Scientists suspect early on that toxic algae are responsible for the mass deaths of fish in the Oder. It remains disputed whether illegal factory discharges also played a role. In a first investigation report, the Polish authorities came to a negative conclusion.
The Polish authorities blame a toxic alga for the mass death of fish in the Oder this summer and rule out industrial wastewater as the cause. A proliferation of the micro-algae Prymnesium parvum, which is poisonous to fish, is the probable cause of the death of almost 250 tons of fish in the German-Polish border river, said Agnieszka Kolada from the Polish Environmental Protection Institute when presenting a preliminary investigation report.
The species of algae usually grows in salty brackish water near the sea and has never been recorded in Poland before, according to Kolada. "The fish kill was not caused by heavy metals, pesticides or hydrocarbons," says the Polish authorities' investigation report. Instead, high temperatures and low water levels may have contributed to the spread of algae this summer.
Andrzej Szweda-Lewandowski, head of the government agency for environmental protection, emphasized that none of the industrial companies examined had introduced pollutants "that went beyond the permitted level". The amount of wastewater discharged into the river did not exceed that of previous years.
The environmental organization Greenpeace, on the other hand, blames salt discharges from the Polish mining industry for the fish kill, which would have favored the appearance of the algae species. The toxin of the alga has "fatal consequences for fish or mussels that come into contact with it and are already damaged by heavy metals".
Greenpeace is calling on the Polish and German governments "to renaturate the river in the future, to monitor it around the clock and to ban the discharge of harmful substances such as salts and heavy metals". A German investigation report on the fish kill is to be published tomorrow, Friday.
