Fig 1.
Map of general field sampling locations in the Patapsco River relative to the locations of Bloede Dam and Daniels Dam.
The locations of sampling sites (A) were categorized into three groups according to their geographic location relative to the Bloede Dam site including “Downstream” of Bloede Dam, “Restored” sites between Bloede Dam and Daniels Dam, and “Above Daniels” sites upstream of Daniels Dam. Individual habitat use sampling sites for eDNA and ichthyoplankton are labeled by site code referenced in Table 1. Specific sites for electrofishing and PIT tag antennas can be found in S2 and S3 Figs. Images show Bloede Dam before removal in 2018 (B) and the former dam site after breaching and full bank and streambed restoration (C). Mapping layers (A) from Chesapeake Assessment and Scenario Tool (CAST) (2020), Maryland iMAP, Maryland Geological Survey, NOAA, Maryland Coastal Zone Management Program (2003), US Census Bureau (2018). Images (B, C) from Maryland Department of Natural Resources.
Table 1.
eDNA sampling effort across Patapsco River study sites from 2015 to 2021.
Fig 2.
Map of positive river herring eDNA detections in the Patapsco River pre- and post- removal of Bloede Dam.
Concentrations of alewife eDNA before (A) and after (B) and blueback herring eDNA before (C) and after (D) the removal of Bloede Dam. Size of the points are relative to the mean number of mtDNA copies/L.
Fig 3.
Probability of detected river herring eDNA in the Patapsco River pre- and post- removal of Bloede Dam.
Estimated detection probability of alewife (A) and blueback herring (B) eDNA at Downstream, Restored, and Above Daniels sites in the Patapsco River pre- and post- removal of Bloede Dam. Least squares means and standard errors are back-transformed from the logistic regression to the response scale.
Fig 4.
Distribution of river herring herring eDNA concentrations.
Concentrations of eDNA for positive detections of alewife (A) and blueback herring (B) from 2015 to 2021 sampling in the Patapsco River. Concentrations are normalized as number of mtDNA copies/L.
Fig 5.
Concentration of river herring eDNA in the Patapsco River pre- and post- removal of Bloede Dam.
Mean concentration of alewife (A) and blueback herring (B) eDNA at Downstream, Restored, and Above Daniels sites in the Patapsco River pre- and post- removal of Bloede Dam. Concentrations are normalized as number of mtDNA copies/L. Means include zeros and are shown on a log scale. Bars show standard errors.
Fig 6.
Map of distribution and abundance of river herring spawning activity in the Patapsco River pre- and post-removal of Bloede Dam.
Abundance of river herring eggs collected pre-removal (A) and post-removal (B) of Bloede Dam. Catch per unit effort is standardized as number of eggs/100 kL.
Fig 7.
Probability and abundance of river herring eggs pre- and post-removal of Bloede Dam.
Estimated detection probability (A) and relative abundance (B) of river herring eggs at Downstream, Restored, and Above Daniels sites in the Patapsco River pre- and post- removal of Bloede Dam. Egg detection probabilities are back-transformed from the logistic regression to the response scale. Values are the least squares means and bars show standard error.
Table 2.
Number of adult alewife (AW) and blueback herring (BB) detected in boat electrofishing surveys in the Patapsco River.
Table 3.
Number of tagged alewife (AW) and blueback herring (BB) detected at PIT receiver antenna sites (Downstream-antenna #1, Downstream-antenna #2, and Restored-antenna).