Phytoplankton Patches at Oceanic Fronts Are Linked to Coastal Upwelling Pulses: Observations and Implications in the California Current System
Phytoplankton Patches at Oceanic Fronts Are Linked to Coastal Upwelling Pulses: Observations and Implications in the California Current System
复制标题
海洋前沿的浮游植物斑块与沿海上升流脉冲有关：加州洋流系统的观测和影响
DOI：
10.1029/2022jc019095
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Franks, Peter J. S.
中科院分区：
文献类型：
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作者：
Gangrade, Shailja;Franks, Peter J. S.
局部增强的生物生产和增加的碳输出是海洋密度锋的持续特征。研究通常假设生物学特性沿沿着前沿是均匀的，或者假设沿着和跨前沿梯度反映了前沿发生的物理生物学过程。然而，沃茨在锋面的停留时间往往短于生物反应时间。因此，另一个经常未经检验的假设是，观察到的生物斑块起源于上游的前线。为了检验这两个假设，我们探讨了一个涡相关的前在加州电流系统采样在两个调查，间隔3周。在两次调查的北方末端都发现了高浮游植物生物量的斑块，浮游植物生物量沿着锋面下降。虽然这些斑块发生在相似的位置，但尚不清楚是否对同一斑块进行了两次采样，或者两个斑块是否不同。使用平流反应框架结合现场和卫星数据，我们发现溶解氧，颗粒生物量和盐度的沿着-锋梯度的变化支持这两个浮游植物斑块不同的结论。它们只是碰巧在相似的地点被采样。对水包裹的向后和向前的时间跟踪表明，这些浮游植物斑块具有不同的起源，与锋面上游特定的、强烈的沿海上升流脉冲有关。浮游植物生长在这些最近上升的沃茨，因为他们平流进入和沿着锋面系统。通过考虑当地和上游的物理-生物强迫，这种方法可以更好地描述在空间和时间尺度上发生在前沿的关键物理和地球化学过程。
Locally enhanced biological production and increased carbon export are persistent features at oceanic density fronts. Studies often assume biological properties are uniform along fronts or hypothesize that along‐ and across‐front gradients reflect physical‐biological processes occurring in the front. However, the residence times of waters in fronts are often shorter than biological response times. Thus, an alternate—often untested—hypothesis is that observed biological patchiness originates upstream of a front. To test these two hypotheses, we explore an eddy‐associated front in the California Current System sampled during two surveys, separated by 3 weeks. Patches of high phytoplankton biomass were found at the northern ends of both surveys, and phytoplankton biomass decreased along the front. While these patches occurred in similar locations, it was unclear whether the same patch was sampled twice, or whether the two patches were different. Using an advection‐reaction framework combined with field and satellite data, we found that variations in along‐front gradients in dissolved oxygen, particle biovolume, and salinity support the conclusion that the two phytoplankton patches were different. They were only coincidentally sampled in similar locations. Backward‐ and forward‐in‐time tracking of water parcels showed that these phytoplankton patches had distinct origins, associated with specific, strong coastal upwelling pulses upstream of the front. Phytoplankton grew in these recently upwelled waters as they advected into and along the frontal system. By considering both local and upstream physical‐biological forcings, this approach enables better characterizations of critical physical and biogeochemical processes that occur at fronts across spatial and temporal scales.