Collaborative Research: Rhizosolenia Mats as a Source of Nitrogen Flux into the Surface Waters of the Pacific Ocean: Fe Stress, NE Excretion and Basin Scale Distribution Patterns

合作研究：根管藻垫作为太平洋表层水氮通量的来源：铁胁迫、NE 排泄和盆地规模分布模式

• 批准号: 0095404
• 负责人: Robert McKay
• 金额: $ 16.91万
• 依托单位: Bowling Green State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-05-15 至 2005-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0095404&HistoricalAwards=false
• 关键词: Collaborative; Research; Rhizosolenia; Mats; Source

Collaborative research: Rhizosolenia mats as a source of nitrogen flux into the surface waters of the Pacific Ocean: Fe stress, N excretion and basin scale distribution patternsThis project will quantify nitrogen cycling dynamics in the euphotic zone by vertically migrating Rhizosolenia mats, and will provide the first physiological data on mats below diver accessible depths. These macroscopic diatom assemblages sink below the euphotic zone to acquire nitrate, store it in their vacuole, and then return to the surface for photosynthesis. This new production is based entirely on a biologically, rather than physically mediated transport of N. These fragile associations require specialized collection techniques such as SCUBA and remotely operated vehicles (ROVs). As a result, their biology and biogeochemical importance has been largely overlooked. Other taxa also vertically migrate, and this project will conduct the first enumeration of this entire community in order to understand the broader role of vertical migration in oceanic nitrogen cycling.In-situ video imaging techniques will be used to quantify mats in the eastern central N. Pacific gyre. Depth specific (MOCNESS) sampling will be used to quantify the remaining taxa. A ROV will be used to collect mats below diver accessible depths in order to compare deep mats with surface mats. An existing computer model will be used to calculate transport/flux rates with these revised estimates. In addition to transporting N, Rhizosolenia mats under Fe and/or light stress may excrete both inorganic and organic nitrogen. This will be evaluated using both laboratory and field Rhizosolenia. Based on previous results, oceanic Rhizosolenia mats in nature appear to be chronically Fe-stressed. However, ferredoxin, a common and convenient in situ marker of cellular Fe status, may not be produced in these oceanic taxa and thus may not be a valid means of characterizing Fe stress in open ocean Rhizosolenia. As part of our research, we will evaluate this indicator for Fe stress in Rhizosolenia isolated from the Pacific Ocean. Our goals are to assess the Fe quotas of rhizosolenid diatoms, document the validity of the ferredoxin index as a measure of Fe stress in large oceanic diatoms, and determine N excretion rates by these taxa. A migration model will be rigorously tested by examining deep mats. These data will provide additional insight into the synergistic relationship between trace nutrient limitation and macronutrient acquisition and assimilation, an important developing theme of modern biological oceanography. The rates of biological N import and release for the eastern half of the central N. Pacific gyre by the entire migrating community will be assessed. This is a fundamental to understanding oceanic N cycles, and has direct relevance for both carbon and nitrogen cycling in the upper ocean.

合作研究：本项目将通过垂直迁移的红管藻席来量化真光层中氮循环动力学，并将提供潜水员可达深度以下的席的第一个生理数据。这些肉眼可见的硅藻组合沉到真光层以下以获取硝酸盐，将其储存在液泡中，然后返回表面进行光合作用。这种新的生产是完全基于生物，而不是物理介导的N的运输。这些脆弱的联系需要专门的收集技术，如潜水器和遥控潜水器。因此，它们的生物学和地球化学重要性在很大程度上被忽视了。其他类群也垂直迁移，这个项目将进行第一次枚举整个社区，以了解更广泛的作用，垂直迁移在海洋氮循环。原位视频成像技术将被用来量化垫在东部中部N。太平洋环流。深度特定（MOCNESS）采样将用于量化剩余的类群。将使用一个收集器收集潜水员可到达深度以下的垫，以便将深垫与表面垫进行比较。将利用现有的计算机模型，根据这些订正估计数计算迁移/通量率。 除运输N外，在Fe和/或光胁迫下，Roccussolenia垫可以排泄无机和有机氮。 这将使用实验室和现场的管螺进行评价。根据以往的研究结果，在自然界中，海洋Rissolenia垫似乎是长期的铁胁迫。 然而，铁氧还蛋白，一种常见的和方便的原位标记细胞铁状态，可能不会产生在这些海洋类群，因此可能不是一个有效的手段，铁应力特征在公海Raculosolenia。 作为我们研究的一部分，我们将评估这一指标的铁应力在Raculsolenia分离自太平洋。我们的目标是评估的根际硅藻的铁配额，文件的铁氧还蛋白指数作为衡量大型海洋硅藻的铁应力的有效性，并确定这些类群的N排泄率。迁移模型将通过检查深垫进行严格测试。这些数据将提供更多的洞察微量营养限制和宏量营养素的获取和同化，现代生物海洋学的一个重要的发展主题之间的协同关系。 中氮东半部的生物氮输入和释放速率与中氮东半部的生物氮输入和释放速率基本一致。整个移民社区的太平洋环流将得到评估。这是理解海洋氮循环的基础，并与上层海洋的碳和氮循环直接相关。