January 28, 2023

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Researchers: Algae may cause fish deaths in the Oder River

Researchers: Algae may cause fish deaths in the Oder River

Not chemical waste, but the toxic substances secreted by algae were the cause of widespread fish deaths in the oder. This is what the German research agency IGB suspects Based on measurements in the river on the border with Poland. However, this does not mean that the fish died of natural causes, the researchers wrote.

According to the researchers, the algae species Prymnesium parvum, which produces powerful toxins, is common in water, although they have not yet confirmed this through DNA research. It is remarkable that these algae live in brackish water, between fresh and salt water, which usually does not occur in the affected part of the Oder. A combination of warm tides from drought and industrial salt discharge may have created conditions for toxic algae to thrive.

end of July drove thousands of dead fish in Oder. At the time, the discharge of chemicals, such as the poisonous mesitylene, was soon considered. German politicians Request clarification from PolandThat just dipped in information. The research by the Leibniz Institute for Freshwater Ecology and Inland Fisheries (IGB) is still ongoing, but due to all the public interest, the research institute is now coming out with preliminary results.

‘Saltwater algae is falling on the side of the road’

German researchers found 100,000 algal cells per milliliter. “So this algae is in bloom,” says Didmer van de Waal, a researcher at the Netherlands Institute of Ecology and professor of aquatic functional ecology at the University of Amsterdam. “If you run out of nutrients, that bloom can start producing toxins.”

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Researchers have not yet discovered the toxin of this specific algae. Van de Waal: “Then you have to examine the tissues of the fish to see if there is a link to the death of the fish. I suppose they are doing that now.”

Prymnesium parvum also occurs in the Netherlands, but according to van de Waal, there is little insight into this. “There are protocols in place for freshwater algae such as blue-green algae, and weekly measurements are taken to find algae in the sea. This includes brackish water algae, which are excluded from the boat.” Van de Waal therefore argues for a better risk assessment of algae, such as the species now associated with fish deaths in the Oder.

Also read the question: Huge fish kill in Oder, but what is the culprit?