Bottom‐associated phytoplankton bloom and its expansion in the Arctic Ocean
Bottom‐associated phytoplankton bloom and its expansion in the Arctic Ocean
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DOI：
10.1111/gcb.16421
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发表时间：
2022-09
影响因子：
11.6
通讯作者：
T. Shiozaki;A. Fujiwara;K. Sugie;S. Nishino;Akiko Makabe;N. Harada
中科院分区：
文献类型：
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作者：
T. Shiozaki;A. Fujiwara;K. Sugie;S. Nishino;Akiko Makabe;N. Harada
由于全球变暖引起的海冰消失，北冰洋的浮游植物产量正在增加，这通常是通过卫星对表面叶绿素的观测来评估的。在这里，我们表明硅藻华可能发生在海底附近，而不是在开放的北冰洋表面。春季水华过后，光线可以到达营养丰富的底层水下的海底，因为地表水变得贫营养，并增加了北极浅陆架区域的透明度。我们的微观实验表明，当陆架区域的沉积物（含有丰富的活硅藻细胞）暴露在到达海底的微弱光线（约表面辐照度的 1％）时，硅藻就会形成水华。在陆架区域的反复船上观测表明，这种与底部相关的水华偶尔发生，并且卫星观测大大低估了初级产量。北冰洋的平均底部辐照度（2003-2017年）在东西伯利亚海东部和福克斯盆地的夏季尤其明显，这些地区在20世纪90年代之前全年都被冰覆盖。我们的结果表明，隐藏的底部相关水华现在广泛分布在北极浅海陆架区域。
Phytoplankton production in the Arctic Ocean is increasing due to global warming‐induced sea ice loss, which is generally assessed through satellite observations of surface chlorophyll. Here we show that a diatom bloom can occur near the seafloor rather than at the surface in the open Arctic Ocean. Light can reach the seafloor underlying nutrient‐rich bottom water after the spring bloom because the surface water becomes oligotrophic and increases transparency in the region of shallow Arctic shelf. Our microcosm experiment demonstrated that diatoms formed a bloom when sediments on the shelf region, which contained abundant viable diatom cells, were exposed to even weak light reaching the seafloor (~1% of the surface irradiance). Repeated shipboard observations in the shelf region suggested that such bottom‐associated blooms occurred occasionally and the primary production was significantly underestimated by satellite observations. The average bottom irradiance (2003–2017) in the Arctic Ocean is particularly promoted in summer in the eastern East Siberian Sea and the Foxe Basin, which were ice‐covered throughout the year until the 1990s. Our results imply that hidden bottom‐associated blooms are now widespread across the shallow Arctic shelf region.