Year-Round Presence of Microcystins and Toxin-Producing Microcystis in the Water Column and Ice Cover of a Eutrophic Lake Located in the Continuous Permafrost Zone (Yakutia, Russia)

Abstract

This study aimed to test the hypothesis of the year-round presence of toxigenic Microcystis and cyanotoxins in the water and ice of the shallow eutrophic Lake Ytyk-Kyuyol located in the continuous permafrost zone. Three independent approaches—mass-spectrometry, molecular methods and light microscopy—were applied in the study. The cyanobacterial biomass ranged from 1.0 × 10−4 to 4.8 mg L−1. Microcystis flos-aquae and M. aeruginosa were the dominant morphospecies in plankton throughout the observation. In environmental DNA, the presence of M. aeruginosa was supported and mcy gene regions responsible for microcystin biosynthesis were detected through a BLAST (Basic Local Alignment Search Tool) search and phylogenetic estimation based on newly obtained 16S rRNA, 16S–23S ITS rRNA, mcyA and mcyE nucleotide sequences. The intracellular microcystin concentration ranged from <0.1 to 803 ng L−1, and the microcystin quota in the Microcystis biomass was extremely low. For the first time, it was shown that Microcystis cells containing mcy genes and microcystins presented permanently in the water column, both during the ice-free period and under ice, as well as inside thick ice covers within 7 months of severe winter. We hypothesized that minor pelagic and ice populations of Microcystis could participate in increasing cell density in the spring. However, further studies are needed to confirm the viability of the overwintering Microcystis colonies in the water and inside the ice of Lake Ytyk-Kyuyol.

Microcystin Concentrations, Partitioning, and Structural Composition during Active Growth and Decline: A Laboratory Study

“…Microcystins (MCs) are a group of cyclic hepatotoxins produced by different genera of cyanobacteria including Microcystis , Dolichospermum , Planktothrix , and Nostoc [ 1 , 2 ]. MCs are the most commonly occurring cyanotoxins globally and have been investigated in various types of waterbodies, especially rivers, lakes, and estuaries prone to cyanobacterial harmful algal blooms (cHABs) [ 3 , 4 , 5 , 6 ]. MCs adversely affect livestock and wildlife and have been linked to gastrointestinal symptoms, liver cancer, and death in humans [ 7 , 8 , 9 , 10 , 11 ].…”

Phytoplankton in the Ecological Assessment of the Mining Facilities Influence on the Anabar River in the Permafrost Zone of the Arctic, Eastern Siberia, Russia

“…It is important to assess the impact not only of climate warming, which is currently receiving considerable attention [2] but also the impact of low-temperature conditions on the diversity and functioning of aquatic ecosystems [3]. Phytoplankton is the most sensitive link, quickly responding to changes in habitat conditions, on the one hand, and on the other hand, retaining the imprint of impact in permafrost conditions [4]. The study of the Arctic rivers shows the dynamics of phytoplankton diversity along the river channel from south to north, which can be used to track the influence of Arctic conditions on its formation [5].…”