| dc.description.abstract | Environmental DNA (eDNA) detection has been proposed as a potential method for
determining the presence, abundance, and biomass of species within aquatic habitats. However, it
is unclear what spatial scale(s) eDNA detections represent in lotic systems due to uncertainties
surrounding its production and persistence. This study had two objectives: (1) to determine at
what spatial scale(s) (length of stream segments) could eDNA concentration be related to the
abundance and/or biomass of Brook Trout (Salvelinus fontinalis), and (2) to determine if the
relationship between eDNA concentration and Brook Trout abundance/biomass could be
improved by accounting for the contribution of eDNA originating upstream of investigated
stream segments. Concentrations of eDNA were related to the abundance of Brook Trout at the
25m (R2 = 0.22), 50m (R2 = 0.18), and 100m (R2 = 0.42) spatial scales, and to the biomass of
Brook Trout at the 25m spatial scale (R2 = 0.06), suggesting that eDNA concentrations can
represent Brook Trout abundance across numerous spatial scales. Variability observed in these
relationships across spatial scales was likely due to (1) the presumably heterogeneous distribution
of Brook Trout within stream segments causing different concentrations of eDNA to be detected
for similar abundances and biomasses, and (2) the contribution of eDNA from upstream of
examined stream segments to the detected eDNA concentrations. Concentrations of eDNA were
calibrated to 25m stream segments by accounting for the contribution of upstream eDNA
assuming either the constant or conditional deposition of eDNA. Both calibration methods
improved the relation of eDNA concentrations to the abundance and biomass of Brook Trout
within the 25m segments (abundance, R2 = 0.327 and R2 = 0.336 for constant and conditional
calibration respectively). However, both methods incorrectly estimated the persistence and
contribution of upstream eDNA on occasion, suggesting that additional investigation is required
before these methods can be reliably and confidently implemented to assess the abundance and
biomass of Brook Trout in lotic environments. | en_US |
