Assessment of phytoplankton photosynthetic activity in the Upper Volga reservoirs via fluorescence diagnosis

Abstract

Based on the materials of field observations in 2015–2018, the first data on the photosynthetic activity of phytoplankton in the Upper Volga reservoirs are estimated using fluorescence diagnostics. During the summer maximum of phytoplankton, the coefficient of photosynthetic activity (CPhA) varied from 0,18 to 0,84 (standard error <0,005), averaging 0,49±0,003, 0,52±0,002, and 0,51±0,004 in Ivankovo, Uglich, and Rybinsk reservoirs. Spatial and interannual changes of CPhA are considered. In interannual dynamics, higher CPhA values were noted in 2015 and 2018 (average 0,53), lower values in 2016 and 2017 (0,47–0,50). A decrease in CPhA with an increase in the concentration of chlorophyll (r = -0.30 – -0.56) was revealed.