Résumé
Warming climate impacts aquatic ectotherms by changes in individual vital rates and declines in body size, a phenomenon known as the temperature‐size rule (TSR), and indirectly through altered species interactions and environmental feedbacks. The relative importance of these effects in shaping community responses to environmental change is incompletely understood. We employ a tri‐trophic food chain model with size‐ and temperature‐dependent vital rates and species interaction strengths to explore the role of direct kinetic effects of temperature and TSR on community structure along resource productivity and temperature gradients. We find that community structure, including the propensity for sudden collapse along resource productivity and temperature gradients, is primarily driven by the direct kinetic effects of temperature on vital rates and thermal mismatches between the consumer and predator species, overshadowing the TSR‐mediated effects. Overall, our study enhances the understanding of the complex interplay between temperature, species traits and community dynamics in aquatic ecosystems. Our study investigates how tri‐trophic community respond differently to the direct effects of warming and resource productivity. Our model covers the main processes driving the dynamics and structure of tri‐trophic chains under the direct influences of warming, i.e. through the temperature‐dependent vital rates of species mediated by the temperature performance curves (TPC) and through the temperature‐induced reduction in body size, also known as the temperature‐size rule (TSR). Using multiple scenarios, we summarise different responses of size‐structured trophic chains across environmental gradients by considering the joint and separate influences of TPC and TSR in consumer and predator traits, when their thermal niches partially or fully overlap.