Periphyton (Aufwuchs) Communities of Ciliated Protozoa in Salt-Polluted Running Waters of the Weser River Basin — Their Structure and Indicator Value (Including Model Ecosystems)

The ciliates in aufwuchs communities on glass slides exposed to different amounts of salt pollution at several locations in the Weser River system were investigated. The results were compared with those from the study of model ecosystems exposed to salts. A comparison of the ciliate occurrence with a number of physical and chemical parameters showed that it is primarily the amount of salt present that determines which species are dominant. The number of species present decreases in the presence of high salt concentrations and in water flowing at a high velocity. A halobic index was formulated to indicate salt pollution quantitatively but turned out not to be useful due to the euryhaline potency of most of the ciliate species. The saprobic index can be used in rivers polluted with salt only if biological indicator species are present in sufficient number.