Nano- and picophytoplankton are a major component of open-ocean ecosystems and one of the main plankton functional types in biogeochemical models, yet little is known about their trace metal contents. In cultures of the picoeukaryote Ostreococcus lucimarinus, iron limitation reduced iron quotas by 68%, a fraction of the plasticity known in diatoms. In contrast, a commonly co-occurring cyanobacterium, Prochlorococcus, showed variable iron contents with iron availability in culture. Synchrotron X-ray fluorescence was used to measure single-cell metal (Mn, Fe, Co, Ni, Zn) quotas of autotrophic flagellates (1.4–16.8-μm diameter) collected from four ocean regions. Iron quotas were tightly constrained and showed little response to iron availability, similar to cultured Ostreococcus. Zinc quotas also did not vary with zinc availability but appeared to vary with phosphorus availability. These results suggest that macronutrient and metal availability may be equally important for controlling metal contents of small eukaryotic open-ocean phytoplankton.

中文翻译：

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来自对比开放海洋生态系统的自养鞭毛虫的微量金属含量

纳米和微型浮游植物是公海生态系统的主要组成部分，也是生物地球化学模型中主要的浮游生物功能类型之一，但对其微量金属含量知之甚少。在picoeukaryote Ostreococcus lucimarinus的培养物中，铁限制减少了 68% 的铁配额，这是硅藻中已知可塑性的一小部分。相比之下，一种常见的蓝藻，原绿球藻，在培养物中显示出可变的铁含量和铁的可用性。同步加速器 X 射线荧光用于测量自养鞭毛虫 (1.4–16.8- μ ) 的单细胞金属 (Mn、Fe、Co、Ni、Zn) 配额m 直径）从四个海洋区域收集。铁配额受到严格限制，对铁的可用性几乎没有反应，类似于培养的 Ostreococcus。锌配额也没有随锌的可用性而变化，但似乎随磷的可用性而变化。这些结果表明，大量营养素和金属的有效性对于控制小型真核海洋浮游植物的金属含量可能同样重要。