Effect of antropogenic pollution on physiological and biochemical parameters of fish and composition of their parasitocenoses
Purpose. To establish the nature of changes in physiological and biochemical parameters of fish, the qualitative and quantitative composition of their parasitocenoses, depending on the degree of the pollution of water bodies. Methodology. The paper contains the results of the determination of hydrochemical composition of water from the lakes of Kyiv, the structure of their food supply (zoobenthos). As a marker of morpho-physiological features of the Prussian carp, rudd and roach, their liver and spleen indices were used. The content of glucose, cortisol and thyroid hormones was determined in fish blood plasma. The collection and processing of ichthyological material was performed in accordance with generally accepted methods. The taxonomic identification of parasites was carried out according to the appropriate identification keys. Findings. The work presents some hydrochemical characteristics of the lakes under study, the development of the natural food supply for fish - zoobenthic organisms, changes in the physiological and biochemical parameters of some representatives of cyprinids in the lakes of Kyiv, which are subjected to different degrees of human impact. First of all, the indices of internal organs and a number of biochemical parameters of fish blood plasma were studied. Parasitocenoses were specific for each lake. Their smallest number was in the lake Luhove, which was characterized by a significant human impact. The lake Babyne, which was taken as conditional control, had some fish parasites, which were not found in other lakes. The rudd from the lake Kyrylivske invaded with parasites had a 13% higher spleen index (r = 0.98). Also, the infected fish from the Kyrylivske and Luhove lakes had a 2.2-fold higher content of triiodothyronine (T<sub>3</sub>) in the blood plasma (r = 0.82 and r = 0.75, respectively) compared with fish from the lake Babyne. The spleen index of the roach from the lake Kyrylivske is 16% more (r = -0.83) compared to this species from the lake Babyne. The roach from the lake Kyrylivske had a 4.7 times smaller number of cortisol in the blood (r = -0.83) and 4 times lower T<sub>3</sub> level (r = -0.71) compared to fish from the lake Babyne. The Prussian carp from the Kyrylivske and Luhove lakes had spleen indices were lower by 44 and 37%, and the glucose content was 3.6 and 2.7 times lower in comparison with fish from the lake Babyne. In addition, the Prussian carp from lake Luhove had a lower content of cortisol and T3 by 1.7 and 1.5 times, respectively, compared with fish from the lake Babyne. It can be assumed that the studied fish species have different sensitivity to the cumulative or individual effects of anthropogenic stress and parasites. Originality. For the first time, multilevel markers (morphophysiological, biochemical and parasitological) were used to establish the response of fish to the complex human impact in the conditions of water bodies in urbanized territories. Practical Value. The obtained data are necessary to determine the patterns of adaptive reactions of economically valuable cyprinids, their parasites and forage objects under the action of adverse conditions of urbanization. The biochemical parameters of fish that can be used to assess the quality of water in water bodies were also studied.