thick shelled river mussel (unio crassus)
TRANSCRIPT
"Restoration of Unio crassus rivers in the Luxemburgish Ardennes" (September 2012 to February 2018)
a LIFE + Nature project
Alexandra ARENDT, Fränk THIELEN, Thierry MÜLLER natur&ëmwelt-Fondation Hëllef fir d’Natur,
2 Kierchestrooss, L-9735 Heinerscheid, Luxembourg Email: [email protected]
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LIFE is a financial instrument of the European Community
Introduction : The thick shelled river mussel Unio crassus (Philipsson, 1788), a formally abundant species of semi-lentic river habitats in Luxemburg, has dramatically declined within the last fifty years. Small populations remain in the river Our that is in the three country region of Belgium, Germany and Luxembourg and the river Sûre on the Luxemburgish-Belgian border with about 9,000 individuals and 32,000 individuals respectively. The aims of the project are to improve the habitat quality of the two rivers and to strengthen the existing populations by various actions.
Threat 1: Lack of young mussel stages
Measures: •Development of a captive breeding method for Unio crassus. •Production of 2,500 young mussels/year at the mussel rearing station on the Our river. •Release 500 to 1,000 mussels at both rivers every 3 years. •Transformation of 6 fish migration obstacles to improve the connectivity of the river system and increase the host fish population. •Muskrat capture (Ondatra zybethicus) twice a year to reduce the predating impact on mussels.
Threat 2: High input of fine sediment in the water
Measures: •Reduction of cattle trampling (erosion) on the river banks by installing fences (2 km, 5 cattle watering tanks, 3 cattle bridges). •Installation of 60 water runoffs on rural and forestry roads to minimize the sediment runoff. •Negotiation of 40 agri-environmental measures to enhance riparian land management. •Restore a tributary river bed by installation of woody debris.
Monitoring: The effectiveness of each measure is controlled by the evolution of the principle indicators ,such as water and substrate quality, turbidity and development of fish and mussel populations.
Threat 3: Insufficient water quality
Measures: •Formulation of a Natura 2000 management plan to help to reduce pollution. •Negotiation of 40 agri-environmental measures to enhance river bank (riparian) land management.
Germany Belgium
River Our River Sûre
Project partners:
Only few young mussels can be found in both rivers.
An old mill transformed to a mussel rearing station by a former LIFE Nature project for Margaritifera margaritifera (2005-2007).
Wood exploitation damages the river bank.
The brown colour of the river after rainfall indicates the high amount of fine sediment in the water.
Project sites in the country Project sites in the region
France
Luxembourg
The high amount of nutrients contributes to the clogging of the stream substratum.
Unio crassus in its natural habitat .
Coordinating beneficiary:
Threats to the Mussels and Measures to Address Them