Sedimentation pathways in the Indian sector of the Southern Ocean during a production regime dominated by regeneration
Sedimentation pathways in the Indian sector of the Southern Ocean during a production regime dominated by regeneration
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以再生为主的生产状态下南大洋印度区的沉积路径
DOI：
10.3354/meps190053
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发表时间：
1999
影响因子：
2.5
通讯作者：
E. Charriaud
中科院分区：
文献类型：
--
作者：
C. Cailliau;S. Belviso;M. Goutx;A. Bedo;Y. Park;E. Charriaud
1994 年夏季，位于南大洋印度区的 2 个地点的生产状况以再生为主（0.3 < f 比 < 0.4），其中一个位于南纬 52° 的永久开放海洋区 (POOZ)，第二个位于南纬 63° 的季节性冰区 (SIZ)。使用在 2 个地点 200 m 处设置的自由漂浮沉积物捕集器，在 4 小时的预定时间间隔内进行两个时间序列，每个时间序列约 4 天。同时测量 C、N、叶绿素 a (chla) 及其降解产物、分类群特异性色素、脂质类别和二甲基磺基丙酸酯 (DMSP) 的每小时变化。水柱中的测量是在沉积物捕集器漂流期间进行的。岩藻黄质是一种典型的硅藻色素，是在两个站的诱集材料中发现的主要辅助色素，而在水柱中，浮游植物以 POOZ 中的鞭毛虫和 SIZ 中的硅藻为主。这表明浮游动物对硅藻的选择性放牧和/或硅藻的大量下沉，至少在 POOZ 中是这样。然而，由于这组化合物在 POOZ 中表现出强烈的昼夜循环，因此输出通量似乎主要来自浮游动物。至于夜间沉积的加剧是否是由于磷虾类的垂直迁移（因为穿越重斜线的桡足类动物很少见）和/或桡足类和微型浮游动物的夜间摄食活动增加所致，结果并不明确。在 SIZ，硅藻在混合层和位于最低温度深度（50 至 100 m）的深层浮游植物最大值（DPM）中占主导地位。然而，陷阱材料中的色素特征表明纳米鞭毛虫（本质上是远海植物）的选择性沉积。相应地，捕获材料中甾醇的比例高达40%。昼夜变化有点类似于 POOZ、较低的叶绿素与色素比以及存在最降解形式的色素，这些都强烈表明了浮游动物在 SIZ 的出口通量中发挥的关键作用。因此，浮游动物对浮游植物的选择性摄食强烈影响了南大洋印度区的沉积路径。此外，表层水中浮游植物产生的 DMSP 在被食草动物加工时与叶绿素一样不稳定。
During summer 1994, the production regime at 2 sites located in the Indian sector of the Southern Ocean, one in the Permanent Open Ocean Zone (POOZ) at 52° S, and a second in the Seasonal Ice Zone (SIZ) at 63° S, was dominated by regeneration (0.3 < f-ratio < 0.4). Two time series, each of about 4 d, were performed over pre-determined time intervals of 4 h using a free-floating sediment trap set at 200 m at the 2 sites. Hourly variations of C, N, chlorophyll a (chl a) and its degradation products, taxon-specific pigments, lipid classes and dimethylsulfoniopropionate (DMSP) were measured simultaneously. Measurements in the water column were done during the sediment trap drifting. Fucoxanthin, a typical diatom pigment, was the major accessory pigment found in the trap material at the 2 stations, whereas, in the water column, the phytoplankton was dominated by flagellates in the POOZ and diatoms in the SIZ. This suggests selective grazing of diatoms by zooplankton and/or mass sinking of diatoms, at least in the POOZ. However, since the set of compounds exhibited strong diel cycles in the POOZ, the export flux appears to mainly result from the zooplankton. The results are ambiguous as to whether the intensified sedimentation at night resulted from vertical migration of euphausiids, since copepods crossing the pycnocline were rare, and/or the nocturnal increase of feeding activity of copepods and microzooplankton. At the SIZ, diatoms dominated in the mixed layer and at the deep phytoplankton maximum (DPM) located at the depth of the temperature minimum (50 to 100 m). However, pigment signature in the trap material suggested the selective sedimentation of nanoflagellates (essentially pelagophytes). Correspondingly, there was high proportions of sterols up to 40 % in the trap material. The diel variations somewhat resembling POOZs, the low chl a-to-phaeopigments ratio and the presence of phaeopigments in their most degraded forms were strong indications of the key role played by zooplankton in the export fluxes in the SIZ. Hence, the selective feeding of phytoplankton by zooplankton strongly influenced the sedimentation pathways in the Indian Sector of the Southern Ocean. Additionally, DMSP, which is produced by phytoplankton in superficial waters, is shown to be as labile as chl a when processed by grazers.