Dead fish in the German-Polish border river Westoder
Photo: Patrick Pleul / dpa
Could an alga be the cause of the mass death of fish in the Oder?
Researchers continue to have their eyes on a venomous species that has been rapidly evolving in the river.
In the meantime, the microalgae with the name Prymnesium parvum has been identified, said the water ecologist Christian Wolter of the dpa on Wednesday.
"The species is known to cause occasional fish kills."
It is still unclear whether the toxin of the algae is the reason for the fish deaths in the Oder.
The researcher at the Berlin Leibniz Institute for Freshwater Ecology and Inland Fisheries emphasized whether it produced toxins in this case.
He spoke of a massive algal bloom with 200 micrograms per liter and more than 100,000 cells per milliliter of water.
However, the toxin of the algae is harmless to humans.
The type of algae actually lives in brackish water, Wolter described.
This typically occurs at estuaries where fresh and salt water mix.
But in a saline environment, they can grow well, said the aquatic ecologist.
In addition, the algae need high pH values.
"Otherwise, as a brackish water species, it would not form a mass development in the Oder."
For the expert there is a clear connection between the introduction of salt and the development of algae.
He personally does not believe in an accident, said Wolter.
Initially, several media reported about the algae, including rbb and "t-online".
Prime Minister reiterates criticism of Poland
The Brandenburg state government assumes that the major fish deaths in the Oder are not only due to natural causes.
"We can safely rule that out, otherwise the high pH values and the increased oxygen content and much more would not explain themselves," said Prime Minister Dietmar Woidke (SPD) on Wednesday in Beelitz.
You still don't know what happened.
"All we know is that something must have happened."
Woidke renewed his criticism of the communication with the Polish side.
"The fact is that six days before fish died here, fish died in Poland - and we were not informed." That is why he is "deeply disappointed" by the Polish government.
Due to international treaties, Poland would have been obliged to provide information at an early stage.