Under-Ice Phytoplankton Blooms Inhibited by Spring Convective Mixing in Refreezing Leads: UNDER-ICE PHYTOPLANKTON BLOOM DYNAMICS
Under-Ice Phytoplankton Blooms Inhibited by Spring Convective Mixing in Refreezing Leads: UNDER-ICE PHYTOPLANKTON BLOOM DYNAMICS
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DOI：
10.1002/2016jc012575
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发表时间：
2018-01
影响因子：
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通讯作者：
Kate E. Lowry;R. Pickart;V. Selz;M. Mills;A. Pacini;K. Lewis;H. Joy‐Warren;C. Nobre;G. V. Dijken;P. Grondin;J. Ferland;K. Arrigo
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作者：
Kate E. Lowry;R. Pickart;V. Selz;M. Mills;A. Pacini;K. Lewis;H. Joy‐Warren;C. Nobre;G. V. Dijken;P. Grondin;J. Ferland;K. Arrigo
春季浮游植物在极地海洋生态系统的增长是有限的光照覆盖的沃茨下，特别是在融雪和融化池形成之前的赛季初。开放水域的引线增加了光传输到冰雪覆盖的海洋，是海气交换的场所。我们探讨的作用，铅在控制浮游植物水华的动态范围内的北冰洋海冰区。数据来自2014年5月和6月在楚科奇生态系统（SUBICE）计划冰下水华研究期间楚科奇海的春季测量。我们观察到，完全巩固的海冰支持适度的冰下水华，而沃茨下的海冰与铅有显着较低的浮游植物生物量，尽管高营养的可用性。通过水文和生物特性的分析，我们将这一违反直觉的发现归因于开放水域再冻结导致的春季对流混合。我们的研究结果表明，沃茨下松散固结海冰（84-95%冰浓度）有弱分层，并经常混合低于临界深度（深度综合生产平衡深度综合呼吸的深度）。这些研究结果得到了理论模型计算的冰下光，初级生产力和临界深度在不同的铅含量。该模型表明，冰下水华甚至可以在没有混合的情况下在冰雪覆盖的海冰下形成，但在具有再冻结铅的海冰下更深混合的沃茨中不会形成。未来对初级生产力的估计应考虑到这些浮游植物在冰层覆盖的沃茨中的动态。
Spring phytoplankton growth in polar marine ecosystems is limited by light availability beneath ice-covered waters, particularly early in the season prior to snowmelt and melt pond formation. Leads of open water increase light transmission to the ice-covered ocean and are sites of air-sea exchange. We explore the role of leads in controlling phytoplankton bloom dynamics within the sea ice zone of the Arctic Ocean. Data are presented from spring measurements in the Chukchi Sea during the Study of Under-ice Blooms In the Chukchi Ecosystem (SUBICE) program in May and June 2014. We observed that fully consolidated sea ice supported modest under-ice blooms, while waters beneath sea ice with leads had significantly lower phytoplankton biomass, despite high nutrient availability. Through an analysis of hydrographic and biological properties, we attribute this counterintuitive finding to springtime convective mixing in refreezing leads of open water. Our results demonstrate that waters beneath loosely consolidated sea ice (84–95% ice concentration) had weak stratification and were frequently mixed below the critical depth (the depth at which depth-integrated production balances depth-integrated respiration). These findings are supported by theoretical model calculations of under-ice light, primary production, and critical depth at varied lead fractions. The model demonstrates that under-ice blooms can form even beneath snow-covered sea ice in the absence of mixing but not in more deeply mixed waters beneath sea ice with refreezing leads. Future estimates of primary production should account for these phytoplankton dynamics in ice-covered waters.