Why is the freshwater pearl mussel endangered?

• Pollution of the Our by organic waste waters and nutrient enrichment

Cattle watering place in the river causing erosion of the banks (Picture Mireille Molitor)

• River engineering, erosion of the river banks, distributed flow regimes and increased turbidity causing siltation. Siltation results in decrease in the levels of oxygen and the small spaces between pebbles become clogged, which harm’s the young, small mussels

Inappropriate bank vegetation (Picture Mireille Molitor)

• Low host fish population. The stock of brown trout in the Our and its tributary is scare

This pipe construction is impassable for migrating trouts (Picture Mireille Molitor)

• Predation by the non native Muskrat (Ondatra zibethicus)

The muskrat (http://weichtiere.at/Muscheln/gefaehrdung.html)

Feeding place of a muskrat with many dead freshwater pearl mussels
(Picture G. Weitmann)