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eDNA Sampling at High-Elevation Lakes

A person with walking poles traversing a steep slopeIn 2020, Olympic National Forest, in partnership with Olympic National Park, U.S. Geological Survey, and Washington Department of Fish & Wildlife, completed eDNA sampling at 20 high-elevation lakes ranging in elevation from 1,745-5,976 feet (average of 4,250 feet).

Environmental DNA, or eDNA, is nuclear or mitochondrial DNA that is released from an organism into the environment. Sources of eDNA include secreted feces, mucous, and gametes; shed skin and hair; and carcasses. eDNA can be detected in cellular or extracellular form.

Fisheries biologist scoops  water sampleThe objective of the project, supported by Forest Service Regional Cost-Share funds, was to complete, for each lake, an aquatic species inventory using eDNA techniques, with a focus on native and non-native fish and amphibian species. This collaboration has included supplies and training for sampling provided by Washington Department of Fish & Wildlife; methodology and guidance based on a pilot year of surveys in 2019 from Olympic National Park and U.S. Geological Survey; and the collection of field samples by Olympic National Forest staff. Eleven of the 20 lakes surveyed are in designated wilderness, and most of the lakes have a management history of repeated fish stocking.

biological technicians, filtering samples at a remote lakeFor all lakes and ponds surveyed, scientists collected and filtered one liter of water at each of three locations along the shore, including one at the outlet and two others equidistant, to the best of our ability, from the outlet site. Depending on the ease of filtering, the processing at each lake took approximately one hour. Researchers also filtered a control sample of 500 ml on site. The greater amount of time came from accessing the lakes, some of which are extremely remote and often accessible only by waytrails.  Notes on visual observations of fish and amphibians as well as Juvenile long-toed salamander at Goat Lakes—North Ponddispersed recreation use were also taken. All samples are currently with the Washington Department of Fish & Wildlife Genetics Laboratory in Olympia and results are expected in spring 2021.

Species of interest in these high-elevation lakes on Olympic National Forest include the Cascades frog (Rana cascadae), a U.S. Fish & Wildlife Species of Concern and the rough-skinned newt (Taricha granulosa), a species highly susceptible to the salamander chytrid fungus, Bsal); brook trout (Salvelinus fontinalis); coastal cutthroat trout (Oncorynchus clarkii clarkii); and rainbow trout (Oncorhynchus mykiss). Land managers will be getting presence information on these species, as well as other local native amphibians and aquatic invertebrates.

This information will Adult long-toed salamander (Ambystoma macrodactylum)be included in the shared Olympic Peninsula lake inventory database currently maintained by Olympic National Park and will be used by the U.S. Forest Service and National Park Service to develop a management plan for invasive species, recreation, and the conservation of sensitive species and their habitats. The surveys will also provide baseline information about these ecosystems for future comparisons under changing climatic conditions.