Изменения в развитии фитопланктона Среднего Каспия в 2021 году

Abstract

The research of taxonomic diversity was completed in the water area of the Middle Caspian as a whole and by sections (Makhachkala - Cape Sagyndyk, Derbent - Cape Peschany, Divichi settlement - Kenderli Bay) for 2021. During the research period 108 samples were collected and processed. As a result of the work performed 105 taxonomic units were found, which is more than the average long-term value (87), but less than the indicators of the previous year of the research (130). The diatoms were the dominant group and accounted for 50% of the total composition. Dinophyte algae were the subdominants. The basis of the ecological complex of 2021 was formed by the representatives of seaweeds. A representative of green algae Ankistrodesmus pseudomirabilis v.spiralis influenced the formation of the abundance, reaching the greatest development in the section of the city of Derbent - Cape Peschany. In the same section of the sea the maximum biomass was also noted with a predominance of a group of dinophytes. In general, in the Middle Caspian the layer of 0–25 m was the most productive. The maximum concentration of plant cells was noted at a horizon of 25–50 m in the section of the city of Makhachkala - Cape Sagyndyk. In the section of the city of Derbent - Cape Peschany it increased from the surface horizon (34.22 mg/m3) up to a layer of 25–50 m. On the section of Divichi village - Kenderli Bay the highest concentrations were noted in the 10–25 m water layer. 
 In 2020–2021 b-mesosaprobes T. nitzschioides, E. cordata, Fragilaria construens were the dominant indicator species. These species are not so demanding to the environment. Organisms of the α-saprobic zone were less common, which suggests that the saprobiological state of the waters of the Middle Caspian is moderately polluted