On the Physicochemical Method of Analysis of the Formation of Secondary Immunodeficiency as a Bioindicator of the State of Ecosystems Using the Example of Seabed Biota of the Caspian Sea

The state of the immune system is a critical indicator of the body’s viability. Population-immunity assessment is an important characteristic of adaptive capacities in resisting environmental physical and chemical stress factors. In modern conditions, populations of aquatic organisms experience toxic stress, which primarily affects the functioning of their immune systems. Speed and quantitative indicators of the development of a humoral immune response in stressed organisms decrease, and immunodeficiency develops. In a special case, in which immunosuppressive changes are recorded on a massive scale for a number of species in the trophic chain, this indicates an increasing crisis in the aquatic biosystem and a decrease in the resistance of the links of the trophic chain to anthropogenic impact. Uncompensated transformations occur in biophysical processes. To identify stress factors, a method of analyzing the forms of the immune response is needed, which should be easily applicable to the diagnosis of immunodeficiency immediately in marine research conditions. The authors develop an original method of analyzing the state of the immune system, which is applicable with the least complexity of laboratory studies to assess the adaptive capabilities of populations of mass fish species. The nature of secondary immunodeficiency has been studied on the example of fish inhabiting in the northern and southern parts of the Russian sector of the North Caspian. The study was conducted on the basis of a modified approach to the study of the immune system, consisting in the identification of a natural inhibitory factor in biological fluids. It is shown that the level of secondary immunodeficiency is an integral indicator that expresses not only the state of the immune system, but also the physiological status of the studied fish and their adaptive capabilities. In the studied areas of the North Caspian, the worst indicators of secondary immunodeficiency were found in gobies (family Gobiidae, genus Proterorhinus, Neogobius, Mesogobius) caught in the areas of Maly Zhemchuzhny Island. The formation of immunodeficiency is associated with prolonged exposure to gobies of flood waters contaminated with toxic substances. The most sedentary representatives of the aquatic fish community, which fully experience the physical and chemical effects associated with large-scale oil production in the North Caspian Sea, were specially selected as objects of research. The authors recommend using the results of immunochemical studies of the goby population as bioindicators for predicting the ecological state of all links of the trophic chain of the Caspian Sea.