title: [Seasonal dynamics of the population structure of Sphaerostomum globiporum (Trematoda: Opecoelidae) maritae in Ladoga Lake].
abstract: Data on the seasonal dynamics of population structure is obtained for the first time for the Trematode species Sphaerostomum globiporum from roach Rutilus rutilus (L) in Ladoga Lake, which situates in the northern limit of the distribution range of this species. The parasites infest the host in October and leave it from the end of July to the beginning of August. The maximum of the magnitude of the Trematode population falls on spring, and the minimum is observed in summer. In August and September roach is free of the parasites. It is established that the period of maturing occupies 10 months for S. globiporum from roach in Ladoga Lake. The prereproductive period takes 5 months and comes to the end in February. The reproductive period occupies 5 months too. Although these two periods of the parasite's life cycle do not separated from each other clearly, an overlapping of two generations was not observed, unlike the case of more southern water bodies.
authors.forename: D I
authors.initials: DI
authors.lastname: Lebedeva
mesh_terms: D000818:Animals; D003530:Cyprinidae / Q000469:parasitology*; D005393:Fish Diseases / Q000453:epidemiology / Q000469:parasitology*; D012426:Russia; D012621:Seasons; D014200:Trematoda; D014201:Trematode Infections / Q000453:epidemiology / Q000469:parasitology*