Collaborative Research: Understanding the Massive Phytoplankton Blooms over the Australian-Antarctic Ridge

合作研究：了解澳大利亚-南极海脊上空大量浮游植物的繁殖

• 批准号: 2135184
• 负责人: Kevin Arrigo
• 金额: $ 127.53万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2135184&HistoricalAwards=false
• 关键词: Collaborative; Research; Understanding; Massive; Phytoplankton

Phytoplankton blooms throughout the world’s oceans support critical marine ecosystems and help remove carbon dioxide (CO2) from the atmosphere. Traditionally, it has been assumed that phytoplankton blooms in the Southern Ocean are stimulated by iron from either nearby land or sea-ice. However, recent work demonstrates that hydrothermal vents may be an additional iron source for phytoplankton blooms. This enhancement of phytoplankton productivity by different iron sources supports rich marine ecosystems and leads to the sequestration of carbon in the deep ocean. Our proposed work will uncover the importance of hydrothermal activity in stimulating a large phytoplankton bloom along the southern boundary of the Antarctic Circumpolar Current just north of the Ross Sea. It will also lead towards a better understanding of the overall impact of hydrothermal activity on the carbon cycle in the Southern Ocean, which appears to trigger local hotspots of biological activity which are a potential sink for atmospheric CO2. This project will encourage the participation of underrepresented groups in ocean sciences, as well as providing educational opportunities for high school and undergraduate students, through three different programs. Stanford University’s Summer Undergraduate Research in Geoscience and Engineering (SURGE) program provides undergraduates from different US universities and diverse cultural backgrounds the opportunity to spend a summer doing a research project at Stanford. The Stanford Earth Summer Undergraduate Research Program (SESUR) is for Stanford undergraduates who want to learn more about environmental science by performing original research. Finally, Stanford’s School of Earth, Energy, and Environmental Sciences High School Internship Program enables young scientists to serve as mentors, prepares high school students for college, and serves to strengthen the partnership between Stanford and local schools. Students present their results at the Fall AGU meeting as part of the AGU Bright STaRS program. This project will form the basis of at least two PhD dissertations. The Stanford student will participate in Stanford’s Woods Institute Rising Environmental Leaders Program (RELP), a year-round program that helps graduate students hone their leadership and communication skills to maximize the impact of their research. The graduate student will also participate in Stanford’s Grant Writing Academy where they will receive training in developing and articulating research strategies to tackle important scientific questions. This interdisciplinary program combines satellite and ship-based measurements of a large poorly understood phytoplankton bloom (the AAR bloom) in the northwestern Ross Sea sector of the Southern Ocean with a detailed modeling study of the physical processes linking deep dissolved iron (DFe) reservoirs to the surface phytoplankton bloom. Prior to the cruise, we will implement a numerical model (CROCO) for our study region so that we can better understand the circulation, plumes, turbulence, fronts, and eddy field around the AAR bloom and how they transport and mix hydrothermally produced DFe vertically. Post cruise, observations of the vertical distribution of 3He (combined with DMn and DFe), will be used as initial conditions for a passive tracer in the model, and tracer dispersal will be assessed to better quantify the role of the various turbulent processes in upwelling DFe-rich waters to the upper ocean. The satellite-based component of the program will characterize the broader sampling region before, during, and after our cruise. During the cruise, our automated software system at Stanford University will download and process images of sea ice concentration, Chl-a concentration, sea surface temperature (SST), and sea surface height (SSH) and send them electronically to the ship. Operationally, our goal is to use all available satellite data and preliminary model results to target shipboard sampling both geographically and temporally to optimize sampling of the AAR bloom. We will use available BGC-Argo float data to help characterize the AAR bloom. In collaboration with SOCCOM, we will deploy additional BGC-Argo floats (if available) during our transit through the study area to allow us to better characterize the bloom. The centerpiece of our program will be a 40-day process study cruise in austral summer. The cruise will consist of an initial “radiator” pattern of hydrographic surveys/sections along the AAR followed by CTDs to selected submarine volcanoes. When/if eddies are identified, they will be sampled either during or after the initial surveys. The radiator pattern, or parts thereof, will be repeated 2-3 times. Hydrographic survey stations will include vertical profiles of temperature, salinity, oxygen, oxidation-reduction potential, light scatter, and PAR (400-700 nm). Samples will be collected for trace metals, ligands, 3He, and total suspended matter. Where intense hydrothermal activity is identified, samples for pH and total CO2 will also be collected to characterize the hydrothermal system. Water samples will be collected for characterization of macronutrients, and phytoplankton physiology, abundance, species composition, and size. During transits, we will continuously measure atmospheric conditions, current speed and direction, and surface SST, salinity, pCO2, and fluorescence from the ship’s systems to provide detailed maps of these parameters. The ship will be used as a platform for conducting phytoplankton DFe bioassay experiments at key stations throughout the study region both inside and outside the bloom. We will also perform detailed comparisons of algal taxonomic composition, physiology, and size structure inside and outside the bloom to determine the potential importance of each community on local biogeochemistry.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

世界海洋中大量繁殖的浮游植物支撑着关键的海洋生态系统，并有助于从大气中去除二氧化碳。传统上，人们一直认为，南大洋浮游植物的大量繁殖是由附近陆地或海冰中的铁刺激的。然而，最近的研究表明，热液喷口可能是浮游植物大量繁殖的另一个铁源。不同铁源对浮游植物生产力的提高支持了丰富的海洋生态系统，并导致了碳在深海的固存。我们提出的工作将揭示热液活动在刺激罗斯海以北的南极环极流南部边界的大型浮游植物繁殖方面的重要性。它还将有助于更好地了解热液活动对南大洋碳循环的总体影响，这似乎引发了局部生物活动热点，这些热点是大气二氧化碳的潜在汇。该项目将通过三个不同的项目，鼓励代表性不足的群体参与海洋科学，并为高中生和本科生提供教育机会。斯坦福大学的暑期本科生地球科学与工程研究项目（SURGE）为来自美国不同大学和不同文化背景的本科生提供了在斯坦福大学度过一个暑期研究项目的机会。斯坦福大学地球暑期本科生研究项目（SESUR）是为希望通过进行原创性研究来了解更多环境科学的斯坦福大学本科生提供的。最后，斯坦福大学地球、能源和环境科学学院的高中实习项目使年轻的科学家能够担任导师，为高中生上大学做准备，并加强斯坦福大学与当地学校之间的合作关系。学生们在秋季AGU会议上展示他们的成果，这是AGU Bright STaRS计划的一部分。本课题将构成至少两篇博士论文的基础。这位斯坦福大学的学生将参加斯坦福大学伍兹研究所新兴环境领袖项目（RELP），这是一个全年的项目，帮助研究生磨练他们的领导能力和沟通技巧，以最大限度地发挥他们的研究影响。研究生还将参加斯坦福大学的拨款写作学院，在那里他们将接受开发和阐明研究策略以解决重要科学问题的培训。这个跨学科项目结合了卫星和船只对南大洋罗斯海西北部浮游植物大量繁殖（AAR bloom）的测量，以及对深层溶解铁（DFe）储层与表层浮游植物大量繁殖之间物理过程的详细建模研究。在巡航之前，我们将为我们的研究区域实施一个数值模型（CROCO），以便我们更好地了解AAR水华周围的环流、羽流、湍流、锋面和涡场，以及它们如何垂直运输和混合热液产生的DFe。巡航后，观测到的3He垂直分布（结合DMn和DFe）将作为模型中被动示踪剂的初始条件，并将评估示踪剂的扩散，以更好地量化富DFe水体上升流到上层海洋的各种湍流过程的作用。该计划的卫星组件将在我们巡航之前，期间和之后描述更广泛的采样区域。在巡航期间，我们在斯坦福大学的自动化软件系统将下载和处理海冰浓度、Chl-a浓度、海面温度（SST）和海面高度（SSH）的图像，并将它们以电子方式发送给船。在操作上，我们的目标是利用所有可用的卫星数据和初步模型结果来定位船上的地理和时间采样，以优化AAR水华的采样。我们将使用现有的BGC-Argo浮子数据来帮助描述AAR水华。在与SOCCOM的合作下，我们将在我们通过研究区域的过程中部署额外的BGC-Argo浮标（如果有的话），以便我们更好地表征水华。我们项目的核心是在南方夏季进行为期40天的过程游学。该巡航将包括沿AAR进行水文测量的初步“辐射”模式/部分，然后是选定的海底火山的CTDs。一旦发现涡流，将在初步调查期间或之后对其进行取样。散热器图案或其部分将重复2-3次。水文测量站将包括温度、盐度、氧气、氧化还原电位、光散射和PAR （400-700 nm）的垂直剖面。样品将收集微量金属、配体、3He和总悬浮物。在确定有强烈热液活动的地方，还将收集pH值和总CO2样品来表征热液系统。将收集水样以表征宏量营养素、浮游植物生理学、丰度、物种组成和大小。在过境期间，我们将持续测量大气条件，当前速度和方向，以及船舶系统的表面海温，盐度，二氧化碳分压和荧光，以提供这些参数的详细地图。该船将作为一个平台，在整个研究区域的关键站点进行浮游植物DFe生物测定实验，包括水华内外。我们还将对藻华内外的藻类分类组成、生理和大小结构进行详细的比较，以确定每个群落对当地生物地球化学的潜在重要性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。