Mussel eDNA Metabarcoding - Choctawhatchee River Drainage

In circumstances where human infrastructure has the potential to adversely affect rare, threatened, or endangered species, consultation is often needed to satisfy the requirements of State and/or Federal statutes intended to protect special status species. Longstanding precedents exist for the use of traditional field data in these consultation processes, while the implementation of environmental DNA (eDNA) for consultation and permitting purposes has been uncommon to date within the U.S. The objective of this study was to evaluate the efficacy of eDNA for freshwater mussel assessments by comparing eDNA surveys to data generated by tactile survey methods. Overall, there was high correspondence between the two survey methods, with eDNA metabarcoding detecting the four federally protected species present within the survey sites. Furthermore, relative abundance obtained from eDNA sequence read counts correlated with relative abundance obtained using visual counts from tactile searches. In its current state, there is tremendous value from applying eDNA methods alongside visual methods in a weight of evidence approach when consequences for identifying potential adverse effects are high. Additionally, with further refinement, eDNA metabarcoding can provide resource agencies with (1) presence or probable absence data, (2) species richness, and (3) estimates of relative abundances, all of which can be used to inform species consultation in similar circumstances to protocols of tactile searches designed for freshwater mussel assessments.