Multiple Stressors From Climate Warming, Neonicotinoid Pesticide, and Nutrient Loading Alter Zooplankton Predator–Prey Dynamics in Freshwaters

Climate warming, nutrient loading, and pesticide pollution are major anthropogenic stressors affecting community dynamics and trophic interactions in aquatic ecosystems. However, the complex interplay among these stressors remains poorly understood as most studies focus on a single stressor and overlook the effects of temporal variations. To address this knowledge gap, we first conducted a long‐term outdoor experiment to examine the effects of climate warming, nutrient loading, and a neonicotinoid pesticide (imidacloprid) on the responses of the common predator–prey pair cyclopoid copepods and rotifers. Additionally, a follow‐up laboratory experiment was conducted to assess the dose‐dependent impact of imidacloprid on the predation rate of cyclopoid copepods on rotifers, and to explore mechanistic alterations in biotic interactions resulting from predator responses to varying neonicotinoid concentrations. The neonicotinoid pesticide was the most influential stressor, significantly reducing cyclopoid copepod populations thereby positively affecting rotifer abundances due to a release from predation. Nutrient loading boosted copepod abundances but weakened their top‐down control on rotifer prey, disrupting predator–prey dynamics. Warming had negligible effects on copepod abundances, but ultimately increased rotifer abundances. Warming predominantly influenced rotifer abundances during the establishment phase, whereas the effects of the pesticide became more pronounced during subsequent growth and reproduction phases. Conversely, the neonicotinoid pesticide consistently emerged as the primary stressor impacting cyclopoid copepods throughout the experiment. Our study underscores the importance of considering temporal dynamics when assessing the combined effects of multiple stressors for understanding responses among interacting organisms and highlights the significance of organism life history stages in their distinct reactions to specific compounded threats over time.