The composition of Cyanoprokaryota in the plankton of Cheboksary reservoir (Nizhnii Novgorod, Russia)

According to the recent data on taxonomy and nomenclature of taxa, a revision of blue-green algae composition (Cyanoprokaryota, Cyanophyta) of the Cheboksary Reservoir (Nizhniy Novgorod Region, Russia) was conducted. The materials for the research were the long-term data on Cyanophyta composition, recorded while studying phytoplankton of the Volga R. at the site of the planned reservoir (1969-1980) and after the Volga R. flow regulation (1981-2012). 73 species from 27 genera, 9 families and 3 orders were identified. The main part of the Cyanoprokaryota flora (50 % of the total species composition) was formed by representatives of genera Dolichospermum, Merismopedia, Chroococcus, Microcystis, Rhabdogloea, Oscillatoria. 138 species, 30 % of which were Chyanophyta, were reported as potential or actual agents of the algae blooms. Taxonomic, ecological and geographical characteristics of blue-green algae were given. Main changes in the taxonomic structure of this algae group after the Volga R. flow regulation were marked. The most important of them were the increase of total species diversity of Cyanophyta, record of new species of five genera and the increasing diversity of the genus Dolichospermum in 2 times.