Assessment of Environmental DNA Survey Design for the Detection of Freshwater Unionid Mussels

Implementation of environmental DNA (eDNA) for environmental consultation in association with permitting purposes has been rare within the United States. In part, this is due to the lack of developed standards and guidelines needed to design robust eDNA surveys. This study provides a descriptive analysis for assessing freshwater mussel eDNA detection compared to an exhaustive visual mussel search. We evaluated an eDNA survey at two different levels of sampling effort: (1) at the transect level assessing the collection of eDNA along transects and (2) at the water sample replicate level assessing species detections obtained from subsamples within a transect. Logistic regression assessed eDNA detection probability against the visually observed abundance for each mussel species, informing the level of effort required to detect rare mussel species. This study offers critical insight into survey design guidelines that will be instrumental for building confidence for the implementation of eDNA into freshwater mussel assessments.