Collaborative Research: Changing Seasonality of the Arctic: Alteration of Production Cycles and Trophic Linkages in Response to Changes in Sea Ice and Upper Ocean Physics

该奖项由2009年《美国复苏和再投资法案》(公法111-5)资助。近年来，北极海冰出现了显著的季节性变化，其特点是由于夏季融化季节延长，融化时间提前，冻结时间较晚，因此出现了前所未有的夏季融化。随着夏季海冰面积缩小到创纪录的低水平，北冰洋周边海域更早地暴露在大气表面热通量中，导致夏季更长、更温暖，海洋吸收的热量更多。北极冰/海洋系统不断变化的季节性将扰乱浮游食物网中的关键营养联系和反馈，从而改变海洋生产周期的时间、规模、持续时间和模式。这些变化将对北极海洋生态系统的结构产生影响，影响波及整个北极系统，包括人类。因此，重要的是要了解北极物理和生物系统中季节性模式的变化。投资促进机构建议将北冰洋海冰、水柱、海洋生产循环和营养结构作为一个综合系统，研究它们之间的季节性联系和相互作用的未来变化。他们的研究将针对以下季节性假设：1)春季海冰消退的时间变化将导致初级和次生生产力的时间错配，从而改变浮游生物群落的大小结构。2)浮游植物和浮游动物生产循环的更紧密结合将导致生产性大陆架春季水华的规模减少，水柱消费者更多地利用初级生产，并减少对底栖动物的出口。3)较长的生长季，可能包括夏末/初秋的第二个生产高峰，将允许目前由于生长季持续时间较短而无法在北冰洋生存的亚北极物种在北冰洋定居。这些假设将通过综合模型估计以及卫星和现场观测来探索。PIS将利用现有的泛北极生物学/冰/海洋模拟和同化系统(BIOAS)，并结合观测，加强他们对北极海冰、海洋和海洋生产循环综合系统的了解。将进行一系列模型后播、敏感性研究和未来情景模拟，以确定季节性敏感联系并检验其假设。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Significant seasonal changes in arctic sea ice have been observed in recent years, characterized by unprecedented summer melt-back because of the lengthening of the summer melt season with earlier melt and later freeze onsets. As summer sea ice extent shrinks to record low levels, the peripheral seas of the Arctic Ocean are exposed much earlier to atmospheric surface heat flux, resulting in longer and warmer summers with more oceanic heat absorption. The changing seasonality in the arctic ice/ocean system will alter the timing, magnitude, duration, and pattern of marine production cycles, by disrupting key trophic linkages and feedbacks in planktonic food webs. These alterations will have consequences on the structure of arctic marine ecosystems with reverberations through the entire arctic system up to and including humans. It is, thus, important to understand the changes in the patterns of seasonality in the arctic physical and biological system. The PIs propose to investigate future changes in the seasonal linkages and interactions among arctic sea ice, the water column, and the marine production cycles and trophic structure as an integrated system. Their investigation will target the following seasonality hypotheses:1) Changes in the timing of spring sea ice retreat will cause a mismatch in the timing of primary and secondary production such that the plankton community size structure is altered. That in turn will modify the utilization of primary production and the availability of large zooplankton prey for upper trophic levels (e.g., whales, fish).2) Closer coupling of phytoplankton and zooplankton production cycles will result in a reduction in the magnitude of the spring bloom over productive shelves, greater utilization of primary production by water column consumers and a reduction in its export to the benthos.3) A longer growing season, which might include a secondary production peak later in summer/early fall, will permit the colonization of the Arctic Ocean by subarctic species that presently are unable to persist there because of the short duration of the growing season. These hypotheses will be explored by synthesizing model estimates and satellite and field observations. The PIs will use the existing coupled pan-Arctic Biology/Ice/Ocean Modeling and Assimilation System (BIOMAS), together with observations, to strengthen their understanding of the integrated arctic system of sea ice, ocean, and the marine production cycles. A series of model hindcasts, sensitivity studies, and future scenario simulations will be conducted to identify seasonally sensitive linkages and to test their hypotheses