Coordination of the mussel conservation in Bavaria
The main objective of the coordination office, which is funded by the Bavarian State Ministry of the Environment and Consumer Protection since 2008, is the networking of research projects and aid programmes in the field of mussel conservation with a focus on freshwater pearl mussels and thick shelled river mussels. The coordination office is affiliated to the Chair of Aquatic Systems Biology at the Technical University of Munich (Prof. Dr. Geist) and works in close consultation with the Bavarian State Office for the Environment.
Main tasks and goals:
- Information and knowledge transfer, moderation
- Advising authorities, organisations and local actors in mussel conservation
- Development of concepts for mussel protection; support in the planning of measures
- Initiation and support of research projects, evaluation
- Monitoring of the stocks, development of a central documentation
- Organisation of a Bavaria-wide support network for priority mussel populations
Distribution and status in Bavaria
The freshwater pearl mussel and the thick shelled river mussel are threatened with extinction. Remaining populations of the pearl mussel in Bavaria can be found in nutrient- and calcium-poor streams of primary rock areas, including the Bavarian Forest, the Fichtel Mountains, and the Rhön Mountains. Up until the last mid-century, the thick shelled river mussel was found in most streams and rivers. Current population studies, however, show that the species has lost more than 90% of its original distribution in Bavaria.
The sharp decline of the freshwater pearl mussel can not be stopped despite extensive efforts, as self-sustaining populations have not occurred in the last several decades. Today, pearl mussel populations with fewer than 100 individuals can be found in about 30 Bavarian streams and rivers. At present, there are only two known populations in Bavaria estimated to have more than 10,000 individuals.
In the past, insufficient water quality was one of the main reasons for pearl mussel population decline. Today, research efforts focus on improving substrate quality, particularly in streams with dwindling mussel populations. Favorable substrate quality is necessary for the development of juvenile mussels, which require a stable substrate with an oxygen rich cavity system, known as interstitial space, in order to survive. Siltation, increased sediment loads, and nutrient input from surrounding areas are therefore the main risk factors affecting current pearl mussel populations.
In the meantime, much work has been done to successfully breed pearl mussels. Juvenile mussels can be selectively placed in structurally restored streams and rivers, in order to support existing populations.
Conservation efforts for the river mussel have existed since the late 1980s, and in recent years, a number of new findings on the ecology of this species have been identified. A new study showed that the river mussel, unlike the pearl mussel, is able to colonize a wider range of habitats. Additionally, intensive waterway maintenance is known to impact the pearl mussel more so than the river mussel. These differences can threaten both species, whose survival is dependent on the development and implementation of effective, species-specific protection strategies.