Environmental DNA Monitoring: Better Tracking of Endangered, Rare, Cryptic, and Invasive Species

As the global number of endangered, rare, and invasive species continues to increase, legally mandated efforts to monitor species’ ranges and abundances have grown exponentially. Human population growth is affecting an increasing number of species that need to be monitored, resulting in difficulties providing necessary data on the abundances, ranges, and movement of these species (Kelly 2014). We currently lack practical monitoring techniques for remote, hard-to-access habitats and species with low population counts, which makes it difficult to make informed management decisions (Kelly et al. 2014). Biologists use a variety of comprehensive field- and labor-based monitoring techniques including mark-recapture studies, depletion surveys, and tracking surveys. Environmental DNA (eDNA) is the genetic material shed by every organism into its surrounding environment, which can then be collected from air, soil, or water and analyzed to assess the composition of species present at a site (Thomsen and Willerslev 2015). eDNA monitoring is a tool that does not require the same man-hours that other techniques require. This allows eDNA to be deployed for biomonitoring, natural resource management, and decision making in ways traditional techniques cannot (Biggs et al. 2015; Kelly et al. 2014). Past use of eDNA in programs, including CaleDNA and the Aquatic eDNA atlas project, demonstrated that eDNA is currently a viable monitoring tool for endangered, rare, cryptic, and invasive species. In 2020, the United States Department of the Interior’s National Invasive Species Council Work Plan recognized the potential of eDNA and prioritized its exploration for the first time (United States Department of the Interior, 2020). We believe developing permanent funding sources or amending AB 2470 to include funds for natural resource managers to implement eDNA monitoring programs and information databases is necessary to continue to support societal growth and biodiversity in California. An eDNA monitoring program will allow natural resource managers to better inform land development, conservation, and environmental management decision-making in California.