Metapopulation Structure of Two Species of Pikeworm (Triaenophorus, Cestoda) Parasitizing the Postglacial Fish Community in an Oligotrophic Lake

SIMPLE SUMMARY: In this study, the levels of infestation of two different species of pikeworm, Triaenophorus crassus and T. nodulosus, inhabiting a deep, oligotrophic mountain lake in Siberia were revealed. Based on results of five years of studies, a significant interannual variation in T. crassus infestation level was found, whereas the stability of T. nodulosus infestation in their host fishes was seen. Differences in feeding habits and physiology of fishesprobably had an effect on the mass of parasite abundance. Moreover, an asymmetry in parasite infestations between the number of T. crassus cysts in the left and right body surfaces of the ‘‘benthivorous” Coregonus lavaretus pidschian was also observed. ABSTRACT: In the present study, we estimated the levels of infestation of the main fish species that are hosts for two Triaenophorus species: T. crassus and T. nodulosus. The prevalence of T. crassus and T. nodulosus infestations in the intestine of their definitive host–pike Esox lucius was similar (71.0% and 77.4%, respectively). At the same time, the prevalence of T. crassus infestation in muscle tissue was significantly different between the second intermediate hosts, Coregonus lavaretus pidschian (31.4%) and Cor. l. pravdinellus (91.2%), due to considerable differences in their diets. For T. nodulosus, we found significant variations in the levels of prevalence among the second intermediate hosts—100% for Lota lota, 81.8% for Cottus sibiricus 31.9% for Thymallus arcticus, and 24.5% for Perca fluviatilis—that we also explained using different diets. Moreover, analysis of the symmetry of parasite infestations did not reveal any asymmetry between the number of cysts in the left and right body surfaces of the “planktivorous” form/species of whitefish, whereas in the ‘‘benthivorous”, an asymmetry of parasite infestations was found.