Long-term dynamics of the parasitological situation in the Baikal omul in the Chivyrkuisky bay of Lake Baikal
Z.N. DUGAROV, D.R. BALDANOVA, L.D. SONDUEVA, T.G. BURDUKOVSKAYA, T.R. KHAMNUEVA, L.V. TOLOCHKO, M.D.-D. BATUEVA, O.B. ZHEPKHOLOVA
Institute of General and Experimental Biology, Siberian Branch, Russian Academy of Sciences, Ulan-Ude, Russia
Keywords: long-term changes in parasite infection, core of the parasite fauna, satellite species, Diphyllobothrium dendriticum, Proteocephalus longicollis, Contracaecum osculatum baicalensis
Abstract
Presented are the results from analyzing a long-term series of observations (1976-2018) of the infection with parasites of the Baikal omul in the Chivyrkuisky Bay of Lake Baikal. Baikal omul (Coregonus migratorius) is one of the most ecologically important and valuable commercial fish species of Lake Baikal, dominating the structure of the ichthyocenosis of the unique reservoir. Parasites observed in each year of research are allocated to the core group; the others are classified as satellite species, and rare species are considered separately among them. There are 31 species of parasites in the Baikal omul in the Chivyrkui Gulf of Lake Baikal, seven species make up the core of its parasitofauna; 24 species are classified as satellite species, including 15 rare species. Among the parasites of the Baikal omul, of the greatest interest to researchers is Diphyllobothrium dendriticum, which has the highest epidemiological significance in Buryatia. The life cycle of the D. dendriticum is complex, proceeding with the change of three hosts: the first intermediate (Cyclopoida), the second intermediate (various fish species), and definitive ones (fish-eating birds and mammals, including humans). The Baikal omul is the dominant second intermediate host of D. dendriticum in Lake Baikal. The level of infection of the Baikal omul with Proteocephalus longicollis and Contracaecum osculatum baicalensis decreases, whereas it increases with D. dendriticum when the water level in Baikal rises. The multidirectional trends in the level of infection of the Baikal omul with mass species of parasites due to changes of the water level in Lake Baikal emphasize the importance of parasitological data for assessing the state of the ecosystem of a unique reservoir.
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