Vertical characterisation of phylogenetic divergence of microbial community structures, interaction, and sustainability in estuary and marine ecosystems

The changes in the aquatic environmental conditions often influence the microbial community assemblages and genome repertoire. Studies investigating the aquatic diversity and ecosystem services were primarily conducted in horizontal environments while neglecting the microbial phylogenetic divergences, biotrophic interactions, and eco-sustainability at water vertical layers. We investigated the mechanisms of microbial transitions, and the ecological sig-nificance of water depth layers in the estuary and marine ecosystems. The results demonstrated that the salinity and turbidity increased with increasing water depth (0-50 m), while temperature and pH decreased significantly. The bac-terial and eukaryotic diversity and composition significantly increased with an elevating water depth. Bacterial phyla such as Desulfobacterota, Acidobacteriota, Myxococcota, Gemmatimonadota, Campilobacterota, and Latescibacterota were increased significantly. However, niche preference occurred, and some microbes showed differential nestedness at water vertical layers. In the eukaryotic community, Eustigmatales group were the only clades predominantly phy-logenetically nested at the surface water depth. c_Conoidasida, o_Gregarinasina, f_Eugregarinorida, and g_Lankesteria were the most predominant at the middle depth. While Mediophyceae clades, p_SAR, and the Animalia clades were the most predominant groups nested at the bottom depths. The microbial interaction, structure, and stability were in-creased with increasing depth. The vertical phylogenetic turnover of the microbial community was related to the feeding mechanisms. Phototrophic organisms were particularly adapted at the surface, and middle depth by parasitic and pathogenic organisms, while the bottom was inhabited by diatoms, decomposers, and detritus protists. This study demonstrated that the bottom depth was the most ecologically stable area with more profound ecosystem services.

Automated summary

Changes in aquatic environmental conditions can affect microbial community assemblages and genome repertoire. Increasing water depth leads to higher bacterial and eukaryotic diversity and composition. Different microbes show differential nestedness at different water depths. The bottom depth is the most ecologically stable area with more profound ecosystem services.