Patterns of iron and siderophore distributions across the California Current System
Patterns of iron and siderophore distributions across the California Current System
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DOI：
10.1002/lno.11046
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发表时间：
2019-01-01
影响因子：
4.5
通讯作者：
Repeta, Daniel J.
中科院分区：
文献类型：
--
作者：
Boiteau, Rene M.;Till, Claire P.;Repeta, Daniel J.
东部边界流沿岸营养物质和金属的上涌为一些最具生物生产力的海洋生态系统提供了燃料。尽管铁是其中许多地区生产力的主要驱动力，但铁的循环和微生物获取铁的限制仍然很少，部分原因是使生物可利用铁保持在溶液中的有机配体的组成未知。在这项研究中，我们研究了通过高生产力的加利福尼亚海岸上升流系统收集的离散水样中的有机配体组成。在从下午1点到18点的浓度范围内，在不同的营养条件下观察到铁载体。在浅海大陆架附近，在最近上升的高叶绿素表层水域中观察到铁胺B，而在60-90m深处的类星状层中发现了联结活力素。在以中等浓度的叶绿素、铁和硝酸盐为特征的近海水域，我们发现了两栖杆菌素和一个未知的铁载体，分子式为C33H58O8N5Fe。在光亮区测得的浓度最高，但在1500米深的水域中也发现了两栖杆菌素。铁载体的分布提供了各种营养制度中微生物铁缺乏的证据，并表明铁载体的生产和获取是铁限制沿海系统生物铁吸收的重要战略。在整个水柱中也发现了多分散的腐殖酸配体，在底栖生物边界附近尤其丰富。我们的结果突出了上升流环境中金属配体组成的精细空间异质性，并阐明了不同的来源，包括生物生产和亚氧水域中有机物的降解。
Coastal upwelling of nutrients and metals along eastern boundary currents fuels some of the most biologically productive marine ecosystems. Although iron is a main driver of productivity in many of these regions, iron cycling and acquisition by microbes remain poorly constrained, in part due to the unknown composition of organic ligands that keep bioavailable iron in solution. In this study, we investigated organic ligand composition in discrete water samples collected across the highly productive California Coastal upwelling system. Siderophores were observed in distinct nutrient regimes at concentrations ranging from 1 pM to 18 pM. Near the shallow continental shelf, ferrioxamine B was observed in recently upwelled, high chlorophyll surface waters while synechobactins were identified within nepheloid layers at 60-90 m depth. In offshore waters characterized by intermediate chlorophyll, iron, and nitrate concentrations, we found amphibactins and an unknown siderophore with a molecular formula of C33H58O8N5Fe. Highest concentrations were measured in the photic zone, however, amphibactins were also found in waters as deep as 1500 m. The distribution of siderophores provides evidence for microbial iron deficiency across a range of nutrient regimes and indicates siderophore production and acquisition is an important strategy for biological iron uptake in iron limited coastal systems. Polydisperse humic ligands were also detected throughout the water column and were particularly abundant near the benthic boundary. Our results highlight the fine-scale spatial heterogeneity of metal ligand composition in an upwelling environment and elucidate distinct sources that include biological production and the degradation of organic matter in suboxic waters.