Results of the PCA analysis with the correlation circle showing the correlations among the 10 environmental factors according to the different environmental factors (a). The breakdown rates K_c (green arrow), K_f (blue arrow) and λ_F (red arrow) are projected as quantitative supplementary variables. Black circles, distribution of the barycentres of each stream; solid lines link station to its different streams at each season (b). CV: current velocity; %Hum: percentage of air humidity; DO: dissolved oxygen; Lux: luminosity; WW: water width; WD: water depth; Cond: conductivity; Lambda: fragmentation rates; Dist: distance to the source.