Top-down control by an aquatic invertebrate predator increases with temperature but does not depend on individual behavioural type

Variation in behavioural traits among individuals within a population can have implications for food webs and ecosystems. Temperature change also alters food web structure and function, but potential interactions between warming and intraspecific behavioural variation are largely unexplored. We aimed to test how increased temperature, individual activity level of a predatory backswimmer (Anisops assimilis), and their interaction influenced the strength of top-down control of zooplankton and phytoplankton. We used stable isotopes to support our assumption that the study population of A. assimilis is zooplanktivorous, and behavioural trials to confirm that activity level is a repeatable trait. We established freshwater microcosms to test for effects of warming, backswimmer presence, and backswimmer behavioural type on zooplankton density, zooplankton composition, and phytoplankton chlorophyll a. Top-down control was present and was generally stronger at increased temperature. There was no...