Diversity of planktonic pro- and microeukaryotes in water bodies of the Volga-Don basin during the period of cyanobacterial bloom according to metabarcoding data

Abstract

The first data on the phylogenetic diversity of planktonic communities of pro- and microeukaryotes in different types of water bodies of the Volga-Don basin during the period of cyanobacterial bloom are presented. Aphanizomenon flos-aquae/Dolichospermum flos-aquae blooms were found mainly in the Kuibyshev Reservoir; Planktothrix agardhii bloom was observed in floodplain lakes of the majority of investigated rivers. Bloom of Raphidiopsis raciborskii was found in a lake on the Volga River terrace, and in a pond in the floodplain of the Samara River Anabaenopsis dominated anong Cyanobacteria. Among heterotrophic prokaryotes, Proteobacteria, Bacteroidota, Verrucomicrobiota, Planctomycetota and Actinobacteriota predominate in the number of sequences, and among protists - Ciliophora, Gyrista (mainly Chrysophyceae), Cryptista and Myzozoa. During the period of cyanobacterial bloom, the contributions of Proteobacteria (especially, Burkholderiales and Pseudomonadales) and Actinobacteriota slightly decrease, while Myzozoa, on the contrary, increase. Monodominant blooms of various species of cyanobacteria significantly change the composition and structure of microbial communities, both at the OTUs and higher taxa levels. The plankton of the pond with Anabaenopsis bloom is most peculiar. Communities with blooms of P. agardhii, R. raciborskii and A. flos-aquae/D. flos-aquae are more similar to each other.