Species Composition and Distribution of Sibling Species Chironomus Meigen (Diptera: Chironomidae) in the Curonian and Vistula Lagoons
Species composition of Chironomus genus in the Curonian and Vistula Lagoons is similar and presented mostly by Ch. balatonicus and Ch. plumosus. Besides these two species, Сh. muratensis and first generation interspecific hybrid of Сh. muratensis × Ch. plumosus occur in the Curonian Lagoon. In the Curonian Lagoon Ch. plumosus is most frequent species (84%), Ch. balatonicus is not so common (14%). In the Vistula Lagoon, on the contrary, high occurrence frequency is typical for Ch. balatonicus (89%), Ch. plumosus frequency is 11%. The population of Ch. plumosus inhabits most art of the Curonian Lagoon area, Ch. balatonicus is present only in the northern region from Juodkrante to Klaipeda. Opposite, in the Vistula Lagoon, Ch. balatonicus is distributed over the almost whole Lagoon and Ch. plumosus found locally only in the near- mouth area of the Nogat river. The distribution of sibling species in the Gulfs is due to the salinity gradient.