Shershnevskoe Reservoir is the main source of water supply of the Chelyabinsk city (South Ural, Russia). It is an artificial reservoir, filled in 1963-1969. The water protection zone of the Shershnevskoe Reservoir is subject to significant anthropogenic impact. Variations in phytoplankton community composition in the artificial waters are still poorly understood. The purpose of this work is to study the changes in the composition of phytoplankton that have occurred since the creation of the reservoir. Identified taxa (381) of the phytoplanktonic community in 1965-1985 are as follows: 150 Chlorophyta, 123 Bacillariophyta, 69 Cyanophyta, 25 Euglenophyta, 6 Chrysophyta, 6 Xantophyta, 1 Dinophyta and 1 Cryptophyta. Identified taxa (134) of the phytoplanktonic community in 2004-2017 are as follows: 67 Chlorophyta, 26 Bacillariophyta, 25 Cyanophyta, 9 Euglenophyta, 4 Chrysophyta, 2 Xantophyta and 1 Dinophyta. The dominants were blue-green algae. The presence of Cyanobacteria as the dominant complex indicates a high degree of eutrophication of the reservoir. The following species were dominant until 2014-2015 Aphanizomenon flosaquae Ralfs ex Bornet & Flahault, Snowella lacustris (Chodat) Komárek & Hindák and Microcystis aeruginosa (Kützing) Kützing, but after 2014-2015 it is Planktothrix agardhii (Gomont) Anagnostidis & Komárek. Over the fifty years of the existence of the Shershnevskoe Reservoir, its ecological state has passed from a long-term sustainable mesotrophic to a eutrophic one. |
