Die Algenflora des Rheines 2. Teil: Die Saprobier von der Quelle (Tomasee) bis Basel

Abstract

In the area under investigation a total of 552 different species of algae have been determined (including 181 Saprobians), of which 455 species were found in the Rhine (including 154 Saprobians).

The degree of pollution was determined on the basis of the well-known Saprobian-system. The trend line shows an increasingly smaller load from the spring to Basel (score 1.8-2). Chemical and biological evaluations run parallel.

The number of algae species increases from the source of the Rhine with increasing chemical load. For the existence of algae a certain amount of nutrition is necessary. In areas with low nutritive value the number of algae species goes parallel to the population density. The actual borderline from the natural unavoidable and the harmful chemical load could not be unequivocally defined. The chemical load of the Rhine water has reached a limit, beyond which an optimal development of fauna and flora is endangered. Autopurification of the water could still be documented in some locations.

As a conclusion, the total load of substances in the Rhine water from a hinterland with about 6 million people is too high. The highest load derives from the tributaries. The percentage of sewage water, calculated from the total Rhine-water in Basel, fluctuates between 2 and 4 percent.