Research groups and laboratories investigating what killed thousands of fish in the Oder River running between Poland and Germany are pointing at algae toxins.
“The results of the research of our experts from the Institute for Inland Fisheries indicate the presence of microorganisms (golden algae) in the water of the Oder,” Polish Environment Minister Anna Moskwa said Thursday. Their bloom can emit toxins lethal to fish and shellfish but not harmful for humans, she added.
German researchers from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) in Berlin said Wednesday they identified Prymnesium parvum, a type of golden algae, in samples from the river.
It is still unclear whether the algae found on the Polish side are the same type as those identified by the German researchers, according to the German Press Agency.
Officials on both sides of the border last week warned of an ecological catastrophe after dead fish clogged the southern reaches of the river. Polish fishermen started noticing problems near Oława, about 400 kilometers from the sea, in late July.
Polish authorities have pulled 100 tons of dead fish from the river, while some 30 tons were recovered on the German side.
The IGB researchers warned that if their theory is confirmed, the growth of algae in the affected stretch of the river is not “a naturally occurring phenomenon” but “definitely a man-made problem.”
Industrial discharges — as well as dry and hot weather conditions — could be the cause, they said.
During droughts, “many creatures are already fighting for survival” as excessively low water, low oxygen levels and “far too high” water temperatures increase the concentration of adverse substances, said Tobias Goldhammer, a researcher at the IGB. “If other hazards such as toxic algal blooms or chemical contamination are added to existing pollution, this can soon destroy entire freshwater ecosystems,” he added.
The die-off is turning into a political problem for Poland’s ruling Law and Justice (PiS) party, as the opposition and environmental groups accuse it of ignoring early signals of pollution.
European Environment Commissioner Virginijus Sinkevičius this week spoke to German Environment Minister Steffi Lemke and to Moskwa.
The EU executive welcomed the creation of a joint Polish-German expert group and offered to support German and Polish authorities in their investigations. “The Commission, together with the Joint Research Centre and the European Environment Agency, is ready to make available as well our own experts,” Commission spokesperson Tim McPhie said Thursday.
“The sooner we can identify the cause of this ecological disaster the sooner we can start to manage and limit the further consequences, for nature, for fisheries, for agriculture and for recreation,” he added.
The Polish region of West Pomerania on Wednesday called on Warsaw to declare a state of natural disaster covering the area affected by the pollution. Such a declaration would allow affected fishermen and businesses to claim compensation. The head of the Lubuskie province last week issued a similar call.
Polish authorities have closed the Oder for swimming until at least August 25. Across the border, the incident is scaring tourists away from the Oder region.
Local authorities fear contaminated water or dead fish could flow downstream to the Szczecin Lagoon, where the Oder flows into the Baltic Sea.
Camille Gijs contributed reporting.