Location of the study waters in the Palatinate Forest-North Vosges Biosphere Reserve at the French-German border (a). Green areas indicate the different zones of the reserve. Circles mark the studied streams and their colors show the taxa found. Population codes are given in Table 1. The shortest distances between all study sites are highlighted in the river network by thicker, dark blue lines. Catchments are given by the respective stream names (cp. Tab. 1). River Rhine is indicated by a thicker line. The dashed line marks the border between France and Germany. For better visibility and scale, the area with sites Stb, FiM and Mob in the Moder catchment is enlarged in b). The location of the biosphere reserve in the border area between north-west France and south-west Germany in central Europe is shown in c).