Impacts of a micro-sewage effluent on the biota of a small Apennine creek

Organic pollution of domestic origin represents the most important cause of water quality deterioration in rural and mountainous areas of the northern Apennines. In this study, the ecological consequences of a small sewage dump in the Caramagna Creek (northwestern Italy) were analyzed. The addition of organic matter and nutrients led to a dramatic change in the taxonomic richness and density of the macrobenthic community. Also functional, biological, and ecological composition of the invertebrate assemblages changed downstream of the effluent. Interestingly, benthic chlorophyll a showed only a weak increase in the downstream section, despite the increased levels of nutrients. This work emphasizes the importance of better management of sewage treatment also in remote areas.