Invasion

Invasion Description

1st Tidal Record: Charles County/MD/lower Potomac River tributaries (2006, USGS Nonindigenous Aquatic Species Program 2017)

!st Nontidal Record: Dauphin County ('to the Fall Line, MD boundary)/PA/Susquehanna River (1976, USNM 147679, U.S. National Museum of Natural History 2017);, 1st Tidal Record? freshwater tidal reach north of River Mile 30 (~168km upriver)[near Haverstraw]/NY/Hudson River (1996, USGS Nonindigenous Aquatic Species Program 2017)

1st Nontidal Record: in an artificial pond about 6 miles west of Schenectady/NY/Hudson River estuar (1968, Crocker 1979; Mills et al. 1996)

Geographic Extent

Tidal Records: Prince Georges-Charles County/MD/lower Potomac River tributaries, Piscatway Creek, Mattawoman Creek, Mallows Bay (2006-2010, USGS Nonindigenous Aquatic Species Program 2017); Charles County/MD/Nanjemoy Creek (2010, USGS Nonindigenous Aquatic Species Program 2017); Dorchester County/MD/Little Blackwater River (2006, USGS Nonindigenous Aquatic Species Program 2017).

Widespread in nontidal upper Bay tributaries, Bush, Gunpowder, Patuxent, Eastern Shore tributaries; Chester, Choptank, Nanticoke, Pocomoke Rivers, (2006, USGS Nonindigenous Aquatic Species Program 2017), freshwater tidal reach north of River Mile 30,[near Haverstraw]/NY/Hudson River (1996, USGS Nonindigenous Aquatic Species Program 2017)