Long-term Changes in Community of Planktonic Algae of the Northeastern Black Sea (2005-2011)

Phytoplankton dynamics in bays and open waters of the northeastern Black Sea was studied in 2005-2011. Species composition comprised 11 classes and 210 species including 19 potentially toxic species and 5 new records for the study area. The maximum species richness was found among dinoflagellates (96 species) and diatoms (78); other major taxonomic groups were represented by a small number of species (2 to 10). The highest abundance of planktonic algae was observed in the Novorossiysk port waters (5.1x105 cells/ L; 1.08 g/m3). Algal abundance and biomass in the bays of Anapa, Gelendzhik and Tuapse were 2 to 5 times less than in the bay of Novorossiysk. Smallcelled mesosaprobic species of diatoms (Skeletonema, Leptocylindrus, Thalassionema and Chaetoceros), euglenophyceans (Eutreptia lanowii), cyanobacteria (Lyngbya and Oscillatoria) and mixotrophic dinoflagellates (Gymnodinium, Heterocapsa, Gyrodinium and Prorocentrum) were found in the bays. Abundance and biomass in the open sea in front of the bays were 1.5-2 times higher than those observed within the bays. The minimum abundance and biomass were observed in the open sea (5.4x104 cells/L, 0.28 g/m3) and the Kerch Strait (9.8x104 cells/L, 0.186 g/m3). In these areas the most significant part of the population (34-40% of phytoplankton abundance) was composed of the nanoplanktonic prymnesiophycean Emiliania huxleyi, the large-celled diatoms Proboscia alata and Pseudosolenia calcar-avis and dinoflagellates of the genus Protoperidinium (up to 45% of phytoplankton biomass).