Salinisation and warming disrupt predator-induced drift behaviour in aquatic predator–prey interactions

Predator-prey interactions drive adaptation in aquatic communities, shaping invertebrate behaviour. In response to predation risk, invertebrates may exhibit behavioral changes, such as drifting with the downstream current or hiding to avoid predators. To investigate the influence of salinisation and warming on predator-induced behaviour and its effects on the invertebrate community, we collected invertebrate samples (drift, leaf litter and community samples) from an outdoor mesocosm system (ExStream system) using a full factorial design between March and April 2022. The collected invertebrates were identified to the lowest possible taxonomic resolution using morphological identification, with abundance recorded, followed by metabarcoding. Drift nets attached to the outflow were collected 24 hours after predator cue exposure (S1) and direct exposure (S6). In the predator exposure treatment, invertebrates were first exposed to elevated chemical cues from fish (Gasterosteus aculeatus and Cottus rhenanus) to simulate indirect predation (S1). On the fifth day after sampling, one Cottus rhenanus was introduced into each predator-treated mesocosm to simulate direct predation (S6).