Invasive–native predator interactions under climate change: trophic and range dynamics of competing catfish in freshwater ecosystems

Invasive species and climate change are among the most significant drivers of biodiversity loss in freshwater ecosystems, yet their combined impacts on predator-prey dynamics remain understudied. Here, we assess the trophic interactions and climate-driven range dynamics of two competing apex predators—the non-native African catfish, Clarias gariepinus and the native Wels catfish, Silurus glanis —in a thermally stable freshwater system in Türkiye. Using stable isotope analysis and comparative functional response experiments, we evaluated predation patterns on a native prey species, Alburnus escherichi and a non-native prey, Carassius gibelio . Both predators exhibited higher attack rates and predatory efficiency on the native prey, with C. gariepinus demonstrating stronger overall ecological impact, particularly under warm conditions. Ecological niche models predicted range expansion for both catfish species under future climate scenarios, with increasing habitat overlap likely to intensify interspecific competition and exacerbate predation pressure on native fish communities. Our findings highlight the complex interplay between biological invasions and climate change, underscoring the urgent need for proactive conservation strategies in Türkiye’s freshwater ecosystems to mitigate compounded ecological threats.