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深海之间的交换对于了解海洋中温度、盐度和其他物理、化学和生物水性质的分布非常重要。尽管它们很重要，而且之前的研究也很多，但这些交流过程并没有被很好地理解。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是一个挑战。这项全面的研究将利用最先进的现实海洋环流模型，结合新的动力系统工具，更好地理解和量化这些交换。研究区域将从缅因湾和大西洋中部海湾延伸到墨西哥湾流和马尾藻海，那里是美国鳗鱼的产卵地点，美国鳗鱼是一种具有重大科学价值和经济价值的物种。这种鱼从北美海岸的淡水栖息地向马尾藻海进行了显著的产卵迁徙，然后其幼体不得不返回主要发生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，它们必须利用海洋循环的特征来完成迁徙。这项研究还将探索他们如何实现这一非凡的壮举。该项目将支持三名职业生涯早期的科学家，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，包括班级访问和主要针对少数族裔学生的实地考察。它还将继续努力，通过艺术和舞蹈将科学带给公众。拟议研究的首要目标是从拉格朗日的观点描述和量化大陆架和开阔海洋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。其中包括地形转向、风强迫、搁置喷流的不稳定性和曲折，以及墨西哥湾流曲折和撞击大陆架的环，将对每一项进行调查和量化。拟议研究的具体区域和特征包括大西洋中部海湾、缅因湾、坡海、墨西哥湾流及其延伸区和马尾藻海。拟议工作的一个重点应用将致力于研究鳗鱼幼体的扩散，作为半拉格朗日生物相关粒子的例子。这项研究将以高分辨率区域模式和数据同化全球模式为基础，将欧拉通量估计值与拉格朗日估算值进行比较，并将传统统计技术与新的动力系统分析相结合。由于其跨学科性质，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种领域产生影响。PI还将与NOAA东北渔业科学中心的同事合作。参与K-12教育计划将包括：(1)与已建立的伙伴学校合作，将项目成果引入他们的地球科学模块，以及(2)东波士顿高中(80%的少数族裔学生)的课堂访问和实地考察。参加麻省理工学院/世界卫生组织海洋学联合计划的PIS将把这项研究的结果纳入他们的研究生课程。

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.