Defining different types of running waters in Germany based on the present occurrence of benthic algae (excl. Charales and diatoms)

The present occurrence of benthic algae (excl. Charales and diatoms) was investigated at 187 sampling sites at streams and rivers all over Germany. In total, more than 170 taxa from 11 algal classes were found. Multivariate statistical analyses showed that species composition at the sampling sites differed mostly with respect to water hardness and acid neutralizing capacity, but also with respect to anthropogenic degradation (higher levels of nutrients or pollution). Five types of running waters could be defined which show a characteristic species composition under reference conditions. Out of these, the siliceous waters in the Central Highlands are the most species-rich. Further research should focus on calcareous waters in the Northern Plains as here a great part of variation in species composition is not well understood yet. Parts of this work were conducted within the PHYLIB project which led to an assessment routine as needed for the application of the Water Framework Directive