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

楚科奇海和波弗特海大型浮游动物[桡足类]的陆架盆地交换

• 批准号: 0125004
• 负责人: Sharon Smith
• 金额: --
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0125004&HistoricalAwards=false
• 关键词: Shelf; Basin; Exchange; Large; Bodied

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.

北太平洋/北极西部地区的物理强迫表现出突然的制度变化，在一到二十年的时间里，几十年(约25-35年)相对寒冷、寒冷(比平均水平高2%)的条件被更温暖、更少冰(比平均水平低3%)的条件所取代；该地区的这种气候周期至少可以追溯到17世纪末。楚科奇/博福特大陆架生态系统对气候变暖的反应可能遵循两条完全不同的途径。在一种情况下，暖期将减少冰盖，并可能造成更强的热分层，更少的混合，有限的营养供应，较低的初级生产力，较小的浮游植物和较小的沿海浮游动物。在第二种情况下，也是在冰层较少的温暖时期，风的增加可能会导致陆架断裂上涌和混合，营养物质供应增加，更大的浮游植物和更大的深水浮游动物进入陆架。全球变化，特别是气候变暖，会不会导致楚科奇和波弗特大陆架和斜坡上出现更多大型浮游动物来支持鱼类、鸟类和哺乳动物，或者小型浮游动物会减少鱼类、鸟类和哺乳动物，而有利于栖息性的底栖生物？楚科奇和波弗特大陆架上的大型桡足类动物必须从北冰洋或白令海的斜坡水域平流而来；它们中没有一个能在大陆架上完成自己的生命周期。因此，它们是陆架-盆地交换的示踪物。该项目将试图了解哪些大型桡足类动物到达楚科奇(宽)和波弗特(窄)陆架，以及造成这种现象的物理压力(上升流、入侵、漩涡)。一旦上架，大型桡足类动物的大小和繁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？这些反应定义了大陆架栖息地支持远洋生态系统的稳健性。该项目将确定哪些桡足类从货架上被运输出去，以及与这种运输相关的物理过程(涡流、羽流)。调查将把这些生态系统测量与物理强迫(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。