Collaborative Research: BEST: The Trophic Role of Euphausiids in the eastern Bering Sea: Ecosystem Responses to Changing Sea-ice Conditions

Lessard 0732389大学华盛顿研究人员的主要假设是，海冰和相关食物资源的时间和覆盖范围的季节性和年际变化将导致磷虾年龄结构，饮食历史和营养条件的差异，最终转化为生产率和可获得性的差异，作为更高营养水平的猎物。本研究提供经费，以量化重要磷虾的年龄结构和食性历史，以及它们的消费和生长的详细信息，并将野外采集和分析与实验室饲养相结合，用于年龄校准和船上饲养实验，以测试营养脂质标志物的有效性和保留以及食物资源的质量和数量。确定气候驱动的海冰条件变化对主要磷虾类脂质含量和脂质类别的潜在影响，从而确定季节和年际时间尺度上的营养状况和繁殖潜力。了解磷虾在变化的空间（即冰覆盖，冰缘和开放水域）和时间（即季节性和年际）猎物场下的摄食历史，摄食率和放牧策略。 将采用多种方法（即喂养实验、肠道内容物分析）验证和测定特定脂质饮食标记物的保留。应用生物化学方法的最新进展来确定磷虾野外种群的年龄结构，以及气候变化对季节性和年际性种群维持或破坏的潜在影响。由阿拉斯加同事平行进行的实验室饲养将允许校准队列中的精确年龄。该项目是一个更大计划的一部分，该计划旨在发展对白令海东部大陆架综合生态系统的理解，这是美国沿海沃茨的一个高产地区。 这个生态系统是美国商业渔业的主要部分，也为阿拉斯加的猎人和渔民提供了重要的资源。 磷虾被认为是该区域浮游生物与鱼类资源之间食物网的关键环节。 了解这些生物的生态对于了解商业和自给性渔业如何应对不断变化的环境至关重要。

Lessard 0732389Univ. of Washington The principal investigators' primary hypothesis is that seasonal and interannual variation in the timing and coverage of sea-ice and associated food resources will lead to differences in age structure, diet history and nutritional condition for euphausids, which ultimately translate into differences in production rates and availability as prey to higher trophic levels. Funds are provided to quantify the age structure and diet history of important euphausids together with detailed information on their consumption and growth and to link field collections and analysis with laboratory rearing for age calibrations and shipboard feeding experiments to test the validation and retention of trophic lipid markers as well as the quality and quantity of food resources.The investigators' objectives include:1. To determine the potential impact of climate driven changes in sea-ice conditions on lipid content and lipid classes in major euphausid species and thus nutritional condition and reproductive potential over seasonal and interannual time scales.2. To understand the feeding history, feeding rates and grazing strategies of euphausids under changing spatial (i.e. ice-covered, ice-edge, and open water zones) and temporal (i.e. seasonal and interannual) prey fields. Multiple approaches (i.e. feeding experiments, gut content analysis) will be used for validation and determination of retention of specific lipid dietary markers.3. To apply recent advances in biochemical approaches to determine the age structure in field populations of euphausids and the potential effects of climate change on maintenance or disruption of cohort populations seasonally and interannually. Laboratory rearing conducted in parallel by Alaskan colleagues will allow calibrating precise ages in cohorts.This project is part of a larger program designed to develop understanding of the integrated ecosystem of the eastern Bering Sea shelf, a highly productive region of US coastal waters. This ecosystem is home to a major portion of the commercial fisheries of the US and also provides significant resources to subsistence hunters and fisherman of Alaska. Euphausids are believed to be a critical link in the food web connecting plankton to fish resources in the region. Understanding the ecology of these organisms is critical to understanding how the commercial and subsistence fisheries may respond to a changing environment.