Indicating the trophic state of running waters - Exemplary implementations of the trophic index of macrophytes (TIM) in the River Sempt (Bavaria, Germany)

The macrophyte vegetation of the river Sempt and its major tributaries was mapped and the nutrient concentrations of both the water body and the sediment were measured. By cluster analysis the mapping sections were grouped into four zones which differed in flowing velocity and degree of shading. The phosphorus concentrations of the water body also show differences between these zones. In every mapping section the Trophic Index of Macrophytes (TIM) was calculated according to SCHNEIDER (2000). In the river Sempt and its tributaries the TIM is not influenced by varying composition of species resulting from different flowing velocities or varying degrees of shade. Even with a generally high supply of phosphorus from the sediment TIM is a useful means to detect differences in the phosphorus concentrations of the water body.