CONDITIONED ECOLOGICAL NICHES OF THE ICHTHYOFAUNA IN KUYBYSHEV WATER RESERVOIR
The ichthyofauna in Kyubyshev water resevoir is divided into 40 conditioned ecological niches that can be subdivided, on the one hand, according to their size, into 3 groups: 1) narrow, with small capacity, consisting of one species of fish, which makes 80 %; 2) medium, with middle-sized capacity, consisting of 2 species of fish, that makes 12.5 %; 3) wide, with large capacity, consisting of 3 and more species of fish, that makes 7.5 %. On the other hand, taking into consideration the possibility and direction of modification in conditioned ecological niches, we can also distihguish 3 groups that are characterised by the different degree of package of the conditioned ecological niches.