Cyclotella-taxa (Bacillariophyceae) in lakes of the Alpine region and their relationship to environmental variables

Surface sediment diatom assemblages for 86 Alpine lakes were analysed focusing on the dominant genus Cyclotella and corresponding environmental data. The range of morphological variability of the Cyclotella bodanica/radiosa, C. distinguenda, C. ocellata, C. comensis and C. stelligera complexes was documented. Significance tests included in the canonical correspondence analysis (CCA) indicated that total phosphorus, conductivity and surface water temperature were significantly correlate with Cyclotella taxa assemblage distribution. Numerical species optima and tolerances were calculated in respect to these significant variables using weighted averaging (WA) regression and calibration. CCA and WA were able to provide information about the environmental preferences of the various morphotypes observed.