Time-energy budgets derived from animal-borne instruments clarify the responses of fish to changing temperatures (#35)
Environmental conditions can have substantial impact on a species’ success and quantifying and/or forecasting the response of biodiversity to change is of great importance in the Anthropocene. In ectotherms, thermal performance curves of physiological traits are generally used to predict how changes in temperature may impact individuals and by extension populations. However, these generally do not consider other ecological constraints that may be faced by free-ranging animals. Quantification of the thermal sensitivity of time and energy budgets offers an opportunity to account for both ecological and physiological performances. Here we show how modern animal attached accelerometers integrated with laboratory studies can be used to generate time-energy budgets and describe their temperature dependence in free-ranging juvenile sharks.Overall, all time budgets revealed an increase in incidence of time engaged in behaviours related to prey capture, such as prey manipulation and burst swimming behaviour that exceeded the increase of metabolic rate with temperature. Whereas metabolic rate increased exponentially with temperature, our proxies of prey capture indicate that fewer prey were caught at extreme temperatures. Importantly, the optimum temperature for prey capture was below that of locomotor performance, suggesting that purely physiological traits may overestimate critical temperatures for wild individuals.