Communities of free-living ciliates in freshwater bodies dominated by different species of cyanobacteria
S.V. Bykova, M.V. Umanskaya, M.Yu. Gorbunov
Section: Monitoring of natural and anthropogenically disturbed areas
Cyanobacteria and their toxins can cause changes in the aquatic food web, affecting almost all components of plankton, including free-living ciliates. The aim of the work is to identify the ciliates diversity in different types of waterbodies in the Samara region (rivers, reservoirs, bays, and lakes with/without outflows) and to establish the dependence between the quantitative and structural characteristics of ciliate communities and the dominant species of cyanobacteria. The composition of cyanobacterial communities was determined using metabarcoding of the V4-V5 regions of the 16S rRNA gene. According to the composition of phototrophic plankton, all samples were divided into four groups: 1) with a low intensity of “cyanobacterial bloom” or without it, but with a great diversity of cyanobacteria; 2) with the dominance of Planktothrix agardhii Gomont; 3) with the dominance of Aphanizomenon flos-aquae (L.) Ralfs; 4) mixed group with different types of cyanobacterial bloom, including one lake with the dominance of Raphidiopsis raciborskii (Woloszynska). 123 species of ciliates were identified in the studied water bodies of Samara region in 2023. The maximum quantitative characteristics of the plankton ciliates communities are observed in floodplain and terrace lakes and coincide with the predominance of P. agardhii and R. rachiborskii. The trophic structure is more diverse in communities dominated by P. agardhii and A. flos-aquae. Conversely, a whole trophic group (histophages) drops out from the trophic structure in samples dominated by eukaryotic algae or R. rachiborskii. In samples with A. flos-aquae bloom, algovores predominate in the ciliates community. Interestingly, predators are more prominent among the ciliates when R. rachiborskii bloom was observed. Generally, during the cyanobacterial blooms, bacterio-detritovores play the leading role among the ciliates.
Keywords: ciliates, biodiversity, freshwater bodies, cyanobacterial blooming, metabarcoding 16S, the structure of the ciliates community
Article published in number 2 for 2025 DOI: 10.25750/1995-4301-2025-2-100-108
ISSN 1995-4301
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