A new subspecies of dinophyte algae, Ceratium tripos var. balticumfrom the Caspian Sea

Abstract

The aim: description of the subspecies of dinophyte algae Ceratium tripos var. balticum , first discovered in the Caspian Sea. Materials : Monitoring observations of the state of the Caspian ecosystem and the food supply of commercial pelagic fish species: collection of hydrobiological material in the Middle Caspian during a sprout survey in the summer of 2024 on the IS «Caspian Researcher» according to the standard grid of stations adopted by the Volga-Caspian branch of the State Scientific Center of the Russian Federation «VNIRO» («CaspNIRKH»). Phytoplankton samples were collected using a BSR bathometer (4 L), fixed with formalin and concentrated. During laboratory processing of the material, the species composition was determined, and the abundance and biomass of planktonic algae were calculated. Research results: when processing phytoplankton samples, a representative of the genus Ceratium , which was not found in the Caspian Sea, was discovered. Scientific novelty: for the first time, a description of a new species of dinophyte algae Ceratium tripos var. balticum (Dinoflagelta: Dinophyceae). Practical significance: due to the fact that the species is large in size, it is inaccessible to zooplankton phytophages, and since there are no species capable of consuming it as food and thereby limiting its development, its rapid development is possible, which may entail a restructuring of the main connections and energy flows in the ecosystem, as happened when the diatom Pseudosolenia calcar-avis invaded the Caspian Sea.