Peculiarities of Phenology of the Primary Production Process in the Pelagic Zone of Lake Onega

The peculiarities of the phenology of the primary production process of phytoplankton have been studied for a large northern lake. The major seasonal events of the primary production process and the seasonal dynamics of the abiotic and biotic environmental factors have been described using the average multiyear curves of the studied parameters in the pelagic zone of Lake Onega. The primary production seasonal cycle is synchronized to the water temperature dynamics, chlorophyll a concentration (phytoplankton), and the density of “nondiatom” phytoplankton. The seasonal dynamics of the diatoms exhibits the opposite pattern. The temperature coefficient of photosynthesis (Q10) has been calculated for the natural phytoplankton community for the different seasons of vegetation period. The phenological phases of the primary production have been defined.