Results of the bacteriological study of the impact of the destruction of the Kakhovka dike

The destruction of the Kakhovka hydroelectric power plant dike by the Russian army last summer caused flooding of farms, dead cattle, cemeteries, and the destruction of wastewater treatment plants. This has led to the chemical and bacteriological pollution of the Black Sea waters, with a high probability of pathogenic and antibiotic-resistant bacteria entering the Black Sea. The state of the Black Sea microbial communities is one of the indicators of changes in water quality.

On June 13-14, with support of the EU-UNDP EU4EMBLAS project, water samples were collected in the Ochakiv and Odesa Bay areas to assess changes in the taxonomic composition of microbial communities and screen them for antibiotic resistance. For comparison, samples were simultaneously taken from the Danube River and the Black Sea near Constanta (Romania). See more here.

The results of the study showed, that genes for resistance to first-line and last-choice antibiotics – betalactams, sulfonamides, quinolones, tetracycline, vancomycin, and colistin – were detected in the Black Sea waters near Ochakiv and Odesa. Antibiotic resistance rates of microbial communities in the Dnipro-Bug estuarine zone and the Gulf of Odesa were higher than in the waters of the Danube River and the Black Sea near Constanta.

A significant part of the microbial community of the Black Sea waters near Ochakiv consisted of microorganisms that are tolerant to pollution, that have the ability to decompose organic pollutants and potential pathogenic properties. For example, 42.5% were Pseudarcobacter, Rivicola, Sphaerotilus, Rhodoferax, which were previously frequently detected in wastewater. 

In the waters of the Gulf of Odesa, the share of Cyanobacteria increased (up to 35%), indicating significant eutrophication after the destruction of the Kakhovka HPP dike. Planktonrix, Aphanizomenon, and Microcystis, capable of producing toxins during algal blooms, were common.

This proves significant bacteriological pollution of the Black Sea. Although the number of cyanobacteria has decreased to normal figures by the autumn, antibiotic resistance genes may still be circulating in the marine community. And this situation can change quickly with the introduction of other pollutants as a result of the military actions which are continued at present. Therefore, further regular monitoring of bacteria is required.