Nile tilapia (Oreochromis niloticus) invasion impacts trophic position and resource use of commercially harvested piscivorous fishes in a large subtropical river

Abstract Background Although freshwater ecosystems cover less than 1% of the earth's surface, they support extremely high levels biodiversity and provide vital ecosystem services. However, due to introduction non-native fishes, aquatic functioning has been altered, in some cases, declined sharply. Quantifying impacts invasive species proven problematic. In this study, we examined relative trophic position native piscivorous fishes estimate effects Nile tilapia on food webs downstream sections an invaded large subtropical river, Pearl River, China. Furthermore, quantified how fish diets changed as invasion progressed. Results The widely distributed locally important economically harvested culter ( Culter recurviceps ), mandarinfish Siniperca kneri catfish Pelteobagrus fulvidraco ) lowered significantly Dongjiang River compared uninvaded reference Beijiang River. lower these was reflected by a major reduction proportion prey biomass their following invasion. Small diet from river (33% small 17% zooplankton) shifted level zooplankton (36% zooplankton, 25% fish), possibly presence tilapia. Additionally, (46% 11% insects) (20% insects, 30% fishes). Similarly, eggs (25% eggs, insects (44% 5% eggs). Conclusions results study contributed growing body evidence, suggesting that can modify interactions ecosystems. It is crucial understand processes outlined order better assess species, conserve stability ecosystems, improve current conservation strategies reaches other similar rivers have experienced invasions species.