Temporal and spatial patterns in the shifting of otter diet to invasive prey after river damming

River damming promotes profound changes in aquatic biodiversity, including the facilitation of biological invasions, with subsequent impacts on native communities. The Eurasian otter (Lutra lutra) is a generalist predator that often incorporates new prey types when they become available. We studied short- and long-term effects river trophic ecology across riverine landscape gradient, from flooded area to upstream tributaries, focusing largest artificial lake Western Europe. Through analysis feces (spraints), we describe diet composition 14 sites at different distances impounded three periods: (i) pre-filling phase (i.e., lotic conditions); (ii) immediate filling phase; (iii) 16 years after dam closure. drastically shifted short term, being dominated by cyprinids mainly composed invasive species fish crayfish. In long number consumed continued increase while completely disappeared as near reservoir. Presumably, construction generated clear spatial gradients abundances species. These patterns arose term but became accentuated were mirrored composition. Our results demonstrate potential analyses surrogate for human alterations ecosystems, those associated invasions.