Using Bio-acoustics on an Autonomous Surveying Platform for the Examination of Phytoplankton-zooplankton and Fish Interactions in the Western Ross Sea

罗斯海是南极洲最具生产力的地区之一，支持罗斯海食物网中几个关键物种的大量种群，包括桡足类，水晶磷虾（Euphausia crystorophias）和南极银鱼（Pleuragramma antarcticum）。桡足类和水晶磷虾是南极高海拔地区的主要鱼类——南极银鱼的主要食物，而银鱼是连接较低（桡足类、磷虾）和较高（鱼类、海洋哺乳动物、飞禽、海鲈和帝企鹅）营养水平的主要纽带。尽管这些关键物种具有重要意义，但对罗斯海桡足类、磷虾和银鱼的中尺度分布、年龄/成熟度的空间结构及其与物理驱动因素的相互作用的了解有限。自主水下剖面滑翔机是一项正在发展的技术，它提供了在区域尺度上提供高空间、时间和深度分辨率数据的潜力。该项目将测试集成在Slocum Webb滑翔机中的多频率回声测深仪的能力，目的是提供第一个基于滑翔机的罗斯海三个营养水平同时分布的声学评估。测量物理、化学和生物参数的互补滑翔机传感器将提供中尺度和亚中尺度水文信息，从中浮游植物-浮游动物-鱼类的相互作用以及这些生物与物理驱动因素（海冰、环流特征）之间的关系将被研究。这里提出的方法，滑翔机声学，相对较新，有可能成为研究食物网和罗斯海生态系统的变革。研究人员将改进并整合声波浮游动物和鱼类分析器（AZFP）多频回声测深仪到Slocum Webb G2滑翔机中，使其能够区分磷虾和其他类型的浮游动物，包括桡足类动物，以及不同大小的磷虾和蠹虫。AZFP将与现有的滑翔机传感器进行补充，包括CTD，用于同时进行叶绿素荧光（浮游植物生物量）和光学后向散射测量的WET实验室BB2FL ECO puck，以及用于测量溶解氧的Aanderaa Optode。新的传感器套件将在为期四周的滑翔机部署中进行测试，在那里，它将进行声学调查，绘制出南部夏季沿特拉诺瓦湾多冰湖冰架和邻近大陆架水域的多种浮游动物分类群和银鱼的分布和丰度。研究浮游植物-浮游动物-鱼类分布与浮游动物和银鱼种类和大小分布的物理驱动因素之间的关系。在滑翔机部署期间，将进行多次协调的船上声学采样和网拖/拖网采集，以验证滑翔机声学测量的物种、大小和丰度。在这个项目中产生的开放可访问的自动化数据将通过RUCOOL（罗格斯大学海洋观测领导中心）和THREDDS（专题实时环境数据分发系统）提供。生产一致的、垂直分辨率的、高分辨率的基于滑翔机的声学测量将定义这个项目的一个成功的结果，这将有助于确定在使用它们作为一个潜在的经济有效的、南极食物网的自动化检查中所面临的挑战。

The Ross Sea is the one of the most productive regions in Antarctica and supports large populations of several key species in the Ross Sea food web, including copepods, crystal krill (Euphausia crystallorophias), and Antarctic silverfish (Pleuragramma antarcticum). Copepods and crystal krill dominate the diets of Antarctic silverfish, the dominant fish species in the high Antarctic zone, and silverfish are a major link between lower (copepods, krill) and higher (fishes, marine mammals, flighted birds, Adélie and Emperor penguins) trophic levels. Despite the significance of these key species, there is limited understanding of copepod, krill, and silverfish mesoscale distribution, spatial structure of age/maturity classes, and their interactions with physical drivers within the Ross Sea. Autonomous underwater profiling gliders are a developing technology that offers the potential for providing high spatial, temporal, and depth resolution data on regional scales. The project will test the capability of a multi-frequency echo sounder integrated into a Slocum Webb glider with the aim of providing the first glider-based acoustic assessment of simultaneous distributions of three trophic levels in the Ross Sea. Complementary glider sensors measuring physical, chemical, and biological parameters will provide mesoscale and sub-mesoscale hydrographic information from which phytoplankton-zooplankton-fish interactions and the relationships between these organisms and physics drivers (sea ice, circulation features) will be investigated. The approach proposed here, glider acoustics, is relatively new and has the potential to be transformational for investigating food webs and the Ross Sea ecosystem. Researchers will modify and integrate an Acoustic Zooplankton and Fish Profiler (AZFP) multi-frequency echo sounder into a Slocum Webb G2 glider with the capability to differentiate between krill and other types of zooplankton, including copepods, and different sizes of krill and silverfish. The AZFP will be complemented with the existing glider sensors including a CTD, a WET Labs BB2FL ECO puck configured for simultaneous chlorophyll fluorescence (phytoplankton biomass) and optical backscatter measurements, and an Aanderaa Optode for measuring dissolved oxygen. The new sensor suite will be tested during a four-week glider deployment, where it will conduct acoustic surveys to map distribution and abundance of multiple zooplankton taxa and silverfish during the austral summer along the Terra Nova Bay polynya ice shelf and in adjacent continental shelf waters. The relationships between phytoplankton-zooplankton-fish distributions and the physical drivers of zooplankton and silverfish species and size distributions will be investigated. Coordinated ship-based acoustic sampling and net tows/trawls will be conducted multiple times during the glider deployment to validate glider acoustic-based species, size, and abundance measurements. Open accessible, automated data produced during this project will be made available through RUCOOL (Rutgers University Center for Ocean Observing Leadership) and THREDDS (Thematic Real-time Environmental Data Distribution System). The production of consistent, vertically-resolved, high resolution glider-based acoustic measurements will define a successful outcome of this project that should help in identifying the challenges in their use as a potentially cost-effective, automated examination of food webs in the Antarctic.