Nitrification plays a key role in marine ecosystems where Thaumarchaeota are thought to be responsible for most of the ammonia oxidation in the water column. Over a 2‐yr, near‐monthly time series at two sites in Monterey Bay we observed repeatable seasonal and depth‐based patterns of Thaumarchaeota ecotype abundance that highlighted a clear delineation between populations in shallow euphotic (< 50 m) vs. deeper mesopelagic (60–500 m) depths. Euphotic depths show greater seasonality and influence from light, while mesopelagic waters have trends based on water mass and other covarying features with depth. Three major ecotypes were recovered: a Nitrosopumilus‐like (NP) group, a Nitrosopelagicus‐like ecotype containing “shallow” water column A (WCA) members, and an ecotype affiliated with the “deep” water column B (WCB) Thaumarchaeota. These ecotypes show a strong depth distribution, with WCB dominant at ≥ 200 m depth and WCA most abundant in surface (5–100 m) waters. The NP ecotype was found throughout the water column with the highest abundance in summer, and was the only ecotype showing a correlation with measured nitrification rates. We also found three abundant taxa related to Nitrospina—the major nitrite‐oxidizing bacteria in the ocean; these showed clear connections to each of the three Thaumarchaeota ecotypes, suggesting a specific relationship between both steps of nitrification. Our results support the importance of ecotype‐based analysis of Thaumarchaeota and show that their abundance and distribution are controlled based on their water column position, with a distinct shift at 50 m between euphotic and mesopelagic depths.

中文翻译：

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蒙特雷湾丘陵古生物生态类型的时间序列评估揭示了水柱位置在预测分布与环境关系中的重要性

硝化作用在海洋生态系统中起着关键作用，其中认为Thaumarchaeota是水柱中大部分氨氧化的原因。在蒙特利湾的两个地点，历时2年近一个月的时间序列中，我们观察到Thaumarchaeota生态型丰度的可重复的季节性和基于深度的模式，突显了浅层富营养化（<50 m）与深层中古生化（ 60–500 m）深度。富营养深度表现出更大的季节性和受光的影响，而中生水具有基于水团和其他随深度变化的特征的趋势。回收了三种主要的生态型：类群的Nitrosopumilus（NP）组，Nitrosopelagicus包含“浅”水列A（WCA）成员以及与“深”水列B（WCB）Thaumarchaeota相关的生态型。这些生态型显示出很强的深度分布，其中WCB在≥200 m的深度占优势，WCA在地表水（5–100 m）中最为丰富。在整个水域中发现的NP生态型在夏季的丰度最高，并且是唯一显示与测得的硝化率相关的生态型。我们还发现了三种与硝化梭菌有关的丰富的分类单元，它们是海洋中主要的亚硝酸盐氧化细菌。这些显示出与三个Thaumarchaeota的清晰联系生态型，暗示硝化两个步骤之间的特定关系。我们的结果支持基于生态型的Thaumarchaeota分析的重要性，并表明它们的丰度和分布是根据它们在水柱中的位置来控制的，其中富营养度和中生度的深度在50 m处有明显的偏移。