Collaborative Research: Elucidating Environmental Controls of Productivity in Polynas and the Western Antarctic Peninsula

南极洲周围的沿海水域代表着地球上一些生物最丰富、最原始的生态系统。在很大程度上，这种丰富的生物集中在南极大陆附近的众多开口中，这些开口困扰着广阔的海冰(这些开口被称为多尼雅冰川)。这些多尼雅群岛代表着被称为热点的高产量地区，并支持南大洋动物密度最高的地区。它们中的许多也位于浩瀚的南极冰盖漂浮延伸的附近，每年夏天都会收到大量融化的径流。然而，人们对使这些生态系统具有如此生物生产力的具体过程知之甚少。在目前已知的46个南极沿海多尼雅物种中，只有几个得到了详细的调查。该项目将为罗斯海波利尼亚、阿蒙森波利尼亚和松岛波利尼亚开发生态系统模型，这三个区域是生产力最高的南极沿海波利尼亚。主要目标是使用这些模型来更好地了解基本的物理、化学和生物相互作用过程以及这些过程中的差异，这些过程使这些系统在生物上具有如此多的生产力，但在某些方面(例如，大小和生产力)在当今环境中有所不同。还将扩大建模工作，以潜在地评估这些生态系统过去可能如何运作，以及它们未来在不同的物理、化学和气候环境下可能会发生什么变化。该项目将通过斯坦福大学-S暑期本科生地球科学与工程研究(浪涌)计划，促进未被充分代表的少数民族的教育。Surge将为本科生提供在斯坦福大学获得工程和地球科学方面的指导研究经验的机会。老道明大学还将利用当地公立和私立学校的外联方案，以及正在进行的支持童子军海洋学荣誉徽章方案的方案，以产生外联和教育影响。波利尼亚(被海冰包围的开阔水域)是极地生态系统中不成比例的生产区，但对其高生产率的控制并不是很好。该项目将提供对控制多尼礁内浮游植物丰度和生产力的物理和化学过程的定量评估，这些过程对于不同的多尼礁有何不同，以及多尼礁未来可能会如何变化。尤其令人感兴趣的是，波尼亚冰川内部的过程之间的相互作用，以及附近冰盖的夏季融化，包括思韦茨冰川和松岛冰川。在这项拟议的研究中，我们将开发一套全面的、高分辨率的物理-生物耦合模型，并对三个主要但不同的南极多年生生物实施这些模式。罗斯海波利尼亚、阿蒙森波利尼亚和松岛波利尼亚占南极波利尼亚总产量的50%。需要解决的研究问题是：1)什么环境因素对南极洲周围的冰川初级生产力起到最大的控制作用？2)什么是导致南极大陆架周围冰川真光带溶解铁供应不均匀的控制物理因素？这对当地的初级生产率有什么影响？3)由于气候引起的物理变化(风、海冰、冰架底部融化、跨陆架交换、层结和垂直混合)，未来几十年真光区的DFE供应可能发生什么变化，这将如何影响整个大陆的初级生产力？罗斯海、阿蒙森和松岛冰川是南极洲采样最好的冰川，便于模型的参数化和验证。此外，这些冰川在大小、位置、海冰动态、与冰架融化的关系以及与大陆架破裂的距离上存在很大差异，这使它们成为理想的案例研究。为了进行比较，还将模拟南极半岛西部(WAP)，这是一个多产的大陆架，多尼雅对生物生产的贡献相对较小。研究不同类型南极沿海水域中的具体过程将有助于更好地了解这些重要的生物绿洲是如何发挥作用的，以及它们在不同环境条件下可能会发生什么变化。

Coastal waters surrounding Antarctica represent some of the most biologically rich and most untouched ecosystems on Earth. In large part, this biological richness is concentrated within the numerous openings that riddle the expansive sea ice (these openings are known as polynyas) near the Antarctic continent. These polynyas represent regions of enhanced production known as hot-spots and support the highest animal densities in the Southern Ocean. Many of them are also located adjacent to floating extensions of the vast Antarctic Ice Sheet and receive a substantial amount of meltwater runoff each year during the summer. However, little is known about the specific processes that make these ecosystems so biologically productive. Of the 46 Antarctic coastal polynyas that are presently known, only a handful have been investigated in detail. This project will develop ecosystem models for the Ross Sea polynya, Amundsen polynya, and Pine Island polynya; three of the most productive Antarctic coastal polynyas. The primary goal is to use these models to better understand the fundamental physical, chemical, and biological interacting processes and differences in these processes that make these systems so biologically productive yet different in some respects (e.g. size and productivity) during the present day settings. Modeling efforts will also be extended to potentially assess how these ecosystems may have functioned in the past and how they might change in the future under different physical and chemical and climatic settings. The project will advance the education of underrepresented minorities through Stanford?s Summer Undergraduate Research in Geoscience and Engineering (SURGE) Program. SURGE will provide undergraduates the opportunity to gain mentored research experiences at Stanford University in engineering and the geosciences. Old Dominion University also will utilize an outreach programs for local public and private schools as well as an ongoing program supporting the Boy Scout Oceanography merit badge program to create outreach and education impacts. Polynyas (areas of open water surrounded by sea ice) are disproportionately productive regions of polar ecosystems, yet controls on their high rates of production are not well understood. This project will provide quantitative assessments of the physical and chemical processes that control phytoplankton abundance and productivity within polynyas, how these differ for different polynyas, and how polynyas may change in the future. Of particular interest are the interactions among processes within the polynyas and the summertime melting of nearby ice sheets, including the Thwaites and Pine Island glaciers. In this proposed study, we will develop a set of comprehensive, high resolution coupled physical-biological models and implement these for three major, but diverse, Antarctic polynyas. These polynyas, the Ross Sea polynya, the Amundsen polynya, and Pine Island polynya, account for 50% of the total Antarctic polynya production. The research questions to be addressed are: 1) What environmental factors exert the greatest control of primary production in polynyas around Antarctica? 2) What are the controlling physics that leads to the heterogeneity of dissolved iron (dFe) supply to the euphotic zone in polynyas around the Antarctic continental shelf? What effect does this have on local rates of primary production? 3) What are the likely changes in the supply of dFe to the euphotic zone in the next several decades due to climate-induced changes in the physics (winds, sea-ice, ice shelf basal melt, cross-shelf exchange, stratification and vertical mixing) and how will this affect primary productivity around the continent? The Ross Sea, Amundsen, and Pine Island polynyas are some of the best-sampled polynyas in Antarctica, facilitating model parameterization and validation. Furthermore, these polynyas differ widely in their size, location, sea ice dynamics, relationship to melting ice shelves, and distance from the continental shelf break, making them ideal case studies. For comparison, the western Antarctic Peninsula (wAP), a productive continental shelf where polynyas are a relatively minor contributor to biological production, will also be modeled. Investigating specific processes within different types Antarctic coastal waters will provide a better understand of how these important biological oases function and how they might change under different environmental conditions.