Disruption of the vertical distribution of plankton in the tributary mouth of a plains reservoir in the summer period of a hot year

Abstract

A stratification site was detected according to the water conductivity in the frontal zone of the mouth part of the tributary of a plains reservoir. The “second bottom” effect is shown to occur in the lower, denser layer of river waters, where the zooplankton, whose structural and functional characteristics differ from those in overlying and underlying water layers, live. The growth of bacterioplankton is controlled by the zooplankton. The “second bottom” effect is disrupted under an oxygen deficiency caused by abnormally high water temperatures.