Molgula manhattensis

History of Spread

Molgula manhattensis (Sea Grapes) was described from Manhatten Island NY by De Kay in 1843 (DeKay 1843), but it was collected earlier by Gould (1841) near Boston, and earlier still by Couthouy, 1838, also from Massachusetts (Van Name 1912). It was described as a new species from Europe in 1844. Some authors have considered it synonymous with M. tubifera and M. socialis, which would gives it a wide range, from Portugal to the White Sea (Van Name 1945; Carlton 2001 personal communication), while others considered it a distinct, introduced species, confined to scattered European ports (Monniot 1969). Recent genetic analysis indicate that M. mollgula is native to the northwest Atlantic, but that M. socialis is a distinct species (Haydar et al. 2010). In the northwest Atlantic, M. manhattensis occurs from the Northwest Atlantic to LA and Northeast TX (Van Name 1921; Van Name 1946; Gosner 1978; McDougall 1943). It was reported from several locations on the East Coast, from Boston to North Carolina in the 19th century (Gould 1841; DeKay 1843; Perkins 1871; Gould 1870; Verrill and Smith 1873); By the early 20th century, it was known over its present range on the Atlantic coast of North America (Van Name 1921).

This tunicate's several invasions in the Pacific suggest that could have been introduced within the Atlantic basin as well, from Europe to North America or vice versa. Recent genetic analysis supports native status in the northwest Atlantic, and introduced status in European Atlantic ports, Japan, San Francisco Bay, and the Black Sea (Haydar et al. 2010).

Molgula manhattensis has been introduced to the Pacific coast of North America, from Newport Beach (Lambert and Lambert 1998) to Puget Sound (Cohen and Carlton 1995; Cohen et al. 1998), to Japan (Asakura 1992), and Australia (Hewitt et al. 1999).

No ascidians were mentioned in an early report of Chesapeake Bay invertebrates from Fort Wool VA in 1878 (Uhler and Lugger 1878). M. manhattensis was reported from the mouth of the Patapsco River by Van Name (1912), and was also collected in the Bureau of Fisheries Survey of 1916-1922, which involved dredging primarily in the mainstem of the Bay. It was found to be 'widely distributed over the northen half of the Bay', and was taken in largest numbers between the Patapsco River and Kent Island. This tunicate was rare below the mouth of the Potomac and absent below the Rappahannock (Cowles et al. 1930). However, in 1978, it was abundant in lower cross-Bay transects near the mouth of the Piankatank, and from New Point Comfort to Cape Charles (Dauer et al. 1984). In shallower water, its range appears to be more widespread, and ranges from mesohaline tributaries to the mouth of the Bay.

Here are selected locality records:

Lower Bay- Virginia Beach/VA/Lynnhaven Bay (Ferguson and Jones 1949; Otsuka and Dauer 1982).

James River- Wreck Shoal-Newport News/VA/James River (Larsen 1985).

York River- Gloucester Point-Norfolk/VA/Hampton Roads-York River (Andrews 1956; Wass 1963; Andrews 1973; Marsh 1973; Dauer et al. 1984).

Potomac River- Cobb Island-Point Lookout/MD-VA/Potomac River (Frey 1946).

Middle Bay- Cambridge/MD/Choptank River (Humphries et al. 1985); Calvert Cliffs Nuclear Power Plant/MD/Chesapeake Bay (Abbe 1987).

Patuxent River- Eagle Harbor-Solomons Island/MD/Patuxent River (Merrill and Boss 1966; Cory 1967).

Upper Bay- Baltimore/MD/Patapsco River (Van Name (1912); MD-VA/'northern half of the Chesapeake Bay (Patapsco River mouth-Potomac river mouth) (Cowles 1930); MD/Severn River (Ruiz et al. unpublished data).

History References- Abbe 1987; Andrews 1956; Andrews 1973; Asakura 1992; Calder and Brehmer 1972; Carlton 2001 personal communication; Cohen and Carlton 1995; Cohen et al. 1998; Cory 1967; Cowles 1930; DeKay 1843; Ferguson and Jones 1949; Frey 1946; Gosner 1978; Gould 1841; Gould 1870; Hewitt et al. 1999; Humphries et al. 1985; Lambert and Lambert 1998; Larsen 1985; Marsh 1973; McDougall 1943; Merrill and Boss 1966; Monniot 1969; Otsuka and Dauer 1982; Perkins 1871; Uhler and Lugger 1878; Van Name 1912; Van Name 1921; Van Name 1945; Verrill and Smith 1873; Wass 1963

Invasion Comments