Characteristic features of the dynamics of environmental parameters of the Saratov Reservoir in the beginning of the 21st century

Abstract

This study, conducted in the Saratov Reservoir in 2001–2020, investigates the dynamics of organic matter (OM), nutrients and phytoplankton under climate change conditions. A negative trend in the content of allochthonous OM and ammonium nitrogen is found. The reservoir water discharge, changes in phosphates and nitrates are associated with the dynamics of the North Atlantic Oscillation Index. A positive trend of iron concentrations in the reservoir is due to an increase in winter runoff caused by frequent winter thaws. The content of total and easily oxidized OM, as well as silicon is less associated with changes in hydrometeorological conditions. During the study period, the total biomass of phytoplankton and the biomass of green algae decreased, the proportion of cyanoprokaryotes increased, and the species composition of algae became simpler. The principal components method allowed us to identify the main factors combining the content of biogenic elements, the total biomass of phytoplankton and the main divisions of Bacillariophyta and Cyanoprokaryota, and the July water temperature.

Keywords

• organic matter
• biogenic elements
• phytoplankton
• climate change
• north atlantic oscillation index