DETERMINATION OF THE ACUTE TOXICITY OF CYANOBACTERIAL TOXINS EXTRACT DURING THEIR MASS DEVELOPMENT IN THE ODESA BAY AFTER THE DETONATION THE DAM OF THE KAKHOVKA HYDROELECTRIC POWER PLANT
DOI:
https://doi.org/10.47143/1684-1557/2026.1.4Keywords:
bioassay, acute toxicity, cyanobacteria, Odessa Bay, destruction of the Kakhovka Hydroelectric Power Plant damAbstract
The results of determining the acute lethal toxicity of cyanobacterial toxins, which developed massively in the coastal waters of the Odessa Bay after the destruction of the Kakhovka Reservoir dam, using the bioassay method are presented. As a result of this disaster, in July 2023, a phase of coastal phytoplankton ‘blooming’ involving cyanobacteria (Microcystis aeruginosa, Planktothrix agardhii, Microcystis flos-aquae) was observed in the Odessa Bay. In accordance with the standardized bioassay methodology, the acute lethal toxicity of cyanobacterial extract was determined using the planktonic crustacean Ceriodaphnia affinis Lilljeborg as a test organism. The test object culture was used, previously adapted to water mineralisation conditions of 5 g/dm3, which corresponded to the current standards and requirements for toxicological research. In accordance with the recommended procedure, toxins and secondary metabolites were extracted by freezing and thawing the phytoplankton sample, with a known number and biomass, three times. The total biomass of cyanobacteria in the sample was 15023.1 mg∙l-1 (15.02 g/dm3), which was taken as 100% when preparing a series of dilutions for further toxicological experiments. It was established that cyanobacterial cell extract in terms of colonies or trichomes (30.4 million/dm3) and total biomass (15.02 g/dm3) contained toxins that caused acute lethal toxicity to the test object. The threshold of acute lethal toxicity of the aqueous extract of cyanobacterial biomass was determined at 5.72±0.48 g/dm3. The toxic effect zone was within the biomass range of 6.10–10.50 g/dm3. The absolute lethal concentration was determined to be 11.60 g/dm3 due to the influence of cyanobacterial biomass. This indicates that the ‘blooming’ of seawater in the Odessa Bay in July 2023 was caused by toxicogenic strains of cyanobacteria.
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