News

In July and August 2022, a man-made environmental disaster occurred in the in the Oder River: a mass die-off of fish, mussels and snails that started in the Polish section of the Oder and then continued downstream until it reached the border Oder. The immediate cause of their death was a toxin-producing (planktonic) brackish water alga, scientifically known as Prymnesium parvum, which was able to grow en masse due to high salinity, high solar radiation, and low water flow. An IGB Fact Sheet summarises the current state of scientific knowledge.

From a scientific perspective, a misleading story is being told about the detection of low concentrations of the toxin-producing brackish water algae Prymnesium parvum in different waters in Brandenburg (Germany): The interpretation spread in the media with reference to the Landesfischereiverband Brandenburg/Berlin e. V. (Brandenburg Fisheries Association) and taken up by institutions, that this result disproves the correlation between algae growth and salt concentration, is scientifically incorrect. IGB therefore puts the facts into a scientific context:

Today, Federal Environment Minister Steffi Lemke visited the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) in Berlin to learn about the first interim results of the special investigation programme on the environmental disaster in the Oder River (“ODER~SO”), which has been funded by the Federal Ministry for the Environment, Nature Conservation, Nuclear Safety and Consumer Protection (BMUV) since February 2023. Fish stocks in the Oder River have declined by 53 to 67 per cent as a result of last summer’s environmental disaster, especially midstream.

IGB and the NABU Naturerlebniszentrum Blumberger Mühle, together with the Lower Oder Valley National Park and the Teichwirtschaft Blumberger Teiche, are carrying out a stocking of Baltic sturgeon in the River Oder. On 8 May 2023, around 2,000 juvenile fish will be released near Stützkow. The original plan was to stock the fish in the autumn of 2022, but this was not possible due to the man-made environmental disaster on the river. Now, the partners involved are making a new attempt and sending a signal for better protection of our river habitats.

A chronicle of an environmental disaster on the River Oder: Images of huge quantities of dead fish – covering all species and sizes – shocked the German, Polish and international public in August 2022. IGB researchers set about tracking down the causes. IGB was the first institution to determine that the disaster was definitely man-made.

Routine fishing on 29 November this year was the first large inventory conducted in the middle of the Oder since the man-made environmental disaster that occurred in summer. The result: much fewer fish were caught in total, and species such as the blue bream and the asp, which are important to this ecosystem, were lacking completely. Moreover, water analysis conducted by the researchers shows that the salt concentration is still far too high. There could be a repeat of the disaster when temperatures increase, endangering remaining stocks.

The man-made environmental disaster, resulting in masses of dead fish, mussels and snails, has caused severe damage to the Oder ecosystem. What can now be done to help the river – and how can the risk of such major ecological and economic damage be reduced in the future? IGB has published its recommendations in an IGB Policy Brief. 

“Those calling for more dams in response to drought and dry riverbeds have nothing understood – they promote habitats with potential for catastrophy,” wrote Christian Wolter in Terra X – Die Wissens-Kolumne.