A fate and transport model for Asian carp environmental DNA in the Chicago area waterways system

Detection of environmental DNA (eDNA) is widely employed to infer the presence of endangered or invasive species in the aquatic environment. Detection of eDNA, however, does not guarantee the presence of the species in question. The location, time, and nature of the eDNA source are unknown. An eDNA fate and transport model can help to address these unknowns. Construction of such a model requires resolution of multiple issues including: 1) Quantification of eDNA concentration in the environment; 2) Quantification of the eDNA source; 3) Quantification of decay rate; and, 4) Model application and validation. We address these issues and present the results of a fate and transport model for eDNA originating from an invasive species, silver carp (Hypophthalmicthys molitrix), in the Chicago Area Waterways System, USA. Results indicate the presence of roughly 4600 kg of silver carp, distributed along the major axes of the system, is required to produce the eDNA detected in routine monitoring. Positive detection of eDNA in a sample suggests a source within days and km of the sample time and location.