A mesocosm comparison of laboratory‐based and on‐site eDNA solutions for detection and quantification of striped bass (Morone saxatilis) in marine ecosystems

Environmental effects monitoring in marine ecosystems are challenging,
particularly in dynamic macrotidal settings like the Bay of
Fundy.  Environmental DNA provides a useful tool for determining
species presence in such challenging places to access and sample.
Moreover, recent studies showing a link between eDNA concentration and
fish density/biomass reveal the great promise for eDNA tools to improve
biodiversity assessments in marine environments.  Three mesocosm
experiments were conducted to assess the accuracy and precision of a
hand-held point-of-need (PoN) tool for quantitative polymerase chain
reaction (qPCR) assay for eDNA detection of striped bass (Morone
saxatilis) versus conventional laboratory-based eDNA techniques. The first
of these experiments determined that striped bass eDNA was reliably
detected using either of the laboratory-based or PoN platforms, with some
variation observed in the estimates of eDNA concentrations derived from
each.  Next, a time series experiment established that eDNA in
water samples collected within a 24-hour period of exposure to striped
bass was reliably and consistently detectable with either platform. Our
final experiment found that the relationship between eDNA concentrations
and manipulated striped bass stocking densities was significant and
positive based on results from each of the laboratory-based or PoN
platforms. Our results validate and advance eDNA approaches towards
environmental monitoring efforts and demonstrate the potential for
real-time eDNA tools to quantify and identify the spatial and temporal
distribution of species-at-risk in an open ocean environment.