Invasion
Invasion Description
1st Record: Portsmouth/VA/Hampton Roads (Virginia Institute of Marine Science 1998; Harding and Mann 1999; Mann and Harding 2000)
Geographic Extent
Portsmouth/VA/Hampton Roads (James River toRappahannock River (Mann and Harding 2000; 1998-2009, Mann and Harding 2017, 305 specimens); Inshore of the Thimble Shoals and Norfolk Channels along the Southern Bay shoreline extending from Lynnhaven Inlet to the Hampton Roads Bridge-Tunnel/VA/Hampton Roads (1998-2009, Mann and Harding 2017, 7,241 specimens); Norfolk area tributariea (1998-2009, Mann and Harding 2017); VA/ Little Creek, Lafayette River, Elizabeth River, Buckroe Beach, Grandview, Back RiverDeep Water Shoal-Hampton Ba/VA/James River (Mann and Haridng 2017, 186, 484 specimens); VA/York River; Butler's Hole/ VA/mouth of Rappahannock River (Mann and Harding 2000; Mann and Harding 2017, 2 specimens); Northampton county/VA/Cherrystone Creek (Harding and Mann 2005); N & E of Cape Henry/VA/Atlantic Ocean-Chesapeake Bay (Harding and Mann 2005); Brown's Shoal and Thomas Rock/VA/James River (Harding and Mann 2005); near Tangier Light, Tangier Island/VA/Chesapeake Bay (Harding and Mann 2005); VA/eastern Shore tributaries (2000, Harding and Mann 2017, 5 specimens 2000-2009); off Cape Henry-Cape Charles/VA/Atlantic Ocean ('within sight of land', Harding and Mann 2017, 5 specimens 2000-2009)
Vectors
| Level | Vector |
|---|---|
| Alternate | Ballast Water |
| Alternate | Hull Fouling |
Regional Impacts
| Ecological Impact | Predation | |
| In laboratory experiments, small R. venosa (60-100 mm) consumed ~3.6% of their body weight in Mercenaria mercenaria (Hard Clams) per day, while large specimens (>101 mm) ate ~0.8% of their body weight per day (Savini et al. 2002). Savini et al. (2012) estimate that a population of 1,000 R. venosa could reduce the annual Hard Clam harvest by 0.3-0.9% per year. Thus, it appears likely that the present population of R. venosa is having at least a small impact on the Hard Clam harvest. Predation on Crassostrea virginica (Eastern Oyster) is expected to be less significant, because most remaining beds are in low-salinity waters, near the tolerance limits of R. venosa (Harding and Mann 1999; Mann and Harding 2000). | ||
| Economic Impact | Fisheries | |
| Savini et al. (2002) estimate that a population of 1,000 R. venosa is having at least a small impact on the Hard Clam harvest. | ||