Chesapeake Bay is a large, dynamic, and productive temperate estuary, which plays an important role in transporting terrestrial materials into the Atlantic Ocean. The bacterioplankton communities experience strong environmental changes both seasonally and along the central axis of the Bay. The goal of this study was to explore the spatiotemporal and interannual patterns of the bacterioplankton communities in the estuary using high‐throughput sequencing of 16S rRNA genes. Deep sequencing uncovered many new bacterial groups not found in earlier studies, and showed that Chesapeake Bay contained highly diverse and dynamic bacterial communities. Bacterioplankton in the Bay in summer and autumn were more diverse and stable than those in winter and spring. The spatial pattern was overruled by strong temporal variations when the samples from all seasons were analyzed together. But, the spatial trend became more visible when samples were analyzed separately in individual seasons. Bacterial diversity indices decreased from the upper Bay to lower Bay. The spatial and temporal distributions of bacterioplankton were best explained by variations of salinity and temperature. In addition, nutrient availability (nitrogen and phosphorus), chlorophyll a, and light availability also contributed significantly to the spatiotemporal variation. Despite the interannual variation of the bacterioplankton communities, a stable and reoccurring spatiotemporal pattern was observed in the Chesapeake Bay, suggesting limited functional redundancy for planktonic estuarine microbiomes. Our results highlight the resilience of the planktonic bacterial communities in estuaries with long residence time, and different bacterial groups have unique responses/adaptation to dynamic environmental gradients.

中文翻译：

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切萨皮克湾浮游细菌的时空变化：高通量测序分析的重新检验

切萨皮克湾（Chesapeake Bay）是一个大型，充满活力且高产的温带河口，在将陆地物质运输到大西洋中起着重要作用。季节性和沿海湾中轴的浮游细菌群落都经历了强烈的环境变化。这项研究的目的是使用16S rRNA基因的高通量测序探索河口浮游生物群落的时空和年际格局。深度测序发现了先前研究中未发现的许多新细菌群，并表明切萨皮克湾包含高度多样化和动态的细菌群落。夏季和秋季，海湾的浮游细菌比冬季和春季的浮游细菌更加多样化和稳定。当一起分析所有季节的样本时，空间格局被强烈的时间变化所否决。但是，当在各个季节分别分析样本时，空间趋势变得更加明显。细菌多样性指数从上海湾到下海湾下降。盐度和温度的变化最好地解释了浮游细菌的时空分布。此外，养分利用率（氮和磷），叶绿素 a，光的可用性也极大地影响了时空变化。尽管浮游植物群落的年际变化，但在切萨皮克湾仍观察到稳定且反复发生的时空格局，表明浮游河口微生物群的功能冗余有限。我们的研究结果突出显示了长时间停留在河口的浮游细菌群落的复原力，并且不同的细菌群体对动态环境梯度具有独特的响应/适应性。