The composition and structure of the benthic diatom taxocene (Bacillariophyta) near Cape Fiolent (the Crimea, the Black Sea)

Abstract

For the first time in the waters of the Cape Fiolent Reserve, a high species richness of benthic diatoms was revealed on natural substrates, 290 species and infraspecific taxa (IT), belonging to 281 species, 68 genera, 32 families, 19 orders, and 3 classes. A total of 68 species and 3 genera were previously registered as new for the flora of the Black Sea; 3 species and 1 taxonomic combination were previously described as new to science, as well as 4 species that did not occur in the Black sea in the past 50 and 100 years of research. Navicula (41 species and IT), Amphora (30), Nitzschia (29), Fallacia (20), Cocconeis (17) and Diploneis (16) were the most represented genera. Only one representative was identified in each of the orders Anaulales, Ardissoneales, Thalassionematales, Rhaphoneidales, and Rhopalodiales. The diversity assessment that was carried out using taxonomic distinctness indices, TaxDI, revealed that the structure of the phylogenetic diatom tree was formed by branches with various species saturation levels and different hierarchical subordination, but with the predominance of polyspecific taxa up to at genera level. The TaxDI values (Δ⁺ = 76.71; Λ⁺ = 361.52) indicate the low evenness and high variability of the structure of the benthic diatom taxocene near Cape Fiolent.