Seasonal and Year-to-Year Variations of Phytoplankton Primary Production in the Rybinsk Reservoir: The Effect of Weather and Climate Variations

Abstract—The seasonal and long-term dynamics of phytoplankton primary production has been studied in the Rybinsk Reservoir (Upper Volga) in 2005–2014. A positive correlation has been found to exist between the values of plankton primary production, averaged over vegetation period, and the abiotic factors of the water medium (temperature, solar radiation, and nutrient concentrations), as well as, excluding the data on the anomalously hot summer of 2010, between the primary production and the index of North Atlantic Oscillation. The increase in water temperature (up to 27.9°C) in the summer of 2010 has caused a considerable increase in phytoplankton production. A considerable increase in phytoplankton primary production has been revealed in the Rybinsk Reservoir in the period under study.