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| NAS - Nonindigenous Aquatic Species |
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Common Name: freshwater hydroid
Taxonomy: available through 
Identification: This colonial hydroid consists of macroscopic polyps (about 1mm) connected by a gastrovascular cavity; branching, moss-like in appearance (Pennak1987). Colonies grow up to 5 cm, which varies depending on conditions (Folino 1999).
Size: Colonies to 5 cm, polyps around 1mm.
Native Range:
Caspian and Black Seas (Folino 1999).
San Francisco Bay, California (Mills and Sommer 1995). Coastal waters of Florida (Carlton and Ruckelshaus 1997). Illinois River, Illinois (personal communication). Hudson River, New York (Mills, et al. 1996). Lake Erie, Ohio (Mills et al. 1993). Coastal waters of Washington (Ruiz and Hines 1997). Connecticut River between Hadley, Massachusetts and Hinsdale, New Hampshire (Smith et al. 2002).
Means of Introduction: Aquarium release in Lake Erie (Mills et al. 1993). Ballast water in Washington (Ruiz and Hines 1997).
Status: Established.
Impact of Introduction:
Smith et al. (2002) described C. caspia as a 'benthic colonial predator' that preys upon chronomids and other larval insects. The ecological impacts of C. caspia, however, have not yet been thoroughly studied. Uncolonized substrate introduced to C. caspia and subsequently colonizied had different realtive abundances of other invertebrates as compared to substrates not colonized by C. caspia (Ruiz et al. 1999). Other studies have suggested that C. caspia may contribute to a restructuring of benthic and pelagic freshwater communities (Folino 1999).
Competition for space, i.e. sutiable substrate for colonization, may occur between zebra mussel (Dreissena polymorpha) and C. caspia (Walton 1996, Folino 1999).
There is a negative economic impact associated with the biofouling caused by Cordylophora caspia (Folino 1999).
Remarks:
Smith et al. (2002) noted that C. caspia shows morphological and ecological changes in habitats of lower salinity such as inland freshwaters. For example, growth rates decrease, reproductive rates decrease (sexually and asexually), polyp size changes, population density changes, and cell size and shape is altered (Smith et al. 2002 and references).
C. caspia is preyed upon by an introduced nudibranch (Tenellia adspersa) (Mills and Sommer 1995).
C. caspia is thought to be taxonomically synonymous with C. lacustris by many scientific researchers (Folino 1999 and references).References
Carlton, J.T. and M.H. Ruckelshaus. 1997. Nonindigenous marine invertebrates and algae. Pages 187-201 In: Simberloff, D., D.C. Schmitz, T.C. Brown (eds), Strangers in Paradise. Island Press, Washington D.C.
Folino, N. C. 1999. The Freshwater Expansion and Classification of the Colonial Hydroid Cordylophora (Phylum Cnidaria, Class Hydrozoa). Marine Bioinvasions. Proceedings of the First National Conference. pp. 139-144.
Mills, C.E., and F. Sommer. 1995. Invertebrate introductions in marine habitats: two species of hydromedusae (Cnidaria) native to the Black Sea, Maeotias inexspectata and Blackfordia virginica, invade San Francisco Bay. Marine Biology 122:279-288.
Mills, E.L., M.D. Scheuerll, D.L. Strayer and J.T. Carlton. 1996. Exotic Species in the Hudson River Basin: A history of invasions and introductions. Estuaries 19(4):814-823.
Mills, E.L., J.H. Leach, J.T. Carlton, and C.L. Secor. 1993. Exotic species in the Great Lakes: a history of biotic crises and anthropogenic introductions. J. Great Lakes Research 19(1):1-54.
Pennak, R. W. 1987. Coelenterata (Hydroids, Jellyfish). Pages 110-123 in Fresh-water invertebrates of the United States, 3rd edition. John Wiley and Sons, Inc., New York. 628 p.
Ruiz, G. M. and A.H. Hines. 1997. The risk of nonindigenous species invasion in Prince William Sound associated with oil tanker traffic and ballast water management: pilot study. Prepared for the Regional Citizens' Advisory Council of Prince William Sound.
Ruiz, G.M., P. Fofonoff, and A.H. Hines. 1999. Non-indigenous species as stressors in estuarine and marine communities:Assessing invasion impacts and interactions. Limnol. Oceanogr. 44(3, part 2):950-972.
Smith, D.G., S.F. Werle, and E. Klekowski. 2002. The Rapid Colonization and Emerging Biology of Cordylophora caspia (Pallas, 1771) (Cnidaria: Clavidae) in the Connecticut River. Journal of Freshwater Ecology 17(3):423-430.
Walton, W. C. 1996. Occurance of Zebra Mussel (Dreissena polymorpha) in the Oligohaline Hudson River, New York. Estuaries. 19(3):612-618.
Wurtz, C.B. and S.S Roback. 1955. The invertebrate fauna of some Gulf Coast rivers. Proceedings of the Natural Sciences Academy of Philadelphia. 107:167-206.
Author: Pam Fuller, Erynn Maynard, and David Raikow
Contributing Agencies: 
NOAA - GLERL
Revision Date: 1/25/2007 Citation for this information:
Pam Fuller, Erynn Maynard, and David Raikow. 2009. Cordylophora caspia. USGS Nonindigenous Aquatic Species Database, Gainesville, FL.
<http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=1060> Revision Date: 1/25/2007
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