MRI: Development of an integrated wide-band acoustical backscattering and large-area camera imaging instrument for studies of mesopelagic and bathypelagic ecosystems

中层和半深海带共同跨越约200米至4000米深的海洋，形成了地球上最大的栖息地之一。这些区域是浮游动物和微型浮游动物的不同群落的家园，包括各种小鱼、头足类、甲壳类和胶状生物。然而，人们对这些深层黑暗生态系统中居民的生物学、适应性、丰富性、生物量和分布知之甚少。一般而言，这些生物很难用常规渔网进行采样，原因包括生物的斑驳、更多移动生物避开渔网、在这种深度使用渔网对脆弱物种进行概括性采样的困难以及渔网对脆弱物种的破坏。然而，最近的证据表明，基于渔网抽样的中上层带微生态鱼类的全球生物量估计可能太低了一个数量级，并表明表层生产量和中上层鱼类生物量之间存在强烈耦合，这暗示了以前被低估的生物地球化学作用。该项目将通过开发声学和光学生态系统综合评估仪，量化浮游动物和微型浮游动物在中上层和底层生态系统中的生物量和分布，填补目前确定中层和底层生态系统特征的技术空白。该仪器特别适合于了解浮游动物和微型浮游动物的不同群落与环境变异性的关系，如中尺度海洋涡旋、锋面和上升区，以及陡峭的地形，如峡谷、海山和陆架断裂。这项研究的影响将从以科学为基础的渔业管理和决策的基础研究问题延伸到更广泛的社会相关问题。项目成果将极有可能指导为科学界和渔业研究界的用户开发未来可用于渔业和生态系统评估的商业工具。该项目将开发一种结合宽带声学散射和两种大规模相机成像的拖曳仪器，其额定深度可达2 000米，与环境传感器相结合，可应对在中大洋和深海区域进行采样所面临的许多挑战。该仪器利用了新兴的宽带声学方法。声频将几乎连续地跨越1-450 kHz，同时提供全频谱？关于浮游动物和微型浮游动物的信息，低频率最适合于含气生物的共振分类，如真菌类和管水母类，较高频率最适合于无气体包裹体的生物的光谱分类，如真毛虫和盐藻。双尺度摄像系统将提供这些生物在大范围内的图像，用于分类/种一级分类以及行为观察，包括成像较大的和移动的微粒子，并将实地核实天气声学数据。

The mesopelagic and bathypelagic zones together span ocean depths from approximately 200 meters to 4,000 meters below the surface and form one of the largest habitats on Earth. These zones are home to diverse communities of zooplankton and micronekton, including a variety of small fishes, cephalopods, crustaceans, and gelatinous organisms. Yet relatively little is known about the biology, adaptations, abundance, biomass, and distribution of the inhabitants of these deep and dark ecosystems. In general, such organisms are difficult to sample by conventional nets due to a combination of the patchiness of the organisms, avoidance of the nets by more mobile organisms, difficulties in sampling synoptically at such depths using nets, and the destruction of fragile species by the nets. However, recent evidence suggests that the global biomass estimates of micronektonic fish in the mesopelagic zone based on sampling by nets may be an order of magnitude too low and suggests a strong coupling between surface production and mesopelagic fish biomass, hinting at a previously under-appreciated biogeochemical role. This project will fill the current technological void for characterizing mesopelagic and bathypelagic ecosystems by developing a combined acoustical and optical ecosystem assessment instrument for quantifying the biomass and distribution of zooplankton and micronekton in the mesopelagic and bathypelagic zones. This instrument is particularly well suited to understanding the diverse communities of zooplankton and micronekton in relation to environmental variability, such as meso-scale oceanic eddies, fronts, and upwelling regions, and abrupt topography, such as canyons, seamounts, and shelf breaks. Impacts from this research will extend from basic research problems underpinning science-based fisheries management and decision making, to broader societally relevant problems. The project outcomes will most likely guide the development of future commercially available instruments for fisheries and ecosystem assessment for users from both the scientific and fisheries research communities.This project will develop a combined wide-band acoustic scattering and two-scale large-area camera imaging towed instrument, rated to depths as great as 2,000 m, integrated with environmental sensors that can address many of the challenges associated with sampling in the mesopelagic and bathypelagic zones. This instrument capitalizes on emerging broadband acoustical approaches. The acoustic frequencies will span 1-450 kHz almost continuously, simultaneously providing ?full spectrum? information on zooplankton and micronekton, with the lower frequencies optimized for resonance classification of gas-bearing organism, such as myctophids and siphonophores, and the higher frequencies optimized for spectral classification of organism without gas-inclusions, such as euphausiids and salps. The two-scale camera system will provide images of these organisms over a large area for taxa/species-level classification as well as behavioral observation, including imaging larger and mobile micronekton, and will ground-truth the synoptic acoustic data.