BRIESKOW-FINKENHEERD, Germany, July 8, 2023 (AFP) – Fisherman Henry Schneider stopped work for several months after a toxic algae bloom hit the Oder river last August, decimating his catch.
Schneider, 43, whose family has made its living from the river for over a century, finally took up his activities again in May.
But fears of a repeat are growing, as global warming adds to the toxic mix of pollution putting the delicate ecosystem under pressure.
“It was unbelievable that we had fish left at all,” Schneider, who lives on the German bank of the river, says of the poisoning.
The disaster wiped out more than half the fish in the river, which traces a long stretch of the Polish-German border.
And while the Oder has had some time to recover, the organism responsible for the disaster, known as Prymnesium parvum, has not been eradicated.
“In a millilitre of Oder water we still see several hundred cells,” says scientist Martin Pusch from the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) in Berlin.
He warns that the risk of another deadly bloom is high.
“It is just waiting for the right conditions to explode.”
Polish and German authorities on either side of the river say they are determined to stop that happening.
But the two have clashed over responsibility for the disaster and the best way to keep the algae in check.
– ‘Immediate collapse’ –
Among fishermen there is concern over the impact of a possible recurrence.
“If it happens again this year then there will be nothing to fish in this river for the next few years,” Schneider says.
The events of last August led to an “immediate collapse in tourism” and fish sales that put bread on the table, he says.
“We came down to the water and we saw all the dead fish in both directions,” he recalls, gesturing up and down the riverbank.
Schneider and his family received financial support from the Brandenburg region to bridge the gap left by the disaster.
“There have never been fish deaths on this scale in the Oder in my lifetime”, says Henry’s 65-year-old father, Peter Schneider.
A confluence of high salt levels in the river and an extended period of high temperatures created the perfect conditions for the algae to flourish upstream.
The question of excess salt “has existed for a long time and is now getting worse with climate change”, says Pusch.
Among other factors, parched waterways mean that dangerous discharges are not being as diluted as before.
Environmental groups have also pointed the finger at mining operations in Poland that tip mineral-packed water into the river.
Now, with the weather warming up once again, increases in the number of algae have already been recorded further up the Oder.
– Bad signs –
In response, Warsaw has ordered affected areas to be sealed off, as well as promising more water treatment plants and the creation of a river police.
But the government faces accusations it is not doing enough to avoid a disastrous repeat.
Scientists believe many fish that survived found refuge in tributaries and corners of the Oder where the deadly algae was less prevalent.
Yet new man-made installations on the river would “only increase the risk of disasters”, the head of WWF Poland, Miroslaw Proppe, told AFP.
“They change the river into a transport route and it is not the same thing,” he explained.
Likewise, despite promises from Warsaw to review all permits for the dispensing of industrial waste waters into the river, Berlin has criticised inaction on the Polish side.
“We see there are no major efforts there to restrict (salt discharges)”, a spokesman for the German environment ministry said earlier this month.
“A second catastrophe is in nobody’s interest,” the spokesman said, but “the signs are not good at the moment”.
For the time being, the fishermen along the Oder will continue cautiously.
“We’re optimistic that in two, three, four years there will again be fish there in bulk,” says elder Schneider, Peter — provided another disaster can be avoided.
