Novel species interactions and environmental conditions reduce foraging competency at the temperate range edge of a range-extending coral reef fish

Poleward range extensions of coral reef species can reshuffle temperate communities by generating competitive interactions that did not exist previously. However, novel environmental conditions and locally adapted native may slow tropical invasions reducing the ability invaders to access local resources (e.g. food shelter). We test this hypothesis on wild marine fish in a climate warming hotspot using field experiment encompassing artificial prey release. evaluated seven behaviours associated with foraging aggressive common range-extending (Abudefduf vaigiensis) co-shoaling (Microcanthus strigatus) along latitudinal temperature gradient (730 km) SE Australia. found had reduced performance (i.e. slower perception, inspection, decreased intake, increased distance prey) their than subtropical range. Furthermore, higher abundance fishes was retreat behaviour withdrawal from released prey), independent latitude. Where ranges overlapped, showed aggression fish. Our findings suggest lower at leading edge is driven combined effect factors seawater and/or unfamiliarity extended ranges) biological larger body sizes fishes). Whilst future increase ocean expected alleviate current limitations edges, under trailing edges appear able extension into ecosystems limiting resources.