Gazetov Ye. I.

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 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.