A few years ago, while working with the Cayuga Lake Floating Classroom, I had the pleasure of bringing schoolchildren to the stream to muck around for macroinvertebrates. No matter how impressive the size of the hellgrammite (a.k.a dobsonfly), the sight of a crayfish will almost always garner all the kids’ attention.

More often than not, the crayfish that we take out of the stream for a closer look is the invasive rusty crayfish (Faxonius rusticus). Originally from Ohio River Basin, it has spread aggressively to many parts of eastern North America (Gunderson, 2000).

While I have and always will enjoy being in the field surveying creatures with my own pair of eyes, I realize that there are some pretty cool molecular biology tools that can help “see” what the eyes sometimes miss, not only because of human error but also the misfortune of not being at the right place at the right time.

This summer I hope to deploy eDNA in our nearby stream to detect the rusty crayfish. eDNA or environmental DNA is DNA that is found in the environment (aquatic or terrestrial), having been shed by organisms in the form of skin, waste, etc. Molecular biology techniques exist to sample eDNA, allowing for a rapid, cost-effective, and less invasive way of figuring out what organisms live in a particular environment especially rare, cryptic, or invasive species (USGS, 2018).

My kids have sighted and caught them in Fall Creek past summers. This time, we’ll collect some stream water samples and see if eDNA assay can reliably indicate the presence of this invasive species.