[Dynamics of parasite communities in an age series of Arctic Cisco Coregonus migratorius (Georgi, 1775)].

Parasite communities of Arctic cisco from Chivyrkui Bay of Lake Baikal have been analyzed at levels of a host individual (infracommunity), a individual age group of a host-(assemblages of infracommunities), and a host population (component community). Significant positive correlations of parameters of species richness (number of parasite species, Margalef and Menhinick indices) with the age of Arctic cisco were recorded only at the level of parasite inffacommunities. The absence of linear positive correlations between the parameters of species richness and the age of Arctic cisco at the level of assemblages of parasite infracommunities were revealed for the first time for fish of Lake Baikal. The peculiarity of the dynamics of parasite communities of. Arctic cisco is determined by specific features of the host physiology and ecology, primarily by the age dynamics of the feeding spectrum.

[Tapeworm Oochoristica tuberculata (Rudolphi, 1819)--parasite of the lizard Eremias argus Peters, 1869 in Zabaikalie].

Morphological characteristics of the tapeworm Oochoristica tuberculata from the lizard Eremias argus is given from the northern border of the host areal. The complexes of most stable and most variable characters of this tapeworm are determined. The list of hosts is given for Oochoristica tuberculata.

[Composition of leucocytes of the head kidney of the crucian carp Carassius auratus gibelio (Cypriniformes: Cyprinidae) as affected by invasion of cestode Digramma interrupta (Cestoda; Pseudophyllidea)].

The composition of leucocytes of the head kidney is studied in the crucian carps (Carassius auratus) either contaminated or uncontaminated with Digramma interrupta. The composition of leucocytes in the pronephros of the crucian carp from Lake Baikal basin has a lymphoid character. Compared to the crucian carp from the European part of Russia, in the fish from Baikal the granulocytopoetic processes are more pronounced. This is proved by the high content of young forms of granulocytes. In the fish infected with digramma, the immune suppression of proliferation of blasts and young forms of eosinophils was revealed. On the other hand, the inflammatory and humoral specific immune reactions are enhanced. Partial suppression of the immune response of C. auratus to invasion by D. interrupta facilitates development of the parasite.

[Distribution of Aspidogaster conchicola (Aspidogastrea, Aspidogastridae) in the organism of Colletopterum spp. (Bivalvia, Unionidae) of different age from the Chivyrkuiski Gulf of Lake Baikal].

Distribution of Aspidogaster conchicola Baer, 1827 in the organisms of its hosts Colletopterum spp. from the Chivyrkuiski Gulf of Lake Baikal was investigated. The number of A. conchicola in the organism of Colletopterum spp. was found to decrease along the row pericardial cavity-mantle cavity-gills-kidney. The pericardial cavity of Colletopterum spp. is the most favorable habitat for A. conchicola with 72% of the helminthes parasitizing in it. In the pericardial cavity the largest number (61%) of A. conchicola was found in its posterior part.

[Baikal whitefish Coregonus baicalensis Dybowski, 1874 parasite communities and host age].

Data on the taxonomic diversity of Baikal whitefish parasites are summarized in the study. Significant correlations of some parasite species' relative abundance and parasite communities' (infracommunities and component communities) parameters with host age were found during the study of parasite distribution in the host's age groups in the Baikal whitefish population from Chivyrkui Bay of Lake Baikal. Study of morphobiological and genetic features which have arisen due to long-term geographic isolation allowed confirming the initial specific independence of lake whitefishes of Lake Baikal as Coregonus baicalensis Dybowski, 1874, i.e., the Baikal whitefish (Sukhanova et al., 2000). The main habitats of this Baikal endemic are Barguzin and Chivyrkui bays, Selenga shallow, and Little Sea strait (Pronin et al., 2007). Local populations from these habitats were previously considered to be independent stocks (Krogius, 1933).

[Characteristics of karyotype structure in Phyllodistomum umblae (Trematoda: Gorgoderidae) from Lake Baikal].

Haploid complement of Phyllodistomumn umblae ex baikal whitefish from Lake Baikal consists of 8 chromosomes (6 metacentrics and 2 submetacentrics). The significant difference is observed in the ratio of acrocentrics and metacentrics in the haploid set of chromosomes between isolated populations of P. umblae from Baikal region and from Chukotka. The hypothesis is advanced that these chromosome populations may be chromosome races of P. umblae.

[The morphological variability of the maritae of Phyllodistomum umblae and Phyllodistomum folium (Trematoda: Gorgoderidae) from fish in the Lake Baikal basin]. / Morfologicheskaia izmenchivost' marit Phyloodistomum umblae i Phyllodistomum folium (Trematoda: Gorgoderidae) ot ryb basseina oz. Baikal.

The host variability of adults of Phyllodistomum umblae and P. folium in fishes of the Baikal region has been studied. The absence of considerable geographical variability of P. umblae in Coregonus lavaretus (Lake Baikal, Lake Storsjön in Sweden) has been shown. The complexes of most stable (the size of acetabulum and eggs, location of acetabulum, ovary and vitelline bodies) and variable (the distance from oral sucker to intestinal bifurcation, distance from intestinal back edge to body end, width of seminal vesicle) features of trematodes of the genus Phyllodistomum have been determined.

[The distribution of Phyllodistomum umblae and Phyllodistomum folium (Trematoda: Gorgoderidae) in the excretory system of fishes]. / Raspredelenie Phyllodistomum umblae i Phyllodistomum folium (Trematoda: Gorgoderidae) v vydelitel'noi sisteme ryb.

It is shown, that the distribution of Phyllodistomum umblae in the excretory system of all investigated species of salmonids has a principal similarity. The distribution of P. umblae in the excretory system of the Siberian dace and the Siberian roach is distinguished from that of P. folium.