Voice of the European Commission on the Oder River

It’s been six months since the Oder disaster. A national report on its causes was presented. In recent days, there has also been a vote by the European Commission on the massive fish die-off in the river in August 2022. The prepared report appeared as a publication of the Joint Research Center (JRC), an EU research center.

The report’s conclusions are consistent with those presented in the document prepared by the Team on the Situation Arising on the Oder River. The main cause of the fish die-offs was a bloom of the haptophyte Prymnesium parvum, the so-called “haptophyte”. golden algae. This was the result of an increase in the salinity of the river’s waters, which directly enabled the growth of algae, which reproduce quickly in such conditions. As a reason for the increase in the salinity of the Oder River was pointed out, on the one hand, human activity, in the form of discharges of industrial wastewater, especially post-mining waters, on the other hand, the importance of the drought occurring in our country in August last year was emphasized. The low water level meant that the salty wastewater was not diluted. The algal bloom was also fostered by significant water pollution by nitrogen and phosphorus compounds.

The conclusions of the JRC report’s authors focus on the need for a Europe-wide pollution monitoring system with real-time online availability of test results. It is also advisable to communicate quickly in the event of heavy river pollution, especially in international catchments such as the Oder River. Conclusions for the future stressed the need to create a system for controlling and limiting wastewater discharge permits when there is an environmental hazard. The authors also point to slowing water runoff as a way to prevent future algal blooms.

The JRC report predicts that a disaster like the one on the Oder River, due to the spread of an invasive species of golden algae, could also affect other rivers in Europe in the future. Therefore, the recommendations do not apply only to Poland. Conditions favorable to golden algae blooms associated with high conductivity (1500 μS/cm), salinity (>3 mEq _SO4/l) and nutrient concentrations (>5 mg _NO3/l) affect about 4% of measurement and control stations in Europe.

The greatest threat of toxic algal blooms is in the area of Spain, which is additionally vulnerable due to the droughts there. In Poland, the risk of a repeat of the ecological disaster affects the upper reaches of the Oder River and its tributaries, as well as the Vistula River at the level of Wloclawek.

[1] Free, G., Van De Bund, W., Gawlik, B., Van Wijk, L., Wood, M., Guagnini, E., Koutelos, K., Annunziato, A., Grizzetti, B., Vigiak, O., Gnecchi, M., Poikane, S., Christiansen, T., Whalley, C., Antognazza, F., Zerger, B., Hoeve, R. and Stielstra, H., An EU analysis of the ecological disaster in the Oder River of 2022, EUR 31418 EN, Publications Office of the European Union, Luxembourg, 2023, ISBN 978-92-76-99314-8, doi:10.2760/067386, JRC132271