Fish Distribution in River Systems as a Dynamic Phenomenon
The distribution of fi sh in river systems should be considered from dynamic positions as a multilevel and continual process. Biological expediency of the dynamic approach to the description of the fi sh distribution, as compared to the static regime, is substantiated. Regularities of the fi sh distribution in their main habitats and river regions analyzing their nomadic migrations and cyclic movements were investigated, as well as regularities in the occupation of reservoirs by fi sh within the limits of different continental basins. The universal characteristics of river systems - biotopic pulsations, ecological differentiation, and integrity - were dеtermined. An integrated scheme for the description of the fi sh distribution status depending on scale and cyclicity of fi sh movements was developed. The notions of instantaneous, situational, territorial, nomadic of migratory status of the object investigated are suggested.