Authorities are investigating an "ecological disaster" after piles of dead fish were removed from River Oder on the border between Germany and Poland.

Huge piles of dead fish have been removed by workers using buckets and diggers, which they then burned.

Although the precise cause of the tragedy is still unknown, investigators think pollution may have played a role.

Inland Fisheries Institute, Poland

The Inland Fisheries Institute of Poland's Andrzej Kapusta said it would be challenging to pinpoint the precise cause. He remarked that it would be challenging to determine the exact cause.

Such a large-scale ecological disaster is unexpected in Poland.

According to Kapusta, it is a catastrophe because they have never discovered so many dead animals, including so many dead fish, clams, and snails. He said that this has never happened before, and it should serve as a grave caution.

High Salt Levels + Hot Summer + Low River

Golden algae are flourishing because of unusually high salt levels discovered by scientists in the water. According to one theory, the hot summer, coupled with an unusually low river likely contributed to the release of toxic substances that killed the fish.

The source of the initial pollution is still unknown, though.

Berlin: Leibniz Institute of Freshwater Ecology and Inland Fisheries

According to Jan Köhler, from Berlin's Leibniz Institute of Freshwater Ecology and Inland Fisheries, the elevated saline levels necessary for golden algae growth are not present in the River Oder naturally.

Andreas Kuebler, a spokesperson for the German Environment Ministry, suggested that different chemicals might be to blame.

He said that a few organic and inorganic substances have been identified thus far as potential culprits.

Deadly Cocktail

According to Kuebler, it appears to be a chemical concoction. All of these factors together did not cause the fish to die off, according to the information available so far. Still, it must be assumed that this incident may have multiple causes.

Since July, when the first dead fish were discovered in Polish waterways, nearly 200 tons of dead fish have been removed from the River Oder.

Over €200,000 ($199,300) in rewards have been offered by the police for information that results in a suspect's capture.

Nearly 300 unauthorized outflow pipes have been discovered and are currently the subject of an investigation along with more than 200 witness interviews.

So that whatever is killing the fish is carried further down the river, there are worries that the catastrophe will last for some time.

Read also: Dead Animals: Increasing Cases of Fish Waste on Sea and Land Reported Worldwide 

Waiting Game

According to Lukas Potkanski of the Polish Fishermen's Association, currently, everyone must wait for the worst to pass.

The most dangerous water must descend and mix with the purest water.

In late July and early August, much of Western Europe experienced a heatwave, which investigators believe may have exacerbated the River Oder situation by lowering the water level.

France and the Iberian Peninsula experienced large forest fires, but the U.K. recorded its hottest day ever on July 19, with highs of about 104 degrees Fahrenheit, Newsweek reports.

Related article: Dutch Trawler Dumps 100,000 Dead Fish into the Western Coast of France