Quagga mussel invasion impacts Rhine and Lake Constance

The invasive Quagga mussel continues to pose significant ecological and economic challenges in the Rhine River and Lake Constance. In the High Rhine, between the Swiss cantons of Schaffhausen and Thurgau, massive accumulations of living mussels and dead shells—estimated at up to 150,000 bathtubs in volume—have caused navigation issues for passenger ships. To address this, a joint working group is exploring industrial uses for the material, including trials at the Holcim cement plant in Siggenthal to use shells as a lime substitute and investigations into fertilizer applications.

Meanwhile, researchers from the University of Konstanz have observed a die-off of the species in certain areas of Lake Constance, specifically in the Gnadensee. Microbiologists suggest that high levels of hydrogen sulfide, a toxic gas, may be preventing sufficient oxygen from reaching the mussels at depths of 14 to 20 meters during warm summer months. While the current concentration of hydrogen sulfide is not considered a threat to humans or other organisms, scientists continue to monitor how water temperature and layering affect the lake's ecosystem.