Planktonic communities are naturally subjected to episodic nutrient enrichments that may stress or redress the imbalances in limiting nutrients. Human‐enhanced atmospheric nitrogen deposition has caused profound N:P imbalance in many remote oligotrophic lakes in which phosphorus has largely become limiting. These lakes offer an opportunity to investigate the relationship between the changes in plankton stoichiometry, productivity, and community structure occurring during nutrient fluctuations in P‐limited conditions. We performed P ( ${\text{PO}}_4^{3‐}$) and N ( ${\text{NH}}_4^{+}$ or ${\text{NO}}_3^{‐}$) pulse additions to the summer epilimnetic community of an ultraoligotrophic lake using self‐filling ~100‐L enclosures and analyzed the response to varying P availability, N:P imbalance, and N source. Seston C:N:P proportions remained fairly unchanged to P additions that were within the range of values seasonally found in the lake. However, the seston N:P ratio abruptly shifted and approached Redfield’s proportions at P additions typical of mesotrophic conditions that provided non‐limiting conditions. N surplus did not affect seston C:N:P proportions. The patterns of seston N:P stability and shift were similar for both N sources. In contrast, productivity was highly sensitive to low and medium P additions and decelerated at high P additions. Phytoplankton biomass dominated particulate organic matter. The autotrophic community differentiated almost linearly across the P gradient. Chrysophytes' dominance decreased, and diatoms and cryptophytes relative abundance increased. Nonetheless, the stoichiometry stability and non‐linear shift involved large biomass proportions of the same species, which indicates that the bulk stoichiometry was related to similar physiological behavior of phylogenetically diverse organisms according to the biogeochemical context. The C:N:P seston stability in P‐limited conditions—with loose coupling with productivity, nutrient supply ratios, and species dominance—and the sudden shift to Redfield proportions in P‐repleted conditions suggest a complex regulation of P scarcity in planktonic communities that goes beyond immediate acclimation growth responses and might include alternative physiological and biogeochemical states.

中文翻译：

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P限制的浮游生物群落化学计量的稳态和非线性位移

浮游生物群落自然经历了周期性的营养富集，这些营养富集可能会强调或纠正限制营养素的不平衡。在许多偏远的贫营养湖泊中，人为增加的大气氮沉积已导致严重的N：P失衡，而磷在很大程度上已经变得有限。这些湖泊提供了一个研究磷限制条件下养分波动期间浮游生物化学计量变化，生产力和群落结构之间关系的机会。我们执行了P（${\text{PO}}_4^{3‐}$）和N（ ${\text{NH}}_4^{+}$ 要么 ${\text{没有}}_3^{‐}$）使用自填充〜100-L围栏向超寡营养湖泊的夏季表生群落添加脉冲，并分析了对变化的P有效性，N：P失衡和N源的响应。硒的C：N：P比例与P的添加量基本保持不变，P的添加量在湖中季节性发现的值范围内。但是，在提供非限制性条件的典型的中营养条件下，添加P的情况下，活塞的N：P比突然变化并接近Redfield的比例。氮过剩不会影响活塞的C：N：P比例。两种氮源的血浆N：P稳定性和迁移模式相似。相反，生产率对低磷和中磷的添加高度敏感，而在高磷的添加下速度降低。浮游植物生物质占主导地位的颗粒有机物。自养群落在P梯度上几乎呈线性分化。锦藻的优势度下降，硅藻和隐藻的相对丰度提高。然而，化学计量学的稳定性和非线性变化涉及同一物种的大量生物量，这表明，根据生物地​​球化学背景，整体化学计量学与系统发育多样性生物的相似生理行为有关。在磷受限的条件下，C：N：P活塞的稳定性与生产率，养分供应比，