Benthos state dynamics in small rivers of Middle Volga

For the first time composition, distribution and structure of benthos communities with detailed analysis of chironomids fauna in small rivers of the Middle Volga basin have been investigated. Studing rivers of forest-steppe and steppe zones of Samara region concerning different substrates (the Sok-river tributaries taken as an example) allows us to reveal dominant, rare and primarily registered species for fauna of the Volga-river basin reservoirs.