Seasonal modulation of phytoplankton biomass in the Southern Ocean.
Seasonal modulation of phytoplankton biomass in the Southern Ocean.
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DOI：
10.1038/s41467-020-19157-2
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发表时间：
2020-10-23
影响因子：
16.6
通讯作者：
Sarmiento JL
中科院分区：
文献类型：
--
作者：
Arteaga LA;Boss E;Behrenfeld MJ;Westberry TK;Sarmiento JL
在过去的十年中，卫星和地理限制的原位观测主要集中在北方，表明浮游植物生物量的年度周期不能从控制浮游植物分裂速率的环境特性（例如，营养和光），因为它们忽略了生态和环境损失过程的作用（例如，放牧、病毒、下沉）。在这里，我们使用多年的观察，从一个非常大的阵列的机器人漂流浮子在南大洋，以确定关键因素的浮游植物生物量动态的年度周期。我们的分析揭示了季节性浮游植物的积累（“开花”）事件发生在下降的建模分裂率，一个观察，突出了损失过程的重要性，在指示生物量的季节性周期的演变。在开放的南大洋，春季水华的规模被认为是最大的地区，高溶解铁浓度，铁是一个完善的主要限制营养素在这一地区一致。冰下观测表明，生物量在初冬开始增加，远在海冰开始消退之前。南大洋的平均理论敏感性的潜在变化，季节性的营养和光的可用性表明，浮游植物分裂率的10%的变化可能与平均水华规模和年度初级生产力减少50%，假设简单的变化，浮游植物分裂率的季节性幅度。总的来说，我们的研究结果强调了在浮游植物生物量周期的未来变化建模时，量化和核算两个部门和损失过程的重要性。浮游植物在地球化学上很重要，但它们在南大洋的季节性周期的驱动因素却没有得到很好的解决。在这里，作者使用了七年的ARGO浮标数据来测量整个南大洋的水华开始，衰退和终止，发现水华动态对细胞分裂速率和损失过程之间的耦合特别敏感。
Over the last ten years, satellite and geographically constrained in situ observations largely focused on the northern hemisphere have suggested that annual phytoplankton biomass cycles cannot be fully understood from environmental properties controlling phytoplankton division rates (e.g., nutrients and light), as they omit the role of ecological and environmental loss processes (e.g., grazing, viruses, sinking). Here, we use multi-year observations from a very large array of robotic drifting floats in the Southern Ocean to determine key factors governing phytoplankton biomass dynamics over the annual cycle. Our analysis reveals seasonal phytoplankton accumulation (‘blooming’) events occurring during periods of declining modeled division rates, an observation that highlights the importance of loss processes in dictating the evolution of the seasonal cycle in biomass. In the open Southern Ocean, the spring bloom magnitude is found to be greatest in areas with high dissolved iron concentrations, consistent with iron being a well-established primary limiting nutrient in this region. Under ice observations show that biomass starts increasing in early winter, well before sea ice begins to retreat. The average theoretical sensitivity of the Southern Ocean to potential changes in seasonal nutrient and light availability suggests that a 10% change in phytoplankton division rate may be associated with a 50% reduction in mean bloom magnitude and annual primary productivity, assuming simple changes in the seasonal magnitude of phytoplankton division rates. Overall, our results highlight the importance of quantifying and accounting for both division and loss processes when modeling future changes in phytoplankton biomass cycles. Phytoplankton are biogeochemically important but the drivers of their seasonal cycles in the Southern Ocean are poorly resolved. Here the authors use seven years of ARGO float data to measure bloom initiation, decline and termination throughout the Southern Ocean, finding that bloom dynamics are especially sensitive to the coupling between cell division rates and loss processes.
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影响因子：
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