Fish deaths in the Oder in Germany: what killed them?

Fish deaths in the Oder in Germany: what killed them?

by Irene Soave

Tons of dead fish in the river between Poland and Germany: hundreds of kilometers of coastline affected. The first hypothesis: industrial pollution. But an independent study is pointing the finger at climate change

Tons of dead fish are floating in the waters of the Oder, the widely-recognized clean river that flows through the Czech Republic, Germany and Poland to empty into the Baltic Sea. A vision of a biblical scourge that stretches over hundreds of kilometers of river coast between Poland and the two eastern German states of Mecklenburg-Western Pomerania and Brandenburg: the authorities in both countries are apparently finding it difficult to coordinate when researching the causes and also when solving the problem, but they agree that the fish kill in the Oder is an environmental catastrophe. Hundreds of volunteers in the affected areas are helping to remove the thousands of dead fish from the shore. But the secret remains. What happened?

The German media, which has been covering the case since July 28, has hypothesized mercury poisoning, and the Polish government has offered a million zloty (220,000 euros) reward for those who report a suspected culprit to the authorities .Chemical spills in water; However, the analyzes carried out in Polish and German laboratories on the waters and dead fish did not show mercury poisoning, but an abnormal salinity. An inexplicable circumstance, i.e. with the hypothesis of a single pollutant release in the water. For example, according to the German research center Leibniz Institute, the problem has several environmental factors: These include low water levels and thus less habitat for fish and the recent heat wave.

The Polish hypotheses: chemical waste. The bounty on the polluter

According to reports from Polish fishermen, the first analyzes found high doses of classic pollutants such as the solvent mesitylene in the water at the end of July. But later tests failed to find them. Climate and Environment Minister Anna Moskwa confirmed yesterday that analyzes of river samples taken in both Poland and Germany showed high levels of salinity. In Poland, he added, extensive toxicological studies are still being conducted. Poland’s state veterinary service tested seven types of dead fish and ruled out mercury as the cause of death, and similar tests conducted in Germany returned identical results. Polish Prime Minister Mateusz Morawiecki said on Friday large amounts of chemical waste are likely to have been dumped intentionally into the river, causing such severe environmental damage that it will take years for the river to recover. And he acknowledged that some officers were slow to respond and two were fired. Poland’s interior minister has offered a 1 million zloty ($220,000) reward for anyone who helps track down those responsible for the river’s pollution. The head of Poland’s national water management agency said Thursday that 10 tons of dead fish had been removed from the river.

In Germany voluntary and bathing bans

Authorities in the north-east German state of Mecklenburg-Western Pomerania have warned citizens not to fish or use the waters of the Szczecin Lagoon, shared between Poland and Germany and reached by the river’s contaminated waters. Hundreds of volunteers are working to collect the dead fish along the German side. The disaster, the authorities repeat, has been announced: Since July 28, very high levels of oxygen in the water have been reported, an official from the Brandenburg Ministry of the Environment explains to the BBC, mostly in connection with poisoning.

The study: problem related to climate change

Currently, however, the revelations of the Leibniz Institute, a network of authoritative multidisciplinary, non-university and independent research institutions, are particularly relevant. Your fish biologist Christian Wolter is often in the media these days and explains, for example to Deutsche Welle, that fish consume more oxygen when they are stressed, and this at a time of very low water levels and abnormal heat waves, and there is no other way. The water of the Oder – as well as that of the Rhine, which has reached historic lows of one and a half meters in places – has never been as low as this summer.
The situation was then made worse, yes, by spilling sewage into the river. All legal, and normally there wouldn’t be any problems. But the water is low and therefore the ratios between the chemical elements change. Construction work on the Polish side of the river then filled the bed with sediment. And oxygen, Wolter explains, would be too little and not too much. So the possible contamination by mesitylene, which at the end of July raised the suspicion of an environmental crime, would have already been absorbed and the pollutants would have traveled much further. Instead it wasn’t. It is most likely the deepest and most profound problem. So the mystery of the dead fish could be another biblical plague caused by climate change.

August 15, 2022 (Modified August 15, 2022 | 1:26 PM)