The content of nonspecific immune complexes, products of lipid peroxidation, and antioxidant activity in the liver, kidney, and spleen were studied in Salvelinus schmidti, S. kronocius, S. albus, and other species of char from Kronotskoe Lake (Kamchatka Peninsula). The interstitial and interspecific differences of the parameters studied were revealed in different char; the parameter values in each organ differed, which is presumably related to the species specificity, living mode, and structural and functional organization of the tissues and organs studied. The results of this study may be used for monitoring the health status of the population and for comparison with closely related species.

A study of changes in some immunological parameters of fish blood serum depending on the average monthly air temperature was carried out. The studies were carried out on bream aged 3+, with an average weight of 375 ± 30 g and a length of 290 ± 20 cm, caught in the Volga reach of the Rybinsk reservoir. The fish were caught using fixed nets in February for several years and the average monthly air temperature was recorded. The studied fish were sampled from the tail vein. Blood was collected in a dry sterile test tube and kept at room temperature. After blood coagulation and retraction of the clot, the serum was taken with a syringe with a fine needle and transferred to another tube. To assess the state of natural immunity in the blood serum, the level of bactericidal activity and nonspecific immune complexes was analyzed. Based on the data obtained, the number of immunodeficient individuals was determined. Variations of the studied parameters in years different in average monthly air temperature were established. The greatest differences between the indicators were revealed in the years with the highest (2003) and lowest (2006) mean monthly temperatures. The minimum indicators of bactericidal activity were recorded in 2003, and the maximum — in 2006. The highest content of immune complexes and immunodeficient individuals was established in 2003, and the lowest in 2006. The study showed the relationship between an increase in the average monthly air temperature and a decrease in functional activity nonspecific humoral immunity. Based on the data obtained, it was concluded that the temperature factor influences the mechanisms of innate immunity of fish.

Results of comparative analysis of the content of immune complexes and lipids and of the oxidative processes in the muscle tissues of Rapana venosa occurring in various sections of the coastal zone of the Caucasus coast of the Black Sea differing in the degree of anthropogenic load are given in the paper. It has been found that the specimens caught in the sections subjected to intensive anthropogenic load were characterized by a rather high content of the products of lipid peroxidation and immune complexes and by a low antioxidant activity.

The results of the study on several immuno-biochemical parameters of blood serum and liver of Engraulis encrasicholus ponticus (L. 1958) and Sprattus sprattus phalericus (L. 1958), that inhabit the Caucasus coastal waters of the Black Sea with various anthropogenic loads are described. The antimicrobial properties of serum, the content of non-specific immune complexes, in the liver antioxidant activity were studied. It was determined that the ratio of immunodeficient individuals was much higher in samples from the polluted areas than in samples from the clean ones. The fish sampled in areas of high anthropogenic load contained higher contents of products of lipid peroxidation and immune complexes, as well as lower values of antioxidants.

This study investigated several immunophysiological indices of the round goby Neogobius melanostomus (Pallas, 1814), which inhabits Caucasian coastal waters of the Black Sea with different levels of anthropogenic load. Fish specimens caught in areas of a high level of pollution differed significantly from fish from pure water areas in low indices of antimicrobial properties of the blood serum, antioxidant activity, and phospholipid contents, and, in contrast, by high levels of immune complexes, total lipids, triacylglycerols, and malonic dialdehyde.

The results of a comparative analysis of some blood serum immune-biochemical indices of bream that inhabits lake Nero and the Rybinsk Reservoir are reported. The following indices were investigated: anti-microbial properties: proportion of immune-deficient animals, common lipids level and their fractional composition, content of malondialdehyde and antioxidant activity. Unlike fishes from relatively clean waters, fishes from ecologically unfavorable areas show low immune status, alterations in lipid metabolism and increased free radical oxidation.

The results of a comparative analysis of some blood serum immune-biochemical indices of bream that inhabits lake Nero and the Rybinsk Reservoir are reported. The following indices were investigated: anti-microbial properties: proportion of immune-deficient animals, common lipids level and their fractional composition, content of malondialdehyde and antioxidant activity. Unlike fishes from relatively clean waters, fishes from ecologically unfavorable areas show low immune status, alterations in lipid metabolism and increased free radical oxidation.

Investigation results are reported on immunobiochemical indices in carassius carassius at a chronic exposure to sub-lethal Zink ions concentrations. In blood serum and liver, the following characteristics were investigated: antimicrobial properties, proportion of immune- deficient animals, content of non specific immune complexes, common lipids level, content of lipids peroxidation products and antioxidant activity. The relation between magnitudes of indices under investigation in fishes and the duration of their presence under experimental conditions is shown.

Antimicrobial properties of the blood serum and the content of immune complexes, lipid peroxidation products, and antioxidants in the blood serum and liver have been analyzed in roach living in areas of the Kuban River with different levels of anthropogenic pollution. The relationship between the studied parameters and fish habitats is shown.

Investigation results are reported on immunobiochemical indices in carassius carassius at a chronic exposure to sub-lethal Zink ions concentrations. In blood serum and liver, the following characteristics were investigated: antimicrobial properties, proportion of immune- deficient animals, content of non specific immune complexes, common lipids level, content of lipids peroxidation products and antioxidant activity. The relation between magnitudes of indices under investigation in fishes and the duration of their presence under experimental conditions is shown.

The results of a study on some parameters of innate immunity and oxidative processes in hepatopancreas of the chub Leuciscus cephalus (L.) inhabiting the river ecosystems of Krasnodar krai and Abkhasia subjected to different degrees of anthropogenic load are presented. Antimicrobial properties of blood serum, the content of nonspecific immune complexes in the liver, and the level of total lipids and antioxidant activity have been studied. It is determined that the portion of immunodeficient specimens is higher in samples from polluted waters than from unpolluted areas. Fishes caught in the river subjected to high anthropogenic load contained higher concentrations of products of lipid peroxidation and immune complexes and had lower levels of antioxidants.

Comparative study of lipid metabolism indices (total lipids, separate lipid fractions, level of the lipid peroxidation processes, and antioxidant protection) was carried out in three parasite species collected from the white char in the Lake Kronotskoe: Diphyllobothrium ditremum Crepin, 1825 (Cestoda), Philonema oncorhynchi Kuitunen-Ekbaum, 1933 (Nematoda) H Neoechinorhynchus salmonis Ching, 1984 (Acanthocephala). Acanthocephalans possessed significantly greater levels of total lipids, triacylglycerol, and malondialdehyde; nematodes, of cholesterol and sterol esters; and cestodes, in phospholipids and constants of the substrate oxidation. Dependence between lipid metabolism of helminths and their taxonomic affiliation, morpho-functional features, the stage of the life cycle, and the site of infection in the host are discussed.

Results of the long-term researches on variability of humoral factors of natural immunity of bream (Abramis brama L.) of the Rybinsk reservoir over the fattening period at various biomasses and composition of forage objects are analyzed. Connection of functional characteristics of immunity and macrozoobenthos' abundance and structure is established. Breams, caught over low abundance of the benthic organisms, were characterized by high portion of immune-deficit specimens and moderate values of antimicrobial properties of blood serum.