Thousands of fish have died in Lake Modlany near the northern Czech town of Usti nad Labem (Aussig on the Elbe) due to a lack of oxygen caused by the heat. On Sunday alone, fishermen and volunteers removed 4.5 tons of dead fish from the lake, local authorities and the fishing association told the news portal "Novinky.cz" on Monday. The clean-up work continued at the beginning of the week.
Heat as the trigger
As Jan Skalsky, spokesman for the North Bohemian Fishing Association, told the portal, several factors had contributed to the fish kill. Even under normal weather conditions, the water is affected by heavy siltation and contains a lot of bacteria and algae. "At high temperatures, the oxygen supply in the water is reduced," explained Skalsky. This causes these organisms to die off and sink to the bottom. "In the process, they continue to consume oxygen, which they literally suck out of the entire water column."
Fishermen do have the technical means to enrich the water in ponds with oxygen. However, this is not enough for such a large volume of water. Lake Modlany on the edge of the municipality of Modlany near the border with Saxony has an area of 41.6 hectares. It was formed from a depression left over from former lignite mining.
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