Comparison of diatom communities in remote high-mountain lakes using index B and cluster analysis

Six remote high-mountain lakes in SE Switzerland were characterized on the basis of their water chemistry and the composition of their epilithic diatom communities. The index B (Renberg & Hellberg, 1982), calculated by summarizing the relative frequencies of occurrence in all five pH classes defined by Hustedt (1938/39), was found to be well correlated with pH values measured from August to October (5.8 to 7.0). Four lakes with pH values from 6.3 to 6.6 could not be distinguished from one another by means of the index B despite some differences in their physical, chemical and biological characteristics. However, it was possible to separate them by cluster analysis using the relative frequencies of the diatom species. We conclude that much ecological information is lost when applying the pH classification of Hustedt (1938/39).