Weak cross-trophic coupling of multidimensional stability in plankton communities under multiple stressors

Nutrient enrichment and biological invasions frequently co-occur in freshwater ecosystems, yet it remains unclear whether stability of entire planktonic groups responds uniformly to these combined stressors. To address this question, we conducted a fully factorial mesocosm experiment that crossed three nutrient regimes with two invasive species that impose distinct disturbance pathways. We quantified temporal stability, resistance, resilience, and recovery across functional and compositional facets in zooplankton, phytoplankton, and bacterioplankton communities. Our results revealed highly taxon- and dimension-specific responses. Snail bioturbation significantly reduced the functional resistance of zooplankton under high nutrient conditions. Meanwhile, the functional resistance of bacterioplankton declined with increasing nutrient levels. This suggests that functionally distinct stressors may affect different trophic guilds through distinct mechanisms. Species richness was consistently positively associated with compositional temporal stability, resistance and recovery across all trophic levels, but was negatively associated with resilience, revealing a fundamental trade-off between maintaining community robustness and enabling rapid adaptability. Functional and compositional stability were positively correlated only in the temporal stability dimension, but exhibited negative associations in the resistance and recovery dimensions. This indicates that biomass-related functions and community structure can follow divergent trajectories throughout perturbation and recovery. Most critically, the multivariate analyses and pairwise correlations among trophic levels indicated generally weak cross-trophic coupling, suggesting that, under the conditions of this mesocosm experiment, no single planktonic group provided a consistently reliable proxy for multidimensional whole-community stability. These findings highlight the value of assessing multiple dimensions of ecological stability across trophic groups. Consideration of stability indicators across multitrophic groups may provide complementary information for adaptive lake management as global pressures from nutrient loading and biological invasions continue to intensify.