Phytoplankton iron contents (i.e., quotas) directly link biogeochemical cycles of iron and carbon and drive patterns of nutrient limitation, recycling, and export. Ocean biogeochemical models typically assume that iron quotas are either static or controlled by dissolved iron availability. We measured iron quotas in phytoplankton communities across nutrient gradients in the Pacific Ocean and found that quotas diverged significantly in taxon‐specific ways from laboratory‐derived predictions. Iron quotas varied 40‐fold across nutrient gradients, and nitrogen‐limitation allowed diatoms to accumulate fivefold more iron than co‐occurring flagellates even under low iron availability. Modeling indicates such “luxury” uptake is common in large regions of the low‐iron Pacific Ocean. Among diatoms, both pennate and centric genera accumulated luxury iron, but the cosmopolitan pennate genus Pseudo‐nitzschia maintained iron quotas 10‐fold higher than co‐occurring centric diatoms, likely due to enhanced iron storage. Biogeochemical models should account for taxonomic and macronutrient controls on phytoplankton iron quotas.

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海洋中浮游植物铁配额的生物分类和营养控制

浮游植物的铁含量（即配额）直接联系了铁和碳的生物地球化学循环，并驱动了养分限制，循环利用和出口的模式。海洋生物地球化学模型通常假设铁的配额是静态的或受溶解的铁的可用性控制。我们测量了太平洋中不同营养梯度下浮游植物群落中的铁配额，发现配额与实验室得出的预测在分类单元上显着不同。在营养梯度上，铁的配额变化了40倍，而氮的限制使硅藻即使在铁的利用率较低的情况下，其铁的累积量仍比同时出现的鞭毛多五倍。模型表明，在低铁太平洋的大部分地区，这种“奢侈”的摄取很普遍。在硅藻中，半夏属和中枢属都积累了丰富的铁，假性紫癜维持的铁含量比同时出现的中心硅藻高出10倍，这可能是由于铁的储存量增加所致。生物地球化学模型应考虑对浮游植物铁配额的分类和大量营养素控制。