Production and downward flux of organic matter and calcite in a North Sea bloom of the coccolithophore Emiliania huxleyi
Production and downward flux of organic matter and calcite in a North Sea bloom of the coccolithophore Emiliania huxleyi
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DOI：
10.3354/meps126247
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发表时间：
1995-10
影响因子：
2.5
通讯作者：
Paul van der Wal;R. Kempers;Marcel;J. W. Veldhuis
中科院分区：
文献类型：
--
作者：
Paul van der Wal;R. Kempers;Marcel;J. W. Veldhuis
1993年7月，对设得兰群岛和挪威之间北海的一次大型水华进行了广泛的研究。本文报道了4个站点(2个在水华内，2个在水华外)24小时的水文、颗粒有机碳(POC)和方解石碳(方解石-C)的产生和沉积。球石类水华仅限于北海水域，在那里形成了一个稳定的浅混合层。水华发育已进入衰败阶段，从活细胞数相对较低(最多1 200个细胞厘米-3)、疏松球藻数量较多(高达350000个球石厘米-3)以及方解石-C的沉积超过产量这一事实来判断。在开花站顶部15米处，平均每天每个细胞产生17个球藻。在开花外的2个站位，优势的球孢子体是全球形体(多达1400个细胞cn1r3)，每个细胞产生的方解石数量很少。在这些站点，营养物质以非石灰浓度存在，POC的产量是水华站点的两倍。在水华期间，混合层硝酸盐水平低于0.2 PM在沉积物捕捉器中采集的粪便颗粒中含有大量的霍克斯勒伊球虫。虽然水华外2个站点的食草动物数量不低于水华，但50m处的粪便沉降量约为水华时的70倍。据推测，赤潮外的粪便颗粒重量很轻，在降解之前没有下沉很远，而赤潮中产生的颗粒由于含有大量方解石而被迅速出口。这意味着，由于向下通量较高，这次水华混合层中的材料回收相对较低。在水深50m处，两个水华站的POC和方解石-C的沉降率平均为1.3。
In July 1993, an extensive study was made of a large bloom of the coccolithophorid Emiliania huxleyi in the North Sea halfway between the Shetland Islands and Norway. Here we report on the hydrography, production and sedimentation of particulate organic carbon (POC) and calcite carbon (calcite-C) at 4 stations occupied for 24 h, 2 inside the bloom and 2 just outside. The coccolithophorid bloom was confined to North Sea waters, where a stable shallow mixed layer had been formed. Bloom development had entered the decaying phase, judged by the relatively low living cell number (maximally 1200 cells cm-3), the high number of loose coccoliths (up to 350000 coccoliths cm-3), and the fact that sedimentation of calcite-C exceeded production. In the top 15 m at the bloom stations, the mean daily production of coccoliths was 17 per cell. At the 2 stations outside the bloom, the dominant coccolithophore was a holococcolithophorid (up to 1400 cells cn1r3), wlth insignificant amounts of calcite produced per cell. At these stations, nutrients were present in non-lim~ting concentrations and production of POC was twice as high as at the bloom stations. In the bloom, mixed layer nitrate levels were below 0.2 PM. Faecal pellets collected in the sediment traps contained large numbers of coccoliths of E, huxleyi. Although the numbers of grazers at the 2 stations outside the bloom were not lower than those in the bloom, the volume of faecal matter sedimenting at 50 m was about 70 times lower. It is hypothesized that faecal pellets outside the bloom were so light in weight that they did not sink very far before degradation, whereas the pellets produced in the E. huxleyi bloom in general were exported rapidly due to their heavy load of calcite. This implies that recycling of materials in the mixed layer of this bloom is relatively low due to high downward flux rate. The ratio at which POC and calcite-C were sedimenting amounted to 1.3 on average for the 2 bloom stations at 50 m water depth.