Haltern am See (dpa/lnw) – An increased amount of algae in the warm water is probably the reason for the low oxygen content of the Stever near Haltern am See, which has led to fish deaths. The head of the Haltern waterworks, Magnus Meckelburg, said on Monday that there had been an increase in algae from the Hullerner reservoir upstream.
The algal bloom – as the occurrence of many algae is called – is therefore a common phenomenon in summer. However, various effects are currently superimposed: the water is clouded by the algae, which reduces photosynthesis. In addition, the water is currently very warm and can therefore absorb less oxygen. At the same time, the oxygen requirements of fish and other creatures increase with the temperatures, as Meckelburg explained.
Countless dead small and medium-sized fish had floated in the river on Sunday. According to Meckelburg, a 500 meter long section of the Stever is affected. Oxygen levels remain low there, he said on Monday.
Oxygen was supplied to the water surface with fans before the weekend. Now, in a more complex process, a “jet aerator” has been installed deeper in the water. This creates a kind of “bubble curtain” that introduces oxygen into the water flowing through.
