Date of Award


Publication Type

Master Thesis

Degree Name



Great Lakes Institute for Environmental Research


MacIsaac, Hugh


Heath, Daniel




Grass carp (Ctenopharyngodon idella) pose a threat to ecosystems within the Great Lakes. While the number of grass carp in the Great Lakes is currently low, management of this non-indigenous species will get increasingly difficult as the species establishes and becomes more abundant. Surveillance of grass carp in the Great Lakes therefore requires early, sensitive detection of the species when it is present at low abundance. The goal of this study was to determine the effectiveness of detecting low abundances of grass carp with environmental DNA (eDNA) and environmental RNA (eRNA), while limiting false positives and false negatives. In-lab experiments with aquarium tanks were used to assess eDNA and eRNA detection for low abundances of grass carp over time. This study is the first to detect eRNA from a freshwater vertebrate species in water samples, though only with a non-species-specific marker and without removal of grass carp from the system. On the other hand, species-specific eDNA markers for grass carp were detected for 32 days after removal of grass carp from experimental tanks. This study highlights the potential role of false positives and false negatives of eDNA and eRNA detection as well as the unpredictability of detection when target species abundance is very low.