Multiple anthropogenic stressors cause ecological surprises in boreal lakes |
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Authors: | MICHAEL R. CHRISTENSEN,MARK D. GRAHAM,ROLF D. VINEBROOKE,DAVID L. FINDLAY&dagger ,MICHAEL J. PATERSON&dagger , MICHAEL A. TURNER&dagger |
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Affiliation: | Freshwater Biodiversity Laboratory, Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9,;Freshwater Institute, 501 University Crescent, Winnipeg, MB, Canada R3T 2N6 |
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Abstract: | The number of combinations of anthropogenic stressors affecting global change is increasing; however, few studies have empirically tested for their interactive effects on ecosystems. Most importantly, interactions among ecological stressors generate nonadditive effects that cannot be easily predicted based on single‐stressor studies. Here, we corroborate findings from an in situ mesocosm experiment with evidence from a whole‐ecosystem manipulation to demonstrate for the first time that interactions between climate and acidification determine their cumulative impact on the food‐web structure of coldwater lakes. Interactions among warming, drought, and acidification, rather than the sum of their individual effects, best explained significant changes in planktonic consumer and producer biomass over a 23‐year period. Further, these stressors interactively exerted significant synergistic and antagonistic effects on consumers and producers, respectively. The observed prevalence of long‐ and short‐term ecological surprises involving the cumulative impacts of multiple anthropogenic stressors highlights the high degree of uncertainty surrounding current forecasts of the consequences of global change. |
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Keywords: | acidification boreal lakes climate warming drought global change nonadditive effects phytoplankton zooplankton |
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