Valkova S.A. Selected aspects of the current state of freshwater resources in the Murmansk Region, Russia. Journal of Environmental Science and Health, Part A. 2017, V. 52, No 9, p. 921-929.

Downloaded by [Professor Vladimir Dauvalter] at 05:55 30 August 2017 JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH, PART A 925 organs of fish were once typical only for the water bodies located in so-called impact zones of large mining and process­ ing enterprises, now, such changes can be observed almost throughout the Murmansk region, and the frequency of such occurrences is increasing. These negative phenomena reflect structural indices of some specified populations characterized by ultimate simplification. Populations are represented by small numbers of age groups and a minimum number of spawning fish. The following pro­ cesses can be observed: reduction of lifetime, domination of fish of younger age groups, reduction of growth rate and average sizes, early spawning, spawning under conditions of extremely small size and/or blocking of maturation processes at elevated growth rates, and prolonged periods of maturation. Symptoms offish degradation can be found both near industrial enterprises and in remote areas. For example, such symptoms are typical for the whitefish population inhabiting the lakes of the Ponoi River basin, despite its distance from industrial facilities. Despite the peaks of pollution load that occurred in the sec­ ond half of the last century, the structure of fish communities has remained only slightly changed for a long time, even in the water bodies subjected to hardest technogenic transformation. As a rule, a decrease in salmon species and the domination of whitefish species was observed. Some trends in the community structure of the fish population in the lakes of the region were outlined in the late 1990s and the beginning of the present cen­ tury. The introduction of new fish species with wide ecological valence and under stressful environments for aboriginal species leads to drastic changes in the structure of ichthyocenoses. Thus, the introduction of vendace changed the structure of fish community in water bodies of the Paz River Basin. Vendace is a plankton-eater with more efficient filtering ability, outcom- peting densely rakered whitefish and occupies their ecological niche. Drastic increase in number of vendace creates tension in the food supply of densely rakered whitefish, adding to the existing stressors of heavy metal contamination. The future of whitefish populations, especially density rakered whitefish, is questionable. The European smelt Osmerus eperlanus previously inhabited a restricted number of bodies of water in the White Sea basin. •Decline in efficiency of hydroelectric power production •Worsening of conditions for fish production •Changes offish living conditions and habitats •Decline of recreational value •Increase of toxicity of water environment •Accumulation of potentially dangerous pollutants in ecosystems (sediments, biota) •Worsening of living conditions for hydrobionts •Fish quality impairment •Drinking water quality deterioration •Potential risk for human health •Blooming of algae •Violation of stability in production processes •Loss of sensitive species •Fish kill •Deteriorated drinking water quality •Potential risk for human health •Active development of stable species, invasion of new species. •Loss of salmon and whitefish species •Introduction of new species and increase in number of aboriginal species of low-value stable to new conditions •Decline in the potential ofmdustnal and sport fishing •Increase of parasitic invasions and fish diseases •Decline of recreational value of the region Figure 3. Main outcomes of climate changes and environmental pollution for water systems.