Twenty-three years of monitoring reveal increased stability of zooplankton communities near subtropical nuclear power plants.

Abstract

Thermal effluents from nuclear power plants are a recognized anthropogenic disturbance that alters the surrounding physicochemical environment, but their long-term effects on zooplankton communities remain poorly understood. Using 23 years (2001-2023) of summer and winter monitoring data from Daya Bay, a typical subtropical bay in the northern South China Sea, we compared the community structure and temporal stability of zooplankton between the nuclear power plant-impacted zone (NPP) and its adjacent control area (ACA). In the NPP, zooplankton abundance and species richness shifted synchronously during summer, with a significant breakpoint detected. Zooplankton structure changed significantly after the breakpoints in both the NPP and ACA, while differences between areas remained insignificant, indicating that community dynamics were dominated by temporal changes at the regional scale. The temporal stability of zooplankton communities in the NPP increased significantly over the study period (p < 0.05) and showed marked seasonal variability, with stability higher in winter than in summer. The five most dominant species accounted for more than 90% of temporal instability in both areas, suggesting that dominant species played a major role in shaping community stability. These findings enhance our understanding of how thermal discharge interacts with local environments to drive planktonic stability, and highlight the importance of long-term monitoring, reference-area comparisons, and stability metrics in environmental assessments and management strategies for coastal energy facilities.