Status of plankton algocenosis in the water area of the port of Tuapse and beyond it in the spring-summer period of 2019

The article presents the research of qualitative structure and quantitative development of phytoplankton in the water area of the port of Tuapse and beyond it in the spring-summer period of 2019. In April 2019, 43 phytoplankton species of 5 divisions were found. In the port area, the mean values of abundance and biomass were of 568 thousand cells·L−1 and 206 mg·m−3, respectively; in the open sea area, the values were 1.5 times higher. In the port area and beyond it, diatoms developed abundantly: 98–99 % of the total phytoplankton abundance and 62–65 % of the biomass. Small-cell species Pseudo-nitzschia spp. and Skeletonema costatum s. l. formed the basis of the abundance; Pseudosolenia calcar-avis, Dactyliosolen fragilissimus, and Chaetoceros affinis formed the basis of the biomass as well. In June 2019, a decrease was recorded in qualitative (13 species from 4 divisions) and quantitative values of phytoplankton development. In the port area, the mean values of planktonic algae abundance and biomass were of 59 thousand cells·L−1 and 81 mg·m−3, respectively; in the open sea area, these values were more than 2 times lower. In the water area of the port, euglenids developed abundantly: % of the phytoplankton abundance and 83 % of the biomass; those were represented by a mesosaprobic species Eutreptia lanowii. Beyond the port of Tuapse, euglenids were not found; in terms of abundance, diatoms predominated (95 %): Skeletonema costatum s. l. and Thalassionema nitzschioides. The following Dinophyta species formed the basis of the phytoplankton biomass (82 %): Ceratium tripos, C. furca, Ensiculifera carinata, Glenodinium paululum, Prorocentrum micans, and Protoperidinium crassipes.