BIOLOGICAL ROLE AND TOXIC INFLUENCE OF MOLYBDENUM IN AQUATIC ECOSYSTEMS (A REVIEW)

Purpose. The consequence of human impact of the ecosystems of water bodies are as a rule the input of xenobiotics of various natures or the excess of the natural level of biogenic trace elements that ultimately leads to negative changes in the structure of aquatic biota communities, disturbances of vital activity processes of some flora and fauna species. The consequences of these processes are presented as a reduction in the productivity of water bodies, impoverishment of their species variety, and subsequently as an unsuitability of water bodies for fisheries related activities. Study, analysis and generalization of information concerning the pathways of toxicants input into water bodies, their behavior in hydroecosystems, possible effects on aquatic organisms of different trophic levels have an important theoretical and practical value. Behavioral, physiological, biochemical, cytological, histological and genetic reactions can serve as a basis for the adoption of necessary measures aimed at improving the ecological state of water bodies or preventing and avoiding potential hazards to aquatic populations. The aim of this work is an analysis and synthesis of the available literature data about the role of a relatively poorly studied trace element molybdenum in hydroecosystems, its biological importance and toxic effect for aquatic organisms. Findings. The data containing in the article were obtained based on reviewing existing publications of domestic and foreign authors. In particular, they describe hydrochemical properties of molybdenum and its compounds, possible sources of input into water bodies, pathways of element migration. A brief description of the identification and control methods for the element content in aquatic environment is presented. Biophilic properties of molybdenum for aquatic flora and fauna as well as the impact on their productive parameters are described. The data regarding the bioaccumulation potential of molybdenum, as well as its distribution in tissues and organs of aquatic organisms are given. The adaptive reactions of aquatic plants, invertebrates and fish in the conditions of elevated molybdenum concentrations in water, the possible adverse effects of such impacts on biota at different levels, in particular on cellular, tissue, whole organism ones are described. The perspectives and theoretic measures of further studies on molybdenum presence and its effect in ecotoxicological aspect are highlighted. Originality. The article contains a summary of research results carried out since the middle of the last century to the present time, on the role and functions of molybdenum in aquatic ecosystems and organisms of certain species of aquatic biota, information on its eco-toxicity in terms of its excessive input into water bodies.. Practical value. The data presented in the article can be the basis for the adoption of measures for the prevention and avoidance of potential hazards to aquatic populations associated with the input of significant amounts of molybdenum into water bodies in the composition of agricultural runoff and industrial effluents.