Temporal niche differentiation of rhythmic taxa enhances microbial network stability in a subtropical reservoir

The composition of planktonic microbial community changes over time in aquatic ecosystems, but how rhythmic subcommunities affect microbial dynamics and network stability remains unclear. Based on year-round monitoring in the subtropical Xin'anjiang Reservoir, this study employed Lomb Scargle periodogram (LSP) time series analysis, co-occurrence network construction, phylogenetic clustering, and community assembly modeling to investigate the temporal niche differentiation of rhythmic taxa and their impact on microbial network stability. Our results revealed that rhythmic taxa constitute a substantial fraction of both bacterial and microeukaryotic communities and dominate seasonal succession patterns. Rhythmic taxa significantly enhance network stability by contributing to keystone roles and improving compositional temporal stability. Phylogenetic analysis demonstrated that rhythmic and non-rhythmic taxa exhibit pronounced temporal niche partitioning, which reduces competitive overlap and promotes long-term coexistence. Furthermore, rhythmic taxa were more constrained by dispersal limitation, indicating stronger spatial-temporal consistency in their ecological responses. The PLS-PM structural equation model revealed that water temperature and nutrient indirectly influenced microbial network stability by regulating rhythmic taxa. Overall, our findings identify rhythmic taxa as key temporal ecological indicators in subtropical freshwater systems. In addition, this study provides a novel framework for incorporating microbial temporal dynamics into ecological monitoring and water resource management.