Taxonomic composition of zooplankton and frequency of occurrence of the taxa (% of samples) in the small river of the industrial zone of Volga region

The presented species list of zooplankton is a summary of long-term observations that took place on the small river Stepnoy Zai, situated in the industrial zone of the Middle Volga region of Russia. The sampling took place in May, July, and September yearly from 2008 to 2019 from 4 sampling stations along the river Stepnoy Zai. The sampling stations were situated upstream and downstream of municipal wastewater discharges of the four cities located in the upper (Bugulma, Leninogorsk), middle (Almetievsk), and lower (Zainsk) reaches of the river. Sampling was performed using Apstein Net from the upper water horizons. Samples were concentrated to 100 ml, and fixed with 4% formaldehyde solution.