Солтис І. Є.

Purpose. Assessment of the trophic status of water in the Kuchurganske Reservoir in 2006-2018. Methods. Determination of hydrological, hydrochemical and hydrobiological characteristics of the water body's environment has been done using standard methodologies. Four indicators of water eutrophication have been used: chlorophyll a concentration, bacterioplankton number, trophic indices TSI and TRIX. Results. Features of physicochemical characteristics of water in the water-body have been analysed. Higher water temperature has been registered in the middle and lower parts of the water-body compared with its upper reaches. Mineral content increase in water has been found in the direction from lower to upper part; the critical for hydrobionts life decrease of oxygen concentration has been registered in the upper reaches the most often. Analysis of long-term changes in chlorophyll a and bacterioplankton has been carried out. Statistical interconnections have been established between trophic state indicators and physicochemical characteristics of the reservoir. A close positive correlation has been registered between chlorophyll а content and bacterioplankton number, which is caused by the functional dependence of bacteria on the organic matter produced by phytoplankton. It has been shown that with an increase of water volume in the reservoir the value of these indicators of trophic status went down, which was proved by close negative correlation dependence between those values and the depth of water-body. It was demonstrated for the first time that water transparency revealed close significant negative correlation with all the indices and indicators of water trophic status, which evidenced the possibility to use the transparency as a simple indicator of water trophic state as the more transparent is the water the lower is trophicity and the higher is the quality of the aquatic environment. Conclusions. It was established that the Kuchurganske Reservoir’s trophic status assessment on chlorophyll a, bacterioplankton and the TSI trophic index practically coincided and evidenced the increase in trophic status of the water-body from eutrophic to hypertrophic in last 2016-2018. The reservoir’s upper reaches were characterized by higher water trophicity compared with the central and lower parts. The values of TRIX trophic index developed for marine water assessment had practically always been showing higher trophic status compared to other indicators.

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.