Using a newly introduced framework to measure ecological stressor interactions

Understanding how stressors combine to affect population abundances and trajectories is a fundamental ecological problem with increasingly important implications worldwide. Generalizations about interactions among stressors are challenging due to different categorization methods and how stressors vary across species and systems. Here, we propose using a newly introduced framework to analyze data from the last 25 years on ecological stressor interactions, e.g. combined effects of temperature, salinity, and nutrients on population survival and growth. We contrast our results with the most commonly-used existing method—analysis of variance (ANOVA)—and show that ANOVA assumptions are often violated and have inherent limitations for detecting interactions. Moreover, we argue that rescaling—examining relative rather than absolute responses—is critical for ensuring that any interaction measure is independent of the strength of single-stressor effects. In contrast, non-rescaled measures—like AN...