Plankton dynamics in a cyclonic eddy in the Southern California Current System
Plankton dynamics in a cyclonic eddy in the Southern California Current System
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DOI：
10.1002/2015jc010826
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发表时间：
2015-08-01
影响因子：
3.6
通讯作者：
Blanke, Bruno
中科院分区：
文献类型：
--
作者：
Chenillat, Fanny;Franks, Peter J. S.;Blanke, Bruno
加州海流系统是一个沿海岸沿着具有高生物产量的东部边界上升流系统。贫营养近海沃茨产生了生物和物理性质的跨岸梯度，这受到强烈的中尺度涡动活动的影响。涡旋对EBUS生态系统动力学的影响仍在争论中。要阐明的机制，影响被困在漩涡中的生态系统的动态，以及水平和垂直平流在确定当地生产的相对贡献，我们分析了一个特定的气旋涡数值欧拉拉格朗日粒子跟踪分析。涡旋形成于沿海上升流系统;被困在涡旋中的沿海沃茨使其能够离开具有高浓度浮游生物和营养盐的上升流区域。生态系统最初主要由生物材料的循环驱动。随着涡流向近海移动，通过Ekman泵送真光层以下的硝酸盐，与涡流外部沃茨相比，其核心的生产得到了增强;由于与涡流外部沃茨相比，涡流中的硝态线较浅，因此Ekman泵送特别有效。涡旋截留和Ekman抽水都有助于隔离和维持涡旋核心区的生态系统生产力。这项研究表明，在EBUS生物生产的气旋性涡旋的重要性：它们有助于沿海上升流生态系统的重新分配，并增强新的生产的本地区域。这些过程共同影响重要生物特性的跨海岸梯度。
The California Current System is an eastern boundary upwelling system (EBUS) with high biological production along the coast. Oligotrophic offshore waters create cross-shore gradients of biological and physical properties, which are affected by intense mesoscale eddy activity. The influence of eddies on ecosystem dynamics in EBUS is still in debate. To elucidate the mechanisms that influence the dynamics of ecosystems trapped in eddies, and the relative contribution of horizontal and vertical advection in determining local production, we analyze a particular cyclonic eddy using Lagrangian particle-tracking analyses of numerical Eulerian. The eddy formed in a coastal upwelling system; coastal waters trapped in the eddy enabled it to leave the upwelling region with high concentrations of plankton and nutrients. The ecosystem was initially driven mainly by recycling of biological material. As the eddy moved offshore, production in its core was enhanced compared to eddy exterior waters through Ekman pumping of nitrate from below the euphotic zone; this Ekman pumping was particularly effective due to the shallow nitracline in the eddy compared to eddy exterior waters. Both eddy trapping and Ekman pumping helped to isolate and maintain the ecosystem productivity in the eddy core. This study shows the importance of cyclonic eddies for biological production in EBUS: they contribute both to the redistribution of the coastal upwelling ecosystem and are local regions of enhanced new production. Together, these processes impact cross-shore gradients of important biological properties.