ASSESSMENT OF PHYTOPLANKTON AS FOOD RESERVE IN MIDDLE CASPIAN
The paper considers the specific features of development of the qualitative composition and ecological groups of plankton algae in the Middle Caspian in the summer of 2019. The yearly dynamics of biomass and the number of algae in the sections of Makhachkala - Cape Sagyndyk, Derbent - Cape Peschanny, Divichi - Kenderly Bay has been examined. During the study period 109 samples were collected and examined and 110 taxonomic units of algae were found, with diatoms always prevailing. The structure-forming role belonged to freshwater algae (37 %), which became characteristic of this part of the sea. The biomass and number of phytoplankton in the Middle Caspian made 12.9 million copies/m3 and 166.56 mg/m3, respectively. The layer-by-layer distribution of biomass was determined by the intensity of development of the diatomaceous alga Pseudosolenia calcaravis. The most favorable conditions for vegetation of dinophytic feed organisms were formed in the western (sections of Makhachkala - Cape Sagyndyk, Derbent - Cape Peschanny) and central (Divichi - Kenderly Bay) parts of the section in a layer of 0-25 m, which presumably has a positive effect on the development of planktonic organisms. Smallcell forms of algae dominated, which is an important aspect in the formation of the fish food reserve.