Using Microcystin Gene Copies to Determine Potentially-Toxic Blooms, Example from a Shallow Eutrophic Lake Peipsi.

Kristel Panksep,Anne Rantala-Ylinen,Olga Tammeorg,Kaarina Sivonen,Marju Tamm,Veljo Kisand,Reet Laugaste,Evanthia Mantzouki

doi:10.3390/toxins12040211

Kristel Panksep, Anne Rantala-Ylinen + Show 6 more

Open Access

https://doi.org/10.3390/toxins12040211

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Abstract

Global warming, paired with eutrophication processes, is shifting phytoplankton communities towards the dominance of bloom-forming and potentially toxic cyanobacteria. The ecosystems of shallow lakes are especially vulnerable to these changes. Traditional monitoring via microscopy is not able to quantify the dynamics of toxin-producing cyanobacteria on a proper spatio-temporal scale. Molecular tools are highly sensitive and can be useful as an early warning tool for lake managers. We quantified the potential microcystin (MC) producers in Lake Peipsi using microscopy and quantitative polymerase chain reaction (qPCR) and analysed the relationship between the abundance of the mcyE genes, MC concentration, MC variants and toxin quota per mcyE gene. We also linked environmental factors to the cyanobacteria community composition. In Lake Peipsi, we found rather moderate MC concentrations, but microcystins and microcystin-producing cyanobacteria were widespread across the lake. Nitrate (NO3−) was a main driver behind the cyanobacterial community at the beginning of the growing season, while in late summer it was primarily associated with the soluble reactive phosphorus (SRP) concentration. A positive relationship was found between the MC quota per mcyE gene and water temperature. The most abundant variant—MC-RR—was associated with MC quota per mcyE gene, while other MC variants did not show any significant impact.

Highlights

Eutrophication of aquatic systems caused by anthropogenic nutrient enrichment is a critical environmental problem of the 21st century [1,2]
Total phosphorus (TP), soluble reactive phosphorus (SRP), total nitrogen (TN) and chl-a values increased from the northern basin towards the southern basins
The current study revealed a clear spatial distribution of cyanobacterial community composition in ecologically contrasting basins of this large and shallow lake

Summary

Introduction

Eutrophication of aquatic systems caused by anthropogenic nutrient enrichment is a critical environmental problem of the 21st century [1,2]. Extensive research has shown that increased nutrient-loading shifts phytoplankton communities towards the dominance of bloom-forming and potentially toxic cyanobacteria [3,4,5]. Anthropogenic pressures render shallow lake ecosystems especially vulnerable to environmental change and the subsequent boosting of cyanobacterial occurrence [11,12]. Cyanobacterial blooms pose a substantial health risk to humans and animal species due to the cyanotoxins they produce. These secondary metabolites are mainly stored inside the cyanobacterial cell and are released into the water during cell lysis, potentially leading to high toxin concentrations [13]

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