Shelf-Basin Exchange of Large-Bodied Zooplankton [Copepods] in the Chukchi and Beaufort Seas

北太平洋/西北极地区的物理强迫表现出突然的状态转变，其中几十年（~25-35年）的相对寒冷、结冰（比平均水平高2%）的条件在一到两年内被几十年的温暖、较少结冰（比平均水平低3%）的条件所取代；该地区的这些气候周期至少可以追溯到18世纪末。楚科奇/博福特陆架生态系统对变暖气候的反应可能遵循两种截然不同的途径。在一种情况下，温暖期会减少冰层覆盖，并可能造成更强的热分层，减少混合，限制营养供应，降低初级产量，较小的浮游植物和较小的沿海浮游动物。在第二种情况下，同样是在冰较少的温暖时期，风的增加可能导致大陆架断裂上升流和混合，增加营养供应，更大的浮游植物和更大的深水浮游动物平流到大陆架上。全球变化，特别是变暖，会导致更多的大型浮游动物在楚科奇和波弗特大陆架和斜坡上生存，它们支持鱼类、鸟类和哺乳动物，还是更小的浮游动物，它们会减少鱼类、鸟类和哺乳动物，而有利于定居的底栖生物？楚科奇和波弗特大陆架上的大型桡足类动物一定是从北冰洋或白令海的斜坡水域平流到这里的；它们都不能在货架上完成自己的生命周期。因此，它们是陆架-盆地交换的示踪剂。该项目将试图了解哪些大型桡足类动物到达楚科奇（宽）和博福特（窄）大陆架，以及对此负责的物理作用力（上升流、侵入、漩涡）。一旦上架，大型桡足类动物的体型和繁殖反应在空间上是如何变化的，物理过程和食物供应在其中起了什么作用？这些响应决定了陆架生境支持远洋生态系统的稳健性。该项目将确定哪些桡足类动物被从货架上运走，以及与这种运输相关的物理过程（漩涡、羽流）。这项调查将把这些生态系统测量与物理强迫（包括观测和模型）结合起来，以了解平流如何塑造该地区的食物网。

Physical forcing in the North Pacific/Western Arctic region exhibits abrupt regime shifts in which several decades (~25-35 years) of relatively cold, icy (2% above average) conditions are replaced in the span of a year or two by decades of warmer, less icy (3% below average) conditions; these cycles of climate in the region can be traced back at least to the late 1700s. The response of the Chukchi/Beaufort shelf ecosystem to warmer climate could follow two quite different pathways. In one scenario, warm periods would reduce ice cover and could create stronger thermal stratification, less mixing, limited nutrient supply, lower primary production, smaller-sized phytoplankton and smaller, coastal-like zooplankton. In a second scenario, also during warm periods with less ice, increased wind could result in shelf-break upwelling and mixing, enhanced nutrient supply, larger-sized phytoplankton and larger, deep-water zooplankton advectedonto the shelf. Will global change, particularly warming, result in more large-sized zooplankton which support fish, birds, and mammals over the Chukchi and Beaufort shelves and slopes or smaller-sized zooplankton which will diminish the fish, birds, and mammals and favor sedentary benthic organisms?Large-bodied copepods on the Chukchi and Beaufort shelves must be advected there from the slope waters of the Arctic Ocean or Bering Sea; none of them can complete their life cycles on the shelf itself. Therefore, they are tracers of shelf-basin exchanges. The project will seek to understand which large-bodied copepods reach the Chukchi (wide) and Beaufort (narrow) shelves, and the physical forcing (upwelling, intrusions, eddies) that is responsible. Once on the shelves, how do size and reproductive responses of large copepods vary spatially, and what are the roles of physical processes and food supply? These responses define the robustness of the shelf habitat for supporting a pelagic ecosystem. The project will determine which copepods are transported off the shelves and the physical processes (eddies, plumes) associated with that transport. The investigation will integrate these ecosystem measurements with the physical forcing (both observations and models) to understand how advection shapes the food web in the region.