Collaborative Proposal: Cross-Shelf Transport and Post-Bloom New Production Near the Pribilof Islands

拟议的研究将检验这样一个假设，即富含营养物和浮游动物的斜坡水在大陆架上的流动影响了普里比洛夫群岛附近春季开花后的新产量和浮游动物种群，从而增强了该地区支持幼鱼和浮游海鸟的能力。该项目将调查斜坡上的水在架子上的运输，这些水在夏季提供维持新的初级生产的养分，在这个季节，架子上的新产品的可用性受到分层的限制。第二种假设是，这种新的生产将由硅藻而不是鞭毛虫主导，以硅藻为基础的食物网将产生比以鞭毛虫为基础的食物网具有更大能量含量的中浮游动物。这些富含能量的浮游动物对幼鱼和以浮游生物为食的海鸟来说，比那些以脂肪含量较低的浮游植物为食的动物更有价值。该项目还将在2004年至2007年7月/ 8月的巡航期间测试这些假设。在这些巡航中，pi将比较在夏季跨大陆架平流较弱的中间大陆架区域（系泊2），在间歇平流但很少垂直混合的中间大陆架区域（系泊4）和在有大陆架上运输和潮汐混合的营养物质进入上层混合层的Pribilof群岛的产量和命运。该项目将测量沿陆架和跨陆架的流量（Stabeno， PMEL）、营养物质浓度（Mordy, UW/PMEL）、浮游植物的常设储量（Zeeman， U. New England）、新产量、再生产量和总产量（Zeeman, Sambrotto, Lamont-Doherty）、与浮游植物常设储量和产量相关的微型浮游动物的放牧率（Strom，西华盛顿大学）、浮游动物生物量和组成（Coyle， U. Alaska, Fairbanks）、脂质含量、脂肪酸组成、浮游动物、幼鱼和海鸟（Napp， NMFS）的稳定同位素特征，以及海鸟的觅食分布和食物习性（Hunt， U. California, Irvine）。此外，该项目将使用卫星跟踪的漂流器和系泊来测量电流。该提案是白令海第一个解决富含营养的斜坡水的陆架通量对春季开花后新产量的影响，以及反过来，这种新产量如何影响幼鱼（即0岁的狭鳕）和浮游海鸟的猎物丰度和质量的提案。花期后的新产量对于提供高质量的猎物尤其重要，因为此时幼鱼正在形成储备，以便过冬，海鸟也在喂养生长中的幼鱼。这项工作的重点是一个具有重大经济和社会重要性的地区，并审查影响普里比洛夫群岛水域生产力的生态过程，以及它们支持幼鱼、海鸟和依赖它们的海洋哺乳动物的能力。该地区最丰富的鱼类是幼斑鳕，是世界上最大的单一物种渔业的目标。所提出的研究所产生的信息将对评估全球气候变化如何影响春花后新产量的数量和上层营养水平猎物的营养质量的机制有价值。该项目将包括实地和实验室的本科生、研究生和博士后，以分析和整理数据，并将努力与圣保罗和圣乔治群岛的学校系统制定外展方案。这项工作将通过评审文献和网站进行传播。

The proposed study will test the hypothesis that on-shelf flow of nutrient- and zooplankton-rich slope water influences post-spring-bloom new production and zooplankton populations in the vicinity of the Pribilof Islands, thereby enhancing the region's ability to support juvenile fish and planktivorous seabirds. The project will investigate on-shelf transport of slope water, which supplies nutrients that sustain new primary production in summer, a season when the availability of new production on the shelf is limited by stratification. A second hypothesis is that this new production will be dominated by diatoms rather than by flagellates, and a diatom-based food web will result in meso-zooplankton with a greater energy content than meso-zooplankton in a flagellate-based food web. These energy-rich zooplankton are expected to be of greater value to juvenile fish and planktivorous seabirds than those that have fed upon less lipid-rich phytoplankton. The project will also test these hypotheses during July/August cruises in 2004 to 2007. During these cruises, the PIs will compare production and its fate in an area on the middle shelf where summer-time cross-shelf advection is weak (Mooring 2), on the middle shelf in an area of episodic advection but little vertical mixing (Mooring 4) and at the Pribilof Islands where there is both on-shelf transport and tidal mixing of nutrients into the upper mixed layer. The project will measure along- and across-shelf flows (Stabeno, PMEL), nutrient concentrations (Mordy, UW/PMEL), standing stocks of phytoplankton (Zeeman, U. New England), new, regenerated and total production (Zeeman, Sambrotto, Lamont-Doherty), the grazing rates of micro-zooplankton in relation to phytoplankton standing stocks and production (Strom, Western Washington University), zooplankton biomass and composition (Coyle, U. Alaska, Fairbanks), lipid content, fatty-acid composition, and stable isotope signatures of zooplankton, juvenile fish and seabirds (Napp, NMFS), and the foraging distributions and food habits of marine birds (Hunt, U. California, Irvine). In addition, the project will use satellite-tracked drifters and moorings to measure currents. This proposal is the first in the Bering Sea to address the effect of on-shelf fluxes of nutrient-rich slope water on post-spring-bloom new production, and in turn, how this new production affects the abundance and quality of prey for juvenile fish (i.e., age-0 walleye pollock) and planktivorous seabirds. Post-bloom new production may be particularly important for providing high quality prey at a time when juvenile fish are developing the reserves to carry them through the winter and seabirds are feeding growing young. The work focuses on a region of great economic and societal importance, and examines the ecological processes that affect the productivity of Pribilof Islands' waters and their ability to support juvenile fish, and the seabirds and marine mammals that depend on them. The most abundant fish in the area are juvenile walleye pollock, the target of the world's largest single-species fishery. The information generated by the proposed research will be of value in assessing the mechanisms whereby global climate change can affect the amount of post- spring bloom new production and the nutritional quality of prey available to upper trophic levels. The project will include undergraduate, graduate and post-doctoral students in the field and in the laboratory for the analysis and workup of the data and will strive to develop outreach programs with the school systems on St Paul and St. George Islands. The work will be disseminated in the refereed literature and through web sites.