James J Roberts, PhD
James J Roberts is a Research Fisheries Biologist based in Huron, OH.
James has broad research expertise and investigates the ecological consequences of stressors like invasive species, climate change, and eutrophication for aquatic systems and specifically fish populations. There are three overall themes his research is split between (Invasive species, native fish ecology/conservation, and climate changes effects) which are all related to the conservation and management of aquatic species and systems.
Currently, he is investigating the movement, behavior, and habitat use of Grass Carp, an invasive species in the Great Lakes. He has also conducted research in the Laurentian Great Lakes examining the ecological consequences of seasonal hypolimnetic hypoxia, dead zones, in Lake Erie. Specifically, he studied the effects (behavioral, physiological, and inter-specific) of hypoxia on the benthic fish assemblage of Lake Erie, while focusing on yellow perch. Previously, James has explored the potential effects climate change may have on the persistence of Cutthroat Trout in stream and lake habitats throughout the Southern Rocky Mountain region."
Professional Experience
Research Fisheries Biologist, USGS 2020-present; Great Lakes Science Center
Fish Biologist, USGS 2015-2020; Colorado Water Science Center
Research Ecologist-Mendenhall Fellow, USGS 2012-2015; Fort Collins Science Center
Education and Certifications
Ph.D. University of Michigan
M.S. University of Wyoming
B.S. University of Michigan
Science and Products
Science pages by this scientist
Data releases by this scientist
Filter Total Items: 15
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Multimedia related to this scientist
Publications by this scientist
Filter Total Items: 42
Thermal regimes of Rocky Mountain lakes warm with climate change Thermal regimes of Rocky Mountain lakes warm with climate change
Anthropogenic climate change is causing a wide range of stresses in aquatic ecosystems, primarily through warming thermal conditions. Lakes, in response to these changes, are experiencing increases in both summer temperatures and ice-free days. We used continuous records of lake surface temperature and air temperature to create statistical models of daily mean lake surface temperature to...
Authors
James Roberts, Kurt D. Fausch, Travis S. Schmidt, David Walters
Effects of internal phosphorus loadings and food-web structure on the recovery of a deep lake from eutrophication Effects of internal phosphorus loadings and food-web structure on the recovery of a deep lake from eutrophication
We used monitoring data from Lake Lugano (Switzerland and Italy) to assess key ecosystem responses to three decades of nutrient management (1983–2014). We investigated whether reductions in external phosphorus loadings (Lext) caused declines in lake phosphorus concentrations (P) and phytoplankton biomass (Chl a), as assumed by the predictive models that underpinned the management plan
Authors
Fabio Lepori, James Roberts
Nonnative trout invasions combined with climate change threaten persistence of isolated cutthroat trout populations in the southern Rocky Mountains Nonnative trout invasions combined with climate change threaten persistence of isolated cutthroat trout populations in the southern Rocky Mountains
Effective conservation of Cutthroat Trout Oncorhynchus clarkii lineages native to the Rocky Mountains will require estimating effects of multiple stressors and directing management toward the most important ones. Recent analyses have focused on the direct and indirect effects of a changing climate on contemporary ranges, which are much reduced from historic ranges owing to past habitat...
Authors
James Roberts, Kurt Fausch, Mevin Hooten, Douglas Peterson
A long-term study of ecological impacts of river channelization on the population of an endangered fish: Lessons learned for assessment and restoration A long-term study of ecological impacts of river channelization on the population of an endangered fish: Lessons learned for assessment and restoration
Projects to assess environmental impact or restoration success in rivers focus on project-specific questions but can also provide valuable insights for future projects. Both restoration actions and impact assessments can become “adaptive” by using the knowledge gained from long-term monitoring and analysis to revise the actions, monitoring, conceptual model, or interpretation of findings...
Authors
James Roberts, Gregory Anderson, Paul Angermeier
Population viability analysis for endangered Roanoke logperch Population viability analysis for endangered Roanoke logperch
A common strategy for recovering endangered species is ensuring that populations exceed the minimum viable population size (MVP), a demographic benchmark that theoretically ensures low long-term extinction risk. One method of establishing MVP is population viability analysis, a modeling technique that simulates population trajectories and forecasts extinction risk based on a series of...
Authors
James Roberts, Paul Angermeier, Gregory Anderson
Extensive dispersal of Roanoke logperch (Percina rex) inferred from genetic marker data Extensive dispersal of Roanoke logperch (Percina rex) inferred from genetic marker data
The dispersal ecology of most stream fishes is poorly characterised, complicating conservation efforts for these species. We used microsatellite DNA marker data to characterise dispersal patterns and effective population size (Ne) for a population of Roanoke logperchPercina rex, an endangered darter (Percidae). Juveniles and candidate parents were sampled for 2 years at sites throughout...
Authors
James Roberts, Paul Angermeier, Eric Hallerman
Past and future warming of a deep European lake (Lake Lugano): What are the climatic drivers? Past and future warming of a deep European lake (Lake Lugano): What are the climatic drivers?
We used four decades (1972–2013) of temperature data from Lake Lugano, Switzerland and Italy, to address the hypotheses that: [i] the lake has been warming; [ii] part of the warming reflects global trends and is independent from climatic oscillations and [iii] the lake will continue to warm until the end of the 21st century. During the time spanned by our data, the surface waters of the...
Authors
Fabio Lepori, James Roberts
Assessing and addressing the re-eutrophication of Lake Erie: central basin hypoxia Assessing and addressing the re-eutrophication of Lake Erie: central basin hypoxia
Relieving phosphorus loading is a key management tool for controlling Lake Erie eutrophication. During the 1960s and 1970s, increased phosphorus inputs degraded water quality and reduced central basin hypolimnetic oxygen levels which, in turn, eliminated thermal habitat vital to cold-water organisms and contributed to the extirpation of important benthic macroinvertebrate prey species...
Authors
Donald Scavia, J. David Allan, Kristin Arend, Steven Bartell, Dmitry Beletsky, Nate Bosch, Stephen Brandt, Ruth Briland, Irem Daloglu, Joseph DePinto, David Dolan, Mary Anne Evans, Troy Farmer, Daisuke Goto, Haejin Han, Tomas Hook, Roger Knight, Stuart Ludsin, Doran Mason, Anna Michalak, R. Richards, James Roberts, Daniel Rucinski, Edward Rutherford, David Schwab, Timothy Sesterhenn, Hongyan Zhang, Yuntao Zhou
Genetic structuring of northern myotis (Myotis septentrionalis) at multiple spatial scales Genetic structuring of northern myotis (Myotis septentrionalis) at multiple spatial scales
Although groups of bats may be genetically distinguishable at large spatial scales, the effects of forest disturbances, particularly permanent land use conversions on fine-scale population structure and gene flow of summer aggregations of philopatric bat species are less clear. We genotyped and analyzed variation at 10 nuclear DNA microsatellite markers in 182 individuals of the forest...
Authors
Joshua Johnson, James Roberts, Tim King, John Edwards, W. Ford, David Ray
Distance, dams and drift: What structures populations of an endangered, benthic stream fish? Distance, dams and drift: What structures populations of an endangered, benthic stream fish?
Spatial population structure plays an important role in species persistence, evolution and conservation. Benthic stream fishes are diverse and frequently imperilled, yet the determinants and spatial scaling of their population structure are understudied. We investigated the range-wide population genetic structure of Roanoke logperch (Percina rex), an endangered, benthic stream fish of...
Authors
James Roberts, Paul Angermeier, Eric Hallerman
Fragmentation and thermal risks from climate change interact to affect persistence of native trout in the Colorado River basin Fragmentation and thermal risks from climate change interact to affect persistence of native trout in the Colorado River basin
Impending changes in climate will interact with other stressors to threaten aquatic ecosystems and their biota. Native Colorado River cutthroat trout (CRCT; Oncorhynchus clarkii pleuriticus) are now relegated to 309 isolated high-elevation (>1700 m) headwater stream fragments in the Upper Colorado River Basin, owing to past nonnative trout invasions and habitat loss. Predicted changes in...
Authors
James Roberts, Kurt D. Fausch, Douglas Peterson, Mevin Hooten
The past as prelude to the future for understanding 21st-century climate effects on Rocky Mountain Trout The past as prelude to the future for understanding 21st-century climate effects on Rocky Mountain Trout
Bioclimatic models predict large reductions in native trout across the Rocky Mountains in the 21st century but lack details about how changes will occur. Through five case histories across the region, we explore how a changing climate has been affecting streams and the potential consequences for trout. Monitoring records show trends in temperature and hydrographs consistent with a...
Authors
Daniel Isaak, Clint Muhlfeld, Andrew S. Todd, Robert Al-chokhachy, James Roberts, Jeffrey Kershner, Kurt D. Fausch, Steven Hostetler
Non-USGS Publications**
Isaak, D.J., C.C. Muhlfeld, A.S. Todd, R. Al-Chokhatchy, J.J. Roberts, K.D. Fausch, J.L. Kershner, and S.W. Hostetler. 2012 The past as prelude to the future: Retrospective assessments for anticipating future climate vulnerabilities of salmonid fishes in the Rocky Mountain West. Fisheries 37(12): 542-556.
Goto, D., K. Lindelof, D.L. Fanslow, S.A. Ludsin, J.J. Roberts, H.A. Vanderploeg, A.F. Wilson, and T.O. Höök. 2012. Indirect consequences of hypolimnetic hypoxia on
zooplankton growth in a large eutrophic lake. Aquatic Biology 16: 217-227.
zooplankton growth in a large eutrophic lake. Aquatic Biology 16: 217-227.
Roberts, J.J., P.A. Grecay, S.A. Ludsin, S.A. Pothoven, H.A. Vanderploeg, and T.O. Höök. 2012 Evidence of hypoxic foraging forays by yellow perch (Perca flavescens) and potential consequences for prey consumption. Freshwater Biology 57: 922-937.
Roberts, J.J., T.O. Hook, S.A. Ludsin, S.A. Pothoven, H.A. Vanderploeg, and S.B. Brandt. 2009. Effects of hypolimnetic hypoxia in Lake Erie's central basin on foraging and distribution of yellow perch. Journal of Experimental Marine Biology and Ecology. 131:S132-S142.
Roberts, J.J. and F.J. Rahel. 2008. Irrigation canals as sink habitat for trout and other fishes in a Wyoming drainage. Transactions of the American Fisheries Society. 137:951-961.
Roberts, J.J. and F.J. Rahel. 2005. Accuracy of aerial telemetry in fisheries studies. North American Journal of Fisheries Management. 25:660-666.
Roberts, J.J. 2010. The ecological consequences of hypoxia for yellow perch (Perca flavescens) in Lake Erie. Doctoral Dissertation. 181 pp.
**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 pages by this scientist
Data releases by this scientist
Filter Total Items: 15
No Result Found
Multimedia related to this scientist
Publications by this scientist
Filter Total Items: 42
Thermal regimes of Rocky Mountain lakes warm with climate change Thermal regimes of Rocky Mountain lakes warm with climate change
Anthropogenic climate change is causing a wide range of stresses in aquatic ecosystems, primarily through warming thermal conditions. Lakes, in response to these changes, are experiencing increases in both summer temperatures and ice-free days. We used continuous records of lake surface temperature and air temperature to create statistical models of daily mean lake surface temperature to...
Authors
James Roberts, Kurt D. Fausch, Travis S. Schmidt, David Walters
Effects of internal phosphorus loadings and food-web structure on the recovery of a deep lake from eutrophication Effects of internal phosphorus loadings and food-web structure on the recovery of a deep lake from eutrophication
We used monitoring data from Lake Lugano (Switzerland and Italy) to assess key ecosystem responses to three decades of nutrient management (1983–2014). We investigated whether reductions in external phosphorus loadings (Lext) caused declines in lake phosphorus concentrations (P) and phytoplankton biomass (Chl a), as assumed by the predictive models that underpinned the management plan
Authors
Fabio Lepori, James Roberts
Nonnative trout invasions combined with climate change threaten persistence of isolated cutthroat trout populations in the southern Rocky Mountains Nonnative trout invasions combined with climate change threaten persistence of isolated cutthroat trout populations in the southern Rocky Mountains
Effective conservation of Cutthroat Trout Oncorhynchus clarkii lineages native to the Rocky Mountains will require estimating effects of multiple stressors and directing management toward the most important ones. Recent analyses have focused on the direct and indirect effects of a changing climate on contemporary ranges, which are much reduced from historic ranges owing to past habitat...
Authors
James Roberts, Kurt Fausch, Mevin Hooten, Douglas Peterson
A long-term study of ecological impacts of river channelization on the population of an endangered fish: Lessons learned for assessment and restoration A long-term study of ecological impacts of river channelization on the population of an endangered fish: Lessons learned for assessment and restoration
Projects to assess environmental impact or restoration success in rivers focus on project-specific questions but can also provide valuable insights for future projects. Both restoration actions and impact assessments can become “adaptive” by using the knowledge gained from long-term monitoring and analysis to revise the actions, monitoring, conceptual model, or interpretation of findings...
Authors
James Roberts, Gregory Anderson, Paul Angermeier
Population viability analysis for endangered Roanoke logperch Population viability analysis for endangered Roanoke logperch
A common strategy for recovering endangered species is ensuring that populations exceed the minimum viable population size (MVP), a demographic benchmark that theoretically ensures low long-term extinction risk. One method of establishing MVP is population viability analysis, a modeling technique that simulates population trajectories and forecasts extinction risk based on a series of...
Authors
James Roberts, Paul Angermeier, Gregory Anderson
Extensive dispersal of Roanoke logperch (Percina rex) inferred from genetic marker data Extensive dispersal of Roanoke logperch (Percina rex) inferred from genetic marker data
The dispersal ecology of most stream fishes is poorly characterised, complicating conservation efforts for these species. We used microsatellite DNA marker data to characterise dispersal patterns and effective population size (Ne) for a population of Roanoke logperchPercina rex, an endangered darter (Percidae). Juveniles and candidate parents were sampled for 2 years at sites throughout...
Authors
James Roberts, Paul Angermeier, Eric Hallerman
Past and future warming of a deep European lake (Lake Lugano): What are the climatic drivers? Past and future warming of a deep European lake (Lake Lugano): What are the climatic drivers?
We used four decades (1972–2013) of temperature data from Lake Lugano, Switzerland and Italy, to address the hypotheses that: [i] the lake has been warming; [ii] part of the warming reflects global trends and is independent from climatic oscillations and [iii] the lake will continue to warm until the end of the 21st century. During the time spanned by our data, the surface waters of the...
Authors
Fabio Lepori, James Roberts
Assessing and addressing the re-eutrophication of Lake Erie: central basin hypoxia Assessing and addressing the re-eutrophication of Lake Erie: central basin hypoxia
Relieving phosphorus loading is a key management tool for controlling Lake Erie eutrophication. During the 1960s and 1970s, increased phosphorus inputs degraded water quality and reduced central basin hypolimnetic oxygen levels which, in turn, eliminated thermal habitat vital to cold-water organisms and contributed to the extirpation of important benthic macroinvertebrate prey species...
Authors
Donald Scavia, J. David Allan, Kristin Arend, Steven Bartell, Dmitry Beletsky, Nate Bosch, Stephen Brandt, Ruth Briland, Irem Daloglu, Joseph DePinto, David Dolan, Mary Anne Evans, Troy Farmer, Daisuke Goto, Haejin Han, Tomas Hook, Roger Knight, Stuart Ludsin, Doran Mason, Anna Michalak, R. Richards, James Roberts, Daniel Rucinski, Edward Rutherford, David Schwab, Timothy Sesterhenn, Hongyan Zhang, Yuntao Zhou
Genetic structuring of northern myotis (Myotis septentrionalis) at multiple spatial scales Genetic structuring of northern myotis (Myotis septentrionalis) at multiple spatial scales
Although groups of bats may be genetically distinguishable at large spatial scales, the effects of forest disturbances, particularly permanent land use conversions on fine-scale population structure and gene flow of summer aggregations of philopatric bat species are less clear. We genotyped and analyzed variation at 10 nuclear DNA microsatellite markers in 182 individuals of the forest...
Authors
Joshua Johnson, James Roberts, Tim King, John Edwards, W. Ford, David Ray
Distance, dams and drift: What structures populations of an endangered, benthic stream fish? Distance, dams and drift: What structures populations of an endangered, benthic stream fish?
Spatial population structure plays an important role in species persistence, evolution and conservation. Benthic stream fishes are diverse and frequently imperilled, yet the determinants and spatial scaling of their population structure are understudied. We investigated the range-wide population genetic structure of Roanoke logperch (Percina rex), an endangered, benthic stream fish of...
Authors
James Roberts, Paul Angermeier, Eric Hallerman
Fragmentation and thermal risks from climate change interact to affect persistence of native trout in the Colorado River basin Fragmentation and thermal risks from climate change interact to affect persistence of native trout in the Colorado River basin
Impending changes in climate will interact with other stressors to threaten aquatic ecosystems and their biota. Native Colorado River cutthroat trout (CRCT; Oncorhynchus clarkii pleuriticus) are now relegated to 309 isolated high-elevation (>1700 m) headwater stream fragments in the Upper Colorado River Basin, owing to past nonnative trout invasions and habitat loss. Predicted changes in...
Authors
James Roberts, Kurt D. Fausch, Douglas Peterson, Mevin Hooten
The past as prelude to the future for understanding 21st-century climate effects on Rocky Mountain Trout The past as prelude to the future for understanding 21st-century climate effects on Rocky Mountain Trout
Bioclimatic models predict large reductions in native trout across the Rocky Mountains in the 21st century but lack details about how changes will occur. Through five case histories across the region, we explore how a changing climate has been affecting streams and the potential consequences for trout. Monitoring records show trends in temperature and hydrographs consistent with a...
Authors
Daniel Isaak, Clint Muhlfeld, Andrew S. Todd, Robert Al-chokhachy, James Roberts, Jeffrey Kershner, Kurt D. Fausch, Steven Hostetler
Non-USGS Publications**
Isaak, D.J., C.C. Muhlfeld, A.S. Todd, R. Al-Chokhatchy, J.J. Roberts, K.D. Fausch, J.L. Kershner, and S.W. Hostetler. 2012 The past as prelude to the future: Retrospective assessments for anticipating future climate vulnerabilities of salmonid fishes in the Rocky Mountain West. Fisheries 37(12): 542-556.
Goto, D., K. Lindelof, D.L. Fanslow, S.A. Ludsin, J.J. Roberts, H.A. Vanderploeg, A.F. Wilson, and T.O. Höök. 2012. Indirect consequences of hypolimnetic hypoxia on
zooplankton growth in a large eutrophic lake. Aquatic Biology 16: 217-227.
zooplankton growth in a large eutrophic lake. Aquatic Biology 16: 217-227.
Roberts, J.J., P.A. Grecay, S.A. Ludsin, S.A. Pothoven, H.A. Vanderploeg, and T.O. Höök. 2012 Evidence of hypoxic foraging forays by yellow perch (Perca flavescens) and potential consequences for prey consumption. Freshwater Biology 57: 922-937.
Roberts, J.J., T.O. Hook, S.A. Ludsin, S.A. Pothoven, H.A. Vanderploeg, and S.B. Brandt. 2009. Effects of hypolimnetic hypoxia in Lake Erie's central basin on foraging and distribution of yellow perch. Journal of Experimental Marine Biology and Ecology. 131:S132-S142.
Roberts, J.J. and F.J. Rahel. 2008. Irrigation canals as sink habitat for trout and other fishes in a Wyoming drainage. Transactions of the American Fisheries Society. 137:951-961.
Roberts, J.J. and F.J. Rahel. 2005. Accuracy of aerial telemetry in fisheries studies. North American Journal of Fisheries Management. 25:660-666.
Roberts, J.J. 2010. The ecological consequences of hypoxia for yellow perch (Perca flavescens) in Lake Erie. Doctoral Dissertation. 181 pp.
**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.