No abstract

The results of original studies (1987–2016) of the floristic composition of diatoms of natural and anthropogenic substrates in different regions of the Black Sea at depths of 0–53 m are summarized. 350 taxa of Bacillariophyta were identified, 77% from them are benthic, 57% – marine, 29% – boreal and 25% – boreal-tropical. In the epilithon, 140 taxa were found, in the epiphyton of macrophytes – 254, the epizoon of the mussel Mytilus galloprovincialis Lam. – 154, on the skin of dolphins – 10 and in the periphyton of anthropogenic substrates – 194. The Сzekonowsky-Sörensen coefficient of species similarity depending on the ecotope varied from 54 to 64%. In both ecotopes of epizoon and periphyton 28 species were common. The maximum values of abundance (N), biomass (B) and the Shannon index of species diversity (H) of diatoms in all ecotopes were observed in the winter-spring season: epilithon – N =416•103 cells•cm-2, B=0.4 mg•cm-2,Н = 1,89; epiphyton – N=366.3•103 cells•cm-2,B=0.82 mg•cm-2, Н=3.03; epizoon – N=179.3•103 cells•cm-2, B=0,54 mg•cm-2, Н=3.81; periphyton at exposure of experimental plates from 1 to 13 months – N =2180.8•103 cells•cm-2, B=0.543 mg•cm-2, H=0.97–3.67 and with monthly exposure – N=1229•103 cells•cm-2, B=0.35 mg•cm-2, H=1.1–3.5. The questions of similarity and dissimilarity of qualitative and quantitative characteristics of microphytobenthos diatoms in different ecotopes and areas of the Black Sea are discussed.

Bioindication of organic pollution and seawater quality was carried out for the first time in the western part of the Sea of Azov on the basis of species composition and quantitative characteristics of microphytobenthos. A total of 229 algal samples were collected at 17 sites over the period of 2005-2014 on three different substrates in three areas under study: Sivash Gulf, the Kerch Strait and Cape Kazantip. In total, 200 taxa of algae were found, which belong to six taxonomic divisions with a predominance of diatoms. Among those, 108 taxa are indicators of substrate, water temperature, salinity, water pH, trophic state, the type of nutrition and organic pollution of water. It has been shown that the most active self-purification of water takes place in communities on stony substrates. The largest number of algae species (50%) occurs in the cleanest waters of the Kazantip Nature Reserve (Water Quality Classes I–II). The species composition of organic pollution indicators in Sivash Gulf corresponds to waters of Classes III–IV, which are more polluted than those of the Kerch Strait and Cape Kazantip. All the studied areas of the Sea of Azov are cleaner compared to some waters of the Eastern Mediterranean and the Sea of Japan.

In this work, the species diversity of epilithon diatoms of Donuzlav Gulf (Crimean coastal waters of the Black Sea) is presented for the first time. A total of 60 taxa of Bacillariophyta belonging to 3 classes, 18 families and 34 genera were found. The largest number of species (45) of diatoms was observed in summer, and the smallest number of species (12) in winter. A total of 25 saprobity indicator species of diatoms was found on the epilithon, 12 taxa of which belong to a group of betamesosaprobionts—indicators of moderate organic pollution of water. Marine species comprise 55% and brackish-marine ones make up 37% of them, but no freshwater species were identified. The diatom community was dominated by cosmopolites (32%) and arctic–boreal–tropical species (27%). The maximal abundance (186.2 × 103 cells cm−2) and biomass (0.083 mg cm−2) of diatoms was noted in June 2018 at salinity 16.58‰ and T = 24.4 °C with the dominant cosmopolites species of Licmophora abbreviata and Cocconeis scutellum. The minimum values, 14.8 × 103 cells cm−2 and 0.005 mg cm−2, were observed in January 2019 at salinity 16.86‰ and T = 9.0 °C with the dominant Berkeleya rutilans and Nitzschia hybrida f. hyalina. The high values of BOD5, oxidizability, silicon, Norg and Porg were noted, indicating a certain degree of water pollution by domestic sewage. It has been shown that the pollution in the southwestern part of the Donuzlav Gulf is greatest since this part of the coast was populated most densely in comparison with the northern coast of the Gulf where there are no coastal settlements except for two mariculture farms.