Features of the Structure and Nutrition of the Fish Population in Mountain Glacial Lakes on the Western Slopes of the Urals

The paper analyzes the modern structure and food relations of the fish population of the small glacial lakes of the Urals. The features that are expressed primarily in the reduction of the species richness of the local ichthyofauna and the predominance of a single-species fish population are revealed. The number of fish species inhabiting these reservoirs correlates with the height of their location above sea level, the area and the value of the redox potential of water. It is shown that the fish population of many small Ural lakes of the Pechora River basin is formed by a single species. It is established that the single-species fish part of the aquatic communities of mountain lakes can be represented by Arctic char, Siberian and European grayling, pike, lake and common minnow, roach and perch. The maximum number of such lakes was found in the highest mountainous region of the Circumpolar Urals. The relative abundance of fish and shifts in the trophic structure of the fish part of aquatic communities are considered. Fish-ichthyophages mainly switch to eating invertebrates, while cases of cannibalism are rare. The data obtained are analyzed from the standpoint of modern ideas about the glacial history of the Urals.