Clint Muhlfeld, Ph.D.
I am a Research Aquatic Ecologist for the USGS Northern Rocky Mountain Science Center stationed in Glacier National Park and Associate Research Professor at the University of Montana’s Flathead Lake Biological Station.
Research interests
My general research interests encompass the fields of aquatic ecology, fisheries biology, and conservation biology. My research goal is to understand how aquatic species interact with physical and biological templates over space and time to inform conservation and management. Specifically, my applied research focuses on assessing how human stressors – invasive species, habitat modification, and climate change – influence native salmonids and rare alpine macroinvertebrates in the Rocky Mountains of United States and Canada.
My research spans a range of scientific and conservation issues from examining evolutionary and ecological impacts of invasive species on native fishes, assessing life history and genetic diversity of native salmonids, assessing the status of threatened freshwater species, investigating the impacts of dams and barriers on aquatic species and ecosystems, developing quantitative models (e.g., stream temperature, instream flow/habitat, bioenergetics, riverscape connectivity, population viability) to predict species’ responses to environmental change, to understanding and predicting the impacts of climate change on freshwater species and ecosystems.
I particularly enjoy collaboration and multidisciplinary research, and advising and educating graduate students working on freshwater ecology and conservation biology projects. Currently, I actively participate on several regional, national, and international science teams that address natural resource issues facing aquatic ecosystems. My hope is that the ecological integrity of aquatic ecosystems will be conserved for future generations through research-informed management and education.
Education and Certifications
Ph.D. 2008. Fish and Wildlife Biology, Montana State University, Bozeman
M.S. 1999. Fishery Resources, University of Idaho, Moscow
B.S. 1994. Aquatic Biology, University of Montana, Missoula; University of Maine, Orono
Affiliations and Memberships*
Flathead Lake Biological Station, University of Montana
Science and Products
Evolutionary mechanisms influencing the spread of hybridization: genomics, fitness and dispersal
Using the past as a prelude to the future to assess climate effects on native trout across the United States
Predicting climate change effects on aquatic ecosystems in the Crown of the Continent
Assessing the impacts of mining in the Transboundary Flathead and Kootenai River systems
Integrated bioassessment of imperiled alpine aquatic ecosystems using NPS vital signs and USGS research data: Implications for conservation under a warming climate
Evaluation of alternative dam operations on the movement and habitat use of bull trout and westslope cutthroat trout
Webinar: Predicting Climate Change Impacts on Aquatic Ecosystems across the Pacific Northwest
The Past as a Prelude to the Future: Assessing Climate Effects on Native Trout in the U.S.
Predicting Climate Change Impacts on River Ecosystems and Salmonids across the Pacific Northwest
An interactive data visualization framework for exploring geospatial environmental datasets and model predictions
Specialized meltwater biodiversity persists despite widespread deglaciation
Climate-induced expansions of invasive species in the Pacific Northwest, North America: A synthesis of observations and projections
A call for global action to conserve native trout in the 21st century and beyond
Global status of trout and char: Conservation challenges in the twenty-first century
Consistent compensatory growth offsets poor condition in trout populations
Microbial assemblages reflect environmental heterogeneity in alpine streams
An integrated framework for ecological drought across riverscapes of North America
Challenges in Columbia River fisheries conservation: Response to Duda et al.
Congruent population genetic structure but differing depths of divergence for three alpine stoneflies with similar ecology and geographic distributions
Effects of land use on summer thermal regimes in critical salmonid habitats of the Pacific Northwest
Trout in hot water: A call for global action
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
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Filter Total Items: 21
Evolutionary mechanisms influencing the spread of hybridization: genomics, fitness and dispersal
Invasive species and hybridization (reproduction between different species or subspecies) – among the most serious threats to native species and biodiversity – provide some of the richest opportunities for “natural experiments” in evolutionary biology. New genomic technologies, combined with long-term hybridization studies in natural populations, provide exciting opportunities to advance our...Using the past as a prelude to the future to assess climate effects on native trout across the United States
Future climate change is expected to dramatically alter the structure and function of freshwater ecosystems that support salmonid species. The response of salmonids to climate change will vary through space and time and manifest in both known and currently unknown ways. A potentially rich source of understanding of how salmonids interact with climate lies in a unified retrospective analysis of...Predicting climate change effects on aquatic ecosystems in the Crown of the Continent
Climate change poses a serious threat to natural resources, biodiversity, and ecosystem services in the United States, especially in the Rocky Mountain Ecoregion. The Crown of the Continent Ecosystem (CCE) is considered one of the largest, most pristine, and biodiverse ecosystems in North America, spanning the northern Rocky Mountains of the United States and Canada. In the heart of the CCE is the...Assessing the impacts of mining in the Transboundary Flathead and Kootenai River systems
The Transboundary Flathead and Kootenai Basins in Montana and British Columbia host some of the most diverse and unique native aquatic ecosystems throughout North America. Headwaters of these basin feed into Waterton-Glacier International Peace Park (U.S. and Canada) and Flathead Lake, and Lake Koocanusa and the Kootenai River in the U.S. Despite the tremendous historical and ecological value of...Integrated bioassessment of imperiled alpine aquatic ecosystems using NPS vital signs and USGS research data: Implications for conservation under a warming climate
Climate warming in the mid- to high-latitudes and high-elevation mountainous regions is occurring more rapidly than anywhere else on Earth, causing extensive loss of glaciers and snowpack. The loss of glaciers in Glacier National Park (GNP) is iconic of the combined impacts of global warming and reduced snowpack−all remaining 25 glaciers are predicted to disappear by 2030. These changes will...Evaluation of alternative dam operations on the movement and habitat use of bull trout and westslope cutthroat trout
The goal of this project is to quantify the operational impacts of Hungry Horse Dam on native bull trout and westslope cutthroat trout in the upper Flathead River system, Montana.Webinar: Predicting Climate Change Impacts on Aquatic Ecosystems across the Pacific Northwest
View this webinar to learn more about the impacts of climate change on Northwest fishes.The Past as a Prelude to the Future: Assessing Climate Effects on Native Trout in the U.S.
Salmonids (a family of fish that includes salmon, trout, and char) are a keystone species for both aquatic and terrestrial ecosystems, and can be an early warning indicator of ecosystem health. Salmonids also have strong societal values and contribute enormously to regional economies and Native American cultures. Today, many native salmonid populations are small, highly fragmented, and isolated frPredicting Climate Change Impacts on River Ecosystems and Salmonids across the Pacific Northwest
Salmonids, a group of coldwater adapted fishes of enormous ecological and socio-economic value, historically inhabited a variety of freshwater habitats throughout the Pacific Northwest (PNW). Over the past century, however, populations have dramatically declined due to habitat loss, overharvest, and invasive species. Consequently, many populations are listed as threatened or endangered under the U - Data
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An interactive data visualization framework for exploring geospatial environmental datasets and model predictions
With the rise of large-scale environmental models comes new challenges for how we best utilize this information in research, management and decision making. Interactive data visualizations can make large and complex datasets easier to access and explore, which can lead to knowledge discovery, hypothesis formation and improved understanding. Here, we present a web-based interactive data visualizatiAuthorsJeffrey D Walker, Benjamin Letcher, Kirk D. Rodgers, Clint C. Muhlfeld, Vincent S. D'AngeloSpecialized meltwater biodiversity persists despite widespread deglaciation
Glaciers are important drivers of environmental heterogeneity and biological diversity across mountain landscapes. Worldwide, glaciers are receding rapidly due to climate change, with important consequences for biodiversity in mountain ecosystems. However, the effects of glacier loss on biodiversity have never been quantified across a mountainous region, primarily due to a lack of adequate data atAuthorsClint C. Muhlfeld, Timothy Joseph Cline, J. Joseph Giersch, Erich Peitzsch, Caitlyn Florentine, Dean Jacobsen, Scott HotalingClimate-induced expansions of invasive species in the Pacific Northwest, North America: A synthesis of observations and projections
Climate change may facilitate the expansion of non-native invasive species (NIS) in aquatic and terrestrial systems. However, empirical evidence remains scarce and poorly synthesized at scales necessary for effective management. We conducted a literature synthesis to assess the state of research on the observed and predicted effects of climate change on a suite of 398 aquatic and terrestrial NIS nAuthorsJennifer Gervais, Ryan P. Kovach, Adam J. Sepulveda, Robert K. Al-Chokhachy, J. Joseph Giersch, Clint C. MuhlfeldA call for global action to conserve native trout in the 21st century and beyond
Trout and char (hereafter, trout ) represent some of the more culturally, economically and ecologically important taxa of freshwater fishes worldwide (Kershner, Williams, Gresswell, & Lobón‐Cerviá, 2019a). Native to all continents in the Northern Hemisphere (as well as western Mediterranean Africa), trout belong to seven genera (Oncorhynchus , Salvelinus, Salmo , Hucho, Parahucho, Brachymystax andAuthorsDaniel C. Dauwalter, Antonino Duchi, John Epifanio, A.J. Gandolfi, Robert E. Gresswell, Francis Juanes, Jeffrey L. Kershner, Javier Lobón-Cerviá, Philip McGinnity, Andreas Meraner, Pavel Mikheev, Kentaro Morita, Clint C. Muhlfeld, Kurt Pinter, John Post, Gunther Unfer, Leif Asbjørn Vøllestad, Jack E. WilliamsGlobal status of trout and char: Conservation challenges in the twenty-first century
Freshwater ecosystems are among the most threatened ecosystems in the world (Richter et al. 1997; Strayer and Dudgeon 2010), and freshwater fishes may now be the most threatened group of vertebrates (Ricciardi and Rasmussen 1999; Vorosmarty et al. 2010; Darwall and Freyhof 2016). Of the 7,300 freshwater fish species globally assessed by the International Union for Conservation of Nature (IUCN, wwwAuthorsClint C. Muhlfeld, Daniel C. Dauwalter, Vincent S. D'Angelo, Andrew Ferguson, J. Joseph Giersch, Dean Impson, Itsuro Koizumi, Ryan Kovach, Philip McGinnity, Johannes Schoeffmann, John Epifanio, Leif Asbjørn VøllestadConsistent compensatory growth offsets poor condition in trout populations
1. Compensatory growth – when individuals in poor condition grow rapidly to “catch up” to conspecifics – may be a mechanism that allows individuals to tolerate stressful environmental conditions, both abiotic and biotic. This phenomenon has been documented fairly widely in laboratory and field experiments, but evidence for compensatory growth in the wild is scarce. 2. Cutthroat trout (OncorhyncAuthorsRobert Al-Chokhachy, Ryan Kovach, Adam J. Sepulveda, Jeff Strait, Bradley B. Shepard, Clint C. MuhlfeldMicrobial assemblages reflect environmental heterogeneity in alpine streams
Alpine streams are dynamic habitats harboring substantial biodiversity across small spatial extents. The diversity of alpine stream biota is largely reflective of environmental heterogeneity stemming from varying hydrological sources. Globally, alpine stream diversity is under threat as meltwater sources recede and stream conditions become increasingly homogeneous. Much attention has been devotedAuthorsScott Hotaling, Mary E. Foley, Lydia Zeglin, Debra S. Finn, Lusha M. Tronstad, J. Joseph Giersch, Clint C. Muhlfeld, David W. WeisrockAn 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. WAuthorsRyan 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. MuhlfeldChallenges in Columbia River fisheries conservation: Response to Duda et al.
The salmonid fisheries of the Columbia River Basin (CRB) have enormous socioeconomic, cultural, and ecological importance to numerous diverse stakeholders (e.g., state, federal, tribal, nonprofit), and there are a wide array of opinions and perspectives on how these fisheries should be managed. Although we appreciate Duda et al.’s commentary, it offers only one perspective of many in this context.AuthorsBrian K. Hand, Courtney G. Flint, Chris A. Frissell, Clint C. Muhlfeld, Shawn P. Devlin, Brian P. Kennedy, Robert L. Crabtree, Arthur McKee, Gordon Luikart, Jack A. StanfordCongruent population genetic structure but differing depths of divergence for three alpine stoneflies with similar ecology and geographic distributions
Comparative population genetic studies provide a powerful means for assessing the degree to which evolutionary histories may be congruent among taxa while also highlighting the potential for cryptic diversity within existing species.In the Rocky Mountains, three confamilial stoneflies (Zapada glacier , Lednia tumana , and Lednia tetonica ; Plecoptera, Nemouridae) occupy cold alpine streams that arAuthorsScott Hotaling, J. Joseph Giersch, Debra S. Finn, Lusha M. Tronstad, Steve Jordan, Larry Serpa, Ronald Call, Clint C. Muhlfeld, David W. WeisrockEffects of land use on summer thermal regimes in critical salmonid habitats of the Pacific Northwest
The effect of climate change on stream temperature regimes is of significant concern to natural resource managers focused on protecting cold-water-dependent species. Nevertheless, understanding of how human land-use activities may act to exacerbate the effects of climate change on stream temperature regimes is limited. Using extensive stream temperature data with high-resolution climate and habitaAuthorsRyan Kovach, Clint C. Muhlfeld, Robert Al-Chokhachy, Jeffrey V. Ojala, Eric ArcherTrout in hot water: A call for global action
Trout are one of the most culturally, economically, and ecologically important taxonomic groups of freshwater fishes worldwide (1). Native to all continents in the Northern Hemisphere, trout are a taxonomically diverse group of fishes belonging to 7 genera (Oncorhynchus, Salvelinus, Salmo, Hucho, Parahucho, Brachymystax, and Salvethymus) distributed across 52 countries. These coldwater specialistsAuthorsClint C. Muhlfeld, Daniel C. Dauwalter, Ryan Kovach, Jeffrey L. Kershner, Jack E. Williams, John EpifanioNon-USGS Publications**
Muhlfeld, Clint C., Thomas E. McMahon, and Durae Belcer. 2009. Spatial and temporal dynamics of spawning between native westslope cutthroat trout (Oncorhynchus clarkii lewisi), introduced rainbow trout (O. mykiss), and their hybrids. Canadian Journal of Fisheries and Aquatic Sciences 66:1153-1168.Muhlfeld, Clint C., Thomas E. McMahon, Matthew C. Boyer, and Robert E. Gresswell. 2009. Local-habitat, watershed, and biotic factors in the spread of hybridization between native westslope cutthroat trout and introduced rainbow trout. Transactions of the American Fisheries Society 138:1036-1051.Boyer, Matthew C., Clint C. Muhlfeld, and Fred Allendorf. 2008. Rainbow trout invasion and the spread of hybridization with westslope cutthroat trout. Canadian Journal of Fisheries and Aquatic Sciences 65:658-669.Muhlfeld, Clint C., David H. Bennett, Kirk Steinhorst, Brian Marotz, and Matthew C. Boyer. 2008. Using bioenergetics modeling to estimate consumption of native juvenile salmonids by nonnative northern pike in the upper Flathead River system, Montana. North American Journal of Fisheries Management 28:636-648.**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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*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government