Snigirov S. M.

Purpose. The results of pilot monitoring project carried out in Odessa Bay coastal waters in 2016-2017 by a research group of the Regional Center for Integrated Monitoring and Environmental Studies (Odessa Na-tional I.I. Mechnikov University) have been summarized. Methods. Primary data on transparency, temperature and salinity of marine water have been collected using standard methods. Data processing, calculation of statis-tics, producing of graphs and maps have been carried out using ArcGIS and Excel software. Results. Temporal and spatial distributions of transparency, temperature and salinity of marine coastal waters of Odessa Bay in the area of Marine Hydrobiological Station of the University for the period from April 2016 to August 2017 have been presented and analyzed. Using the results of analysis of the accumulated experimental data on transparency, temperature and salinity of seawater the peculiarities of those characteristics’ seasonal changes have been revealed. It was demonstrated that marine water transparency was minimal in May and June 2016 (2.2-2.8 m); maximal transparency values for the entire period of observation (7.0 m) was registered in May 2017. A strongly pronounced seasonal variation was revealed in the distribution of marine water temperature in Odessa Bay in 2016-2017, which was determined by spring-summer warming up / autumn-winter cooling down, as well as coastal upwelling, advection of water masses from other marine areas. It was shown that with observations performed every 10 days the desalinated water masses were registered in 13.5% of measurements but never found during monthly surveys at 13 of the micro-polygon. It means that during the detailed monthly surveys in Odessa Bay coastal waters all the cases of advection of desalinated water stayed unregistered. Conclusions. Impact of transformed water masses from the Dnieper-Bug mouth on seasonal cycles of hydrological characteristics in Odessa Bay in 2016-2017 has been established. Violations of the seasonality of thermohaline structure formation in Odessa Bay waters in 2016–2017 due to the longshore cyclonic and compensatory currents impact in the coastal zone have been recorded. Forming of stable two-layer vertical density stratification in Odessa Bay coastal waters at the spring and summer periods of 2016-2017 has been traced.

One of the main reasons for the necessity of our study was the fact that previous researchers used only model experiments on the impact of dilution of sulfuric mud on seawater and did not take into account in their conclusions the fundamental foundations of the functioning of ecosystems, such as the cyclicity of the salt and hydrological balance and the cyclic functioning of biocenosis in Ecosystem of the estuarine complex.Purpose. Revealing of real biological consequences of the Kuyalnik Estuary filling with big amounts of marine water in 2014-2016. Methods. Standard methods of hydrological, hydrochemical, hydrobiological and microbiological studies. Results. Based on the comprehensive studies the analysis of dynamics of the Kuyalnik Estuary ecosystem’s main physicochemical and hydrobiological characteristics has been performed, first of all of species composition, abundance and biomass of phytoplankton, bacterioplankton, zooplankton and concentrations of photosynthetic pigments. It has been shown that the studied biological characteristics have seasonal variations, the main reasons of which are changes in temperature and mineral content of the estuarine water, as well as the cases of gypsum sedimentation observed in summer of 2015 and 2016. Conclusions. Feeding of marine water did not achieve the expected result of stable estuarine water freshening, but worsened the situation with the unique biocoenosis. The current methodology of the estuary refilling with marine water causes negative consequences, which aggravate with each next feeding of marine water into the estuary and will accrue and entail the irreversible processes and complete degradation of the estuary’s ecosystem. We propose to focus on the restoration of the freshwater flow of the Big Kuyalnik River and the search for other engineering solutions.