The paper presents the results of taxonomic revision of the species composition of cyanobacteria of the Ukrainian coast of the Black Sea (UCBS) occupying the northern and northwestern extremity of the sea. A verified list of the UCBS cyanobacteria includes 184 species from 68 genera. That makes 75.1% of species and 81.7% of the generic spectrum of the total Black Sea diversity of cyanobacteria. For each species data on ecological peculiarities and general distribution are given. In terms of ecological ranges, marine (35.5%) and brackish (13.9%) species make up about half of the list. The share of freshwater cyanobacteria (29.4%) is also high. It is mostly due to the records in plankton of the northwestern part of the sea where their proportion (48.6%) exceeds the combined share of marine (18.1%) and brackish (27.8%) species. Totally 77 cyanobacterial species from 35 genera were recorded in plankton and 132 species from 50 genera occurred on various substrates of natural and artificial origin. Biogeographically most of the revealed species have cosmopolitan (37.8%), subcosmopolitan (19.2%) and European (15.8%) ranges. UCBS includes two natural regions differing in geomorphological and climatic features: northwestern part and Crimean coast. In the northwestern part of the Black Sea, 94 species of 37 genera of cyanobacteria were found. Most of them (33 genera, 71 species) were revealed in plankton communities. For microphytobenthos, 27 species from 10 genera are cited. For the Crimean coast, 124 species of cyanobacteria from 54 genera are known. Among them 14 species from 10 genera were recorded in plankton, and 117 species from 51 genera in benthos. 17 species of cyanobacteria caused summer water blooms in the UCBS. Among them Dolichospermum flosaquae, Glaucospira laxissima, Nodularia spumigena, Planktolyngbya limnetica and Synechocystis salina appeared among the causative agents of water bloom at the Ukrainian coast only in the last decade. In recent decades, the list of species has been enlarged due to invaders from equatorial and subtropical regions, and freshwater forms. This indicates the need for further monitoring of the species composition of the Black Sea Cyanobacteria.
Keywords: Cyanobacteria, Cyanoprokaryota, species composition, ecological structure, distribution, Black Sea, Ukraine