BIOCOMPLEXITY: Collaborative Research: Factors Affecting, and Impact of, Diazotraphic Microorganisms in the Western Equatorial Atlantic

生物复杂性：合作研究：西赤道大西洋固氮微生物的影响因素和影响

• 批准号: 9912333
• 负责人: Sergio Sanudo-Wilhelmy
• 金额: $ 33.5万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-01-01 至 2004-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9912333&HistoricalAwards=false
• 关键词: BIOCOMPLEXITY; Collaborative; Research; Factors; Affecting

BIOCOMPLEXITY: Collaborative Research: Factors affecting, and impact of,diazotrophic microorganisms in the western Equatorial Atlantic Ocean This biocomplexity research focuses on plankton dynamics in the western Equatorial Atlantic Ocean (WEQAT). This is a complex and understudied ecosystem that has significant impacts on marine resourcesin the region as well as in downstream areas such as the Caribbean Sea. The study centers ondiazotrophic (nitrogen fixing) microorganisms as keystone species. Geological, physical, biological,chemical and even social factors all have a major influence on population biology and activity ofdiazotrophs in the WEQAT. Diazotrophs in turn have a major impact on other phytoplankton andtrophic levels through input of fixed nitrogen (N). The Amazon River affects the regionphysically by changing salinity and thereby water column stratification, and geochemically byintroducing iron and silicate which can then biologically stimulate the growth of diatoms thatcontain the N2 fixing endosymbiont Richelia intracellularis. Furthermore, the area receivessignificant seasonal atmospheric inputs of iron in dust from the Sahel region of Africa, which canpromote the growth of the important N2 fixing cyanobacterium Trichodesmium. Thisatmospheric iron source is directly deposited on the surface waters where biological activity isgreatest. For Trichodesmium, the physical environment (e.g. high wind speed) can also inhibitactivity and the formation of blooms. Diazotrophs may be affected by land use practices in theAmazon Basin and the African Sahel, and N2 fixed by marine plankton can affect humans bystimulating primary productivity and fishery yields. Using both remote sensing and shipboard measurements, scientists will examine the complex processes which structure these planktonic diazotroph populations, influence their importance in CO2 andN2 fixation, which, in turn, affect other planktonic processes. The seasonal and spatialrelationships of Trichodesmium and Hemiaulus / Richelia associations will be examined withdirect reference to the major routes of inputs of Fe and Si, and with regard to the physicalenvironment. The group of collaborating scientists will examine the trophic structures associated with each diazotrophic community, including the vertical distribution of processes and associated autotrophic andheterotrophic plankton populations. These data will be used to develop and verifybiogeochemical and trophodynamic models that incorporate the complex physical, chemical andbiological interactions that characterize the WEQAT region. The models will, in turn, be used toexamine the hypothesis that physical forcing, through its effect on the diazotrophic populationsand the structure of the food web, influences N2 fixation and, in part, determines the highproductivity of the WEQAT. The work uses a combination of both observations and models to address threefundamental issues in biocomplexity: 1) the relationship between ecosystem structure andfunction in a system that is both nonlinear and high-dimensional; 2) the response of a nonlinearecosystem to environmental forcing; and 3) the relevant level of detail, including the resolutionof physical space, that must be incorporated in nonlinear systems to capture the dynamics of aglobal ecosystem property (here, high productivity). The research will significantly advance our understanding of the interaction between physical and biogeochemical processes in an important area the world's oceans, and identify how these interactions regulate variability in marine ecosystem productivity.

生物复杂性：协作研究：影响和影响的因素，在西赤道大西洋中重生营养微生物的影响和影响。这种生物复杂性研究重点侧重于西赤道大西洋（WEQAT）的浮游生物动力学。 这是一个复杂而研究的生态系统，对该地区以及加勒比海等下游地区的海洋资源产生重大影响。该研究以甲二氮杂性（氮固定）微生物为基石物种。地质，物理，生物学，化学甚至社会因素都对WEQAT中二氮杂嗜性的人群生物学和活性产生了重大影响。重生营养依次通过输入固定氮（N）对其他浮游植物水平产生重大影响。亚马逊河通过变化的盐度和水柱分层对区域影响，并通过引入铁和硅酸盐的地球化学，然后可以生物学地刺激硅藻固定内菌的Richelia richelia richelia incellularis的硅藻的生长。此外，非洲萨赫勒地区的灰尘中尘埃的接收季节性大气输入，这可以推动重要的N2固定蓝细菌trichodesmium的生长。此atmoslosper铁源直接沉积在生物活性最高的地表水上。对于毛状体，物理环境（例如，高风速）也可以抑制盛开的形成。重18zotrophs可能会受到Theamazon盆地和非洲萨赫勒地区土地利用实践的影响，而由海洋浮游生物固定的N2可能会通过刺激人类来影响人类，从而通过刺激一级生产力和渔业产量来影响人类。利用遥感和船上测量值，科学家将检查结构这些浮游物质的重生种群的复杂过程，影响它们在CO2和N2固定中的重要性，这反过来又影响了其他浮游物质过程。将检查trichodesmium和hemiaulus / richelia关联的季节性和空间关系，并以FE和SI的主要投入途径以及实质环境的主要参考。一组合作的科学家将检查与每个重18zotrophic社区相关的营养结构，包括过程的垂直分布以及相关的自养生体营养性浮游生物种群。这些数据将用于开发和验证bio地球化学和滋养动力学模型，这些模型结合了特征于WEQAT区域的复杂物理，化学和生物学相互作用。反过来，这些模型将被用来检查以下假设，即物理强迫通过对重生营养群体的影响和食物网的结构影响N2固定，并部分决定了WEQAT的高生产力。这项工作结合了观测和模型来解决生物复杂性中的三个基本问题：1）生态系统结构与函数之间的关系，在非线性和高维度的系统中； 2）非线性生殖器系统对环境强迫的响应； 3）相关的细节级别，包括物理空间的分辨率，必须将其纳入非线性系统，以捕获Aglobal生态系统属性的动力学（在这里，高生产率）。 这项研究将大大提高我们对世界海洋重要领域中物理和生物地球化学过程之间相互作用的理解，并确定这些相互作用如何调节海洋生态系统生产力的变异性。