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| NAS - Nonindigenous Aquatic Species |
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Common Name: a tubificid worm
Synonyms and Other Names: Tubifex (Ilyodrilus) and Euilyodrilus, tubificid, annelid
Taxonomy: available through 
Identification:
The body of this oligochaete consists of 33–90 segments and displays a rounded to triangular prostomium. There are dorsal and ventral bundles along its length of up to 5 chaetae, most of which are bifurcate. There are also 2 modified, blade-shaped spermathecal chaetae located on any one of segments 6–12. The clitellum is generally found on segments 8 and 9 or 9 and 10 and the male pores are usually on segment 9 (Timm 1970; Timm 1972; Spencer 1978; Steinlechner 1987; Wang and Liang 2001).
P. bedoti is typically around 7–12 mm long but specimens of 18 mm have been recorded from Estonia (Timm 1970; Timm 1972; Spencer 1978; Finogenova and Poddubnaja 1990; Wang and Liang 2001).
Size: 7-18mm
Native Range: P. bedoti is native to parts of the Ponto-Caspian region within the Black Sea, Caspian Sea, and Aral Sea drainages (Finogenova 1990).
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Interactive maps: Continental US, Alaska, Hawaii, Caribbean
Nonindigenous Occurrences: Species of this genus were probably introduced to the Great Lakes before 1959 and simply remained undetected. P. bedoti has been recorded from Lake Ontario, Lake Superior, Lake Erie, Lake Michigan, Lake Huron, and Cayuga Lake, New York state, which is part of the Lake Ontario drainage (Stimpson et al. 1975; Spencer 1978; Nalepa et al. 2002; Grigorovich et al. 2003; Spencer and Hudson 2003).
Ecology: P. bedoti occurs at depths of 1–190 m. It is generally associated with eutrophic conditions and fine substrates containing high proportions of clay and silt. It occurs in rivers, lakes, and springs, typically in freshwater, but has been recorded in very low salinities around 0.1‰. It occurs at water temperatures of 0–34ºC and pH of around 7–9 (Timm 1970, 1972; Spencer 1978; Probst 1987; Sauter and Gude 1996; Cellot and Juget 1998; Melbrink 1999; Wolfram et al. 2002; Timm and Mols 2005; Yildiz and Balik 2005, 2006).
P. bedoti usually reproduces asexually. Sexual reproduction is rare and when it does occur it is often followed by resorption of the genital organs, and then continued asexual reproduction. Individuals have been known to survive up to 5 years and a cloned group can persist up to around 15 years. Asexual reproduction in individuals from Estonia occurs between 11.5–26ºC, while sexual reproduction, resulting in cocoons, occurs at temperatures of 14–18.5ºC. In each cocoon there are usually 1–5 embryos (Timm 1972; Timm 1984; Wang and Liang 2001).
In general, tubificids are known to feed selectively and probably favor heterotrophic aerobic bacteria found in the sediments (Ratsak and Verkuijlen 2006).
Means of Introduction: Unknown, but shipping is a strong possibility (Grigorovich et al. 2003).
Status: Established in Great Lakes (U.S.EPA 2008).
Impact of Introduction:
A) Realized: Unknown.
B) Potential: Some studies suggest that Potamothrix spp. may have a positive impact on native oligochaetes in Europe. The benefit could result from the numerous bacteria found in Potamothrix spp. faeces, which could allow for improved feeding by natives (Milbrink and Timm 2001).
Remarks: P. bedoti is synonymous with Tubifex (Ilyodrilus) bedoti and Euilyodrilus bedoti.
References
Cellot, B. and J. Juget. 1998. Oligochaete drift in a large river (French Upper Rhone): the effect of life cycle and discharge. Hydrobiologia 389:183-191.
Finogenova, N. P. and T. L. Poddubnaja. 1990. One more revision of the genus Potamothrix Vejdovsky et Mrazek 1902 (Oligochaeta, Tubificidae). Zoologische Jahrbuecher Abteilung fuer Systematik Oekologie und Geographie der Tiere 117(1):55-83.
Grigorovich, I. A., R. I. Colautti, E. L. Mills, K. Holeck, A. G. Ballert, and H. J. MacIsaac. 2003. Ballast-mediated animal introductions in the Laurentian Great Lakes: retrospective and prospective analyses. Canadian Journal of Fisheries and Aquatic Sciences 60:740-756.
Milbrink, G. 1999. Distribution and dispersal capacity of the Ponto-Caspian tubificid oligochaete Potamothrix heuscheri (Bretscher, 1990) in Scandinavia. Hydrobiologia 406:133-142.
Milbrink, G. and T. Timm. 2001. Distribution and dispersal capacity of the Ponto-Caspian tubificid oligochaete Potamothrix moldaviensis Vejdovsky et Mrazek, 1903 in the Baltic Sea region. Hydrobiologia 463:93-102.
Nalepa, T. F., D. L. Fanslow, M. B. Lansing, G. A. Lang, M. Ford, G. Gostenik, and D. J. Hartson. 2002. Abundance, biomass, and species composition of benthic macroinvertebrate populations in Saginaw Bay, Lake Huron, 1987-96, NOAA Technical Memorandum GLERL-122, Ann Arbor, Michigan. 32 pp.
Probst, L. 1987. Sublittoral and profundal Oligochaeta fauna of the Lake Constance. Hydrobiologia 155:277-282.
Ratsak, C. H. and J. Verkuijlen. 2006. Sludge reduction by predatory activity of aquatic oligochaetes in wastewater treatment plants: science or fiction? A review. Hydrobiologia 564:197-211.
Sauter, G. and H. Gude. 1996. Influence of grain size on the distribution of tubificid oligochaete species. Hydrobiologia 334:97-101.
Spencer, D. R. 1978. The Oligochaeta of Cayuga Lake, New York with a redescription of Potamothrix bavaricus and P. bedoti. Transactions of the American Miscroscopical Society 97(2):139-147.
Spencer, D. R. and P. L. Hudson. 2003. The Oligochaeta (Annelida, Clitellata) of the St. Lawrence Great Lakes region: an update. Journal of Great Lakes Research 29(1):89-104.
Steinlechner, R. 1987. Identification of immature tubificids (Oligochaeta) of Lake Constance, Central Europe and it is influence on the evaluation of species distribution. Hydrobiologia 155:57-64.
Stimpson, K. S., J. R. Brice, M. T. Barbour, and P. Howe. 1975. Distribution and abundance of inshore oligochaetes in Lake Michigan. Transactions of the American Microscopical Society 94(3):384-394.
Timm, T. 1970. On the fauna of the Estonian Oligochaeta. Pedobiologia 10:52-78.
Timm, T. 1984. Potential age of Oligochaeta. Hydrobiologia 115:101-104.
Timm, T. 1972. On the reproduction of Euilyodrilus bedoti (Piguet, 1913) (Oligochaeta, Tubificidae). Proceedings of the Estonian Academy of Science (Biologia) 21:235-241.
Timm, H. and T. Mols. 2005. Macrozoobenthos of Lake Verevi. Hydrobiologia 547:185-195.
U.S. EPA (Environmental Protection Agency). (2008) Predicting future introductions of nonindigenous species to the Great Lakes. National Center for Environmental Assessment, Washington, DC; EPA/600/R-08/066F. Available from the National Technical Information Service, Springfield, VA, and http://www.epa.gov/ncea.
Wang, H. and Y. Liang. 2001. A preliminary study of oligochaetes in Poyang Lake, the largest freshwater lake of China, and its vicinity, with description of a new species of Limnodrilus. Hydrobiologia 463:29-38.
Wolfram, G., V. A. Kowarc, U. H. Humpesch, and W. Siegl. 2002. Distribution pattern of benthic invertebrate communities in Traunsee (Austria) in relation to industrial tailings and trophy. Water, Air and Soil Pollution 2:63-91.
Yildiz, S. and S. Balik. 2005. The Oligochaeta (Annelida) Fauna of the inland waters in the lakes district (Turkey). E. U. Journal of Fisheries and Aquatic Sciences 22(1-2):165-172.
Yildiz, S. and S. Balik. 2006. The Oligochaeta (Annelida) fauna of Topcam Dam-Lake (Aydin, Turkey). Turkish Journal of Zoology 30:83-89.
Author: Rebekah M. Kipp
Contributing Agencies: 
NOAA - GLERL
Revision Date: 4/8/2007 Citation for this information:
Rebekah M. Kipp. 2009. Potamothrix bedoti. USGS Nonindigenous Aquatic Species Database, Gainesville, FL.
<http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=2703> Revision Date: 4/8/2007
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