The range expansion of the North American beaver (Castor canadensis) has implications for water quality, aquatic ecosystems, and fisheries in Arctic streams.
Return to Ecosystems >> Fish and Aquatic Ecology
Landscape change in the Arctic has altered the historical range and distribution of terrestrial mammals, including moose and snowshoe hares, which have moved northward into tundra ecosystems during the 20th century. Recent field and remote sensing observations indicate that beavers (Castor canadensis) have also expanded their range from boreal forest to tundra ecosystems over the past 15 to 30 years. Extensive research from boreal and temperate regions show that beavers dramatically alter stream hydrology and water quality by building dams, creating impoundments, and modifying the transport of particulates and solutes downstream of the dam. However, little is known about beaver impacts to streams and rivers draining arctic tundra catchments, and how changing environmental conditions or management practices are driving beaver range expansion.
Compared to impacts in other regions and biomes, beaver range expansion in tundra ecosystems is unique as impoundments from beaver dams triggers rapid permafrost thaw due to inundation of valley bottom soils. Permafrost stores large reservoirs of organic carbon (C), nutrients, and mercury (Hg) in perennially frozen soils. Permafrost degradation will impact terrestrial and aquatic ecosystems by altering catchment hydrology, water temperatures and biogeochemical processes. Soil inundation increases wetland extent, which is critical for the production of dissolved organic C and the formation of toxic methylmercury. Further, enhanced hydrologic connectivity following inundation drives the mobilization of these constituents to surface waters and downstream ecosystems, where they can alter water quality and be taken up by stream food webs. Beaver dams may impact fish directly by restricting migration and movement or altering habitat for foraging and spawning, and indirectly by altering water quality through the release of C, nutrients and Hg from inundated permafrost soils. The more variable aquatic thermal habitat created by beavers may also have positive impacts on fish species. Ponded water may lead to warmer stream temperatures, providing greater unfrozen habitat in winter and warmer and more constant water temperatures throughout the year.
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Fish and Aquatic Ecology
Hydro-Ecology of Arctic Thawing (HEAT): Ecology
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The range expansion of the North American beaver (Castor canadensis) has implications for water quality, aquatic ecosystems, and fisheries in Arctic streams.
Return to Ecosystems >> Fish and Aquatic Ecology
Sources/Usage: Public Domain.Beaver lodge and drained impoundment in tributary of the Noatak River, Noatak National Preserve.(Credit: Michael Carey, USGS. Public domain.) Landscape change in the Arctic has altered the historical range and distribution of terrestrial mammals, including moose and snowshoe hares, which have moved northward into tundra ecosystems during the 20th century. Recent field and remote sensing observations indicate that beavers (Castor canadensis) have also expanded their range from boreal forest to tundra ecosystems over the past 15 to 30 years. Extensive research from boreal and temperate regions show that beavers dramatically alter stream hydrology and water quality by building dams, creating impoundments, and modifying the transport of particulates and solutes downstream of the dam. However, little is known about beaver impacts to streams and rivers draining arctic tundra catchments, and how changing environmental conditions or management practices are driving beaver range expansion.
Compared to impacts in other regions and biomes, beaver range expansion in tundra ecosystems is unique as impoundments from beaver dams triggers rapid permafrost thaw due to inundation of valley bottom soils. Permafrost stores large reservoirs of organic carbon (C), nutrients, and mercury (Hg) in perennially frozen soils. Permafrost degradation will impact terrestrial and aquatic ecosystems by altering catchment hydrology, water temperatures and biogeochemical processes. Soil inundation increases wetland extent, which is critical for the production of dissolved organic C and the formation of toxic methylmercury. Further, enhanced hydrologic connectivity following inundation drives the mobilization of these constituents to surface waters and downstream ecosystems, where they can alter water quality and be taken up by stream food webs. Beaver dams may impact fish directly by restricting migration and movement or altering habitat for foraging and spawning, and indirectly by altering water quality through the release of C, nutrients and Hg from inundated permafrost soils. The more variable aquatic thermal habitat created by beavers may also have positive impacts on fish species. Ponded water may lead to warmer stream temperatures, providing greater unfrozen habitat in winter and warmer and more constant water temperatures throughout the year.
Sources/Usage: Public Domain.Adult Pacific salmon (Oncorhynchus nerka) caught in impounded water above beaver dam. >25rKM from coast.(Credit: Brett Poulin, USGS. Public domain.)
Sources/Usage: Public Domain.Measuring temperature and dissolved oxygen in impounded water of beaver dam on the Wrench Creek, Noatak National Preserve.(Credit: Michael Carey, USGS. Public domain.)
Sources/Usage: Public Domain.Beaver dam and lodge on the Ahaliknak Creek, Noatak National Preserve. (Credit: Michael Carey, USGS. Public domain.)
Sources/Usage: Public Domain.Beaver dams on Rabbit Creek, Cape Krusenstern National Monument.(Credit: Brett Poulin, USGS. Public domain.) - Science
Below are other science projects associated with this project.
Fish and Aquatic Ecology
Fish and aquatic habitats in Alaska support important commercial, sport, and subsistence fisheries and provide forage fish that support wildlife populations. The USGS Alaska Science Center conducts interdisciplinary research to inform local, state, federal, and international policy makers regarding conservation of fish, aquatic species, and their habitats. We work collaboratively with hydrologists...Hydro-Ecology of Arctic Thawing (HEAT): Ecology
Permafrost thaw is leading to a myriad of changes in physical and chemical conditions throughout the Arctic. - Multimedia
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