Morphometric variability in the diatom Fragilariopsis kerguelensis:: Implications for Southern Ocean paleoceanography
Morphometric variability in the diatom Fragilariopsis kerguelensis:: Implications for Southern Ocean paleoceanography
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DOI：
10.1016/j.epsl.2007.03.021
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发表时间：
2007-05-30
影响因子：
5.3
通讯作者：
Gersonde, R.
中科院分区：
文献类型：
--
作者：
Cortese, G.;Gersonde, R.
硅藻在南大洋生态系统中发挥着核心作用，是向深海输送有机碳和溶解硅的主要生产者和载体。最丰富物种（凯尔盖脆脆片）的大小在空间和时间上的变化可能会直接影响该生态系统的运作方式，并且还会影响全球海洋的营养平衡，因为重要的水团（例如南极中层水）在该地区获得营养特征。我们使用生物识别方法，分析了来自南大洋的 64 个表面沉积物样本、南极极锋 (APF) 系泊处 (PF3 点) 以及附近活塞核心 (PS1654-2) 沉积物陷阱样本中 F kerguelensis 阀门的尺寸变异性。 F. kerguelensis 的平均长度和瓣膜面积在 APF 附近显着增加，而在其北部和南部则较低，并且随着硅藻华和养分有效性的盛衰，在季节周期中也发生显着变化。最后一次冰期到间冰期的过渡也见证了 F. kerguelensis 的总体形状和瓣膜尺寸的重要变化，来自冰期间隔的标本大约为 100 到 100 毫米。比间冰期对应物大 30%（195 与 150 μ m(2) 阀门面积）。平均面积的尖锐峰值和非常特殊的阀门形态对应于冰川消退和同时发生的海表温度（SST）增加和海冰消退的最初迹象。后者与融化的冰山一起可能向地表水中贡献了溶解的铁。冰期期间的最大平均尺寸比当今南大洋的任何地方都要大。因此，新提出的替代物（F. kerguelensis 的瓣膜面积和形状）可能有助于重建 APF 和“蛋白石带”的过去位置和营养特征，“蛋白石带”是一个以生物二氧化硅高产量和出口为特征的区域，位于南大洋等特别敏感和动态的区域。 (c) 2007 Elsevier B.V. 保留所有权利。
Diatoms play a central role in the ecosystem of the Southern Ocean, where they represent the main producers and carriers of organic carbon and dissolved silicon towards the deep ocean. Variability in space and time of the size of the most abundant species (Fragilariopsis kerguelensis) may directly impact the way this ecosystem functions, and also affect the nutrient balance of the global ocean, as important water masses (e.g. the Antarctic Intermediate Water) get their nutrient signature in this area. We used a biometric approach and analyzed the size variability of F kerguelensis valves in sixty-four surface sediment samples from the Southern Ocean, in sediment trap samples from a mooring (Site PF3) at the Antarctic Polar Front (APF), and along a nearby piston core (PS1654-2). The average length and valve area of F. kerguelensis displayed a distinct increase in the proximity of the APF, and lower values to the north and south of it, and also changed markedly over seasonal cycles, as diatom blooms and nutrient availability waxe and wane. The last glacial to interglacial transition also witnesses important changes in the general shape and valve size of F. kerguelensis, with specimens from glacial intervals being ca. 30% larger than their interglacial counterparts (195 versus 150 mu m(2) valve area). A sharp peak in average area and a very specific valve morphology correspond to the first signs of deglaciation and concurring SST (Sea Surface Temperature) increase and sea-ice retreat. The latter, together with melting icebergs, may have contributed dissolved iron to surface waters. The highest average sizes during glacial intervals are higher than what found anywhere in the Southern Ocean today. The newly proposed proxy (valve area and shape of F. kerguelensis) may thus prove useful for the reconstruction of the past position and nutrient characteristics of the APF and "opal belt", a region characterized by high production and export of biogenic silica, in a particularly sensitive and dynamic area such as the Southern Ocean. (c) 2007 Elsevier B.V. All rights reserved.