The ecological mechanisms regulating long-term variations of bacterioplankton communities in lake ecosystems remains poorly understood. Prof. YU Yuhe and his colleagues from Institute of Hydrobiology (IHB) of Chinese Academy of Sciences performed nearly a decade-long study of bacterioplankton communities in the eutrophic Lake Donghu (Wuhan, China). They found the strong repeatable seasonal diversity patterns of bacterioplankton were mainly controlled by niche-based processes.    

To understand how environmental factors regulate long-term community succession in lake ecosystems, the bacterioplankton communities collected from Lake Donghu during the past decade were analyzed by the 16S rRNA gene amplicon sequencing. The major ecological processes and their contributions to the community turnover were then determined by phylogenetic-based beta mean nearest taxon distance (βMNTD) in combination of Bray-Curtis-based Raup-Crick (RC_bray) distance analyses.    

The strong repeatable seasonal diversity patterns were found to be determined by strong homogeneous selection with modest dispersal limitation. That means when there has turnover in community membership, ecologically similar (and closely related) taxa in the community are interchanged, suggesting functional (or least ecological) redundancy within a season. However, the microbial taxa are more specialized among seasons due to environmental filtering (e.g. temperature, nutrient availability, and heavy metal contamination) and some related biological interactions (e.g. predation, and symbiosis).    

The dominant bacterial niches available in each season are occupied by similar combinations of bacterial taxa, and therefore show repeatable seasonal patterns across nearly a decade-long period. This study will improve our ability to use process-based models to predict ecosystem response to environmental change in lake ecosystems.   

This study was mainly finished with the cooperation of Prof. YU Yuhe at Institute of Hydrobiology, Chinese Academy of Sciences, Prof. YAN Qingyun at Sun Yat-sen University, and Prof. ZHOU Jizhong at University of Oklahoma.    

This work was published online in Molecular Ecology entitled “Nearly a decade-long repeatable seasonal diversity patterns of bacterioplankton communities in the eutrophic Lake Donghu (Wuhan, China)”. It was funded by the National Natural Science Foundation of China. 

Summary of ecological processes govern the bacterioplankton community turnover within each season
(Image by YAN Qingyun)