INFLUENZA DELL'INVASO DI MONTEDOGLIO SULLA FAUNA ITTICA DELL'ALTO TEVERE INFLUENCE OF THE MONTEDOGLIO RESERVOIR ON FISH FAUNA IN THE UPPER TIBER

Summary Dams and barriers interrupt the continuity of rivers and have an impact on their hydrological and thermal regimes and on sedimentation. Such variations in physical conditions affect the organization, structure and processes of biotic communities in a long stretch of the river both upstream and downstream of the barrier. The downstream effects of the Montedoglio Reservoir on fish communities were examined by comparing the composition of the fish community in the mid-upper River Tiber before and after the creation of this impoundment. Three sampling sites were selected, one above and two below the dam, and three series of data (1992, 2004, 2010) were examined in order to trace the temporal evolution of the fish populations in these stretches of the river. At each sampling site, a census of the fish