Food Web Regulation of Particulate Export Flux in High Nitrate-Low Chlorophyll Regions

了解控制真光层碳输出量的因素是美国JGOFS合成与建模项目(SMP)最重要的目标之一。据推测，这种出口的大小及其在颗粒物和溶解形式之间的分配是由食物网的大小结构决定的，但这一点从未用模型进行过明确的检验，因此存在争议。目前的一种模式是，浮游系统以两种截然不同的状态存在。群落结构取决于系统是否处于平衡状态(稳定状态或状态一)，还是受到瞬时事件--营养输入、混合或光照的变化--的影响，这些事件使浮游植物和浮游动物的增长率脱钩(状态二)。假设出口通量和颗粒有机物-溶解有机物分配在这两个状态之间是不同的。高硝酸盐-低叶绿素(HNLC)是JGOFS期间研究的最重要的海洋类型之一。美国联合全球海洋观测系统在赤道太平洋(EqPac)和南大洋(AESOPS)以及加拿大联合全球海洋观测系统(JGOFS)在亚北极北太平洋进行了主要过程研究。在JGOFS之前，亚北极北太平洋P站的研究是由SUPER(亚北极太平洋生态系统研究)进行的。这项研究的目标是1)综合和分析全球HNLC系统的数据，2)使用一维模型来探索不同放牧方式对HNLC地区生态系统功能和颗粒有机碳输出的影响，3)评估颗粒和溶解输出的相对重要性，包括细菌和浮游动物作为再矿化因子的作用，4)评估连接不同水库的元素化学计量关系，以及5)探索将异速生长关系用于生产和消费作为理解和模拟HNLC地区多个状态的工具。总体目标是根据环境条件的变化，为真光区碳及相关元素(SMP元素2)的生产、消费和出口的SMP提供HNLC合成。

StromUnderstanding the factors that control the magnitude of carbon export from the euphotic zone is one of the most important goals of the US JGOFS Synthesis and Modeling Project (SMP). It is assumed that the magnitude of this export, and its partitioning between particulate and dissolved forms, is determined by the size structure of the food web, but this has never been explicitly tested with models and is subject to debate. A current paradigm is that planktonic systems exist in two contrasting states. Community structure is a function of whether the system is in balance (steady state or State I) or under the influence of transient events - changes in nutrient input, mixing or light - which allow decoupling of phytoplankton and zooplankton growth rates (State II). Export flux and particulate organic matter-dissolved organic matter partitioning are hypothesized to be different between these two states. The high nitrate-low chlorophyll (HNLC) regime is one of the most important ocean types studied during JGOFS. Major process studies were undertaken by US JGOFS in the equatorial Pacific (EqPac) and Southern Ocean (AESOPS) and by Canadian JGOFS in the subarctic north Pacific. Prior to JGOFS, the subarctic north Pacific at Station P was studied by SUPER (Subarctic Pacific Ecosystem Research). The goals of this study are to 1) synthesize and analyze data from HNLC regimes worldwide, 2) use a 1-D model to explore the implications of different grazing formulations for ecosystem function and particulate organic carbon export in HNLC regions, 3) assess the relative importance of particulate and dissolved export, including the role of bacteria and zooplankton as remineralizers, 4) evaluate the elemental stoichiometric relationships that link the various reservoirs, and 5) explore the use of allometric relationships for production and consumption as a tool for understanding and modeling multiple states in HNLC regions. The overall goal is to provide a HNLC synthesis for the SMP of euphotic zone production, consumption and export of carbon and related elements (SMP Element 2), as regulated by variations in environmental conditions.