Acoustic Assessment of Southern Ocean Salps and Their Ecosystem Impact

凝胶状浮游动物在全世界海洋系统中的重要性正在增加。 在南大洋，不断增加的海鞘密度可能会对更高级的捕食者产生不利影响，包括企鹅、海狗和须鲸。拟议的研究是一个方法开发项目，将提高通过声学调查间接评估南大洋海鞘丰度和分布的能力。将在南设得兰群岛和南极半岛周围的沃茨收集水文、净拖曳和声学后向散射数据，在那里发现了磷虾和海鞘，它们争夺食物。船上的实验操作和测量将导致改进的技术，用于评估salp生物量的声学。实验将集中在材料特性（密度和声速），尺寸和形状的salps，以及如何这些物理特性将随着salp的环境，喂养率和繁殖状态的变化。在实地，将在与网拖相同的地点收集声学回声测深仪的体积后向散射数据，以便能够比较网拖和声学估计的salp丰度。将开发和验证一个基于物理学的海鞘散射模型，以确定是否可以使用多个声频来区分与磷虾群和海鞘水华相关的散射。 在南极实地工作的同一期间，将在纽约长岛进行一项平行的推广和教育研究，检查当地的凝胶状浮游动物。这项研究将使项目参与者能够在前往南极洲之前学习和实践研究程序和方法;提供将用于教育目的的比较时间序列;并使更多的学生和教师参加研究项目，而不是参加南极实地考察部分。

The importance of gelatinous zooplankton in marine systems worldwide is increasing. In Southern Ocean, increasing salp densities could have a detrimental effect on higher predators, including penguins, fur seals, and baleen whales. The proposed research is a methods-develoment project that will improve the capability to indirectly assess abundances and distributions of salps in the Southern Ocean through acoustic surveys. Hydrographic, net tow, and acoustic backscatter data will be collected in the waters surrounding the South Shetland Islands and the Antarctic peninsula, where both krill and salps are found and compete for food. Shipboard experimental manipulations and measurements will lead to improved techniques for assessment of salp biomass acoustically. Experiments will focus on material properties (density and sound speed), size and shape of salps, as well as how these physical properties will vary with the salp's environment, feeding rate, and reproductive status. In the field, volume backscattering data from an acoustic echosounder will be collected at the same locations as the net tows to enable comparison of net and acoustic estimates of salp abundance. A physics-based scattering model for salps will be developed and validated, to determine if multiple acoustic frequencies can be used to discriminate between scattering associated with krill swarms and that from salp blooms. During the same period as the Antarctic field work, a parallel outreach and education study will be undertaken in Long Island, New York examining local gelatinous zooplankton. This study will enable project participants to learn and practice research procedures and methods before traveling to Antarctica; provide a comparison time-series that will be used for educational purposes; and include many more students and teachers in the research project than would be able to participate in the Antarctic field component.