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 35%. Apart from parasite description and prevalence data, very little has been reported on LMB parasite communities and their structure. In 1975, Cloutman studied fish parasite community structure in LMB in Lake Fort Smith, Arkansas, among other centrarchids, and found that diversity did not fluctuate noticeably on a seasonal basis.



40

He also found that there was no significant difference in parasite community structure between sexes or ages. Szalai and Dick (1990) studied parasites of LMB in its new habitat in Canada and found four parasite species only: Diplostomum sp., Proteocephalus ambloplitis, Pomphorhynchus bulbocolli, and Contracaecum sp. Banks and Ashley (2000) conducted a survey of the helminth fauna of LMB to examine helminth biodiversity and community structure in a northwestern Missouri reservoir. Seven species of helminths were recovered: Proteocephalus ambloplitis, Spinitectus sp., Contracaecum sp., Camallanus sp., Posthodiplostomum minimum, Crepidostomum sp., and Neoechinorhynchus cylindratus. The acanthocephalan N. cylindratus was the most prevalent parasite in fish sampled and its prevalence reached up to 95%. A study on habitat influences on parasite assemblages of youngof-the-year LMB in the Lower Atchafalaya River Basin, Louisiana was conducted by Landry and Kelso (2000). The authors found that physicochemical characteristics of Basin habitats may significantly influence parasite assemblages of young-of-the-year LMB. VI. LWF and its GIT parasites

 Order:

Salmoniformes

Family:

Salmonidae

Genus:

Coregonus

Species:

clupeaformis

    The LWF, one of the most economically valuable freshwater species, feeds primarily on benthic macroinvertebrates (Bernatchez et al. 1991; Nalepa et al. 2005b). Following the Wisconsin glaciation during the Pleistocene, several members of the



41

genus Coregonus, native to northern Europe and Asia, reached North America (Bernatchez et al. 1991) and formed sustainable colonies in the Great Lakes (Bailey and Smith 1981; Stott et al. 2004). Because LWF primarily lives along the shorelines of lakes in relatively shallow water (15-55 m in depth) (Selgeby and Hoff 1996), LWF constituted the first commercial fisheries in the Great Lakes (Cleland 1982; Spangler and Peters 1995; Brown et al. 1999). By the end of the 19th century, LWF fisheries started a long, steady decline from 11 million kg in 1879 to 701,000 kg by 1959 (Fleischer 1992; Spangler and Peters 1995). Habitat degradation, excessive exploitation by commercial fisheries, sea lamprey invasion, and the influx of toxic chemicals to the lakes have been blamed as causes for the decline. As a result, tribal, state, federal, and binational agencies undertook a number of managerial measures that allowed LWF populations to recover (Fleischer 1992; Spangler and Peters 1995). Unfortunately, the condition of LWF has worsened with the invasion of the Great Lakes basin by dreissenid mussels, which have moved into lakes Erie, Huron, Michigan, and Ontario. When the zebra (Dreissena polymorpha) and quagga (D. bugensis) mussels’ abundance increased in water