Physical and Biological Exchange Processes and Lagrangian Pathways of Eel Larvae Between Deep Ocean and Shelf Regions of the Northwestern Atlantic

大陆架或斜坡上的水与近海更深的海洋之间的交换对于了解海洋中温度、盐度和其他物理、化学和生物水特性的分布非常重要。尽管它们很重要，而且以前的研究也很广泛，但这些交换过程并没有得到很好的理解。这是因为它们发生在时间和空间的短尺度上，这使得用现场测量或数值模型来解决它们成为一个挑战。这项综合研究将利用最先进的现实海洋环流模型与新的动力系统工具相结合，以更好地理解和量化这些交换。研究区域将从缅因湾和中大西洋湾延伸到墨西哥湾流和马尾藻海，马尾藻海是美洲鳗的产卵地，这是一种具有重大科学价值和经济价值的物种。这种鱼进行了一次引人注目的产卵迁徙，从北美沿岸的淡水栖息地到马尾藻海，然后它的幼虫必须返回主要分布在北美东海岸的沿海苗圃栖息地。由于幼虫的游泳能力有限，它们必须通过海洋环流特征来完成迁徙。本研究还将探讨它们是如何实现这一非凡壮举的。该项目将支持三名早期职业科学家，并将促进物理海洋学家和生物学家之间的合作。该项目还将为K-12教育项目做出贡献，包括针对少数民族学生的课堂参观和实地考察。它还将继续努力通过艺术和舞蹈将科学带给公众。拟议研究的总体目标是从拉格朗日的观点来描述和量化大陆架和公海之间的水团交换和性质通量。预计有几种物理机制会影响该区域的交换过程。这些因素包括地形导向、风的强迫、破碎陆架射流的不稳定性和弯曲，以及墨西哥湾流的弯曲和环撞击陆架，每一个都将被调查和量化。拟议研究的具体区域和特征包括大西洋中部湾，缅因湾，坡海，墨西哥湾流及其延伸，以及马尾藻海。所提议的努力的一个重点应用将致力于调查鳗鱼幼虫的扩散，作为半拉格朗日的例子，生物相关颗粒。这项研究将基于一个高分辨率的区域模型和一个数据同化的全球模型，并将欧拉通量估计与拉格朗日通量估计进行比较，并将传统的统计技术与新的动力系统分析相结合。由于其跨学科的性质，该项目将对包括物理海洋学、海洋生物学和动力系统在内的各个领域产生影响。pi还将与NOAA东北渔业科学中心的同事合作。参与K-12教育项目将包括(1)与已建立的合作学校一起努力，将项目成果引入他们的地球科学模块，(2)为东波士顿高中（80%的少数民族学生）的学生进行课堂参观和实地考察。参加麻省理工学院/世界卫生组织海洋学联合方案的私人学院将把这项研究的结果纳入其研究生课程。

Exchange between waters over the continental shelf or slope and the deeper ocean offshore is important for understanding the distribution of temperature, salinity and other physical, chemical, and biological water properties in the ocean. Despite their importance and the extensive number of previous studies, these exchange processes are not well understood. This is because they occur over short scales in time and space, which makes it a challenge to resolve them with field measurements or numerical models. This comprehensive study will make use of state-of-the-art realistic ocean circulation models in combination with novel dynamical system tools to better understand and quantify these exchanges. The study area will extend from Gulf of Maine and the Mid-Atlantic Bight to the Gulf Stream and the Sargasso Sea, which is the spawning site for the American eel, a species of great scientific interest and economic value. This fish undertakes a remarkable spawning migration from freshwater habitats along the North American coast to the Sargasso Sea, and its larvae then have to return to coastal nursery habitats that predominantly occur along the eastern seaboard of North America. Since the larvae have only limited swimming ability, they have to navigate ocean circulation features to complete their migration. This study will also explore how they achieve this remarkable feat. The project will support three early-career scientists and will promote collaboration between physical oceanographers and biologists. The project will also contribute to K-12 educational programs, including class visits and field trips targeting mostly minority students. It will also continue efforts to bring science to the public through art and dance. The overarching goal of the proposed study is to characterize and quantify, from a Lagrangian viewpoint, water mass exchanges and property fluxes between the continental shelf and the open ocean. Several physical mechanisms are expected to influence the exchange processes in this region. These include topographic steering, wind forcing, instabilities and meanders of the shelfbreak jet, and Gulf Stream meanders and rings impinging on the shelf, each of which will be investigated and quantified. Specific regions and features of interest for the proposed study include the Mid-Atlantic Bight, the Gulf of Maine, the Slope Sea, the Gulf Stream and its extension, and the Sargasso Sea. A focused application of the proposed effort will be devoted to investigating the dispersal of eel larvae as an example of semi-Lagrangian, biologically relevant particles. The study will be based on a high-resolution regional model and a data-assimilative global model, and would compare Eulerian flux estimates with their Lagrangian counterparts and combine conventional statistical techniques with novel dynamical systems analysis. By its interdisciplinary nature, this project will have impacts across a variety of fields, including physical oceanography, marine biology, and dynamical systems. The PIs will also collaborate with colleagues at the NOAA Northeast Fisheries Science Center. Participation in K-12 educational programs will include (1) efforts with established partner schools to introduce project results into their earth science module, and (2) class visits and field trips for East Boston High School (80% minority students) students. PIs participating in the MIT/WHOI Joint Program in Oceanography will incorporate the study's findings into their graduate courses.