ZOOBENTHOS OF WATERCOURSES IN THE BUKHTARMA RIVER BASIN (UPPER IRTYSH, SOUTH-WESTERN ALTAI) AT REFERENCE SITES AND IN THE IMPACT ZONE

The composition, structure, and spatial distribution of zoobenthos in streams of the Bukhtarma River basin are described and quantitative indicators of benthos in the lower course of the Bukhtarma River are given. The predominance of insects from the orders of mayflies, caddisflies, and freckles is characteristic of the water-courses in the Bukhtarma River basin and is associated with the presence of stony soils in the rivers, rapid flow, moderate-cold-water temperature regime, and high oxygen content in the water – factors that are most favorable for these groups of invertebrates. To assess the ecological state of surface waters in the streams under study by bioindication methods, TBI, BMWP, ASPT, and ERT biotic indices are used. The taxonomic composition of each of the studied watercourses and river sections is formed in accordance with specific environmental conditions associated with natural and anthropogenic factors. It is established that watercourses in the reference areas can be used as reference ones in accordance with the requirements of the EU Framework Water Directive, and the characteristics of invariant States of biocenoses of the lower course of the Bukhtarma River in the impact zone are also given using the criteria of the V. A. Abakumov system of ecological modulations.