Comparing eDNA Detection Methods for Locating Aquatic Invasive Species in Lake Erie of the Laurentian Great Lakes, Across Five Months in Multiple Localities

Fast, reliable detection methods are paramount in the fight against the spread of aquatic invasive species (AIS), and eDNA techniques provide many benefits over traditional sampling methods. AIS are spreading rapidly around the world, reshaping ecosystems, outcompeting native species, and experiencing explosive population growth. Some sources cite the Laurentian Great Lakes as the most heavily invaded freshwater system in the world. The advantages of using eDNA technology for AIS detection include: (1) it is often more sensitive, (2) it can cover much more area, (3) it is less destructive, (4) it does not require trapping of threatened species, and (5) it can be done with considerably less taxonomic training. This study was implemented to test the utility of a commercially available metabarcoding assay against a targeted, qPCR approach for the detection of four AIS in Lake Erie. We sampled eight localities monthly throughout the summer of 2024 using both techniques. Our target AIS were the bloody red shrimp Hemimysis anomala, the fishhook waterflea Cercopagis pengoi, the water flea Daphnia lumholtzi, and the gammarid scud Echinogammarus ishnus. We found that the targeted, qPCR approach was more successful at AIS detection for our four target organisms than the specific, commercially available metabarcoding assay that was used.