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，并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 crystallorophias）和南极银鱼（Pleuragramma anastricum）。 桡足类和水晶磷虾是南极高纬度地区的主要鱼种，是南极银鱼的主要食物，而银鱼是低营养级（桡足类、磷虾）和高营养级（鱼类、海洋哺乳动物、飞鸟、阿德利企鹅和帝企鹅）之间的主要联系。尽管这些关键物种的意义，有桡足类，磷虾和银鱼中尺度分布，年龄/成熟度类的空间结构，以及它们与罗斯海内的物理驱动程序的相互作用的了解有限。 自主水下剖面滑翔器是一种发展中的技术，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Slocum Webb滑翔机中集成的多频回声测深仪的能力，目的是首次对罗斯海三个营养级的同时分布情况进行基于滑翔机的声学评估。测量物理、化学和生物参数的辅助滑翔机传感器将提供中尺度和次中尺度水文信息，从中将研究浮游植物-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。这里提出的方法，滑翔机声学，是相对较新的，有可能是转型调查食物网和罗斯海生态系统。研究人员将修改并将声学浮游动物和鱼类剖面仪（AZFP）多频回声测深仪集成到Slocum Webb G2滑翔机中，该滑翔机能够区分磷虾和其他类型的浮游动物，包括桡足类，以及不同大小的磷虾和银鱼。AZFP将与现有的滑翔机传感器进行补充，包括CTD，WET Labs BB 2FL ECO冰球，用于同步叶绿素荧光（浮游植物生物量）和光学后向散射测量，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期间进行测试，在那里它将进行声学调查，以绘制南部夏季沿着特拉诺瓦湾冰间冰架和邻近大陆架沃茨的多种浮游动物类群和银鱼的分布和丰度。将研究浮游植物-浮游动物-鱼类分布与浮游动物和银鱼物种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，将多次进行协调一致的船基声学取样和拖网/拖网，以验证滑翔机声学物种、大小和丰度测量。该项目期间产生的开放式自动数据将通过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。产生一致的，垂直分辨率，高分辨率的滑翔机声学测量将确定该项目的成功成果，这将有助于确定在使用它们作为一个潜在的成本效益，自动化检查在南极的食物网的挑战。

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.