This study identifies structural relationships among algae of various ecological groups (phytoplankton, microphytobenthos, and phytoepiphytes) in the littoral zone of various types of aquatic ecosystems in the city of Kyiv. It has been demonstrated that phytoplankton, microphytobenthos, and phytoepiphytes are not isolated in space and time, but rather form a single algal system characterized by the presence of shared species, which explains the similarity in water quality indicators in both lotic and lentic ecosystems. The dynamic properties of phytoplankton and contour communities are determined by active or passive migration, during which algae from one community replenish another, thereby influencing the taxonomic composition, quantitative indicators (abundance, biomass), and the dominant complex of these algal communities. To identify the relationships between algae of different ecological groups in lotic and lentic ecosystems, a comprehensive methodological approach was applied, based on the parallel, simultaneous sampling of phytoplankton, microphytobenthos, and phytoepiphyton at each of the study sites throughout various growing seasons, including the winter of 2022–2025. Based on the results of a comprehensive study of phytoplankton and contour communities, similarities were demonstrated: taxonomic composition (at the species and phylum levels), the structure of algal communities in terms of abundance, dominant complexes, saprobity index values, and information diversity indices, as well as the presence was established of correlations and shared dominant species; the seasonal dynamics were demonstrated, and the biotopic preferences of shared species was determined, which forms the basis for the structural relationships between algal communities in the littoral zones of different types of aquatic ecosystems.
In Lake Verbne (lentic ecosystem), 462 species (482 infraspecies taxa) have been identified, belonging to 8 phyla, 19 classes, 53 orders, 92 families, and 197 genera, with 142 taxonomic units shared among them. The riverine zone of the Kaniv Reservoir (lotic ecosystem) is represented by 401 species (416 infraspecies taxa) from 8 phyla, 19 classes, 49 orders, 83 families, and 170 genera, with 101 individuals shared among them. In total, over the course of the study, 563 species (597 infraspecies taxa) from 8 phyla, 21 classes, 56 orders, 100 families, and 223 genera were identified in the lake and the watercourse. The uniqueness of the species composition of algal communities in each of the studied aquatic ecosystems was established; these ecosystems were characterized by distinct clusters represented by algal communities of lentic and lotic ecosystems, between which the Sørensen’s similarity index (KS) was less than 0.5. The results also indicate similarities between algae of different ecological groups, both in the lake and in the riverine zone of the Kaniv Reservoir. It was found that the level of species similarity between the microphytobenthos and the phytoepiphyton was higher (KS = 0.62 in the lake and KS = 0.57 in the watercourse) than between the phytoplankton and the components of the contour communities (KS ≤ 0,5). In both lentic and lotic ecosystems, microphytobenthos and phytoepiphyton were represented by the largest number of shared taxa (254 and 174 taxa, respectively). Based on the studies conducted, it has been demonstrated that the similarity in the taxonomic composition of phytoplankton, microphytobenthos, and phytoepiphyton is a characteristic feature of the structural relationships among these ecological groups of algae and is represented by a polydominant complex: Bacillariophyta–Chlorophyta–Cyanobacteria. At the same time, the distinctiveness of the species composition of algal communities in different types of aquatic ecosystems was determined by the fact that in the lentic ecosystem, the floristic structure was dominated by Bacillariophyta (phytoplankton – 25%, microphytobenthos – 42%, phytoepiphyton – 43%, respectively) and Chlorophyta (41%, 29%, 30%), while in the lotic ecosystem, it was dominated by Bacillariophyta (36%, 61%, 60%). It was found that 142 infraspecies taxa were common to the phytoplankton, phytoepiphyton, and microphytobenthos of the lentic ecosystem, among which planktonic forms predominated (69%), while periphytic (16%) and benthic (15%) forms accounted for a smaller proportion. In the lotic ecosystem, 101 shared species were identified, represented mainly by planktonic (47%) and benthic (36%) forms, with periphytic forms accounting for a significantly smaller proportion (17%).
