The investigation of the interactions between different elements in a river, like flora, sediment and hydraulics, are a topic of increasing importance. Many freshwater mussels in Europe are on the red-list and therefore their protection and evolution is a topic of high interest. Most of these mussels are well investigated according to their reactions on water quality. However it must be seen, that not all behaviour of the mussels can be explained only by the water chemism. It is found that for instance even with a very good water quality some freshwater mussels do not reproduce, like the Margaritifera margaritifera, and the reason might be a change in the sediment or the hydraulics.And also the mussel itself influences the sediment and the erosion of the fine particles.

To come closer to such effects experimental studies were conducted in the laboratory at TUM. The experimental set-up was mimicking a natural river using natural water and sediment. The behaviour of the used species was monitored with optical tracking over a period of two month without any intervention. The effects of their migration on the sediment were observed, scanned and evaluated as a 3D model. Also the interaction with the flow was measured using particle image velocity (PIV) to gain information about the turbulent structures and the velocities around the mussels. The results are evaluated to gain information about the influence of the mussels on the bed structure and the influence of the hydraulics on the migration behaviour of the mussels.