Additional file 4. Fig. S2 Presence of diatoms around the ‘Teñidero’ confluence. a) Relative abundance of cyanobacteria-like ASVs in the different samples. Most of the Bacillariophyta ASVs could be further assigned to different diatom groups (Additional file 5: Table S3). Sample codes are described in the legend for Figure 3b, b) Light microscopy image from a Río Celeste sample showing the presence of diatoms with different morphologies, c) Light microscopy image from a Río Celeste sample showing the presence of the dinoflagellate Peridinium, d-f) Electronic microscopy images showing details on diatom frustules.