Context-dependent relationships between metabolism and behavior across temperature acclimations in sheepshead minnows...

Marine fish are able to cope with environmental changes through altering their physiology and behavior. Among environmental stressors, thermal stress is particularly relevant for fish because increased temperature leads to elevated baseline metabolic costs and also has known impacts on behavior. The Performance Model provides a conceptual framework linking metabolism and behavior such that individual differences in baseline metabolic demand influence behavioral expression specifically related to acquiring resources that support metabolic machinery. Thus, under warming, increased energy demand should lead to increased risk-taking and lower behaviors that deter predation (e.g., shoaling and scototaxis). On this background, our objective was to assess behavioral and metabolic responses to warming and the relationship these traits across two temperatures in an estuarine model teleost, the sheepshead minnow (Cyprinodon variegatus). Fish were exposed to 22 °C or 32 °C for 14-days and standard metabolic rate (SMR) was measured. Each fish was subsequently tested in a series of behavioral assays to assess activity, exploration, sociability, and anxiety-like behavior. As anticipated, warmer temperatures increased in SMR and increased activity while reducing anxiety-like behavior. However, relationships between behavior and metabolism were present only in control conditions and, composite behavioral scores indicated negative relationships in in the opposite direction of predictions based on the performance model. Interestingly, trait patterns dissipated under warming suggesting that predictions based on models in control conditions may have dubious utility under climate change. We argue that behavioral-metabolic relationships are sensitive to context, and environmental factors should be considered when exploring the intersection between behavior and physiology.