Collaborative Research: Diatoms, Food Webs and Carbon Export - Leveraging NASA EXPORTS to Test the Role of Diatom Physiology in the Biological Carbon Pump

合作研究：硅藻、食物网和碳输出 - 利用 NASA EXPORTS 测试硅藻生理学在生物碳泵中的作用

• 批准号: 1756442
• 负责人: Mark Brzezinski
• 金额: $ 51.22万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-03-01 至 2024-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1756442&HistoricalAwards=false
• 关键词: Collaborative; Research; Diatoms; Food; Webs

This project focuses on a group of microscopic single-celled photosynthetic organisms in the ocean called diatoms. Diatoms float in the surface ocean as part of a group of organisms collectively called phytoplankton. There are thousands of different species of diatoms distributed across the global ocean. A famous oceanographer Henry Bigelow once said "All fish is diatoms" reflecting the importance of diatoms as the base of the food chain that supports the world's largest fisheries. Despite their small size, diatom photosynthesis produces 20% of the oxygen on earth each year. That's more than all of the tropical rainforests on land. The major objective of the research is to understand how the metabolic differences among diatom species affects the amount of diatom organic carbon that is carried, or exported, from the surface ocean to the deep ocean. As diatoms are photosynthesizers like green plants, their biological carbon comes from converting carbon dioxide dissolved in seawater from the atmosphere into organic forms. Diatoms also require a series of other nurtrients supplied by the ocean such as nitrogen and phosphorous and, uniquely for diatoms, the silicon used to construct their glass shells. This research will investigate how genetic and physiological differences among diatoms influence how each species react to changes in nutrient levels in the ocean and how those shifts affect the export of diatom carbon to the deep sea. The link between diatoms' physiological response and their carbon export comes about because shifts in physiology affect diatom attributes like how fast they sink and how tasty they are to predators. So if we can relate the physiological condition of different diatoms to the food-web pathways followed by different species, we can ultimately use knowledge of diatom physiological status and food web structure to predict how much diatom carbon gets to the deep sea. The research involves investigators with expertise in the physiology and genomics of diatoms and in the ocean's chemistry. The work will initially take place in the subarctic North Pacific in conjunction with the NASA Export Processes in the Ocean from RemoTe Sensing (EXPORTS) field program. The EXPORTS program is using a wide variety of methods to quantify the export and fate of photosynthetically fixed carbon in the upper ocean. The research supports the training of undergraduate students, graduate students and a postdoctoral scholar. The research will also serve as the basis for activities aimed at K-12 and junior high school students. The research will broadly impact our understanding of the biology of the biological pump (the transport of photosynthetically fixed organic carbon to the deep sea) by forming a mechanistic basis for predicting the export of diatom carbon. It is hypothesized that the type and degree of diatom physiological stress are vital aspects of ecosystem state that drive export. To test this hypothesis, the genetic composition, rates of nutrient use and growth response of diatom communities will be evaluated and supported with measurements of silicon and iron stress to evaluate stress as a predictor of the path of diatom carbon export. The subarctic N. Pacific ecosystem is characterized as high nutrient low chlorophyll (HNLC) due to low iron (Fe) levels that are primary controllers constraining phytoplankton utilization of other nutrients. It has been a paradigm in low Fe, HNLC systems that diatoms grow at elevated Si:C and Si:N ratios and should be efficiently exported as particles significantly enriched in Si relative to C. However, Fe limitation also alters diatoms species composition and the high Si demand imposed by low Fe can drive HNLC regions to Si limitation or Si/Fe co-limitation. Thus, the degree of Si and/or Fe stress in HNLC waters can all alter diatom taxonomic composition, the elemental composition of diatom cells, and the path cells follow through the food web ultimately altering diatom carbon export.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.

该项目着重于海洋中的一组微粒单细胞光合生物，称为硅藻。硅藻漂浮在地面海洋中，这是一组生物的一部分，称为浮游植物。在全球海洋中分布着数千种不同种类的硅藻。 一位著名的海洋学家亨利·比格洛（Henry Bigelow）曾说过“所有鱼都是硅藻”，反映了硅藻作为支持世界上最大渔业的食物链的重要性。尽管它们的尺寸很小，但每年的硅藻光合作用仍会产生地球上20％的氧气。这比陆地上的所有热带雨林都多。该研究的主要目的是了解硅藻种之间的代谢差异如何影响从地表海到深海携带或出口的硅藻有机碳的数量。由于硅藻是像绿色植物这样的光合作用剂，因此它们的生物碳来自将二氧化碳从大气中溶于海水中的二氧化碳转化为有机形式。 硅藻还需要一系列由海洋提供的其他养育物，例如氮和磷，并且独特地用于硅藻，用于构造其玻璃壳的硅。 这项研究将研究硅藻之间的遗传和生理差异如何影响每个物种对海洋营养水平变化的反应以及这些转移如何影响硅藻碳向深海的出口。硅藻的生理反应与其碳输出之间的联系是因为生理学的变化会影响硅藻属性，例如它们下沉的速度和对捕食者的美味。因此，如果我们能够将不同硅藻的生理状况与食物网途径随后是不同物种联系起来，我们最终可以使用硅藻生理状态和食物网络结构的知识来预测多少硅藻碳进入深海。该研究涉及在硅藻的生理学和基因组和海洋化学方面具有专业知识的研究者。这项工作最初将在北太平洋亚北太平洋和NASA出口过程中从遥感（出口）现场计划进行。该出口计划正在使用多种方法来量化上海中光合固定碳的出口和命运。该研究支持对本科生，研究生和博士后学者的培训。该研究还将作为针对K-12和初中学生的活动的基础。这项研究将广泛影响我们对生物泵生物学的理解（光合固定有机碳向深海的运输），形成了预测硅藻碳出口的机械基础。假设硅藻生理压力的类型和程度是驱动出口的生态系统状态的重要方面。为了检验这一假设，将通过测量硅和铁应激来评估和支持硅藻群落的遗传组成，养分使用率和生长反应，以评估应激作为硅藻碳出口路径的预测指标。亚北极链球菌生态系统的特征是高营养低叶绿素（HNLC），这是由于低铁（Fe）水平，这是限制其他营养素的浮游植物利用的主要控制器。 It has been a paradigm in low Fe, HNLC systems that diatoms grow at elevated Si:C and Si:N ratios and should be efficiently exported as particles significantly enriched in Si relative to C. However, Fe limitation also alters diatoms species composition and the high Si demand imposed by low Fe can drive HNLC regions to Si limitation or Si/Fe co-limitation. Thus, the degree of Si and/or Fe stress in HNLC waters can all alter diatom taxonomic composition, the elemental composition of diatom cells, and the path cells follow through the food web ultimately altering diatom carbon export.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.

项目成果

The upper ocean silicon cycle of the subarctic Pacific during the EXPORTS field campaign

• DOI: 10.1525/elementa.2021.00087
• 发表时间: 2022
• 期刊: Elementa: Science of the Anthropocene
• 作者: M. Brzezinski;D. Varela;B. Jenkins;K. Buck;Sile M. Kafrissen;Janice L. Jones