Multiple stressors, state-dependence and predation risk — foraging trade-offs: toward a modern concept of trait-mediated indirect effects in communities and ecosystems

Abstract

• Species in communities generally must trade-off foraging and avoiding predators. • Individuals within species vary in their physiological and morphological traits. • Trait variation causes state-dependent trade-off behavior. • Environmental stressors change the context for state-dependent trade-offs. • Linking stressors to state-dependent behavior enhances prediction in ecology. Trait-mediated indirect effects driven by organismal foraging-predation risk trade-offs can determine food web structure and ecosystem functioning. How this trade-off is shaped by organismal state in relation to multiple environmental stressors remains poorly understood. Attention to this issue is fundamentally important in an era of global change where multiple stressors increasingly present unique challenges for populations of organisms. The challenges are compounded by geographic patterns in adaptation that influence organismal state and the scope of trade-off responses. We argue for a modern approach that links evolutionary history to state-dependence to determine the scope of organismal foraging-predation risk trade-off behavior in the face of multiple stressors. Such integration will enhance predictions of the ecological consequences of organism living in different environmental contexts.