Date of Award
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The Ponto-Caspian cladoceran Cercopagis pengoi (fishhook waterflea) was first discovered in Lake Ontario in 1998. In 1999, it had spread to 5 Finger Lakes in upper New York State and to upper and lower Lake Michigan. By 2001, it was found in western Lake Erie. Cercopagis was transported to North America in ballast water of a transoceanic shipping freighter. A survey of zooplankton community composition of Lake Ontario was made to assess the impact of Cercopagis predation. The relative abundance of zooplankton species of Lake Ontario has not changed from the early 1980's. However, Cercopagis has affected the species community composition through decreased abundances of total rotifers and major crustacean species such as Bosmina longirostris, Daphnia retrocurva and Diacyclops thomasi. Laboratory experiments were conducted to determine possible prey species of Cercopagis. Cercopagis is able to prey upon the rotifer Asplanchna priodonta and the cladocerans Bosmina longirostris, Daphnia retrocurva, Ceriodaphnia lacustris, Scapheloberis kingi, Moina micrura and Leptodora kindtii. In situ field experiments were conducted to assess natural zooplankton community impacts. Four different experiments failed to detect significant differences between control and predator treatments, thus predatory effects of Cercopagis were not apparent. Lack of predatory events may be attributed to experimental design. Problems that may have affected results include improper light levels, animal stress, mutual interference by Cercopagis individuals, and mortality of experimental Cercopagis. Source: Masters Abstracts International, Volume: 40-06, page: 1475. Adviser: Hugh MacIsaac. Thesis (M.Sc.)--University of Windsor (Canada), 2001.
McPhedran, Kerry Neil., "Predation by the exotic cladoceran Cercopagis pengoi on the zooplankton community of Lake Ontario." (2001). Electronic Theses and Dissertations. 3147.