Application of a robotic underwater probe for limnological research. A case study of Lake Glubokoe, Ruzsky district, Moscow region

The paper deals with a new approach to conducting experimental limnologic observations by using the automatic moored profiler Winchi. The autonomous underwater profiler is designed for regular multiparametric measurements of vertical profiles from the lake bottom (maximum depth of 60 m) upward to air-sea interface during an extended deployment (more than 1 month) at a hydrological station. Trial operation of the device was carried out in the lake Glubokoe near Moscow in 2022-2023. Observations made it possible to describe in detail the seasonal evolution of the underwater environment, including the transition from a state of homothermy to a direct thermal stratification with the formation of hypoxia in the hypolimnion in the deep central part of the lake. Intense intraday fluctuations of dissolved oxygen, temperature and water turbidity were found in the near-bottom layer. It has been hypothesized that in the spring-summer period, hypoxia is formed not only due to the barrier effect of the metalimnion, but also due to an increase in oxygen consumption for the microbial oxidation of detritus particles stirred up bottom sediments due to pulsating flows of groundwater discharge.