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

北太平洋/北极西部地区的物理强迫表现出突然的体制转变，其中几十年（约25-35年）相对寒冷，冰冷（高于平均水平2%）的条件在一年或二十年的时间内被几十年温暖，少冰（低于平均水平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气候变暖的响应可能遵循两条完全不同的途径。在一种情况下，温暖时期将减少冰盖，并可能产生更强的热分层，减少混合，限制营养供应，降低初级生产，较小的浮游植物和较小的沿海浮游动物。在第二种情况下，也是在温暖的时期，冰少，风力增加可能导致陆架断裂上升流和混合，营养供应增加，大型浮游植物和大型深水浮游动物平流到陆架上。全球变化，特别是变暖，是否会导致楚科奇和博福特大陆架和斜坡上支持鱼类、鸟类和哺乳动物的大型浮游动物增多，或导致鱼类、鸟类和哺乳动物减少，有利于定居的底栖生物？楚科奇大陆架和博福特大陆架上的大型桡足类，一定是从北冰洋或白令海的斜坡沃茨平流而来的;它们都无法在大陆架上完成自己的生命周期。因此，它们是陆棚-海盆交换的示踪物。该项目将试图了解哪些大型桡足类到达楚科奇（宽）和博福特（窄）货架，以及物理强迫（上升流，入侵，漩涡），这是负责。一旦上架，大型桡足类的大小和生殖反应在空间上是如何变化的，物理过程和食物供应的作用是什么？这些反应确定了支持远洋生态系统的大陆架生境的稳健性。该项目将确定哪些桡足类被移出大陆架，以及与这种迁移有关的物理过程（涡流、羽流）。调查将把这些生态系统测量与物理强迫（观测和模型）相结合，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.