Multiple stressors simplify freshwater food webs

Globally, freshwater ecosystems are threatened by multiple stressors, yet our knowledge of how they combine to regulate the structure and energy dynamics of food webs remains scant. To address this knowledge gap, we conducted a large-scale mesocosm experiment to quantify the single and combined effects of three common anthropogenic stressors, including warming, increased nutrient loading, and insecticide pollution, on the network structure and energetic processes of shallow lake food webs. We identified both antagonistic and synergistic interactive effects on aquatic food webs. Overall, multiple stressors simplified the food web, elongated energy transfer pathways, and shifted energy flow from benthic to more pelagic pathways. This increased the risk of a regime shift from a clear-water state dominated by submerged macrophytes to a turbid state dominated by phytoplankton. Our study highlights how multiple anthropogenic stressors can interactively disrupt food webs, with implications for understanding and managing these ecosystems in a changing world.

Methods
Collecting from the experiment