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: 2135185
• 负责人: Joseph Resing
• 金额: $ 50.89万
• 依托单位: University of Washington
• 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=2135185&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.

世界各地海洋中的浮游植物大量繁殖，支持着重要的海洋生态系统，并有助于清除大气中的二氧化碳（CO2）。传统上，人们认为南大洋的浮游植物大量繁殖是受到附近陆地或海冰中铁的刺激。最近的研究表明，热液喷口可能是浮游植物大量繁殖的额外铁源，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，并导致了浮游植物的繁殖。我们提出的工作将揭示热液活动对刺激罗斯海以北南极绕极流南部边界大量浮游植物的重要性。热液活动对南大洋碳循环的总体影响，这似乎引发了当地的生物活动热点，而这些热点是大气二氧化碳的潜在汇。该项目将鼓励海洋中代表性不足的群体参与。斯坦福大学地球科学与工程暑期本科生研究 (SURGE) 项目为来自美国不同大学和不同文化背景的本科生提供了度过一个暑假的机会。斯坦福大学地球暑期本科生研究计划 (SESUR) 是为那些希望通过开展原创研究来了解更多环境科学的斯坦福大学本科生提供的。年轻科学家作为导师，为高中生上大学做准备，并加强斯坦福大学和当地学校之间的合作关系，作为 AGU Bright STaRS 计划的一部分，学生们在秋季 AGU 会议上展示他们的成果。至少两篇博士论文将参加斯坦福大学伍兹研究所的环境领袖计划（RELP），这是一个全年计划，帮助研究生磨练他们的领导力和沟通技巧，以最大限度地发挥他们的研究的影响力。也参加他们将在斯坦福大学格兰特写作学院接受培训，制定和阐明研究策略，以解决重要的科学问题。这个跨学科项目结合了卫星和船基测量，对罗斯海西北部的大型浮游植物水华（AAR水华）进行了测量。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），对南大洋的深层溶解铁（DFe）储层与表面浮游植物繁殖之间的物理过程进行详细的建模研究。我们可以更好地了解 AAR 水华周围的环流、羽流、湍流、锋面和涡流场，以及它们如何垂直输送和混合热液产生的 DFe。巡航后，将观察 3He 的垂直分布（结合 DMn 和 DFe）。用作模型中被动示踪剂的初始条件，并且将评估示踪剂的扩散，以更好地量化各种湍流过程在富含 DFe 的水域上涌到上部的过程中的作用该计划的卫星部分将在巡航之前、期间和之后描述更广泛的采样区域，在巡航期间，我们位于斯坦福大学的自动化软件系统将下载并处理海冰浓度、叶绿素a浓度的图像。 、海面温度 (SST) 和海面高度 (SSH) 并将其以电子方式发送到船舶。在操作上，我们的目标是使用所有可用的卫星数据和初步模型结果在地理和时间上对船上进行采样，以优化采样。我们将使用可用的 AAR。 BGC-Argo 浮标数据有助于描述 AAR 水华的特征 与 SOCCOM 合作，我们将在穿越研究区域期间部署额外的 BGC-Argo 浮标（如果有），以便我们更好地描述水华的特征。将在澳大利亚夏季进行为期 40 天的过程研究巡航，该巡航将包括沿 AAR 进行初步“辐射”模式的水文测量/部分，然后在选定的海底火山出现时进行 CTD。确定后，将在初次调查期间或之后进行采样。 辐射器模式或其部分内容将重复 2-3 次，包括温度、盐度、氧气、氧化还原电位、光照的垂直剖面。散射和 PAR (400-700 nm) 将收集痕量金属、配体、 3He 和总悬浮物质的样品。收集水样以表征热液系统的特征，以及浮游植物的生理学、丰度、物种组成和大小。 pCO2 和来自船舶系统的荧光，以提供这些参数的详细地图。该船将用作在整个研究区域内外的关键站进行浮游植物 DFe 生物测定实验的平台。我们还将对水华内部和外部的藻类分类组成、生理学和大小结构进行详细比较，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 NSF 的法定使命，并被认为值得通过支持。使用基金会的智力价值和更广泛的影响审查标准进行评估。