Мединец В. И.

Purpose. Determination of long-term changes in bacterioplankton number in the Dnistrovskiy Estuary in 2003-2018 and data usage for aquatic environment quality assessment. Methods. Bacterioplankton number determination was done using direct microscopy method under microscope with magnification of 1200. Ecological classification of surface waters quality adopted in Ukraine was used for water trophic status assessment. Results. Changes of bacterioplankton quantitative characteristics in summer periods of 2003-2018 have been analyzed. Tendency of increase in bacteria quantity has been revealed in the past eight years, as well as the waters’ trophic status increase from polytrophic in summer periods of 2003-2005, 2007-2009 and 2015-2016 to hypertrophic in 2011-2014 and 2017-2018. Maximal out of all the years bacterial number was identified in July 2012 that exceeded the peak value in the end of past century. Existence of statistical connections between bacterioplankton and water conductivity, transparency, chlorophyll a, pheophytin and total phosphorus were shown. Conclusions. It has been established that microbiological regime forming in the Dnistrovskiy Estuary took place under the influence of natural processes of organic matter production and pollution factors that revealed themselves the most in the middle and southern parts of the estuary. Among the aquatic environment parameters controlled bacterioplankton number, like chlorophyll a, reflected the changes of the Dnistrovskiy Estuary trophic state the most realistic way. At that, index of bacterioplankton is indispensible for indication of water pollution with organic matter of anthropogenic origin.

Purpose. Study of macrozoobenthos contemporary state in Odessa Bay coastal waters in 2016-2017. Methods. Standard methods of macrozoobenthos sampling, determination, estimation of number and biomass Results. The results of macrozoobenthos biodiversity, structural characteristics and taxonomic composition in Odessa bay coastal waters have been presented. Seasonal dynamics of its number and biomass. has been studied. Assessment of marine environment quality has been performed on the metrics of macrozoobenthos. Conclusions. Altogether 121 taxa of benthic invertebrates were identified in Odessa Bay in 2016-2017. Taxonomic composition and quantitative indicators of macrozoobenthos had clear seasonal variation with maximal devel-opment of benthos in summer period. In spring of 2016, 75 taxa of macrozoobenthos were registered in samples, in summer – 82 taxa, in autumn – 60 taxa, in summer of 2017 – 62 taxa. The basis of macrozoobenthos community was formed be mollusks (Mollusca) with domination of species М. galloprovincialis, as well as representatives of Arthropoda and Annelida. Significant input into macrozoobenthos species composition was made by representatives of the following groups: Bryozoa, Nemertea and Platyhelminthes. Contribution of Porifera, Cnidaria and Phoronida to Odessa Bay benthic communities was insignificant. In 2016-2017 3 alien species were registered in Odessa Bay – bivalves Anadara kagoshimensis and Mya arenaria, as well as gastropod Rapana venosa. Out of 121 macrozoobenthos taxa 4 were listed in the Red Data Book of Ukraine and 6 – in the Black Sea Red Data Book. During the period of studies practically equal quantities of macrozoobenthos taxa were found on different substrates. In samples from loose substrates the number of taxa at different depths varied from 5 to 40 with Shannon diversity index (Н) making 1.7-2.9; on mixed substrate – from 19 to 48 species with Н = 1.3-2.8. Macrozoobenthos number and biomass varied on loose substrates from 0.070х104 to 3.227х104 ind/m2 and from 0.002 to 5.361 kg/m2 and on stony substrate – from 0.667х104 to 170х104 ind/m2 and from 0.088 to 46.811 kg/m2 respectively. Quality of marine environment estimated using AMBI and M-AMBI indices calculated for all the 26 samples was assessed as High in 4 cases, Good in 17 cases and Moderate in 5 cases out of 26. Mean values of the AMBI and M-AMBI indices for different seasons of year were as follows: first decade of June 2016 – 1.84±0.07 and 0.69±0.04 respectively; August 2016 – 1.66±0.12 and 0.84±0.05 respectively; November 2016 – 2.62±0.13 and 0.60±0.02 respectively; June 2017 – 2.72±0.11 and 0.73±0.05 respectively.

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.

Purpose. To reveal seasonal changes in phytoplankton quantitative characteristics including biodiversity and species composition of potentially dangerous (toxic) species. Methods. Phytoplankton sampling in Odessa bay coastal waters and sample analyses were carried out using standard methodologies. The samples were preserved using formalin. Microscopes HUND−H600 and OLYMPUS−BH2 have been used for sample analyses. Classification of microalgae and Cyanobacteria was done according to the standards of the international database. Results. Analysis of the main abiotic factors influencing the state of phytocene has been carried out. In the species composition, 238 species of phytoplankton belonging to 11 classes have been registered: diatoms − Bacillariophyceae, dinophytes − Dinophyceae, green − Chlorophyceae, Cyanobacteria, Prymnesiophyceae, Euglenoidea, Chrysophyceae, Cryptophyceae, Dictyochophyceae, Choanoflagellatea. It was shown that the dominant phytoplankton species were Bacillariophyceae, Dinophyceae, Chlorophyceae and Cyanobacteria. For the first time, 11 freshwater species of dinophytes were registered in the Zmiinyi Island area. Statistical interconnections between phytoplankton metrics and abiotic characteristics were analysed. Development of 54 phytoplankton species, which refer to the group of potentially harmful (toxic) was registered; out of this number, 21 reached blooming level. Conclusions. The main abiotic factors determining the state of phytoplankton and its seasonal changes are salinity and transparency. During 2016−2017, 4 seasonal maximums of microalgae development were registered in the photic layer of the Zmiinyi Island coastal waters (in spring, summer, autumn and winter), which corresponded to the terms of the normal periodicity of the Black Sea phytoplankton vegetation. Comparison of modern maximum values with similar data obtained in previous years, allows us to conclude that a significant increase in the quantitative characteristics of phytoplankton took place in 2016−2017. The quality of water in the surface layers in the Zmiinyi Island area assessed using the main metrics of phytoplankton was much lower than that in the bottom water layers, which was caused by the Danube River discharge impact, first of all, observed in the surface layers of water.

Purpose. The study of the features of long-term changes of the Dniester Estuary hydrological regime main characteristics in 2012-2017 based on the results of annual surveys performed by Odessa National I. I. Mechnikov University. Methods. Measuring of the water transparency, temperature and electrical conductivity in the surface and near-bottom layers were carried out using standard techniques with Secchi disk and portable HACH analyser with temperature and conductivity sensors. Results. Based on the studies performed, almost two times decrease in water transparency values in summer of 2012-2017 has been established compared with the same period of 2003-2011. It was shown that the maximum transparency values were observed in the southern part of the estuary, where the presence of seawater is almost constant. Analysis of electrical conductivity spatial distribution has revealed practically constant influence effect of seawater intrusion in the southern part of the estuary, especially in the bottom layer, and periodical influence effect in the middle and northern parts. Significant increasing of the range of water temperature and electrical conductivity variations in the Dniester Estuary has been recorded in summer 2012-2017 comparison with summer 2003-2011. Conclusions. The established peculiarities of hydrological characteristics’ spatial distribution indicate that river discharge and intrusion of marine water are the most important factors determining the Dniester Estuary hydrological regime. Increase of temperature and conductivity of the Dniester Estuary water in summer 2012-2017 in comparison with 2003-2011 was registered. An anomalous penetration of marine waters into most part of the estuary was detected in July 2016, which in the past was observed for the last time in 2011.

To analyze the current state of marine research problems and to formulate proposals for the establishment of a national system of sustainable development of marine research in Ukraine and ways of their implementa-tion. Analysis of current problems in the marine research and respective national and international legal frame-work has been performed. It was shown that the problems of investigations are directly connected with natural and anthropogenic changes and pressures in marine ecosystems. Detailed analysis of national low base present-ed. Some grounded measures and steps to establish the national system for sustainable development of marine studies and technologies in Ukraine have been proposed. Are discussed the actual directions and their im-portance for science and research taking into account the national interests of Ukraine and to ensure compliance with the Association Agreement and other international commitments of Ukraine. The establishment the Black Sea joint international network of reference (basic) marine research stations for using in interests of all the Black Sea countries are proposed. Conclusions: Renovation of national system of the scientific research and technologies cannot be developed without establishing of respective infrastructure, restoration of marine potential and modern system of marine specialists education taking into account experience of European and global science.

Purpose. To study hydrodynamic prerequisites of forming and to assess the volume of subaqueous discharge of Upper-Sarmatian aquifer into the Kuyalnyk Estuary. Objects and methods. Hydrodynamic model determining changes in direction and volume of exchange between groundwater and surface water of estuary based on the ratio of levels (pressures) has been taken as the methodological basis. Results. It has been established based on many years’ hydrogeological and hydrological observations (1950 - 2016) that water exchange between groundwater and surface water of the estuary, depending on changes of hydrogeodynamic conditions with time, is characterized by both up and down flows. The results of calculation of specific discharge of water exchange between Upper-Sarmatian aquifer and surface water of the estuary show that after a long (30 - 40 years) period of water down filtration from the estuary just after mid-90th of last century a slow process of estuary refilling with groundwater started. As of 2016, the subaqueous constituent of the estuary ground feeding makes around 20% of the total water volume in the estuary. Conclusions. Assessing water balance of the Kuyalnyk Estuary, together with traditional factors forming its hydrogeological regime (atmospheric precipitation, river discharge, surface run-off and evaporation), one should take into account spatial and temporal changes in subaqueous constituent of the estuary groundwater feeding.

Purpose. Assessment of bottom sediments accumulation rate for two areas of the Kuyalnyk Estuary using radionuclide method. Methods. The study has been done in two areas of the Kuyalnyk Estuary: the middle part near Kovalivka village and the lower part to the north from the sanatorium, using the standard methods of sedi-ment columns sampling and gamma-spectrometric analysis of radionuclides concentration. Results. Based on the results of the studies of 2016, layer-by-layer concentrations of Cesium-137, Potassium-40, Radium-226 and Torium-232 were determined. Analysis of vertical profiles of Cesium-137 concentrations enabled us to assess, for the first time, the intensity of sediments accumulation in two areas of the estuary for the periods 1962-1986-2016, which later were used for indicative dating of anomalies in the distribution of natural radionuclides Potas-sium-40, Radium-226 and Torium-232 concentrations. Conclusions. It has been shown that in the lower and middle parts of the Kuyalnyk Estuary the average rate of sediments accumulation in 1986 – 2016 made 0.8±0.1 mm/year and 1.8±0.2 mm/year respectively. In 1962-1986 sediments accumulation rate was prac-tically the same in both parts of the estuary and made 1.9±0. mm/year. The average values for the period 1962-2016 made 1.6±0.1 mm/year and 1.8±0.2 mm/year for the lower and middle parts of the estuary respectively. It has been proposed to perform additional mineralogical studies for more precise dating of the sediment layers accumulated before 1962 and to use radionuclide method for determination of sediment accumulation rate in other water bodies of the Black Sea region.

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.