Content of Photosynthetic Pigments in the Upper Volga Reservoirs (2005–2016)

Abstract

Data on the composition, content, and interannual dynamics of photosynthetic pigments in water of the Upper Volga reservoirs in the summers of 2005 and 2012–2016, continuing the series of long-term observations, are given. With an average content of chlorophyll (Chl a) from 13.1 ± 1.4 to 52.5 ± 2.7 μg/L in the Ivankovo Reservoir and from 7.6 ± 1.6 to 27.5 ± 2.5 μg/L in the Uglich Reservoir, an increase in Chl a is observed after the anomalously hot 2010. Interannual changes in Chl a in dependence on the water temperature, as well as the Wolf numbers and North Atlantic Oscillation index (NAO) that indirectly affect phytoplankton productivity, are analyzed. Chl a content in the Ivankovo Reservoir, which retains the eutrophic status, does not go beyond the long-term fluctuations, while an increase in the absolute and relative amounts of Chl a in the Uglich Reservoir indicate an increased role of blue-green algae and transition of the reservoir to the eutrophic category.