From the point of view of the Leibniz Institute for Freshwater Ecology and Inland Fisheries (IGB), in the guesswork surrounding the massive fish kill in the Oder, there are increasing indications that the animals died from a poison produced by algae. The strong growth of the algae, which actually thrives in brackish water, is in turn due to the fact that large amounts of saline sewage got into the river, said researcher Tobias Goldhammer of the German Press Agency. »That is our currently most likely hypothesis.«
Last week, researchers at the Berlin institute pointed out the strong growth of the algae species Prymnesium parvum pointed out, which can form a deadly poison for fish. Now they added that this poison had actually been detected in the water of the Oder. In addition, satellite data would have shown a massive bloom of algae in the Oder.
Initial tests on fish eggs with the Oder water have confirmed the deadly effect, said Goldhammer, research group leader in the Ecohydrology and Biogeochemistry department at the IGB. “In the chain of evidence, it is very likely that this algal bloom is the cause of the fish kill.” However, this has not yet been definitively proven.
It is also important that the algal bloom is not a natural event, but is due to human influences, namely the increased salt load in the river water. It is currently not possible to prove where the salt came from. Other factors also likely played a role, including low water and increased water temperature, Goldhammer said.
A spokesman for the Federal Environment Ministry said that several organic and inorganic substances had now been detected in water samples that could be responsible for the strong growth of algae. “It really does seem to be a chemical cocktail. According to our current knowledge, none of these substances alone caused the fish to die.« It could be a »multi-causal event«.