Sediment-Associated Phytoplankton Release From the Seafloor in Response to Wind-Induced Barotropic Currents in the Bering Strait
Sediment-Associated Phytoplankton Release From the Seafloor in Response to Wind-Induced Barotropic Currents in the Bering Strait
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DOI：
10.3389/fmars.2019.00097
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发表时间：
2019-03-08
影响因子：
3.7
通讯作者：
Ooki, Atsushi
中科院分区：
文献类型：
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作者：
Abe, Hiroto;Sampei, Makoto;Ooki, Atsushi
白令海峡是北冰洋和太平洋之间的唯一门户，局部地区有强大的洋流，其流速可超过100 cm s(-1)。尽管在白令海峡周边地区观察到春季浮游植物大量繁殖，并随后产生沉入海底的颗粒有机物，但局部强流对颗粒水平和垂直输送的影响仍不清楚。因此，我们从2016年到2017年进行了全年系泊测量，重点关注与洋流相关的近海底过程。我们的时间序列分析表明，由强正压洋流引发的高浊度事件在所有季节都发生在海底附近。因此，荧光传感器在重悬浮的沉积物中检测到高浓度的叶绿素a；然而，叶绿素的释放量是季节性的，在温暖季节和寒冷季节分别释放大量和少量叶绿素。叶绿素a含量低可能是由于上覆水体新鲜浮游植物输入量较少以及无光条件下沉积物中有机物分解所致，沉积物中浮游植物量较少。正压流受到与洲际大气模式相关的地面风的调节，该洲际大气模式在6天的时间尺度上具有5000公里的空间尺度。白令海峡局部较强的洋流驱动了沉积物的向上输送和随后的水平输送，可能在向据报道形成生物热点的楚科奇海南部下游地区提供颗粒有机物/浮游植物/营养物方面发挥着至关重要的作用。
Bering Strait is the single gateway between the Arctic and Pacific Oceans, and has localized strong currents, which can exceed 100 cm s(-1). Although massive spring phytoplankton blooms and the subsequent production of particulate organic matter that sinks to the seafloor are observed in the surrounding regions of the Bering Strait, the impact of the locally strong current on the horizontal and vertical transport of the particles remains unclear. Therefore, we conducted year-round mooring measurements from 2016 to 2017 by focusing on near-bottom processes associated with ocean currents. Our time-series analysis showed that high-turbidity events, triggered by strong barotropic currents, occurred near the seafloor in all seasons. Consequently, the fluorescence sensor detected highly concentrated chlorophyll a in the resuspended sediment; however, the amount of chlorophyll a release was seasonal, with large and small amounts being released during the warm and cold seasons, respectively. The small amounts of chlorophyll a may be attributed to small amounts of phytoplankton in the sediment owing to less input of fresh phytoplankton from the overlaying water column and organic matter decomposition in the sediments under no-light conditions. The barotropic currents were modulated by surface winds associated with an intercontinental atmospheric pattern having a 5000-km spatial scale on a timescale of 6 days. The locally strong ocean current in the Bering Strait, driving the upward transport of sediment and the subsequent horizontal transport, may play a vital role in supplying particulate organic matter/phytoplankton/nutrients to the downstream region of the southern Chukchi Sea where the formation of biological hotspots is reported.