Nathaniel (Than) Hitt, PhD (Former Employee)
Science and Products
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An integrated framework for ecological drought across riverscapes of North America
Climate change is increasing the severity and extent of extreme droughts events, posing a critical threat to freshwater ecosystems, particularly with increasing human demands for diminishing water supplies. Despite the importance of drought as a significant driver of ecological and evolutionary dynamics, current understanding of drought consequences for freshwater biodiversity is very limited. W
Authors
Ryan Kovach, Jason B. Dunham, Robert Al-Chokhachy, Craig Snyder, Erik A. Beever, Gregory T. Pederson, Abigail Lynch, Nathaniel P. Hitt, Christopher P. Konrad, Kristin Jaeger, Alan H. Rea, Adam J. Sepulveda, Patrick M. Lambert, Jason M. Stoker, J. Joseph Giersch, Clint C. Muhlfeld
State-space analysis of power to detect regional brook trout population trends over time
Threats to aquatic biodiversity are expressed at broad spatial scales, but identifying regional trends in abundance is challenging owing to variable sampling designs, and temporal and spatial variation in abundance. We compiled a regional dataset of brook trout Salvelinus fontinalis counts across their southern range representing 326 sites from eight states between 1982-2014, and conducted a stati
Authors
Kasey C. Pregler, R. Daniel Hanks, Evan S. Childress, Nathaniel P. Hitt, Daniel J. Hocking, Benjamin H. Letcher, Yoichiro Kanno
Inferring watershed hydraulics and cold-water habitat persistence using multi-year air and stream temperature signals
Streams strongly influenced by groundwater discharge may serve as “climate refugia” for sensitive species in regions of increasingly marginal thermal conditions. The main goal of this study is to develop paired air and stream water annual temperature signal analysis techniques to elucidate the relative groundwater contribution to stream water and the effective groundwater flowpath depth. Groundwat
Authors
Martin A. Briggs, Zachary C. Johnson, Craig D. Snyder, Nathaniel P. Hitt, Barret L. Kurylyk, Laura K. Lautz, Dylan J. Irvine, Stephen T. Hurley, John W. Lane
Forecasting stream habitat and Brook Trout responses to climate change in Catoctin Mountain Park
Anticipating and mitigating the effects of climate change is a fundamental challenge for natural resource conservation. In this report, we respond to research needs identified by Catoctin Mountain Park (CATO) for native Brook Trout (Salvelinus fontinalis) conservation and management as part of the US Geological Survey (USGS) Natural Resources Preservation Program in FY15-16. We addressed three ove
Authors
Nathaniel P. Hitt, Craig D. Snyder, Erin Snook, Zachary Johnson, Matthew Morgan
Landform features and seasonal precipitation predict shallow groundwater influence on temperature in headwater streams
Headwater stream responses to climate change will depend in part on groundwater‐surface water exchanges. We used linear modeling techniques to partition likely effects of shallow groundwater seepage and air temperature on stream temperatures for 79 sites in nine focal watersheds using hourly air and water temperature measurements collected during summer months from 2012 to 2015 in Shenandoah Natio
Authors
Zachary C. Johnson, Craig D. Snyder, Nathaniel P. Hitt
Shallow bedrock limits groundwater seepage-based headwater climate refugia
Groundwater/surface-water exchanges in streams are inexorably linked to adjacent aquifer dynamics. As surface-water temperatures continue to increase with climate warming, refugia created by groundwater connectivity is expected to enable cold water fish species to survive. The shallow alluvial aquifers that source groundwater seepage to headwater streams, however, may also be sensitive to seasonal
Authors
Martin A. Briggs, John W. Lane, Craig D. Snyder, Eric A. White, Zachary Johnson, David L. Nelms, Nathaniel P. Hitt
Brook trout use of thermal refugia and foraging habitat influenced by brown trout
The distribution of native brook trout (Salvelinus fontinalis) in eastern North America is often limited by temperature and introduced brown trout (Salmo trutta), the relative importance of which is poorly understood but critical for conservation and restoration planning. We evaluated effects of brown trout on brook trout behavior and habitat use in experimental streams across increasing temperatu
Authors
Nathaniel P. Hitt, Erin Snook, Danielle L. Massie
Dermocystidium sp. infection in Blue Ridge Sculpin captured in Maryland
Raised pale cysts were observed on Blue Ridge Sculpin Cottus caeruleomentum during stream fish community surveys in Catoctin Mountain Park, Maryland. When examined histologically, preserved sculpin exhibited multiple cysts containing spherical endospores with a refractile central body characteristic of Dermocystidiumspp. Cysts were not observed on the gills or internally. The portion of the waters
Authors
Vicki S. Blazer, Nathaniel P. Hitt, Craig D. Snyder, Erin Snook, Cynthia R. Adams
Threshold responses of Blackside Dace (Chrosomus cumberlandensis) and Kentucky Arrow Darter (Etheostoma spilotum) to stream conductivity
Chrosomus cumberlandensis (Blackside Dace [BSD]) and Etheostoma spilotum (Kentucky Arrow Darter [KAD]) are fish species of conservation concern due to their fragmented distributions, their low population sizes, and threats from anthropogenic stressors in the southeastern United States. We evaluated the relationship between fish abundance and stream conductivity, an index of environmental quality a
Authors
Nathaniel P. Hitt, Michael Floyd, Michael Compton, Kenneth McDonald
Seasonal temperature and precipitation regulate brook trout young-of-the-year abundance and population dynamics
Abundance of the young‐of‐the‐year (YOY) fish can vary greatly among years and it may be driven by several key biological processes (i.e. adult spawning, egg survival and fry survival) that span several months. However, the relative influence of seasonal weather patterns on YOY abundance is poorly understood.We assessed the importance of seasonal air temperature (a surrogate for stream temperature
Authors
Yoichiro Kanno, Kasey C. Pregler, Nathaniel P. Hitt, Benjamin Letcher, Daniel Hocking, John E. B. Wofford
Accounting for groundwater in stream fish thermal habitat responses to climate change
Forecasting climate change effects on aquatic fauna and their habitat requires an understanding of how water temperature responds to changing air temperature (i.e., thermal sensitivity). Previous efforts to forecast climate effects on brook trout habitat have generally assumed uniform air-water temperature relationships over large areas that cannot account for groundwater inputs and other processe
Authors
Craig D. Snyder, Nathaniel P. Hitt, John A. Young
Seasonal weather patterns drive population vital rates and persistence in a stream fish
Climate change affects seasonal weather patterns, but little is known about the relative importance of seasonal weather patterns on animal population vital rates. Even when such information exists, data are typically only available from intensive fieldwork (e.g., mark–recapture studies) at a limited spatial extent. Here, we investigated effects of seasonal air temperature and precipitation (fall,
Authors
Yoichiro Kanno, Benjamin Letcher, Nathaniel P. Hitt, David A. Boughton, John E. B. Wofford, Elise Zipkin
Non-USGS Publications**
Hitt, N.P. and M. Hendryx. 2010. Ecological integrity of streams linked to human cancer mortality rates. EcoHealth 7:91-104.
Hitt, N.P. and P.L. Angermeier. 2008. River-stream connectivity affects fish bioassessment performance. Environmental Management 42:132-150.
Hitt, N.P. and P.L. Angermeier. 2008. Evidence for fish dispersal from spatial analysis of stream network topology. Journal of the North American Benthological Society 27:304-320.
Hitt, N.P. and B.R. Murphy. 2007. An inquiry-based case study for conservation biology. Journal of Virginia Science Education 2:43-50.
Hitt, N.P. and P.L. Angermeier. 2006. Effects of adjacent streams on local fish assemblage structure in western Virginia: implications for biomonitoring. American Fisheries Society Symposium 48:75-86.
Vignieri, S.N., E.M. Hallerman, B.J. Bergstrom, D.J. Hafner, A.P. Martin, P. Devers, P. Grobler and N.P. Hitt. 2006. Mistaken view of taxonomy undermines conservation of an evolutionarily distinct mouse: a response to Ramey et al. Journal of Animal Conservation 9:237-243.
Allendorf, F.W., R. Leary, N.P. Hitt, K. Knudsen, M. Boyer and P. Spruell. 2005. Cutthroat trout hybridization and the U.S. Endangered Species Act: one species, two policies. Conservation Biology 19:1326-1328.
Hitt, N.P. and C.A. Frissell. 2004. A case study of surrogate species in aquatic conservation planning. Aquatic Conservation: Marine and Freshwater Ecosystems 14:625-633.
Allendorf, F.W., R. Leary, N.P. Hitt, K. Knudsen, L. Lundquist, and P. Spruell. 2004. Intercrosses and the U.S. Endangered Species Act: should hybridized populations be included as westslope cutthroat trout? Conservation Biology 18: 1203-1213.
Hitt, N.P., C.A. Frissell, C.C. Muhlfeld and F.W. Allendorf. 2003. Spread of hybridization between native westslope cutthroat trout, Oncorhynchus clarki lewisi, and non-native rainbow trout, O. mykiss. Canadian Journal of Fisheries and Aquatic Sciences 60:1440-1451.
Hitt, N.P. 2003. Immediate effects of wildfire on stream temperature. Journal of Freshwater Ecology 18:171-173.
**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
Filter Total Items: 16
Filter Total Items: 20
No Result Found
Filter Total Items: 50
An integrated framework for ecological drought across riverscapes of North America
Climate change is increasing the severity and extent of extreme droughts events, posing a critical threat to freshwater ecosystems, particularly with increasing human demands for diminishing water supplies. Despite the importance of drought as a significant driver of ecological and evolutionary dynamics, current understanding of drought consequences for freshwater biodiversity is very limited. W
Authors
Ryan Kovach, Jason B. Dunham, Robert Al-Chokhachy, Craig Snyder, Erik A. Beever, Gregory T. Pederson, Abigail Lynch, Nathaniel P. Hitt, Christopher P. Konrad, Kristin Jaeger, Alan H. Rea, Adam J. Sepulveda, Patrick M. Lambert, Jason M. Stoker, J. Joseph Giersch, Clint C. Muhlfeld
State-space analysis of power to detect regional brook trout population trends over time
Threats to aquatic biodiversity are expressed at broad spatial scales, but identifying regional trends in abundance is challenging owing to variable sampling designs, and temporal and spatial variation in abundance. We compiled a regional dataset of brook trout Salvelinus fontinalis counts across their southern range representing 326 sites from eight states between 1982-2014, and conducted a stati
Authors
Kasey C. Pregler, R. Daniel Hanks, Evan S. Childress, Nathaniel P. Hitt, Daniel J. Hocking, Benjamin H. Letcher, Yoichiro Kanno
Inferring watershed hydraulics and cold-water habitat persistence using multi-year air and stream temperature signals
Streams strongly influenced by groundwater discharge may serve as “climate refugia” for sensitive species in regions of increasingly marginal thermal conditions. The main goal of this study is to develop paired air and stream water annual temperature signal analysis techniques to elucidate the relative groundwater contribution to stream water and the effective groundwater flowpath depth. Groundwat
Authors
Martin A. Briggs, Zachary C. Johnson, Craig D. Snyder, Nathaniel P. Hitt, Barret L. Kurylyk, Laura K. Lautz, Dylan J. Irvine, Stephen T. Hurley, John W. Lane
Forecasting stream habitat and Brook Trout responses to climate change in Catoctin Mountain Park
Anticipating and mitigating the effects of climate change is a fundamental challenge for natural resource conservation. In this report, we respond to research needs identified by Catoctin Mountain Park (CATO) for native Brook Trout (Salvelinus fontinalis) conservation and management as part of the US Geological Survey (USGS) Natural Resources Preservation Program in FY15-16. We addressed three ove
Authors
Nathaniel P. Hitt, Craig D. Snyder, Erin Snook, Zachary Johnson, Matthew Morgan
Landform features and seasonal precipitation predict shallow groundwater influence on temperature in headwater streams
Headwater stream responses to climate change will depend in part on groundwater‐surface water exchanges. We used linear modeling techniques to partition likely effects of shallow groundwater seepage and air temperature on stream temperatures for 79 sites in nine focal watersheds using hourly air and water temperature measurements collected during summer months from 2012 to 2015 in Shenandoah Natio
Authors
Zachary C. Johnson, Craig D. Snyder, Nathaniel P. Hitt
Shallow bedrock limits groundwater seepage-based headwater climate refugia
Groundwater/surface-water exchanges in streams are inexorably linked to adjacent aquifer dynamics. As surface-water temperatures continue to increase with climate warming, refugia created by groundwater connectivity is expected to enable cold water fish species to survive. The shallow alluvial aquifers that source groundwater seepage to headwater streams, however, may also be sensitive to seasonal
Authors
Martin A. Briggs, John W. Lane, Craig D. Snyder, Eric A. White, Zachary Johnson, David L. Nelms, Nathaniel P. Hitt
Brook trout use of thermal refugia and foraging habitat influenced by brown trout
The distribution of native brook trout (Salvelinus fontinalis) in eastern North America is often limited by temperature and introduced brown trout (Salmo trutta), the relative importance of which is poorly understood but critical for conservation and restoration planning. We evaluated effects of brown trout on brook trout behavior and habitat use in experimental streams across increasing temperatu
Authors
Nathaniel P. Hitt, Erin Snook, Danielle L. Massie
Dermocystidium sp. infection in Blue Ridge Sculpin captured in Maryland
Raised pale cysts were observed on Blue Ridge Sculpin Cottus caeruleomentum during stream fish community surveys in Catoctin Mountain Park, Maryland. When examined histologically, preserved sculpin exhibited multiple cysts containing spherical endospores with a refractile central body characteristic of Dermocystidiumspp. Cysts were not observed on the gills or internally. The portion of the waters
Authors
Vicki S. Blazer, Nathaniel P. Hitt, Craig D. Snyder, Erin Snook, Cynthia R. Adams
Threshold responses of Blackside Dace (Chrosomus cumberlandensis) and Kentucky Arrow Darter (Etheostoma spilotum) to stream conductivity
Chrosomus cumberlandensis (Blackside Dace [BSD]) and Etheostoma spilotum (Kentucky Arrow Darter [KAD]) are fish species of conservation concern due to their fragmented distributions, their low population sizes, and threats from anthropogenic stressors in the southeastern United States. We evaluated the relationship between fish abundance and stream conductivity, an index of environmental quality a
Authors
Nathaniel P. Hitt, Michael Floyd, Michael Compton, Kenneth McDonald
Seasonal temperature and precipitation regulate brook trout young-of-the-year abundance and population dynamics
Abundance of the young‐of‐the‐year (YOY) fish can vary greatly among years and it may be driven by several key biological processes (i.e. adult spawning, egg survival and fry survival) that span several months. However, the relative influence of seasonal weather patterns on YOY abundance is poorly understood.We assessed the importance of seasonal air temperature (a surrogate for stream temperature
Authors
Yoichiro Kanno, Kasey C. Pregler, Nathaniel P. Hitt, Benjamin Letcher, Daniel Hocking, John E. B. Wofford
Accounting for groundwater in stream fish thermal habitat responses to climate change
Forecasting climate change effects on aquatic fauna and their habitat requires an understanding of how water temperature responds to changing air temperature (i.e., thermal sensitivity). Previous efforts to forecast climate effects on brook trout habitat have generally assumed uniform air-water temperature relationships over large areas that cannot account for groundwater inputs and other processe
Authors
Craig D. Snyder, Nathaniel P. Hitt, John A. Young
Seasonal weather patterns drive population vital rates and persistence in a stream fish
Climate change affects seasonal weather patterns, but little is known about the relative importance of seasonal weather patterns on animal population vital rates. Even when such information exists, data are typically only available from intensive fieldwork (e.g., mark–recapture studies) at a limited spatial extent. Here, we investigated effects of seasonal air temperature and precipitation (fall,
Authors
Yoichiro Kanno, Benjamin Letcher, Nathaniel P. Hitt, David A. Boughton, John E. B. Wofford, Elise Zipkin
Non-USGS Publications**
Hitt, N.P. and M. Hendryx. 2010. Ecological integrity of streams linked to human cancer mortality rates. EcoHealth 7:91-104.
Hitt, N.P. and P.L. Angermeier. 2008. River-stream connectivity affects fish bioassessment performance. Environmental Management 42:132-150.
Hitt, N.P. and P.L. Angermeier. 2008. Evidence for fish dispersal from spatial analysis of stream network topology. Journal of the North American Benthological Society 27:304-320.
Hitt, N.P. and B.R. Murphy. 2007. An inquiry-based case study for conservation biology. Journal of Virginia Science Education 2:43-50.
Hitt, N.P. and P.L. Angermeier. 2006. Effects of adjacent streams on local fish assemblage structure in western Virginia: implications for biomonitoring. American Fisheries Society Symposium 48:75-86.
Vignieri, S.N., E.M. Hallerman, B.J. Bergstrom, D.J. Hafner, A.P. Martin, P. Devers, P. Grobler and N.P. Hitt. 2006. Mistaken view of taxonomy undermines conservation of an evolutionarily distinct mouse: a response to Ramey et al. Journal of Animal Conservation 9:237-243.
Allendorf, F.W., R. Leary, N.P. Hitt, K. Knudsen, M. Boyer and P. Spruell. 2005. Cutthroat trout hybridization and the U.S. Endangered Species Act: one species, two policies. Conservation Biology 19:1326-1328.
Hitt, N.P. and C.A. Frissell. 2004. A case study of surrogate species in aquatic conservation planning. Aquatic Conservation: Marine and Freshwater Ecosystems 14:625-633.
Allendorf, F.W., R. Leary, N.P. Hitt, K. Knudsen, L. Lundquist, and P. Spruell. 2004. Intercrosses and the U.S. Endangered Species Act: should hybridized populations be included as westslope cutthroat trout? Conservation Biology 18: 1203-1213.
Hitt, N.P., C.A. Frissell, C.C. Muhlfeld and F.W. Allendorf. 2003. Spread of hybridization between native westslope cutthroat trout, Oncorhynchus clarki lewisi, and non-native rainbow trout, O. mykiss. Canadian Journal of Fisheries and Aquatic Sciences 60:1440-1451.
Hitt, N.P. 2003. Immediate effects of wildfire on stream temperature. Journal of Freshwater Ecology 18:171-173.
**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.