Evaluation of environmental DNA to detect Sistrurus catenatus and Ophidiomyces ophiodiicola in crayfish burrows

Environmental DNA represents a potentially cost-effective method for detection of rare and cryptic species, for which traditional sampling can be logistically costly. We tested species-specific probe-based assays to detect eDNA for the federally threatened eastern massasauga rattlesnake and the causative agent of snake fungal disease, Ophidiomyces ophiodiicola. We collected water samples from 100 crayfish burrows (over-wintering refugia) during spring emergence and screened them for snake and fungal DNA. We detected snake DNA in two samples and failed to detect O. ophiodiicola DNA. Given the high density of both target species at the sites, we suggest these methods may not offer a logistical and financial improvement over traditional sampling protocols.