Diversity, Assembly, and Habitat-Driven Dynamics of Microbial Communities in Eutrophic Dianchi Lake, Southwest China

Microbial communities, as key components of aquatic ecosystems, serve as sensitive indicators of environmental changes and potential drivers of ecological degradation and restoration. This study focuses on three representative regions of Dianchi Lake – a plateau lake with coexisting algal blooms and aquatic vegetation: submerged plant residual zone (SubmP), heavily polluted area (hPollut), and algal aggregation zone (HABs). The results revealed a high diversity of microbial communities across these regions, with 69 bacterial phyla and 1,128 genera, as well as 9 fungal phyla and 477 genera identified. However, significant spatial differences in microbial communities were observed, primarily driven by rare taxa, including region-specific rare taxa. The main environmental drivers of microbial differentiation include total nitrogen (TN), dissolved oxygen, water temperature, and transparency, with TN identified as the key factor shaping microbial community structure. The study also found that core microbial taxa, such as Flavobacterium and Metschnikowia, were prevalent across the regions and occupied significant ecological niches, contributing to community stability and potentially acting as resistance agents in environmental remediation. Furthermore, rare taxa play a crucial role in maintaining community diversity and stability, serving as sensitive bioindicators of environmental change. Functional predictions reveal clear ecological adaptation of microbial communities across the regions. These findings provide important insights into microbial community structure and function in eutrophic lake ecosystems, suggesting that strategies to reduce external nitrogen inputs, restore submerged vegetation, and optimize dissolved oxygen management could effectively reverse microbial degradation in plateau lakes.