Fluxes of carbon in the upper ocean: regulation by food-web control nodes
Fluxes of carbon in the upper ocean: regulation by food-web control nodes
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上层海洋的碳通量：食物网控制节点的调节
DOI：
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发表时间：
2002
期刊：
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通讯作者：
R. Rivkin
中科院分区：
文献类型：
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作者：
L. Legendre;R. Rivkin
我们提出了一种新的方法来评估上层海洋中上层食物网在浮游植物生产(P-T)分配中的作用，将其划分为3个主成分通量：再矿化为CO2(即呼吸作用，R)、向下转移到中上层食物网(F)和向下输出(E-T)，E-T是其颗粒(POC)和溶解(DOC)有机碳成分的总和(E-T=E-DOC+E-POC)。虽然浮游生物群落的大小和营养结构与真光层有机碳(OC)的输出及其在永久跃层下的潜在封存之间存在着一定的关系，但这些关系的产生机制还不是很清楚。在这里，我们认为，上层海洋有机碳的通量取决于一个相对较小的POC池和一个大得多的DOC池的共存，前者负责通量P-T、R、F和E-POC，后者既支持细菌生产又支持E-DOC。在我们的模型中，浮游植物、微生物异养浮游生物和大型浮游动物是5个碳通量(P-T、R、F、E-DOC和E-DOC)的3个食物网控制节点。浮游植物节点控制着植物碎屑向下的通量(主要来自大型浮游植物)，这通常是E POC的主要组成部分。微生物异养浮游生物结点负责有机碳向二氧化碳的再矿化和DOC的吸收与释放。因此，该节点控制可以向下导出的DOC池的大小。大型浮游动物节点既控制POC向大型后生动物的转移，也控制部分向下的POC通量(E POC；粪便颗粒和垂直迁移的生物)。我们通过估计世界大洋不同区域8个地点的出口量E T=P T-R来实现我们的模型。E-T和P-new之间的函数关系非常显著(r2=0.85)：与其他方法不同的是，出口是以P-T的分数来计算的，我们估计E-T是两个自变量(即P-T和R)之间的差值；因此，我们的方法产生了一些区域值E-T<；0--这些区域是净异养的。总体而言，我们的方法提高了我们对上层海洋中碳循环和出口的理解。
We present a new approach to assess the role of upper ocean pelagic food webs on the partitioning of phytoplankton production (P T ) into its 3 principal component fluxes: remineralization to CO 2 (i.e. respiration, R), transfer to the pelagic food web (F), and downward export (E T ); E T is the sum of its particulate (POC) and dissolved (DOC) organic carbon components (E T = E DOC + E POC ). Although it is well known that there are relationships between the size and trophic structure of the planktonic community on the one hand, and the export of organic carbon (OC) from the euphotic zone and its potential sequestration below the permanent pycnocline on the other hand, the causative mechanisms for these relationships are not well understood. Here, we propose that the fluxes of OC in the upper ocean depend on the coexistence of a relatively small POC pool, which is responsible for the fluxes P T , R, F and E POC , and a much larger DOC pool, which sustains both bacterial production and E DOC . In our model, phytoplankton, microbial heterotrophic plankton, and large zooplankton are the 3 food-web control nodes of the 5 carbon fluxes (P T , R, F, E DOC and E DOC ). The phytoplankton node controls the downward flux of phytodetritus (mostly from large phytoplankton), which is often the major component of E POC . The microbial heterotrophic plankton node is responsible for most of the remineralization of OC to CO 2 and the uptake and release of DOC. This node therefore controls the size of the DOC pool that can be exported downwards. The large zooplankton node controls both the transfer of POC to large metazoans and part of the downward POC flux (E POC ; faecal pellets and vertically migrating organisms). We implemented our model by estimating export as E T = P T - R at 8 sites in different regions of the World Ocean. The functional relationship between E T and P new was highly significant (r 2 = 0.85): In contrast to other approaches, where export is calculated as a fraction of P T , we estimate E T as the difference between 2 independent variables (i.e. P T and R); hence our approach produces some regional values E T < 0 - these regions are net heterotrophic. Overall, our approach improves our understanding of carbon cycling and export in the upper ocean.