A Fresh Look at the use of Environmental DNA to Study Aquatic Animals (entry by Taylor Wilcox)
Environmental DNA (also called “eDNA” for short) uses samples of the environment (like a cup of water from a stream) to detect the presence of species (like brook trout) without ever actually seeing one. Aquatic animals slough DNA-containing particles into the water from their skin and gut, leaving a genetic trace of their presence. Detecting this trace with new eDNA methods has recently emerged as a powerful way to detect species with less effort (and harm to the animals) than traditional methods like electrofishing.
However, we still don’t know a whole lot about eDNA. For example, how much DNA does a fish produce? This is an important question, because the probability of detecting a fish is in part dependent on how much DNA they leave in the environment. This summer I collaborated with researchers at the U.S. Forest Service Rocky Mountain Research Station to measure how much DNA brook trout release into the water.
We placed individual fish in tanks in the field that were fed with water from a small stream where there are no brook trout. We then collected water samples from each tank over the course of two days, and measured how much brook trout DNA was in each sample.
We’ll keep you updated on the results!