Canonical correspondence analysis (CCA) relating the benthic diatom community (a) to the physicochemical variables (b). Different colors of text on the left plot indicate the indicator genera in each diatom assemblage (yellow text denotes indicator genera from cluster Ia and red and blue from clusters Ib and II, respectively), while the grey texts on the right plot shows the monitoring sites. The blue arrows represent the vectors of physiochemical variables; only significant variables are depicted (Monte Carlo permutation tests with 999 permutations, p-value < 0.05). A detailed description of the benthic diatom genera and Monte Carlo permutation tests are given in Tabs. S1 and S2.