EFFECT OF AQUATIC ENVIRONMENT PH ON THE LEVEL OF ECTOPARASITE INFESTATION, PROTEIN AND LYSOZYME CONTENT IN SOME CYPRINID SPECIES (CYPRINIDAE)

Purpose. To study the effect of рН values of the aquatic environment on the level of ectoparasite infestation, protein and lysozyme content in organs and serum of some cyprinid species in experimental conditions. Methodology. The objects of the study were yearlings of Cyprinus carpio, Carassius auratus gibelio and Pseudorasbora parva caught in ponds of fish farm “Nyvka” (Kiev region) in spring. Fish were kept in experimental conditions at neutral pH water (6.8-7.2) and a temperature of 17-18оC. To study the changes in the level of fish parasite infestation at different pH values, we used carp yearlings, as an object, the most infected with parasites. Fish were placed in aquariums with water pH of 5.0-5.5 (slightly acidic environment) and 8.5-9.0 (slightly alkaline environment) for 5 days. Thereafter, the ectoparasites were counted on fish body surface and gills. The protein content in serum and tissue extracts of organs (liver, kidney, spleen) of Carassius auratus gibelio and Pseudorasbora parva infected and uninfected ectoparasites, after holding them in slightly acidic or slightly alkaline environment for 8 days, was determined by Lowry’s method, while lysozyme content was determined by a diffusion method on agar. Findings. A comparative assessment of the number of ectoparasites (Ichthyophthirius multifiliis, Trichodina sp., Dactylogyrus sp., Gyrodactylus sp.) on fish body surface and gills, the content of protein and lysozyme in serum and organs at different pH values of aquatic environment has been presented. It was demonstrated that the number of ectoparasites on fish body surface and gills was significantly reduced when keeping the fish in both slightly acidic and slightly alkaline environments. In infected Carassius auratus gibelio, a reduction in the protein and lysozyme content in liver, kidney and serum was observed only in the neutral pH environment compared to uninfected individuals. In the slightly acidic or slightly alkaline environments with a significant reduction in the number of ectoparasites, the protein and lysozyme levels in fish serum and organs were not significantly different from those of non-infected individuals that were kept in water of corresponding pH values. In Pseudorasbora parva with low level of parasite infestation, we did not detect any changes in the protein and lysozyme levels in fish serum and organs in a neutral pH environment. The effect of different pH levels of water on the studied parameters of Pseudorasbora parva showed their significant changes. Originality. For the first time, we demonstrated the change in the level of ectoparasite infestation, protein and lysozyme contents in fish serum and organs (Cyprinus carpio, Carassius auratus gibelio, Pseudorasbora parva), which were kept in the slightly acidic or slightly alkaline aquatic environments. Practical value. The concentration of hydrogen ions, or an aqueous active reaction (pH), plays an important role in the life of fish, their development and in the predisposition to various diseases. The performed studies showed that infestation of fish with parasites can be significantly decreased when changing water pH. This leads to the recovery and restoration of fish normal physiological functions, the impairment of which causes the toxic effects of parasites.