The microbial community composition and biogeochemical dynamics of coastal permeable (sand) sediments differs from cohesive (mud) sediments. Tide- and wave-driven hydrodynamic disturbance causes spatiotemporal variations in oxygen levels, which select for microbial generalists and disrupt redox cascades. In this work, we profiled microbial communities and biogeochemical dynamics in sediment profiles from three sites varying in their exposure to hydrodynamic disturbance. Strong variations in sediment geochemistry, biogeochemical activities, and microbial abundance, composition, and capabilities were observed between the sites. Most of these variations, except for microbial abundance and diversity, significantly correlated with the relative disturbance level of each sample. In line with previous findings, metabolically flexible habitat generalists (e.g., Flavobacteriaceae, Woeseaiceae, Rhodobacteraceae) dominated in all samples. However, we present evidence that aerobic specialists such as ammonia-oxidizing archaea (Nitrosopumilaceae) were more abundant and active in more disturbed samples, whereas bacteria capable of sulfate reduction (e.g., uncultured Desulfobacterales), dissimilatory nitrate reduction to ammonium (DNRA; e.g., Ignavibacteriaceae), and sulfide-dependent chemolithoautotrophy (e.g., Sulfurovaceae) were enriched and active in less disturbed samples. These findings are supported by insights from nine deeply sequenced metagenomes and 169 derived metagenome-assembled genomes. Altogether, these findings suggest that hydrodynamic disturbance is a critical factor controlling microbial community assembly and biogeochemical processes in coastal sediments. Moreover, they strengthen our understanding of the relationships between microbial composition and biogeochemical processes in these unique environments.

沿海渗透性（沙）沉积物的微生物群落组成和生物地球化学动力学不同于粘性（泥）沉积物。潮汐和波浪驱动的水动力干扰会导致氧气水平的时空变化，这会选择微生物通才并破坏氧化还原级联。在这项工作中，我们分析了三个地点的沉积物剖面中的微生物群落和生物地球化学动力学，这些地点的水动力干扰暴露程度不同。在不同地点之间观察到沉积物地球化学、生物地球化学活动以及微生物丰度、组成和能力的强烈变化。除微生物丰度和多样性外，这些变化中的大多数都与每个样本的相对干扰水平显着相关。与之前的研究结果一致，代谢灵活的栖息地通才（例如，黄杆菌科，Woeseaiceae，Rhodobacteraceae）在所有样本中占主导地位。然而，我们提出的证据表明，需氧专家如氨氧化古菌（亚硝基菌科）在更受干扰的样品中更为丰富和活跃，而能够进行硫酸盐还原的细菌（例如，未培养的脱硫杆菌目）、异化硝酸盐还原为铵（DNRA；例如， Ignavibacteriaceae) 和硫化物依赖性化能自养（例如 Sulfurovaceae）在受干扰较小的样品中富集和活跃。这些发现得到了来自 9 个深度测序的宏基因组和 169 个衍生的宏基因组组装基因组的见解的支持。共，这些研究结果表明，水动力干扰是控制沿海沉积物中微生物群落组装和生物地球化学过程的关键因素。此外，它们加强了我们对这些独特环境中微生物组成与生物地球化学过程之间关系的理解。