On Tuesday, August 16, at the dam, built in front of the entrance to Shetsi Bay, located at the mouth of the Oder, collection began for later disposal of dead fish found in the river in recent days. According to German media company NDR, volunteers will pull the fish out of the water, after which they will be loaded into special containers and burned in the Brandenburg town of Schwedt, whose mayor Annekathrin Hoppe has already called the incident “an unprecedented environmental incident.” disaster.” DW talks about what is known to this day.

When did mass fish mortality become known?

As early as July 26, Polish fishermen near Wroclaw noticed an unusually large number of dead fish swimming in the Oder. According to the Polish Ministry of Infrastructure, the authorities received the first information about the death of fish in the Oder between 26 and 28 July. As of July 28, water samples collected by Polish authorities showed an unusually low oxygen content.

On August 4, the Environmental Protection Agency in Wrocław detected a toxic substance in samples taken from the Lipki Lock near Olawa. According to the newspaper Märkischer Oderzeitung, the president of the Polish Fishing Association in Wroclaw, Andrzej Swietach, reported on 6 August that more than five tons of dead fish had been recovered from the Oder.

On August 9, the Polish Public Ministry launched an investigation into a possible environmental crime. On the same day, the death of the fish became known in Germany. The information was given to the authorities by the captain of one of the ships. On August 10, dead fish were seen in the waters near the city of Frankfurt an der Oder, and on August 11 – along the entire length of the river to Schwedt, located almost 100 km downstream.

How did the notification system work?

The environmental catastrophe became evidence of a major failure of intra and interstate information transmission systems. Local Polish authorities, who had information about the death of fish as early as the end of July, not only informed their colleagues in Germany, but also their own government about it. Polish Prime Minister Mateusz Morawiecki admitted that he was informed about the death of fish and water pollution with great delay – “August 9 or 10”. Until August 11, the Ministry of Environmental Protection of the Land of Brandenburg had also not received any information from the Polish side. According to experts, early warning would have made it possible to better organize the necessary measures in this case. For example, to carry out a timely collection of dead fish and thus, if not protect, at least mitigate the consequences of water poisoning in the food chain.

Volunteers collect dead fish

What caused the disaster?

It is still unknown for sure. The Brandenburg Office of Criminal Affairs (LKA) is conducting an investigation, the results of which have not been announced.

At the same time, the head of the Polish government, Morawiecki, speaks of signs of an environmental crime: “It is likely that a huge amount of chemical waste was dumped into the river with full awareness of the risks and consequences,” he said. in a video message posted to Facebook on August 12. “We want to find those responsible and punish the culprits,” said Mateusz Morawiecki. Polish police have offered a reward of 1 million zlotys (over 210,000 euros) for information leading to the arrest of criminals responsible for the pollution of the Oder and the mass killing of fish.

What do laboratory tests show?

In Poland, water samples and dead fish are tested for about 300 harmful substances, including pesticides. Axel Vogel, Minister of Agriculture and Environment for the federal state of Brandenburg, believes the reason for the fish death could be complex. In particular, one of the contributing factors to the disaster could be drought and low water levels in the Oder. According to him, quoted by the dpa agency, the entire river ecosystem suffered.

Laboratories in Germany and Poland are looking for the substance that caused the fish to die

Although mercury was found in German laboratories in samples of dead fish, experts said, it was not the root cause of the disaster. Farmers have been using this heavy metal for seed fertilization for decades. As a result, he settled at the bottom of the river. “There are mercury compounds in the sediments,” Wolf von Tümpling, head of water analysis and chemometrics at the Helmholtz Center for Environmental Research, told Die Zeit. According to the scientist, mercury could return to the water during dredging. Maybe that’s why it was found only on the German side.

In addition, it is known that an increase in the salt content of the water has been found. Water analyst von Tyumpling believes this could also be one of the reasons for what happened. In his opinion, “it is quite possible that freshwater fish will have serious problems” in salt water. At the moment, this is just one of the possibilities, he says, as it is not known exactly what kind of salt it is. However, according to von Tümpling, the increase in salt content is another sign that something has entered the water that shouldn’t be there.

What will happen next?

By now, it’s clear that the lab research and subsequent hunt for criminals can take a long time. Without specific information about the incident, scientists must methodically eliminate possible options. Starting from common substances that enter the water as a result of agricultural activities or the work of industrial companies, ending up with a variety of even unlikely chemical compounds. This takes time, even though several labs in different countries are working on it in parallel. “There is a certain risk that the cause of the fish’s death will never be found,” says von Tümpling.

If the laboratories still establish the causes of the environmental catastrophe, it may be possible to avoid similar incidents in the future. Against the background of what happened, the authorities and experts from Germany and Poland agreed to work more closely together in the future. But more importantly, figuring out all the reasons for what happened is necessary to understand how this catastrophe could threaten the ecosystem of one of Eastern Europe’s biggest rivers in the long term.