List of taxa, taxa codes and total abundances per taxa for each site

Salinity of rivers is an expression of the concentration of soluble salts dissolved in the water body. Secondary salinisation is the increase in salinity of a water body as a result of human activities. Salinity affects aquatic biota, allowing the presence of species that tolerate such characteristic. Using natural and anthropized systems, we studied benthic communities and their relation to physicochemical variables. We collected benthic community samples using a D-net and surface water samples for laboratory major ions analysis. We noted a critical limit of Electrical Conductivity above 800µS/cm breaking up taxa pools of benthic macroinvertebrates. We observed that taxonomic richness is a sensitive indicator to detect effects of secondary salinisation. We hypothesized that monsoonal regime of precipitation in the studied region is an important driver of conditions for benthic fauna because of dilution effects. Evidence showed seasonal rainfall affecting benthic communities differently, more equitably improving conditions below 800µS/cm in more saline sites and disturbing the system in less saline sites. No relation was found in the system affected by secondary salinisation by activities of a salt factory.