Paranais frici

History of Spread

Opinions appear to be divided on the origins of Paranais frici, and several other oligochaetes, and on their native status in Europe and North America. European workers consider P. frici, and several species of Potamothrix (P. vejdovskyi, P. heuscheri, P. moldaviensis, P. bavaricus) to be of Ponto-Caspian origin. Paranais frici was first reported in the Baltic Sea in 1995 (Leppakoski and Olenin 1999). These forms are believed to have colonized western Europe via canals and shipping. Arrival of these species in western European lakes and coastal waters is often well-documented because of numerous early oligochaete surveys (Timm 1979; Millbrink 1999).

R.O. Brinkhurst, the leading North American taxonomist of Oligochaeta, originally treated several of the 'Ponto-Caspian' species as introductions, based on first occurrences in the Great Lakes (e.g. Brinkhurst 1965), but as they were found in lakes not connected to the basin, or receiving shipping. he revised their status to cosmopolitan, Holarctic (Brinkhurst 1978) or possibly cryptogenic (Brinkhurst and Gelder 1991). Consequently, these species have not been included on lists of invaders for most regions of North America. Many records of oligochaetes are unpublished, so that it is difficult to obtain a clear impression of the distribution of these animals. Currently the present range of P. frici includes: inland and estuarine waters of Europe (Timm 1980); estuarine waters of the Northwest Atlantic (Bely 2001 personal communication; Chesapeake Bay Program 2001), interior waters of North America, including the Great Lakes (Brinkhurst 1978), estuarine waters of the Northeast Pacific (Brinkhurst 1978; Cohen and Carlton 1995), and estuarine waters of China (Brinkhurst and Coates 1985).

Such a wide range is comparable to that of a few other Ponto-Caspian species, such as the cnidarians Cordylophora caspia and Maeotias inexspectata. The contradictions between the North American and European views of the origin and status of this and other 'Ponto-Caspian' oligochaetes are not yet resolved. Genetic studies and studies of historical collections might be needed.

Paranais frici was apparently first reported from North America in 1961-1962 in San Francisco Bay CA, and was subsequently found in West Coast estuaries from Newport Bay to British Columbia, where it is considered an introduction (Cohen and Carlton 1995). It was later found in the Great Lakes (Brinkhurst 1978; Spencer 1980), and inland waters, including those of Great Smoky Mountains National Park (NC-TN) (Wetzel 2001). Mills et al. (1993) omitted it from their Great Lakes exotic species list, because of Brinkhurst's skepticism on its introduced status.

On the East Coast of the U.S., Paranais frici is known from Constitution Marsh, near West Point NY, on the tidal fresh Hudson River, where it was collected in 1999 (Bely 2001) and from Chesapeake Bay, where it has been reported since 1996 (Chesapeake Bay Program 2001). Paranais frici is known from fresh-mesohaline waters in the James, Elizabeth, and Rappahannock Rivers (Chesapeake Bay Program 2001).

References- Bely 2001; Brinkhurst 1965; Brinkhurst 1978; Brinkhurst and Coates 1985; Brinkhurst and Gelder 1991; Chesapeake Bay Program 2001; Cohen and Carlton 1995; Leppakoski and Olenin 1999; Millbrink 1999; Mills et al. 1993; Spencer 1980; Timm 1980; Wetzel 2001

Invasion Comments