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For the first time, an assessment of the taxonomic and quantitative structure of the phytobenthos of seven saline rivers in the basin of the hypersaline Lake Elton (Volgograd region) is presented. The main types of algal communities developing on substrates were revealed: diatom phytobenthos, communities of diatoms with cyanoprokaryotes, cyanobacterial films and mats, and epiphyton. The phytobenthos consists of local, mosaic-distributed communities with a small similarity in their species composition. The structure of algal communities is determined by Bacillariophyta (with the predominance of species of g. Navicula) and Cyanoprokaryota (of the gg. Phormidium, Leptolyngbya, and Geitlerinema). The abundance and biomass values vary widely, reaching their highest values (109 834–417 472 million cells/m2 and 523.6–567.6 g/m2) in cyanobacterial communities of mesohaline rivers at a water salinity reaching 16–19 g/L. Mineralization as a factor influencing the structure of communities most rigidly acts in the mouth sections of rivers, by controlling the composition of the dominant species. For critical salinity values (>70 g/L), characteristic structural transformations of communities by the type of replacement of planktonic and benthic Bacillariophyta and Cyanoprokaryota by planktonic Chlorophyta (of the g. Dunaliella) and picoplankton were revealed. [ABSTRACT FROM AUTHOR]