Changes in the algocenoses in the estuary area of the Don River, Russia in different seasons

This study aimed to describe the seasonal dynamics of phytoplankton in the estuary area of the River Don, by comparing the seasonal and spatial patterns. The temperature and pH were measured during phytoplankton growth periods in 3 seasons of 2019. Diatoms formed the largest taxa of the phytoplankton and biomass of phytoplankton (67.56% of the total species composition in spring at station 4). Total number of phytoplankton was 413.33 to 1030 (Cell*103/L), while phytoplankton biomass ranged 33.94-1028.03mg/l. In the early spring, Nitzschia sp. and N. scalaris, N. subtilis, Melosira varians, Cyclotella meneghiniana, in summer, N. distans and Cyclotella meneghiniana, M. varians, N. scalaris, eptocylindrus minimus were dominant. Based on the results, the abundance peaks for blue-green algea occur in summer.