Fluctuating fortunes: Stressor synchronicity and fluctuating intensity influence biological impacts. (11th October 2022)

• Record Type: Journal Article
• Authors: Ostrowski, Andria; Connolly, Rod M.; Brown, Christopher J.; Sievers, Michael
• Is Part Of: Ecology letters. Volume 25:Number 12(2022)
• Page Start: 2611
• Page End: 2623
• Publication Date: 2022-10-11
• Subjects: anthropogenic impact -- asynchronous -- ecological realism -- experimental design -- nonadditive effects -- static stressors -- synchronous; Ecology -- Periodicals; 577
• DOI: 10.1111/ele.14120
• Languages: English
• ISSNs: 1461-023X

Abstract

Abstract: Ecosystems remain under enormous pressure from multiple anthropogenic stressors. Manipulative experiments evaluating stressor interactions and impacts mostly apply stressors under static conditions without considering how variable stressor intensity (i.e. fluctuations) and synchronicity (i.e. timing of fluctuations) affect biological responses. We ask how variable stressor intensity and synchronicity, and interaction type, can influence how multiple stressors affect seagrass. At the highest intensities, fluctuating stressors applied asynchronously reduced seagrass biomass 36% more than for static stressors, yet no such difference occurred for photosynthetic capacity. Testing three separate hypotheses to predict underlying drivers of differences in biological responses highlighted alternative modes of action dependent on how stressors fluctuated over time. Given that environmental conditions are constantly changing, assessing static stressors may lead to inaccurate predictions of cumulative effects. Translating multiple stressor experiments to the real world, therefore, requires considering variability in stressor intensity and the synchronicity of fluctuations. Abstract : Manipulative multiple stressor experiments mostly apply stressors under static conditions without incorporating variable stressor intensity (i.e. fluctuations) and synchronicity (i.e. timing of fluctuations). Here, we found asynchronous stressor fluctuations reduced seagrass biomass 36% more than static stressors. Our results highlight the importance of considering environmentally relevant changes in stressor intensity and synchronicity in future experimental designs to enhance our understanding of multiple stressor effects on biological responses.