Figure 1. Conceptual Framework: integrating the behavior, physiology, and bioenergetics of coping with multiple stressors. Energy is allocated among key components (thick arrows) leading ultimately to fitness effects; the 4 key trade-offs are color-coded. Assimilated Energy pays the energy cost of basal metabolism (BMR), and the remaining Net Energy Gain Rate is subdivided into three competing energy sinks (yellow rectangles, trade-off 3). The energy flow into response to stressors powers two types of escape plus tolerance (green rectangles, trade-off 4). Stressor Tolerance provides energy for the mechanisms to avoid when possible or otherwise to mitigate the stressor effects. These mechanisms may be behavioral or physiological or both (blue rectangles, trade-off 1); they are triggered by the Stressors and ameliorate them while potentially interacting with each other. Activity creates a trade-off between Energy Assimilation Rate and Survival (pink rectangles, trade-off 2). Food Availability and Risk of Predation or Other Mortality sources potentially increased by activity act on these linkages. Survival and Growth/Reproduction are influenced by the Stressors and Coping Mechanisms, jointly yielding Fitness.
Figure 2 . Categories of multiple stressor combination types according to degrees of feedback between stressor(s) and focal organisms from A) no feedback, B) uni-directional feedback and C) bi-directional feedback.