Fig. 3. Periphyton mass dynamics along glacier-fed rivers with different degrees of glaciated catchment (% GCC) with dry mass (top), ash-free dry mass (AFDM, center), and chlorophyll a concentration (bottom).

Periphyton community composition

The analysis of the community composition (relative abundance of the three groups) revealed the dominance of pigment-group B (diatoms and chrysophytes) over the other two groups, cyanobacteria and green algae (Fig. 4). While we found individual transects being dominated by green algae or cyanobacteria, all stream reaches and most sampled transects (87 %) were dominated by pigment-group B (diatoms and chrysophytes). Across all samples (n=45), diatoms made up between 62 % and 74 % (95% CI) of the producer communities.