Hellbenders can reach lengths of over two feet, making them the largest salamander in North America. Affectionately nicknamed “snot otters” due to their slimy skin secretions, hellbenders live in cool, swift mountain streams with rocky beds and eat crayfish and other small aquatic species. While they were once found extensively throughout the east coast, they are now limited to three different areas of the United States: the southern Ozark Mountains, the northern Ozark Mountains, and the Appalachian Mountains. Hellbender populations are not well-studied, but available data suggest that many populations are experiencing steep declines, some as much as 77%. These declines are of concern, since amphibians are good indicators of overall environmental health. Understanding and reversing hellbender declines will also help us protect the water resources which other wildlife and humans rely on.
Tracking Hellbenders with eDNA
North Carolina Zoo staff, in partnership with the North Carolina Wildlife Resources Commission, several North Carolina Universities and state and federal agencies have been surveying hellbender populations in the mountains of North Carolina since 2006. Surveying for hellbenders involves donning wetsuits and snorkel gear while swimming and wading in cold mountain streams and looking under the large rocks that hellbenders call home. While this method is still the basis for much of our work, we are also exploring a new method called environmental DNA. Environmental DNA (or eDNA) is a recently developed technique that relies on detecting the miniscule number of cells shed into the water by animals living in aquatic environments. Staff surveying for hellbenders take water samples from rivers which are then analyzed for the presence of hellbender DNA. By utilizing this method, research teams have been able to rapidly survey more areas for hellbenders, as well as monitor other species whose DNA is found.
Future Hellbender Research
To date, NC Zoo has surveyed six river drainage systems in the Appalachian Mountains. We are monitoring these river systems for water quality (critical for healthy hellbender populations), hellbender population stability over time, and the presence of diseases that can threaten their survival. So far we have found that areas in the western-most portion of the state, where human development is relatively low, have larger and healthier populations of hellbenders than sites further east. Collaborating with the US Fish and Wildlife Service, research is now underway to determine how human development impacts hellbenders and other amphibian populations. Findings from this ten year study will help to determine whether hellbenders should be considered endangered or threatened, which in turn could create stricter laws concerning how land is developed and waterways are utilized.