAuthorsRichard B. Wanty, Laurie S. Balistrieri, Jeff S. Wesner, David Walters, Travis S. Schmidt, Francesca Podda, G. De Giudici, Craig A. Stricker, Johanna M. Kraus, Pierfranco Lattanzi, Ruth E. Wolf, R. CiduAquatic pollution increases use of terrestrial prey subsidies by stream fish
Stream food webs are connected with their riparian zones through cross-ecosystem movements of energy and nutrients. The use and impact of terrestrial subsidies on aquatic consumers is determined in part by in situ biomass of aquatic prey. Thus, stressors such as aquatic pollutants that greatly reduce aquatic secondary production could increase the need for and reliance of stream consumers on terrAuthorsJohanna M. Kraus, Justin F. Pomeranz, Andrew S. Todd, David M. Walters, Travis S. Schmidt, Richard B. WantyExpanding metal mixture toxicity models to natural stream and lake invertebrate communities
A modeling approach that was used to predict the toxicity of dissolved single and multiple metals to trout is extended to stream benthic macroinvertebrates, freshwater zooplankton, and Daphnia magna. The approach predicts the accumulation of toxicants (H, Al, Cd, Cu, Ni, Pb, and Zn) in organisms using 3 equilibrium accumulation models that define interactions between dissolved cations and biologicAuthorsLaurie S. Balistrieri, Christopher A. Mebane, Travis S. Schmidt, William (Bill) KellerSoil disturbance as a driver of increased stream salinity in a semiarid watershed undergoing energy development
Salinization is a global threat to the quality of streams and rivers, but it can have many causes. Oil and gas development were investigated as one of several potential causes of changes in the salinity of Muddy Creek, which drains 2470 km2 of mostly public land in Wyoming, U.S.A. Stream discharge and salinity vary with seasonal snowmelt and define a primary salinity-discharge relationship. SaliniAuthorsCarleton R. Bern, Melanie L. Clark, Travis S. Schmidt, JoAnn M. Holloway, Robert McdougalMetamorphosis alters contaminants and chemical tracers in insects: implications for food webs
Insects are integral to most freshwater and terrestrial food webs, but due to their accumulation of environmental pollutants they are also contaminant vectors that threaten reproduction, development, and survival of consumers. Metamorphosis from larvae to adult can cause large chemical changes in insects, altering contaminant concentrations and fractionation of chemical tracers used to establish cAuthorsJohanna M. Kraus, David M. Walters, Jeff S. Wesner, Craig A. Stricker, Travis S. Schmidt, Robert E. ZuelligMetamorphosis enhances the effects of metal exposure on the mayfly, Centroptilum triangulifer
The response of larval aquatic insects to stressors such as metals is used to assess the ecological condition of streams worldwide. However, nearly all larval insects metamorphose from aquatic larvae to winged adults, and recent surveys indicate that adults may be a more sensitive indicator of stream metal toxicity than larvae. One hypothesis to explain this pattern is that insects exposed to elevAuthorsJeff S. Wesner, Johanna M. Kraus, Travis S. Schmidt, David M. Walters, William H. ClementsCross-ecosystem impacts of stream pollution reduce resource and contaminant flux to riparian food webs
The effects of aquatic contaminants are propagated across ecosystem boundaries by aquatic insects that export resources and contaminants to terrestrial food webs; however, the mechanisms driving these effects are poorly understood. We examined how emergence, contaminant concentration, and total contaminant flux by adult aquatic insects changed over a gradient of bioavailable metals in streams andAuthorsJohanna M. Kraus, Travis S. Schmidt, David Walters, Richard B. Wanty, Robert E. Zuellig, Ruth E. WolfEmergence flux declines disproportionately to larval density along a stream metals gradient
Effects of contaminants on adult aquatic insect emergence are less well understood than effects on insect larvae. We compared responses of larval density and adult emergence along a metal contamination gradient. Nonlinear threshold responses were generally observed for larvae and emergers. Larval densities decreased significantly at low metal concentrations but precipitously at concentrations of mAuthorsTravis S. Schmidt, Johanna M. Kraus, David M. Walters, Richard B. WantyZinc isotope and transition-element dynamics accompanying hydrozincite biomineralization in the Rio Naracauli, Sardinia, Italy
The Rio Naracauli in SW Sardinia drains part of the Ingurtosu Zn–Pb mining district, and contains extreme concentrations of dissolved Zn at near-neutral pH. In the upper reaches of the stream, pH, alkalinity and Zn concentrations are such that hydrozincite [Zn5(CO3)2(OH)6] precipitates in a biologically mediated process facilitated by a microalga (Chlorella sp.) and a cyanobacterium (Scytonema sp.AuthorsRichard B. Wanty, F. Podda, Giovanni De Giudici, R. Cidu, Pierfranco LattanziCharacterizing invertebrate traits in wadeable streams of the contiguous US: differences among ecoregions and land uses
Much is known about invertebrate community traits in basins across Europe, but no comprehensive description of traits exists for the continental US. Little is known about the trait composition of invertebrates in reference or least-disturbed basins of the US, how trait composition varies among ecoregions, or how consistently traits respond to land use. These elements are essential to development oAuthorsRobert E. Zuellig, Travis S. SchmidtNon-USGS Publications**
Stahl, Ralph G., Kapustka, Lawrence A., Munns, Wayne R., and Bruins, Randall J. F. 2007. Organizing and Integrating the Valuation Process. pp.129–163. DOI: 10.1201/9781420062632.ch6Church, S.E., R.B. Wanty, T.S. Schmidt, D.L. Fey, B.W. Rockwell, and C.A. San Juan. 2008. Environmental Assessment of Central Colorado-Effects of hydrothermal alteration on water and sediment quality. [abs.]. In: Society of Environmental Toxicology and Chemistry, November 16-20, 2008, Tampa, Florida, USA. Society of Environmental Toxicology and Chemistry. p. 1.Church, S.E., D.L. Fey, T.L. Klein, T.S. Schmidt, R.B. Wanty, E.H. DeWitt, B.W. Rockwell, and C.A. San Juan. 2008. Environmental effects of hydrothermal alteration and historical mining on water and sediment quality in central Colorado. [pages in] In: The Third Interagency Conference on Research in Watersheds, September 8-11, 2008, Estes Park, Colorado, USA. p. 1.
Van Metre. (2022). Sediment Sources and Sealed-Pavement Area Drive Polycyclic Aromatic Hydrocarbon and Metal Occurrence in Urban Streams. Environmental Science & Technology., 56(3), 1615–1626. https://doi.org/10.1021/acs.est.1c00414**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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