Biological and Physical Determinants of Euphausiid Aggregation, Behavior, and Interaction with Higher Predators at an Abrupt Topographical Feature in the Gulf of Maine

浮游动物是海洋生态系统的重要成员，但控制其分布和聚集的生物和物理因素尚未完全了解，特别是在大陆架断裂和大陆架深盆地边缘。琵鳅是北大西洋中上层食物网中重要的甲壳类浮游动物，由于其强大的游动能力和活跃的聚集行为，是研究浮游动物聚集的一个有趣的模式物种。该项目将探讨以下假设：秋季沿乔治河岸北侧和缅因湾南部形成的黄鳞鲷聚集的形成和变化与当地地形的物理集中机制、鱼类垂直迁移和活跃聚集行为的可塑性的相互作用有关，而这种可塑性源于食物供应的变化和鲱鱼的捕食。这些假设将通过一个采用综合传感器阵列的现场项目来解决，包括传统的窄带和最近开发的宽带声学系统来取样，以及各种其他声学、光学、网络和其他采样设备来量化它们的物理和生物环境。这些传感器将用于以下创造性的组合：(1)粗尺度网格调查，以描述环鳞鲷、它们的捕食者、其他浮游动物、浮游植物和物理条件（例如，流场）沿坡和跨坡分布的变化特征；(2)精细尺度自适应调查，用于跟踪环鳞鲷的个体聚集，观察它们的三维结构和垂直位置如何随着环境条件的变化而变化。重复调查的时间将利用已知的或可能的流场变化、食物供应、光照水平和捕食。这项研究将通过研究生、本科生和高中学生的参与来促进教学、培训和学习。研究结果将通过科学出版物传播，并将召开一次全国会议。工作的描述和它的发现可理解的外行观众将传播通过门户网站的组合。通过与海洋科学卓越教育网络海洋世界中心合作制作和分发在线课程，这项研究将进一步与教育相结合。对整个社会的好处将来自于关注绿腹鱼与鲱鱼（一种重要的商业鱼类）的相互作用，以及关注世界上最多产的捕鱼区之一的乔治河岸/缅因湾综合的远洋生态系统。

Zooplankton are key members of marine ecosystems, but the biological and physical factors governing their distribution and aggregation are not fully understood, especially at the continental shelf break and margins of the deep basins of the shelf. Euphausiids are an important group of crustacean zooplankton in North Atlantic pelagic food webs and represent an interesting model species for the study of zooplankton aggregation due to their strong swimming capabilities and active aggregative behaviors. This project will address the hypotheses that the formation and variability of euphausiid aggregations along the northern flank of Georges Bank and the southern portion of the Gulf of Maine during fall relate to the interaction of physical concentration mechanisms with local topography and with plasticity in diel vertical migration and active aggregative behaviors, and that this plasticity arises from variability in food availability and predation by herring. These hypotheses will be addressed through a field program employing a comprehensive array of sensors, including both conventional narrowband and recently-developed broadband acoustic systems to sample the euphausiids, and a variety of other acoustic, optical, net, and other sampling devices to quantify their physical and biological environment. These sensors will be used in an inventive combination of (1) coarse-scale grid surveys to characterize along- and across-slope variability in the distribution of euphausiids, their predators, other zooplankton, phytoplankton, and physical conditions (e.g., the flow field), and (2) fine-scale adaptive surveys used to track individual euphausiid aggregations and observe how their three-dimensional structure and vertical position vary with changing environmental conditions. Repeat surveys will be timed to capitalize on known or likely variations in the flow field, food availability, light levels, and predation. The study will promote teaching, training, and learning via the participation of students at the graduate, undergraduate, and high school levels. The results will be disseminated via scientific publications and a session to be convened a national meeting. Descriptions of the work and its findings intelligible to a lay audience will be disseminated via a combination of web portals. The research will be further integrated with education by developing on-line lessons produced and distributed in collaboration with the Centers for Ocean Sciences Education Excellence Networked Ocean World. Benefits to society as a whole will arise from focusing on the interactions of euphausiids with herring, a commercially-important fish species, and on the pelagic ecosystem of the Georges Bank/Gulf of Maine complex, one of the world's most productive fishing areas.