small rivers

ESTIMATION OF THE ZONAL DISTRIBUTION OF SPECIES OF THE BOTTOM COMMUNITIES IN RIVERS OF THE MIDDLE AND LOWER VOLGA BASINS

A comparative analysis of the variability of the specific structure of macrozoobenthos communities in small and medium rivers of the Middle and Lower Volga basin was made. A statistically significant influence of the natural-climatic zone where the waterway is located and a manifestation of the latitudinal gradient of biodiversity were shown. The list of indicator species with the use of various criteria of biotopic correspondence was composed for each identified geographical zone.

ESTIMATION OF THE ZONAL DISTRIBUTION OF SPECIES OF THE BOTTOM COMMUNITIES IN RIVERS OF THE MIDDLE AND LOWER VOLGA BASINS

A comparative analysis of the variability of the specific structure of macrozoobenthos communities in small and medium rivers of the Middle and Lower Volga basin was made. A statistically significant influence of the natural-climatic zone where the waterway is located and a manifestation of the latitudinal gradient of biodiversity were shown. The list of indicator species with the use of various criteria of biotopic correspondence was composed for each identified geographical zone.

ON THE CASTOR FIBER (CASTORIDAE, MAMMALIA) ACTIVITY INFLUENCE ON THE ECOSYSTEM BIODIVERSITY OF SMALL RIVERS IN THE FOREST-STEPPE ZONE

Preliminary data on the Castor fiber activity influence on the ecosystem biodiversity of small rivers in three steppe clusters within the State Nature Reserve “Volga forest-steppe” were obtained. With zooplankton, amphibians and fish as examples, it was shown that after beaver-made ponds had appeared, the abundance of all these groups increased. In old ponds, the fish abundance decreases whilst the amphibian one continues to increase. In drained ponds, the zooplankton and amphibian abundance decreases while the fishes become more numerous, due to the appearance of better flowability.