Cyanobacterial harmful algal blooms (HABs) are increasing in frequency and magnitude worldwide. A number of parameters are thought to underlie HABs, including the ratio at which two key elements, nitrogen (N) and phosphorus (P) are supplied, although a predictive understanding eludes us. While the physiological importance of iron (Fe) in electron transport and N-fixation is well known, relatively little is known about its impacts on the growth of freshwater cyanobacteria. Moreover, there is growing appreciation for correlated changes in the quotas of multiple elements encompassing an organism (i.e. the ionome) when the supply of one element changes, indicating that growth differences arise from complex biochemical adjustments rather than limitation of a key anabolic process by a single element. In this study, the effects of supply N:P and Fe on the growth and ionome of Dolichospermum, a nitrogen-fixing cyanobacterium found in freshwater ecosystems, were examined. Changes in both supply N:P and Fe had significant effects on yield. Consistent with prior observations, cyanobacterial growth was higher at N:P = 20, compared to N:P = 5, and quotas of all elements decreased with growth. Yield was negatively related with the degree of imbalance between dissolved supply and intracellular concentrations of not only N and Fe, but also multiple other elements. Changes in Fe supply had a significant effect on yield in N-limited conditions (N:P = 5). Again, ionome-wide imbalances decreased yield. Together, these results indicate that attention to multiple elements encompassing the ionome of a HAB-forming taxon, and the supplies of such elements may help improve the ability to forecast blooms. Such elemental interactions may be critical as limnologists begin to appreciate the staggering variation in the supplies of such elements among lakes, and anthropogenic activities continue to alter global biogeochemical cycles.

蓝藻有害藻华（HAB）在全球范围内的频率和规模都在增加。许多参数被认为是 HAB 的基础，包括提供两种关键元素氮 (N) 和磷 (P) 的比率，尽管我们无法预测。虽然铁 (Fe) 在电子传输和固氮中的生理重要性众所周知，但对其对淡水蓝藻生长的影响知之甚少。此外，当一种元素的供应发生变化时，包含生物体的多种元素（即离子体）的配额的相关变化越来越受到重视，这表明生长差异源于复杂的生化调整，而不是一个关键合成代谢过程的限制。单个元素。在本研究中，供给 N 的影响：紫草，一种在淡水生态系统中发现的固氮蓝藻，进行了检查。供应 N:P 和 Fe 的变化对产量有显着影响。与先前的观察结果一致，与 N:P = 5 相比，N:P = 20 时蓝藻的生长更高，并且所有元素的配额都随着生长而减少。产量与溶解供应和细胞内浓度之间的不平衡程度呈负相关，不仅是 N 和 Fe，还与多种其他元素有关。在氮限制条件下（N:P = 5），Fe 供应的变化对产量有显着影响。同样，离子体范围内的不平衡降低了产量。总之，这些结果表明，关注包含形成 HAB 的分类群的离子组的多种元素，以及这些元素的供应可能有助于提高预测水华的能力。