Taxonomic Structure and Diversity of Benthic Diatoms (Bacillariophyta) in the Northern Shelf of the Black Sea

The key role of benthic diatoms in coastal ecosystems highlights the relevance of studying their biodiversity and developing integrated biodiversity conservation measures. Benthic diatom richness in the northern part of the Black Sea was estimated based on both published data and our own data. The checklist of benthic diatoms includes 1100 species and intraspecific taxa, 953 species, 149 genera, 61 families, 32 orders, and 3 classes of Bacillariophyta. More than 280 species and intraspecific taxa, as well as 8 genera new to the diatom flora of the Black Sea and 7 species new to science, were revealed. An interregional analysis of the diversity of benthic Bacillariophyta along the coasts of Bulgaria, Romania, and Crimea, as well as the northwestern and northeastern parts of the Black Sea shelf, was carried out using the Taxonomic Distinctness Indices (TaxDI). The lowest TaxDI value for Crimea was closest to the average value expected for the Black Sea diatom flora, indicating a large proportion of polyspecies branches in the taxocene structure, which resulted in the maximum species richness (species/genus = 7) and led to a decrease in the vertical evenness of hierarchical tree. On the contrary, the highest TaxDI value was detected off the Romanian coast, which was caused by the significant proportion of mono- and oligospecies branches and minimal species saturation in the taxocene structure (species/genus = 4). We also identified some species with a high taxonomic exclusivity rank. If these species disappear, the entire architectonics of the Black Sea hierarchical tree of Bacillariophyta may be significantly altered. Such region-specific species are given the highest protection priority since they have great importance for gene pool conservation

THE COMPOSITION, DISTRIBUTION AND DYNAMICS OF DEVELOPMENT OF THE BOTTOM DIATOMS IS SOME AREAS OF THE BLACK SEA

The purpose of the work: the analysis of the ecologo-floristic composition, seasonal dynamics of species and the character of distribution of bottom diatoms in the sublittoral of the Black Sea, the revealation of the peculiarities of the mass species development in cultures. For the first time, the seasonal dynamics of the species composition, number and biomass, the vertical distribution on the natural substrates have been studied. The peculiarities of multiplication of diatoms in the cultures have been described. The results can be practically used with the introduction of the maricaltural production and performance of biotesting. The data can be used in the design of productivity of the Black Sea sublittoral ecosystems, at the control of the benthonic communities stateAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Comparison of benthic diatoms diversity (Bacillariophyta) in the Special Protected Area Cape Sarych and other water areas of the Crimea (the Black Sea)

The structure of diatom taxocenes in the Special Protected Area “Coastal Aquatic Complex Cape Sarych” and the previously studied areas of the Crimea (conditionally clean Cape Fiolent, Novy Svet settl., Bay Dvuyakornaya and heavily polluted bays Balaklavskaya, Karantinnaya, Inkerman, and Sevastopolskaya) were analyzed with the use of the index TaxDI. At Cape Sarych, we identified 82 species and intraspecific taxa of diatoms belonging to 35 genera, 25 families, 15 orders, 3 classes of Bacillariophyta, among which 18 species were new to the flora of the Black Sea. The structure of diatom taxocenes in pristine water areas was formed by branches of different hierarchy and predominance of close at the genus level polyspecies taxa. Diatom taxocenes of polluted waters were characterized by a high proportion of mono- and oligospecies branches closing at the family or order levels that brought to reduced diatom taxonomic diversity, increased evenness and decreased variability of their hierarchical structure. The impact of technogenic pollutants caused a transformation of the primary link of the marine sublittoral ecosystem which is expressed in the reduced structure of diatom taxocenes and disappearance of diatom species with low resistance to negative factors