The Seine Aval is the stretch of the Seine from the Dam of Poses upstream of Rouan to Vieux Port 125 km downstream. In coorparation with Ecoconsult and Waterfauna we investigated the macroinvertebrates in the freshwater tidal part of the Seine Aval.
Upstream of Rouan 26 species were encountered, In the area polluted by Rouan wastewater 16 species were found. In the downstream section only 4 species managed to survive on the mudbanks or in the tidal sands.