Taxonomic composition of phytoplankton in various continental aquatic hydroecosystems of Ukraine

Abstract

The paper deals with present-day taxonomic composition of phytoplankton in various continental aquatic ecosystems of Ukraine (Kaniv Reservoir, the Western Bug River (with tributaries), Prypiat River (with tributaries), Sula River (within Nyzhniosulskyi National Natural Park, ponds (Hostomel town), large lakes of the Danube River) according to the modern algological nomenclature AlgaeBase. Within 2000–2022 in the phytoplankton of aquatic ecosystems under study 455 species of algae were identified, represented by 467 infraspecies taxa from 206 genera, 102 families, 53 orders, 18 classes and 8 phyla. The most diverse were Bacillariophyta (25–50%), Chlorophyta (22–39%) and Cyanobacteria (7–16% of floristic spectrum). Phytoplankton responds to present climate change by increase in Cyanobacteria share. The taxonomic hierarchy of algae, identified in plankton, is characterized by the following regression: Bacillariophyta > Chlorophyta > Cyanobacteria > Ochrophyta > Euglenozoa. Analysis of the taxonomic composition of Bacillariophyta at different levels of their systematic hierarchy (families, genera — according to Kendall index; species (infraspecie taxa) — according to Sørensen index) has made it possible to reveal the following patterns. The Kendall index for leading families varied within 0.31–0.72. The highest level of similarity was observed for lotic ecosystems. The Kendall index for leading genera varied between 0.11 and 0.59. The highest similarity level was observed between ecosystems of one type, for example, lotic (the Prypiat River and the Western Bug River) or lentic (ponds of Hostomel town and large Danube lakes). Cluster analysis of species similarity according to Sørensen index shows that two clusters can be distinguished in the dendrogram: lotic ecosystems and lentic ecosystems. The long-term data on the taxonomic composition of phytoplankton (algae present in water column at the moment of sampling) give evidence of high diversity thereof in various aquatic ecosystems of Ukraine.