Collaborative Research: ETBC: Amazon iNfluence on the Atlantic: CarbOn export from Nitrogen fixation by DiAtom Symbioses (ANACONDAS)

合作研究：ETBC：亚马逊对大西洋的影响：DiAtom Symbioses 固氮产生的碳输出 (ANACONDAS)

• 批准号: 0934035
• 负责人: Edward Carpenter
• 金额: $ 35.14万
• 依托单位: San Francisco State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2013-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0934035&HistoricalAwards=false
• 关键词: Collaborative; Research; ETBC; Amazon; iNfluence

The investigators hypothesize that large tropical river plumes with low N: P ratios provide an ideal niche for diatom-diazotroph assemblages (DDAs). They suggest that the ability of these organisms to fix N2 within the surface ocean is responsible for significant C export in the Amazon River plume. Their previous observations in the Amazon River plume helped reveal that blooms comprised of the endosymbiotic N2-fixing cyanobacterium Richelia and its diatom hosts (e.g. Hemiaulus) were a significant source of new production and carbon export. The previous work focused largely on the sensitivity of DDAs to external forcing from dust and riverine inputs, so the ecology of these organisms and the fate of their new production were largely unstudied. It is now known that DDAs are responsible for a significant amount of CO2 drawdown in the Amazon River plume, and floating sediment traps at 200 m measured 4x higher mass fluxes beneath the plume than outside the plume. This led the researchers to hypothesize that this greater export is due either to aggregation and sinking of DDAs themselves or to grazing of DDAs by zooplankton.In this study the researchers will undertake a suite of field, satellite and modeling studies aimed at understanding the ecology and tracing the fate of C and N fixed by DDAs and other phytoplankton living in the plume. By examining C and silicate (Si) export from offshore surface waters, through the upper oceanic food web, the mesopelagic, and down to the deep sea floor, they will quantify the impact of the Amazon River on biological processes that control C sequestration and the implications of these regional processes on C, N and Si budgets. The study will go beyond previous research because they will quantify 1) the distribution, nutrient demands, and activity of DDAs in the context of phytoplankton species succession, 2) the sensitivity of the CO2 drawdown to the mix of phytoplankton, 3) the grazing and aggregation processes contributing to the sinking flux, 4) the composition of this flux, and 5) the proportion of this material that reaches the seafloor. This effort truly represents a measure of C sequestration and pump efficiency. Ecological modeling will be used to place observational results from field studies and satellites into the context of the larger Atlantic basin with tropical climate variability on interannual and longer time scales.Intellectual Merit: The PIs have identified a potentially significant but poorly understood, ecosystem-controlled, climate-sensitive C sequestration pathway that seems to violate the expectation of an inefficient open-ocean biological pump. Since primary production fueled by allochthonous sources of N such as N2 fixation can drive a net, biologically mediated transfer of C from the atmosphere to the ocean, C sequestration by DDAs in the Amazon River plume is a regionally significant process. Because DDAs have been found in other tropical river systems, they may represent a globally significant, yet previously overlooked biological pump mechanism.Broader Impacts: The Amazon River has captured the public's imagination more than any other river. This study aims to take advantage of such high profile earth science to promote science literacy among all our citizens. This project will support graduate and postdoctoral education, undergraduates through training cruises, and ocean science education of K-12 teachers and undergraduates through the COSEE-West, the Mid Atlantic COSEE and the COSEEOS programs. The results of this research will be made available to other scientists through peer reviewed publications, public databases, and an ANACONDAS website, as well as to the general public through the SFSU RTC-Bay Area Discovery Museum Program.

研究人员假设较低的N：P比的大型热带河流为硅藻二唑营养组合（DDAS）提供了理想的利基市场。他们认为，这些生物在地面海洋中固定N2的能力是亚马逊河羽流中的大量C出口。他们以前在亚马逊河羽流中的观察结果揭示了由内共生N2固定蓝细菌Richelia及其硅藻宿主（例如Hemiaulus）组成的花朵是新产量和碳出口的重要来源。先前的工作主要集中在DDA对灰尘和河流输入中外部强迫的敏感性上，因此这些生物的生态及其新生产的命运在很大程度上没有研究。现在众所周知，DDAS负责在亚马逊河羽流中大量的二氧化碳减速，并且在羽流下方的浮质陷阱浮点陷阱比羽流的质量高4倍。 This led the researchers to hypothesize that this greater export is due either to aggregation and sinking of DDAs themselves or to grazing of DDAs by zooplankton.In this study the researchers will undertake a suite of field, satellite and modeling studies aimed at understanding the ecology and tracing the fate of C and N fixed by DDAs and other phytoplankton living in the plume.通过检查C和硅酸盐（SI）从近海地表水的出口，通过海洋上海食品网，中质质量以及向下到深海地板，它们将量化亚马逊河对控制C隔离的生物学过程的影响以及这些区域过程对C，N和SI预算的影响。这项研究将超越先前的研究，因为它们将量化1）在浮游植物物种的背景下，DDA的分布，营养需求和活动的分布和活动，2）CO2缩减对浮游植物的混合的敏感性，3）3）绘制了这一材料的材料，并在5）材料中造成了绘制的材料和5），并在5）范围造成了5）。这项工作确实代表了C固换和泵效率的量度。 Ecological modeling will be used to place observational results from field studies and satellites into the context of the larger Atlantic basin with tropical climate variability on interannual and longer time scales.Intellectual Merit: The PIs have identified a potentially significant but poorly understood, ecosystem-controlled, climate-sensitive C sequestration pathway that seems to violate the expectation of an inefficient open-ocean biological pump.由于由N2固定量的同种异体来源推动的一级生产可以驱动网络，因此C从大气到海洋的生物学介导的转移到海洋中，因此DDA在亚马逊河羽流中由DDA进行了C隔离，这是一个重要的过程。由于在其他热带河流系统中发现了DDA，因此它们可能代表着全球意义重大但以前被忽视的生物泵机制。Boader的影响：亚马逊河比其他任何河都更具吸引公众的想象力。这项研究旨在利用如此著名的地球科学来促进我们所有公民的科学素养。该项目将通过培训巡游来支持毕业生和博士后教育，本科生，以及通过Cosee-West，中大西洋中部的Cosee和Coseeos计划对K-12教师和本科生的海洋科学教育。这项研究的结果将通过同行评审的出版物，公共数据库和Anacondas网站以及通过SFSU RTC-Bay地区发现博物馆计划提供给其他科学家的结果。