The contribution of zooplankton faecal pellets to deep-carbon transport in the Scotia Sea (Southern Ocean)
The contribution of zooplankton faecal pellets to deep-carbon transport in the Scotia Sea (Southern Ocean)
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DOI：
10.5194/bg-12-1955-2015
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发表时间：
2014-11
期刊：
影响因子：
4.9
通讯作者：
C. Manno;G. Stowasser;P. Enderlein;Sophie Fielding;G. Tarling
中科院分区：
文献类型：
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作者：
C. Manno;G. Stowasser;P. Enderlein;Sophie Fielding;G. Tarling
抽象的。北斯科舍海是在南大洋测得的最大的大气二氧化碳季节性吸收区域。这项研究考察了碳流入深海的主要途径之一：通过浮游动物群落产生粪便颗粒(FP)。深层沉积物捕集器部署在同一水域内两个海洋生产力状况不同的地点(P3，自然铁肥沃，P2，铁限制)。两地圈闭中颗粒有机碳(POC)和颗粒有机碳(FP)的大小和季节格局明显不同。P3(22.91mgCm−2d−1；2534fp m−2d1)的最大通量比P2(4.01mgCm−2d−1；915fpm−2d1)高1个数量级，P3处的通量呈现双季节高峰，而P2处为单峰平坦。Fp碳对POC总量的最大贡献在P3(91%)是P2(40%)的两倍。在一年中，P3的优势FP类型在圆形、卵形、圆柱形和表面型之间变化，而在P2，卵形FP始终占优势，始终占FP组合的60%以上。这两个部位的FP状态也有差异，在P3处FP相对完整，而在P2处FP经常碎裂，周围膜破裂。唯一的例外是OvoidaFP，它们在两个地点都相对完好。我们的观察表明，从春季到秋季，P3的群落从草食性转变为杂食性，而有害食性在P2的一年中具有更高的相对重要性。此外，通量主要是P3的浮游动物群落垂直迁移的产物，而FP通量更有可能是P2的深水浮游动物以回收的材料为食产生的。结果表明，浮游动物群落的摄食行为和垂直分布对控制该区域向深海输出碳的数量起着关键作用。
Abstract. The northern Scotia Sea contains the largest seasonal uptake of atmospheric carbon dioxide yet measured in the Southern Ocean. This study examines one of the main routes by which this carbon fluxes to the deep ocean: through the production of faecal pellets (FPs) by the zooplankton community. Deep sediment traps were deployed at two sites with contrasting ocean productivity regimes (P3, naturally iron-fertilized, and P2, iron-limited) within the same water mass. The magnitude and seasonal pattern of particulate organic carbon (POC) and FPs in the traps was markedly different between the two sites. Maximum fluxes at P3 (22.91 mg C m−2 d−1; 2534 FP m−2 d1) were 1 order of magnitude higher than at P2 (4.01 mg C m−2 d−1; 915 FP m−2 d1, with flux at P3 exhibiting a double seasonal peak, compared to a single flatter peak at P2. The maximum contribution of FP carbon to the total amount of POC was twice as high at P3 (91%) compared to P2 (40%). The dominant FP category at P3 varied between round, ovoidal, cylindrical and tabular over the course of the year, while, at P2, ovoidal FPs were consistently dominant, always making up more than 60% of the FP assemblage. There was also a difference in the FP state between the two sites, with FPs being relatively intact at P3, while FPs were often fragmented with broken peritrophic membranes at P2. The exception was ovoidal FPs, which were relatively intact at both sites. Our observations suggest that there was a community shift from a herbivorous to an omnivorous diet from spring through to autumn at P3, while detritivores had a higher relative importance over the year at P2. Furthermore, the flux was mainly a product of the vertically migrating zooplankton community at P3, while the FP flux was more likely to be generated by deeper-dwelling zooplankton feeding on recycled material at P2. The results demonstrate that the feeding behaviour and vertical distribution of the zooplankton community plays a critical role in controlling the magnitude of carbon export to the deep ocean in this region.