Diatoms from the Holocene sediments of lakes Pustoye and Chernoe (Nizhny Novgorod region)

The diatom analysis of the Holocene sediments of Pustoye and Chernoe lakes revealed 37 taxa of diatoms of two classes, five orders, eighteen families and twenty-five genera with a low degree of similarity of species composition (39%) and differences in the ecological priorities of the diatoms according to the leading abiotic factors – salinity and pH. Lake Chernoe is characterized by a greater number of species (26), the presence of halophilic species, as well as the prevalence of indicators of alkaline reaction of the environment. A feature of Lake Pustoye is the complete absence of halophilic forms and the predominance of species that prefer an acidic water reaction. A greater number of planktonic species was characteristic of Lake Chernoe due to the greater depths of this karst reservoir. According to the geographical location in these lakes, arcto-alpine species are noted.