Assessment of benthic diatoms taxonomic diversity at coastal biotopes with different anthropogenic impact (Crimea, the Black Sea)

An analysis of the taxonomic diversity of benthic diatoms was carried out for near-shore biotopes of Crimea with different content of trace metals and organic pollutants (PCBs, PAHs, DDTs). Taxonomic distinctness indices such as average taxonomic distinctness, AvTD (Δ+) and variation in taxonomic distinctness, VarTD (Λ+) were used for evaluation of the hierarchical structure of diatom taxocenes of two intact sites (Dvuyakornaya Bay and Cape Fiolent) and two heavily polluted water areas (Sevastopol Bay and Balaklava Bay). The highest similarity of species was revealed between healthy biotopes, in spite of their differences in hydrological and hydrochemical conditions. AvTD values for Dvuyakornaya Bay and Cape Fiolent (Δ+ = 79.0 and 76.7, respectively) were lower in comparison with expected average levels (Δ+ = 82.2) evaluated for the flora of benthic Bacillariophyta (1094 species) registered for the Northern part of the Black Sea (NPBS).