Uncommon microorganisms often called golden algae may very well be the trigger behind a mass loss of life of fish within the Oder River that has puzzled scientists for days, Poland’s setting minister has instructed.
“After additional investigations, the Institute of Inland Fisheries in Olsztyn has discovered uncommon microorganisms, so-called golden algae, in water samples from the Oder River,” Anna Moskwa mentioned on Thursday.
The algal bloom may trigger the looks of poisons that killed fish and clams however weren’t thought of dangerous to people, she mentioned.
German municipalities banned bathing and fishing within the Oder after plenty of useless fish and molluscs had been discovered floating on the water floor and washed up on the banks of the 520-mile (840km) river, which runs from the Czech Republic to the Baltic Sea alongside the border between Germany and Poland.
Since final Friday Polish firefighters have recovered greater than 100 tonnes of useless fish from the Oder, with the German setting minister, Steffi Lemke, reporting an estimated 35 tonnes of killed fish in her territories.
Scientists have struggled to search out a proof for the die-off. Early studies of elevated ranges of mercury within the Oder waters had been later discovered to be deceptive.
Water samples had been despatched to laboratories within the Czech Republic, the Netherlands and Britain within the hopes of discovering the trigger.
Golden algae (Prymnesium parvum) are normally present in brackish waters the place rivers meet the ocean, however are recognized to unfold farther inland when there are excessive ranges of salinity within the water.
“This species of algae requires raised saline ranges that don’t naturally happen on the affected stretch of the Oder in any respect”, mentioned scientist Jan Köhler of Berlin’s Leibniz Institute of Freshwater Ecology and Inland Fisheries.
Polish officers have investigated whether or not specific larger concentrations of pollution and salinity may very well be linked to local weather change, with exceptionally excessive temperatures throughout Europe in latest weeks resulting in extra water evaporating from inland waters.
Mineral fertilisers seeping into the river from adjoining farmland additionally has the potential to result in huge algal bloom, scientists mentioned.
A chemical spill was one other speculation being investigated, with Poland providing a reward of 1m złoty or €210,000 (£180,000) for anybody who can “assist discover these accountable for this environmental catastrophe”.