Cyanobacterial Diazotroph Distributions in the Western South Atlantic
Cyanobacterial Diazotroph Distributions in the Western South Atlantic
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DOI：
10.3389/fmars.2022.856643
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发表时间：
2022-05
期刊：
影响因子：
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通讯作者：
A. Detoni;A. Subramaniam;S. T. Haley;S. Dyhrman;P. Calil
中科院分区：
文献类型：
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作者：
A. Detoni;A. Subramaniam;S. T. Haley;S. Dyhrman;P. Calil
蓝藻重氮营养体的新氮输入对海洋生态系统的结构和功能至关重要。与其他海洋区域相比，南大西洋西部缺乏这些微生物分布的数据。本研究利用nifH基因的定量PCR (qPCR)，沿Vitória-Trindade海山链（1200 km）从陆架断裂延伸至开放海洋的样带，测量了6个重氮营养菌种型的丰度：Trichodesmium、Crocosphaera、UCYN-A、与rhizzosolenia相关的Richelia （ht -1）或hemiulus （ht -2）以及与Chaetoceros相关的Calothrix （ht -3）。用nifH基因拷贝数作为物种型丰度的代表，鳄鱼信号最丰富，在整个研究区域分布广泛。霉丝菌的信号是第二丰富的，在靠近海岸的温暖水域中数量最多，并且与温度显著正相关。宿主相关重氮营养体（UCYN-A， Het-1和Het-2）的平均信号始终低于其他种型。这些发现扩大了南大西洋西部蓝藻重氮营养盐分布的测量范围，并为加强全球海洋固氮模式的建模研究提供了新的资源。
Inputs of new nitrogen by cyanobacterial diazotrophs are critical to ocean ecosystem structure and function. Relative to other ocean regions, there is a lack of data on the distribution of these microbes in the western South Atlantic. Here, the abundance of six diazotroph phylotypes: Trichodesmium, Crocosphaera, UCYN-A, Richelia associated with Rhizosolenia (Het-1) or Hemiaulus (Het-2), and Calothrix associated with Chaetoceros (Het-3) was measured by quantitative PCR (qPCR) of the nifH gene along a transect extending from the shelf-break to the open ocean along the Vitória-Trindade seamount chain (1200 km). Using nifH gene copies as a proxy for phylotype abundance, Crocosphaera signals were the most abundant, with a broad distribution throughout the study region. Trichodesmium signals were the second most abundant, with the greatest numbers confined to the warmer waters closer to the coast, and a significant positive correlation with temperature. The average signals for the host-associated diazotrophs (UCYN-A, Het-1, and Het-2) were consistently lower than for the other phylotypes. These findings expand measurements of cyanobacterial diazotroph distribution in the western South Atlantic, and provide a new resource to enhance modeling studies focused on patterns of nitrogen fixation in the global ocean.