PDF(Pubmed)
Abstract：
The Pollution Nagasaki (PN) section of the East China Sea (ECS) is a typical area for studying the complex hydrographic dynamics between Changjiang River discharge and Kuroshio, displaying intense variations of environmental gradients from nearshore to offshore. However, the temporal and spatial changes of microbial communities along the PN section have long been overlooked. In this study, we performed a comprehensive investigation into the abundance, diversity and ecology of free-living (FL) and particle-associated (PA) microbial communities in seawater samples along the PN section during both summer and winter. Distinct hydrological conditions and resulting environmental gradients were observed between summer and winter, with clear features of intrusive Kuroshio subsurface water in summer and strong vertical mixing of seawater in winter. Bacterial abundance along the PN section was higher in summer (1.11 × 108 copies·L-1 - 7.37 × 108 copies·L-1) than in winter (1.83 × 106 copies·L-1 - 1.34 × 108 copies·L-1). Microbial diversity, as indicated by α-diversity indices, remained at relatively stable levels in summer, while a clear decreasing trend was observed in winter along the PN section. Additionally, the winter communities exhibited a more evident spatial shift along the PN section compared to the summer communities. 16S rRNA gene amplicon sequencing showed that microbial community composition varied considerably between different seasons (summer and winter) and lifestyles (FL and PA), with a notable dominance of Ralstonia species. in winter. Regarding the assembly of microbial communities, the stochastic process represented by dispersal limitation was the dominant process in summer, while the deterministic homogeneous selection was the most important process in winter. Correspondingly, distinct topological properties of the microbial co-occurrence networks were shown between different seasons and along the PN section. These results enhance our understanding of how hydrological conditions influence dynamic changes of microbial communities along the PN section, providing new insights for the microbial community assembly and interactions in such a complex environment.
摘要：
东海（ECS）的长崎（PN）段是研究长江泄流与黑潮之间复杂水文动力学的典型区域，从近岸到近海显示出强烈的环境梯度变化。然而,PN剖面微生物群落的时空变化一直被忽视。在这项研究中,我们对丰度进行了全面调查，夏季和冬季沿PN剖面的海水样品中自由生活（FL）和颗粒相关（PA）微生物群落的多样性和生态学。在夏季和冬季之间观察到不同的水文条件和由此产生的环境梯度，夏季黑潮地下水侵入性明显，冬季海水垂直混合强烈。夏季沿PN剖面的细菌丰度（1.11×108拷贝·L-1-7.37×108拷贝·L-1）高于冬季（1.83×106拷贝·L-1-1.34×108拷贝·L-1）。微生物多样性,如α-多样性指数所示，夏季保持在相对稳定的水平，而在冬季沿PN剖面观察到明显的下降趋势。此外,与夏季群落相比，冬季群落沿PN剖面表现出更明显的空间变化。16SrRNA基因扩增子测序表明，不同季节（夏季和冬季）和生活方式（FL和PA）之间的微生物群落组成差异很大。Ralstonia物种的显着优势。在冬天。关于微生物群落的组装，以分散限制为代表的随机过程是夏季的主导过程，而确定性同质选择是冬季最重要的过程。相应地,在不同季节之间和沿PN截面显示出微生物共生网络的不同拓扑特性。这些结果增强了我们对水文条件如何影响PN剖面微生物群落动态变化的理解，在如此复杂的环境中，为微生物群落的组装和相互作用提供了新的见解。
