After the great death of fish in the Oder, there is reason to hope for life in the border river. Scientists from the Potsdam Institute for Inland Fisheries had found numerous healthy specimens of many fish species during a test fishing, the Brandenburg/Berlin State Fishing Association announced on Friday together with the State Anglers’ Association. Crayfish and other aquatic organisms such as zebra mussels or freshwater shrimp are also out and about in the Oder and appear healthy. The institute itself could not be reached by telephone in the afternoon.

“The fact that fish and other aquatic organisms have survived in the Oder is finally good news that gives hope,” said Andreas Koppetzki, general manager of the state anglers’ association. “But further studies are needed to really assess the state of the fish stocks and the entire species community.” The damage is very great given the masses of dead fish. “Nevertheless, today’s results speak for a rather rapid recovery of this sensitive ecosystem,” said Koppetzki.

Meanwhile, Federal Environment Minister Steffi Lemke (Greens) has promised support to companies affected by the death of fish in the Oder. The cabinet discussed on Wednesday “that we will get help for the companies affected by the disaster if that becomes necessary,” Lemke told the news magazine “Der Spiegel”.

In addition, the federal government will support the state of Brandenburg “in the ongoing analyzes of the cause of damage via the Federal Environment Agency and the Federal Institute for Hydrology”. She expects results from the federal agency by the end of August, said the minister.

Lemke rejected the criticism from local politicians along the Oder that the federal government had reacted too late to the disaster: “When my ministry found out about the fish death, we immediately contacted Brandenburg and offered support.”

On the German side, the massive death of fish in the Oder became known on August 9th. In Poland, on the other hand, there were first indications of fish carcasses in the border river at the end of July. The German authorities accuse the Polish side of informing them too late, making it difficult to find the cause.

Lemke admitted that not everything went perfectly in dealing with the catastrophe. The German side was “obviously informed too late”. “The Polish side did not activate the alarm plan in time. But assigning blame is useless. We must overcome this tragedy together.”

The Ministry of the Environment in Brandenburg has meanwhile declared that it will check its own warning and reporting chains. Among other things, it is about whether the existing measurement practice needs to be reassessed and adjusted, it said on Thursday.

The “Spiegel” had previously reported that the State Office for the Environment had already registered at the beginning of August that the water of the Oder had changed. The authority had remained inactive, it said, among other things, in the report.

“From the values ​​measured up to that point in the automated measuring point in Frankfurt (Oder) alone, it was not to be assumed that the fish were dying,” said a ministry spokeswoman. According to her, there had already been significantly high values ​​in the past, which indicated salt loads, but would not have caused fish to die in the Oder. According to the ministry, there have been increased salt concentrations in the Oder for many decades.

The automatic measuring station in Frankfurt (Oder) recorded an increase in the curves for the parameters conductivity, oxygen content and chlorophyll from August 7th to 8th. According to the Ministry of the Environment, these were not yet capable of interpretation on their own.

In particular, with a view to the fact that the Oder is already under stress due to the extremely low water, intense heat and high water temperatures, they did not provide any more direct information. However, the values ​​continued to be monitored.

According to an international agreement, the Polish side should have triggered the reporting system applicable to the Oder when a massive fish kill became known there at the end of July. The ministry spokeswoman made it clear that Poland did not do this promptly, but too late. Better precautions could have been taken with a warning, barriers set up.

The state authorities are now constantly supplying data to the Polish side, from where the first test results came on Thursday evening, which, according to the Ministry of the Environment, are now being compared.

The cause of the biggest environmental catastrophe in Brandenburg for decades is still unclear, more than a week after the mass death of fish became known. The State Office for the Environment and research institutes are investigating water and fish at high pressure. Authorities and scientists no longer grope in the dark. There are now various explanations for the death of the many fish.

Scientists say a toxic species of algae could be a key factor in fish kills. A researcher at Berlin’s Leibniz Institute for Freshwater Ecology and Inland Fisheries identified the toxic species as a microalgae named Prymnesium parvum. According to the water ecologist Christian Wolter, it is known for occasionally leading to fish deaths.

This is also confirmed by Jörg Oehlmann, head of the Aquatic Ecotoxicology department at the Goethe University in Frankfurt. However, it has not yet been proven that the alga’s poison is the reason for the fish die-off, only their mass development has been proven.

According to the researchers, the algae species Prymnesium parvum actually only occurs in brackish water. It requires increased salinity, which does not normally exist on the affected Oder stretch. At the official measuring station of the State Office for the Environment in Frankfurt an der Oder, however, massively increased, unnatural salt loads were measured for around two weeks, which, according to the researchers, must have their origin upstream.

According to the scientists, the mass growth of the algae also caused significantly increased measured values ​​for oxygen, pH and chlorophyll. There are many barrages in the upper part of the Oder. Due to the low water there is currently hardly any water exchange there.

According to a Polish media report, the alga could have originated in a clarifier in Glogau, Poland. The RBB reported this late Thursday evening. According to the RBB report, the clarifier belongs to the Polish mining company KGHM, according to the Wroclaw-based “Gazeta Wyborcza”. As the newspaper goes on to write, between July 29 and August 10, the KGHM company discharged salty water, which had been standing still in the clarifier for a long time, into the Oder. The algae, which are deadly for fish and mussels, could have gotten into the river.

The chemistry professor Marcin Drag from the University of Applied Sciences in Wroclaw (Breslau) also suspects that the river was contaminated with discharges from Silesian mining due to the high salt content. According to the opposition member of parliament Piotr Borys, the state mining company near Glogow regularly discharges saline wastewater from the retention basin into the Oder – but it also has the approval of the water authority for this.

Investigators are also currently checking other industrial plants located near the river. In the days after the first indications of the fish kill, a paper mill in Olawa, Lower Silesia, south of Wrocław, was blamed on social media in Poland. The company denies. The plant had “neither anything to do with the environmental disaster on the Oder nor contributed in any way to it,” it said in a statement last week.

Climate change is also stressing the sensitive ecosystem. For the researchers at the Berlin Leibniz Institute for Freshwater Ecology and Inland Fisheries, several harmful factors come together. Periods of drought and levels that are far too low, low oxygen levels and far too high water temperatures are “man-made” problems that increase the risk of environmental disasters, they say. At low tide, for example, harmful substances would be transported in a much smaller volume of water.

This extreme condition stresses the fish. If other hazards such as toxic algal blooms or chemical contamination are added to the existing pollution, the entire ecosystem in water bodies can be destroyed, says researcher Jörg Oehlmann.

The Berlin-Brandenburg State Laboratory (LLBB) continues to examine water samples from different days and measuring points as well as fish. According to the Brandenburg Environment Ministry, the search for the cause of the fish kill is also difficult because there is no information from the Polish side, for example on possible discharges or specific reasons for the environmental disaster.

Researchers say that research into the causes of the disaster by analyzing the substances in the Oder is a real Sisyphean task, since around 350,000 substances could potentially be present in a water sample – and even detailed diagnostics never cover all of them. The investigation could take weeks, according to the ecotoxicologist Oehlmann.

Poland’s Environment Minister Anna Moskwa announced on Thursday evening that toxic algae had been discovered in water samples. It was therefore so-called gold algae, which are deadly for fish and mussels. It is the species Prymnesium parvum, said Agnieszka Napiorkowska-Krebietke from the responsible institute for inland fisheries in Olsztyn on Friday of the German Press Agency.