Ecological processes occurring at the water-sediment interface have major effects on the dynamics of nutrients in low order streams. Nutrients are removed from the water column by microbial biofilms that, in turn, are consumed by the invertebrate assemblage. In this study we estimated the amount of elements (C, N, P) that flow through the invertebrate assemblages of several streams throughout Europe, all of them impacted by wastewater treatment plants. Our approach coupled secondary production estimates with elemental measures of C, N, P content of invertebrate taxa. This research is part of the EU-project STREAMESJRC.H.5 - Rural, water and ecosystem resource