Meta-analysis using new methods for three-stressor combinations reveal
substantial higher-order interactions and emergent properties
Abstract
Although natural populations are typically subjected to multiple
stressors, most past research has focused on single stressors and
two-stressor interactions, with little attention paid to higher-order
interactions among three or more stressors. However, higher-order
interactions increasingly appear to be widespread. Consequently, we used
a recently introduced and improved framework to re-analyze higher-order
ecological interactions. We conducted a literature review of the last
100 years (1920-2020) and reanalyzed 151 ecological three-stressor
interactions from 45 published papers. We found that 89% (n=134) of the
three-stressor combinations resulted in new or different interactions
than previously reported. We also found substantial levels of emergent
properties—interactions that are only revealed when all three
stressors are present. Antagonism was the most prevalent net interaction
whereas synergy was the most prevalent emergent interaction.
Understanding multiple stressor interactions is crucial for fundamental
questions in ecology and also has implications for conservation biology
and population management.