Proper management of riverine ecosystems require physical, chemical, and biological data, but acquisition of the biological information has been a challenge because of the time, effort, and cost of traditional assessments. As a solution to this problem, USGS and BLM scientists explored integration of environmental DNA – eDNA – into the USGS National Streamflow Network. The proof-of-concept study involved collecting monthly eDNA samples alongside physical measurements at five streamgages in southwest Idaho for an entire water year. Samples were also collected at equally spaced intervals between streamgages during three sampling events to determine whether the spacing of existing gages was adequate. Using rainbow and bull trout, two species with different distribution and environmental tolerances, researchers found that eDNA analyses at streamgages provided useful information about distribution and habitat associations for both species. However, to meet regulatory requirements, occasional sampling between streamgages may be necessary for species that occur at very low density, have restricted distributions, or have narrow environmental tolerances or habitat preferences.
