Carbon Export in the Seasonal Sea Ice Zone North of Svalbard From Winter to Late Summer
Carbon Export in the Seasonal Sea Ice Zone North of Svalbard From Winter to Late Summer
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DOI：
10.3389/fmars.2020.525800
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发表时间：
2021-01-21
影响因子：
3.7
通讯作者：
Reigstad, Marit
中科院分区：
文献类型：
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作者：
Dybwad, Christine;Assmy, Philipp;Reigstad, Marit
北冰洋季节性海冰区的浮游植物水华预计将更早开始，并随着海冰覆盖的消退和变薄而发生在更北的地方。目前的研究是第一次汇编浮游植物水华的发展和命运的季节性变化海冰区北部的斯瓦尔巴群岛从冬季到夏末，使用短期沉积物陷阱部署。明确的季节性模式，发现低冬季和开花前浮游植物的常备库存和出口通量，一个短暂而激烈的生产季节在5月和6月，低叶绿素a常备库存，但温和的碳出口通量在秋季开花后的条件。我们观察到强烈的浮游植物水华与叶绿素a常备股票>350毫克米（-2）以下巩固海冰覆盖，主要是由prymnesiophyte棕囊藻poucheti。在以硅藻为主的站点记录到的100 m以下的最大垂直有机碳输出通量高达513 mg Cm（-2）day（-1），而以P. poucheti为主的站点记录到的碳输出通量高达310 mg Cm（-2）day（-1）。磷虾和桡足类的粪便颗粒在某些地区的碳输出中占很大比例，特别是在P. pouchetii水华占主导地位和大西洋水平流突出的地方。原生生物组合的分类组成，大型食草动物，距离开阔水域，和大西洋水平流之间的相互作用被认为是至关重要的，在确定的命运的水华和有机碳出口的幅度的表面水柱。以前，边缘冰区被认为是该地区最具生产力的地区，但我们的研究显示，在冰雪覆盖的沃茨，密集的水华和高出口事件。这是第一次对冰下浮游植物大量繁殖的碳输出通量进行全面研究，这一现象在新的北极海冰制度下的重要性有所增加。
Phytoplankton blooms in the Arctic Ocean's seasonal sea ice zone are expected to start earlier and occur further north with retreating and thinning sea ice cover. The current study is the first compilation of phytoplankton bloom development and fate in the seasonally variable sea ice zone north of Svalbard from winter to late summer, using short-term sediment trap deployments. Clear seasonal patterns were discovered, with low winter and pre-bloom phytoplankton standing stocks and export fluxes, a short and intense productive season in May and June, and low Chl a standing stocks but moderate carbon export fluxes in the autumn post-bloom conditions. We observed intense phytoplankton blooms with Chl a standing stocks of >350 mg m(-2) below consolidated sea ice cover, dominated by the prymnesiophyte Phaeocystis poucheti. The largest vertical organic carbon export fluxes to 100 m, of up to 513 mg C m(-2) day-1, were recorded at stations dominated by diatoms, while those dominated by P. poucheti recorded carbon export fluxes up to 310 mg C m(-2) day(-1). Fecal pellets from krill and copepods contributed a substantial fraction to carbon export in certain areas, especially where blooms of P. pouchetii dominated and Atlantic water advection was prominent. The interplay between the taxonomic composition of protist assemblages, large grazers, distance to open water, and Atlantic water advection was found to be crucial in determining the fate of the blooms and the magnitude of organic carbon exported out of the surface water column. Previously, the marginal ice zone was considered the most productive region in the area, but our study reveals intense blooms and high export events in ice-covered waters. This is the first comprehensive study on carbon export fluxes for under-ice phytoplankton blooms, a phenomenon suggested to have increased in importance under the new Arctic sea ice regime.