Comparison of Water and Sediment Sampling Techniques for the Evaluation of Amphibian eDNA in Lentic Waterbodies in Alberta
Kris Kendell, Caren S. Goldberg
Environmental DNA, or eDNA, refers to the DNA that organisms leave behind or shed as they pass through the environment. DNA technology has evolved to allow researchers to detect DNA signatures from material such as mucus, feces, urine, or sloughed skin that is naturally contained within water, soil and other mediums. Through this project, ACA worked towards a reliable method of detecting amphibians using eDNA in pond water and pond-bottom sediment. The first phase involved a collaboration on a M.Sc. project developing an approach for detecting amphibians with eDNA from water and sediment samples. The second phase, reported here, involved a partnership with Washington State University to further refine and compare techniques for collecting eDNA from water and sediment sampling methods. In 2018, we adjusted our sampling protocols to enable more complete coverage of study ponds to improve the likelihood that target species’ eDNA were present in the samples of water and sediment collected. We believed this new strategy would improve our ability to detect species that occur in lower densities or have tadpoles with schooling behaviour (e.g., boreal toad) that may result in patchy distribution of their eDNA in a pond. Both sampling techniques were successful in detecting amphibians; the water filtration technique was as good as field surveys for detecting the presence of amphibian species at the ponds sampled, whereas detection was lower from samples assayed using pond-bottom sediment. When deciding on which method to use, the greater simplicity of sampling sediment but uncertainty from the potential of including relic DNA must be weighed against the increased detection ability of the water filtration technique. These results indicate eDNA sampling can be an effective alternative to more traditional amphibian monitoring methods in Alberta, when studying cryptic or non-vocalizing species, or species that occur at low abundance in aquatic systems.