Ocean processes over the southern Weddell Sea shelf using seal tags

使用密封标签在威德尔海南部陆架上进行海洋过程

• 批准号: NE/G014086/1
• 负责人: Keith Nicholls
• 金额: $ 44.94万
• 依托单位: British Antarctic Survey
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FG014086%2F1
• 关键词: Ocean; processes; over; southern; Weddell; Ocean; processes; over; southern; Weddell

Antarctic Bottom Water (AABW) is an important water mass in the cooling and ventilation of the World's deep ocean. One of the principal sources of AABW has its roots in the production of cold, dense water that results from wintertime sea-ice production over the continental shelf of the southwestern Weddell Sea. However, there remains great uncertainty about the processes controlling the initial import of the source waters onto the continental shelf, and the export of the dense waters from the shelf regime. The uncertainty results from the extremely challenging sea ice conditions existing in the southern Weddell Sea, especially during winter. Conditions in the area of interest during winter are exceptionally difficult for any ship-based work, and instruments deployed in the ocean during the rather less difficult summer months, and which are left to monitor the water properties over the Winter period, are vulnerable to dredging by passing icebergs. We will tackle the problem using a technology that has recently come of age. We propose to attach conductivity-temperature-deph (CTD) tags, miniaturised oceanographic instruments, to Weddell seals (Leptonychotes weddellii). The tags have a satellite transmitter that relays the oceanographic data collected during the seals' dives, together with the dive location. The tag is glued harmlessly to the animal's fur using standard marine two-component epoxy and comes off again during the annual moult about eleven months later. A pilot study undertaken by the British Antarctic Survey involved the tagging of four seals, three of which supplied over-winter datasets. Although the coverage was impressive from only three tags, emphatically confirming the practicality of the technique, the region of interest is nearly 500,000 km^2 in area and a comprehensive dataset requires substantially more tagged animals. We will tag 20 Weddell seals at the eastern end of the shelfbreak north of the Filchner-Ronne Ice Shelf during the late Austral summer of 2010/2011. The resulting dataset resulting from the animals' dives during the winter will give the most comprehensive picture to date of the ocean conditions over the southern Weddell Sea continental shelf. By mapping the temperature of the water near the sea floor we will determine the locations where dense waters leave the shelf, and the processes involved: either a direct flow down the slope under gravity, or initially mixing at the shelf edge with waters from off the shelf before descending down the slope. We will also be able to determine where the source waters come on to the shelf. Weddell seals are very accomplished divers, diving repeatedly for long periods and to depths regularly reaching the on-shelf seafloor. Among Antarctic seals, Weddell seals also inhabit the southernmost waters, and remain within the pack-ice in winter when the ice expands northward. These characteristics make Weddell seals ideally suited for the proposed study. Although primarily an oceanographic project, the movements and diving behaviour of Weddell seals is of great interest to seal biologists who wish to understand differing behaviours in different parts of Antarctica. These variations were ably demonstrated by the extraordinarily diverse behaviour of the animals tagged during the pilot, and by comparisons with previous tracking of this species in other parts of the Antarctic. The long-ranging movements displayed by some of the seals tracked during the pilot study are untypical for the species, at least at other Antarctic locations, and may be related to the local oceanographic conditions. It is widely recognised that multidisciplinary studies such as proposed here will provide us with the tools to better predict how the distribution, behaviour and ultimately population status may be affected by changing ocean and climate conditions.

南极底水（AABW）是世界深海冷却和通风的重要水质量。 AABW的主要来源之一起源于寒冷，稠密的水生产，这是由于冬季海冰在西南韦德尔海的大陆架上产生的。但是，控制源水的初始进口到大陆架的过程以及从架子政策中出口茂密的水。不确定性是由于南部韦德尔海（Weddell Sea）（尤其是冬季）存在极具挑战性的海冰条件而产生的。对于任何基于船舶的工作而言，冬季感兴趣领域的状况极为困难，在夏季较难的夏季，在海洋中部署在海洋中的仪器，这些仪器在冬季不得不监测水性，这很容易受到通过冰山的挖泥。我们将使用最近成年的技术解决这个问题。我们建议将电导率 - 温度 - deph（CTD）标签（小型海洋学仪器）连接到Weddell密封件（LeptonyChotes Weddellii）。这些标签具有卫星发射器，该发射器将传达在海豹潜水期间收集的海洋数据以及潜水位置。该标签使用标准海洋两种组分环氧树脂将标签无害地粘在动物的皮毛上，并在大约11个月后的年度换羽中再次出现。英国南极调查进行的一项试点研究涉及四个密封的标签，其中三个提供了冬季的数据集。尽管仅来自三个标签的覆盖范围令人印象深刻，这强调了这项技术的实用性，但感兴趣的区域的面积为近500,000 km^2，而全面的数据集则需要更具标记的动物。在2010/2011年澳大利亚夏季，我们将在Filchner-Ronne Ice架以北的货架上的东端标记20个Weddell Seals。由动物在冬季潜水产生的数据集将为迄今为止在韦德尔海洋大陆货架上的海洋条件迄今为止提供最全面的图像。通过映射海底附近的水温度，我们将确定密集的水离开架子的位置以及所涉及的过程：要么在重力下方的斜坡下方直接流动，要么最初在架子边缘与从架子上的水混合，然后再下降。我们还将能够确定源水进入货架的位置。 Weddell密封非常出色，长期以来反复潜水，并定期到达架子上的海底。在南极海豹中，韦德尔海豹（Weddell Seals）还居住在最南端的水域，并在冬季冰冰向北扩展时留在冰之冰中。这些特征使Weddell密封非常适合拟议的研究。尽管主要是一个海洋图项目，但Weddell Seals的运动和潜水行为非常感兴趣，因为他们希望了解南极不同地区不同行为的生物学家。这些变化是通过在飞行员期间标记的动物的异常多样的行为来证明的，并且与先前在南极其他地区对该物种的追踪进行了比较。在试点研究期间跟踪的一些密封件显示的远程运动对该物种而言是毫无疑问的，至少在其他南极位置，可能与局部海洋学条件有关。人们普遍认为，此处提出的跨学科研究将为我们提供更好的工具，以更好地预测海洋和气候状况的变化如何影响分布，行为和最终人口状况。