Education
Ph.D. Fisheries Science, 2002, Oregon State University
M.S. Fisheries Science (Geography minor), 1996, Oregon State University
B.A. Geography, German (double major), 1993, Robert D. Clark Honors College, University of Oregon
Research Interests
Landscape ecology, riverine landscapes, watershed processes, ecological scaling, water quality, fish habitat, land use/land cover change, landscape scenario modeling, spatial analysis, remote sensing, GIS
Fresh waters are one of the most valuable and threatened resources worldwide. They supply critical services to society and harbor many of the world’s most imperiled species. We conduct research and provide technical assistance to address challenges to fresh waters. Our research focuses on ecological processes in freshwater and terrestrial systems and the effects of those processes on landscape...
Increases in summer stream temperature as a result of human impacts and climate change may exceed the thermal tolerances of aquatic biota that are adapted to colder environments and climates. The combined effects of humans and climate change are of global concern across the range of coldwater aquatic organisms.
Water resources, riparian areas, and aquatic organisms are of critical importance in natural resource management. Yet, they are difficult to map, monitor, and understand in a spatially explicit and extensive manner as can be done more easily in terrestrial environments.
FRESC scientists investigate whole-system processes and relationships across space and time in order to advance understanding of natural, managed, and disturbed ecosystems. This includes research, monitoring, remote sensing, modeling, and synthesis to describe the patterns of change across landscapes and the biological and physical processes that generate them.
The seasonal and inter-annual variability of flow presence and water temperature within headwater streams of the Great Basin of the western United States limit the occurrence and distribution of coldwater fish and other aquatic species. To evaluate changes in flow presence and water temperature during seasonal dry periods, we developed spatial...
Gendaszek, Andrew S.; Dunham, Jason B.; Torgersen, Christian E.; Hockman-Wert, David P; Heck, Michael; Thorson, Justin Martin; Mintz, Jeffrey Michael; Allai, Todd Conservation planners and resource managers seek information about how the availability and locations of cold-water habitats will change in the future and how these predictions vary among models. We used a physical process-based model to demonstrate the implications of climate change for streamflow and water temperature in two watersheds with...
Lee, Se Yeun; Fullerton, Aimee H.; Sun, Ning; Torgersen, Christian E. Dam operations can affect mixing of the water column, thereby influencing thermal heterogeneity spatially and temporally. This occurs by restricting or eliminating connectivity in longitudinal, lateral, vertical, and temporal dimensions. We examined thermal heterogeneity across space and time and identified potential cold-water refuges for...
Mejia, Francine H.; Torgersen, Christian E.; Berntsen, Eric K; Maroney, Joseph R; Connor, J M; Fullerton, Aimee H.; Ebersole, Joseph L.; Lorang, Mark L Methods to quantify solar insolation in riparian landscapes are needed due to the importance of stream temperature to aquatic biota. We have tested three lidar predictors using two approaches developed for other applications of estimating solar insolation from airborne lidar using field data collected in a heavily forested narrow stream in western...
Richardson, Jeffrey J; Torgersen, Christian E.; Moskal, L Monika One of the desired outcomes of dam decommissioning and removal is the recovery of aquatic and riparian ecosystems. To investigate this common objective, we synthesized information from empirical studies and ecological theory into conceptual models that depict key physical and biological links driving ecological responses to removing dams. We...
Bellmore, J. Ryan; Pess, George R.; Duda, Jeffrey J.; O'Connor, Jim E.; East, Amy E.; Foley, Melissa M.; Wilcox, Andrew C.; Major, Jon J.; Shafroth, Patrick B.; Morley, Sarah A.; Magirl, Christopher S.; Anderson, Chauncey W.; Evans, James E.; Torgersen, Christian E.; Craig, Laura S. Through their dam-building activities and subsequent water storage, beaver have the potential to restore riparian ecosystems and offset some of the predicted effects of climate change by modulating streamflow. Thus, it is not surprising that reintroducing beaver to watersheds from which they have been extirpated is an often-used restoration and...
Dittbrenner, Benjamin J.; Pollack, Michael M.; Schilling, Jason W.; Olden, Julian D.; Lawler, Joshua J.; Torgersen, Christian E. Climate-change driven increases in water temperature pose challenges for aquatic organisms. Predictions of impacts typically do not account for fine-grained spatiotemporal thermal patterns in rivers. Patches of cooler water could serve as refuges for anadromous species like salmon that migrate during summer. We used high-resolution remotely sensed...
Fullerton, A.H.; Torgersen, Christian E.; Lawer, J.J.; Steel, E. A.; Ebersole, J.L.; Lee, S.Y. It is generally accepted that climate change will stress coldwater species such as Pacific salmon. However, it is unclear what aspect of altered thermal regimes (e.g., warmer winters, springs, summers, or increased variability) will have the greatest effect, and what role the spatial properties of river networks play. Thermally diverse habitats...
Fullerton, Aimee H.; Burke, Brian J.; Lawler, Joshua J.; Torgersen, Christian E.; Ebersole, Joseph L.; Leibowitz, Scott G. Dam removal is widely used as an approach for river restoration in the United States. The increase in dam removals—particularly large dams—and associated dam-removal studies over the last few decades motivated a working group at the USGS John Wesley Powell Center for Analysis and Synthesis to review and synthesize available studies of dam removals...
Foley, Melissa M.; Bellmore, James; O'Connor, James E.; Duda, Jeffrey J.; East, Amy E.; Grant, Gordon G.; Anderson, Chauncey W.; Bountry, Jennifer A.; Collins, Mathias J.; Connolly, Patrick J.; Craig, Laura S.; Evans, James E.; Greene, Samantha; Magilligan, Francis J.; Magirl, Christopher S.; Major, Jon J.; Pess, George R.; Randle, Timothy J.; Shafroth, Patrick B.; Torgersen, Christian E.; Tullos, Desiree D.; Wilcox, Andrew C. Dams have been a fundamental part of the U.S. national agenda over the past two hundred years. Recently, however, dam removal has emerged as a strategy for addressing aging, obsolete infrastructure and more than 1,100 dams have been removed since the 1970s. However, only 130 of these removals had any ecological or geomorphic assessments, and fewer...
Foley, Melissa M.; Magilligan, Francis J.; Torgersen, Christian E.; Major, Jon J.; Anderson, Chauncey W.; Connolly, Patrick J.; Wieferich, Daniel J.; Shafroth, Patrick B.; Evans, James E.; Infante, Dana M.; Craig, Laura Water temperatures fluctuate in time and space, creating diverse thermal regimes on river networks. Temporal variability in these thermal landscapes has important biological and ecological consequences because of nonlinearities in physiological reactions; spatial diversity in thermal landscapes provides aquatic organisms with options to maximize...
Steel, E. Ashley; Beechie, Timothy J.; Torgersen, Christian E.; Fullerton, Aimee H. Aging infrastructure coupled with growing interest in river restoration has driven a dramatic increase in the practice of dam removal. With this increase, there has been a proliferation of studies that assess the physical and ecological responses of rivers to these removals. As more dams are considered for removal, scientific information from...
Bellmore, James; Duda, Jeffrey J.; Craig, Laura; Greene, Samantha L.; Torgersen, Christian E.; Collins, Mathias J.; Vittum, Katherine
Resource managers need more accurate information about how cold-water habitats for fish will change in the future.
Dam operations can influence spatial and temporal thermal heterogeneity in rivers, yet quantity and distribution of cold-water refuges for salmonids in large impounded rivers have not been well studied.
The ability to understand a given ecological process depends on the scale of observation.
Stream temperature is affected by solar insolation, which is the amount of solar radiation at a given location over time.
In aquatic ecology, the term "thermal refuge" refers to a cold or warm area in which organisms are protected from unfavorable water temperatures.