Advancing our Understanding of Elusive At-risk Species
At the edge of a cold, fast-flowing mountain stream in the Rocky Mountain foothills of southeastern British Columbia’s Kootenay region, a tiny tan-colored frog hides under a rock. Locating the Rocky Mountain tailed frog and learning more about its distribution in BC have been difficult and costly – that is, until recently. In 2014 a team of Ausenco researchers employed environmental DNA (eDNA), a new species inventory technique, to learn more about this reclusive species. What they learned in one short five-day field trip has advanced the scientific community’s understanding of the Rocky Mountain tailed frog and its distribution – all at a fraction of the cost of conventional survey techniques.
Determining the distribution of species in aquatic water bodies has traditionally been expensive and time-consuming. Conventional survey techniques can also be harmful to the species and surrounding environment, require special permits, and do not often yield accurate results, particularly if the species is difficult to detect. In the case of the Rocky Mountain tailed frog, researchers face additional limitations since the species is not vocal and is difficult to locate due to its small size, muted coloring, and preference for hiding, fully submerged, under rocks in the substrate of the stream. “Even the best researchers are bound to miss individuals using conventional survey methods,” explains Jared Hobbs, a senior biologist at Ausenco with more than two decades of field and study design experience. Researchers also risk harming or killing tailed frogs and their tadpoles during physical surveys.
Alternatively, eDNA survey techniques are faster, less obtrusive, less costly, and more accurate at inferring species presence or absence in an aquatic environment. A typical eDNA survey involves simply collecting a water sample; animals that spend at least part of their lives in that aquatic environment shed DNA through feces, exfoliation, mucus, and urine, which then becomes suspended in the waterbody. “We were able to identify an expanded range for this species into two other areas in the east Kootenay region, explains Hobbs. “We didn’t know these frogs existed in these areas until we conducted the eDNA water sampling. This result defines a significant range expansion for this species.”
Exciting results are also being realized on more than 20 other eDNA projects that we are conducting for a variety of public and private-sector clients, from arctic grayling, chinook salmon, and western toad studies in the Yukon to frog, salamander, toad, and Pacific water shrew studies in BC. eDNA sampling is non-invasive to the target species, reduces the risk of pathogen transfer between sites, is highly accurate for detection of species in both freshwater and still-water habitats, is effective for detecting pathogens, and is often a more accurate and cost-effective survey technique for species that are difficult to detect using traditional methods. Our initial eDNA studies on the Rocky Mountain tailed frog was one of the first commercial applications of this method in Western Canada.