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关键成员，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。真甲藻是北大西洋浮游食物网中一类重要的甲壳类浮游动物，具有较强的游动能力和活跃的聚集行为，是浮游动物聚集研究的重要模式物种。该项目将处理以下假设，即秋季期间沿乔治斯浅滩北侧和缅因湾南部的Euphausiid聚集物的形成和变异性与物理聚集机制与当地地形的相互作用以及与鱼类垂直迁徙和活跃聚集行为的可塑性有关，这种可塑性产生于食物可获得性和鲱鱼捕食的变异性。这些假设将通过一个现场计划得到解决，该计划采用了一系列全面的传感器，包括常规窄带和最近开发的宽带声学系统来采样真尾目动物，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。这些传感器将用于一种创造性的组合：(1)粗略的网格调查，以表征真浮游动物、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)分布中沿坡和跨坡的变异性；(2)精细的适应性调查，用于跟踪单个真浮游动物的聚集，并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或可能的变化，在流场，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。结果将通过科学出版物和将召开的一次全国会议进行传播。对这项工作及其发现的描述将通过多个门户网站的组合进行传播，这对非专业观众来说是易懂的。这项研究将通过开发与海洋科学卓越教育中心合作制作和分发的网上课程，进一步与教育相结合。把重点放在具有重要商业价值的鱼类--鲱鱼之间的相互作用，以及世界上产量最高的捕鱼区之一--乔治斯海岸/缅因湾复合体的远洋生态系统，将使整个社会受益。

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.