Comprehensive Research of the Environmental Status of Coastal Waters of Sevastopol (Western Crimea, Black Sea)
The status of the aquatic environment and biota in the Sevastopol coastal area was monitored in five expeditions in 2018-2019. The sampling was performed at 15 sites from the mouth of the Belbek River to Cape Margopulo. Temperature, salinity, dissolved oxygen, biochemical oxygen demand (BOD<sub>5</sub>), oxidizability, silicates, mineral forms of nitrogen and phosphorus, and qualitative and quantitative phyto- and meroplanktonic indicators were determined in the samples. It is established that the Kacha region has a uniform spatial thermohaline structure. The influence of the riverine runoff on the distribution of salinity is not found. High oxygen supply, low biochemical oxygen demand and oxidizability as well as low and uniform concentrations of mineral forms of nitrogen and phosphorus are noted. The values of the eutrophication index (E-TRIX), which vary from 1.44 to 2.20, indicate the low trophic level of waters. 63 species of microalgae are registered, among which the number of potentially toxic species is negligible. In meroplankton, larvae of 45 species of bottom invertebrates have been identified. The minimum number of species (5) was noted in March, and the maximum (24) was observed in summer. It is advisable to continue to monitor the oceanoographic, hydrochemical and ecological status of the water area under study.