It is still unclear what caused the fish kill in the Oder. At the same time, allegations against the Brandenburg authorities are being made. The salinity of the Oder was already unusually high at the beginning of August. Should they have reacted earlier?

Tons of dead fish, 200+ witness interviews, and loads of questions. What caused the fish kill in the Oder is still unclear. And nobody can currently say with certainty whether the contaminated water will reach the Baltic Sea.

At the same time, allegations are being made that the Brandenburg authorities did not react quickly enough. As the “Spiegel” reports, the measured values ​​at the Frankfurt an der Oder station changed at the beginning of August. So a few days before the first dead fish floated in the German Oder waters.

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The electrical conductivity, which indicates the salinity of the water, is said to have been 1300 microsiemens per centimeter on August 1st. According to “Spiegel”, on August 6th it was already more than 2000 microsiemens per centimeter.

Should the increase have been cause for concern? reason to act?

“The values ​​are high, but not exceptionally high,” says Tillmann Buttschardt in an interview with FOCUS online. He works as a professor for applied landscape ecology and ecological planning at the Westphalian Wilhelms University in Münster.

Buttschardt is also a member of the “Water Network”, an association of researchers founded in 2004 who deal with the topic of “water” on an interdisciplinary basis. “The limit value according to the Drinking Water Ordinance (2013) is 2790 microsiemens per centimeter at 25 degrees Celsius,” he says.

“Accordingly, no action could be derived initially.” In addition, a high salt content is something that other rivers also have to struggle with. For example the Werra: It is one of the most polluted watercourses in Germany. !function(){var t=window.addEventListener?”addEventListener”:”attachEvent”;(0,window[t])(“attachEvent”==t?”onmessage”:”message”,function(t){if (“string”==typeof t.data

A spokesman for the Brandenburg Ministry of the Environment made a similar statement to Buttschardt. “There have been increased salt concentrations in the Oder for many decades – without the result of a fish die-off,” he told the “Spiegel”.

The fact that some values ​​​​increased was “not yet interpretable on its own”. The authority initially observed the situation. When masses of dead fish were swimming in the river a few days later, the public was informed. Many affected districts now advise against fishing or swimming.

“I don’t see any omissions here,” says Buttschardt. In view of the unusual salt levels, the Brandenburg authorities could not have done anything else.

However, they are not only criticized for slower reactions. Your entire crisis management causes resentment. René Wilke, Mayor of Frankfurt an der Oder, claimed in an interview with the “Spiegel” that no one had “declared themselves responsible”.

At a conference call on August 11, the state is said to have shifted responsibility to the affected cities and municipalities. “The federal government would be responsible for the water, but because the fish are lying on the bank, it was pushed to us,” complains Wilke.

The question that remains is how an environmental catastrophe of this magnitude could have happened in the first place. So far, little is known about the actual causes – despite site visits in Poland, witness interviews and sample taking.

But there are a few theories. “Watercourses – especially large rivers – are complex on the one hand and exposed to a variety of stressors as ecosystems on the other,” says Buttschardt. If many such factors come together, a body of water could “overturn”.

Stressors are, for example, the current low water level, changes in water temperature due to the withdrawal of cooling water or the discharge of fully, partially or untreated waste water.

According to the expert, data from the State Environment Agency indicate a biotic process. “The fact that fish died despite the rising oxygen content suggests that other toxins, for example from algae proliferation, could also be involved,” says Buttschardt.

The microalgae Prymnesium parvum, which was detected in the Oder on Wednesday, would fit in with this. According to Butschardt, the high salt content of the Oder at the beginning of August would have to be “clarified otherwise”. “Increased salt loads have evidently been repeatedly described in the past,” says the expert.

It is also possible that companies are to blame for the fish deaths. The Polish politician Piotr Borys, for example, suspects the Silesian mining group KGHM of having discharged large quantities of salt water into the Oder. He told the daily newspaper “Gazeta Wyborcza”.

And the Brandenburg state government also assumes that the fish kills are not only due to natural causes. “We can safely rule that out, otherwise the high pH values ​​and the increased oxygen content and much more would not explain themselves,” said Prime Minister Dietmar Woidke (SPD) in Beelitz.

But no matter what caused it: the catastrophe has happened, masses of fish have died and are floating lifeless on the water surface.

There are several ways to prevent worse from happening now, says landscape ecologist Buttschardt. “It would be beneficial to supply fresh water, i.e. to dilute it. But that’s not possible given the water shortage.” He also considers algae barriers to be an option – but points out that it’s difficult to judge from a distance.

It will probably take some time before the situation in the Oder improves. Rain, preferably a lot, can help, says Buttschardt. However, he also believes that fish populations in the river will only recover in a few years.

For the landscape ecologist, the environmental disaster in the Oder is ultimately a warning signal. “Of course, such fish deaths are spectacular – but fish also die on small rivers due to the drought,” he says.

That’s a big problem right now. The Rhine, one of the largest rivers flowing through Germany, has reached historic lows in some places. Cargo ships can no longer accommodate their normal loading capacity. Drought and low water also threaten the security of supply for industry.

Climate change is considered a key cause of the drought. For Buttschardt it is clear: If we want to stop global warming, we have to do without a lot. “It starts with a free and effective speed limit, leads to a low-meat diet to a society that uses at least half less energy.”