Ontogenetic shift in the trophic role of the invasive killer shrimp Dikerogammarus villosus: a stable isotope study

Abstract The introduction of the amphipod Dikerogammarus villosus in European fresh waters is to date recognized as a threat integrity invaded communities. Predation by D. on native benthic invertebrates assumed key determinant its ecological impact, yet available information describe species primary consumer well carnivore depending local conditions. Here, we assessed trophic position (TP) Lake Trasimeno, recently lentic system central Italy, using CN isotopic signatures individuals captured winter spanning two orders magnitude body size. TP estimations were compared with those characterizing Echinogammarus veneris and other representative invertebrate predators. On average, showed higher than E. , comparable that odonate nymphs. An in-depth analysis revealed large-sized had 3.07, odonates close hirudinean predator Erpobdella octoculata while small-sized specimens 2.57, similar (2.41). These findings indicate size-related ontogenetic shifts dietary habits may per se vary nature interaction between from competition predation. Information collated published studies corroborated generality our results. We conclude intra-specific flexibility potentially amplify make more multifaceted impact food webs.