Features of Plankton Metabolism: Results of Automated Measurements in the Mozhaisk Reservoir

Abstract

Plankton metabolism determines fluctuations in the oxygen concentrations of a water body, its ecological condition, and exchange of СО2 with the atmosphere. We used an automated device that allowed us to make mass measurements of intraday values of the gross primary production (GPP) and respiration (R) of plankton. During our studies of the Mozhaisk reservoir (Russia) in the summer of 2017, we established an important fact: the maximum values of GPP are observed essentially earlier in the daytime than those of R. This is explained by the fact that GPP is related to solar radiation (the maximum values are observed at noon), whereas R is related to the temperature of water, which reaches its maximum several hours after in the afternoon. As a result, the maximum value of dissolved oxygen is observed in the second half of the day, when GPP and R become even. The device we have designed may be used for continuous monitoring of metabolism of plankton and of its responses to various hydrometeorological, hydrochemical and anthropogenic impacts.