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

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: 9980726
• 负责人: Mercedes Pascual
• 金额: $ 15.43万
• 依托单位: University of Maryland Biotechnology Institute
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-06-15 至 2001-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9980726&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 resources in the region as well as in downstream areas such as the Caribbean Sea. The study centers on diazotrophic (nitrogen fixing) microorganisms as keystone species. Geological, physical, biological, chemical and even social factors all have a major influence on population biology and activity of diazotrophs in the WEQAT. Diazotrophs in turn have a major impact on other phytoplankton and trophic levels through input of fixed nitrogen (N). The Amazon River affects the region physically by changing salinity and thereby water column stratification, and geochemically by introducing iron and silicate which can then biologically stimulate the growth of diatoms that contain the N2 fixing endosymbiont Richelia intracellularis. Furthermore, the area receives significant seasonal atmospheric inputs of iron in dust from the Sahel region of Africa, which can promote the growth of the important N2 fixing cyanobacterium Trichodesmium. This atmospheric iron source is directly deposited on the surface waters where biological activity is greatest. For Trichodesmium, the physical environment (e.g. high wind speed) can also inhibit activity and the formation of blooms. Diazotrophs may be affected by land use practices in the Amazon Basin and the African Sahel, and N2 fixed by marine plankton can affect humans by stimulating 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 and N2 fixation, which, in turn, affect other planktonic processes. The seasonal and spatial relationships of Trichodesmium and Hemiaulus / Richelia associations will be examined with direct reference to the major routes of inputs of Fe and Si, and with regard to the physical environment. The group of collaborating scientists will examine the trophic structures associated with each diazotrophic community, including the vertical distribution of processes and associated autotrophic and heterotrophic plankton populations. These data will be used to develop and verify biogeochemical and trophodynamic models that incorporate the complex physical, chemical and biological interactions that characterize the WEQAT region. The models will, in turn, be used to examine the hypothesis that physical forcing, through its effect on the diazotrophic populations and the structure of the food web, influences N2 fixation and, in part, determines the high productivity of the WEQAT. The work uses a combination of both observations and models to address three fundamental issues in biocomplexity: 1) the relationship between ecosystem structure and function in a system that is both nonlinear and high-dimensional; 2) the response of a nonlinear ecosystem to environmental forcing; and 3) the relevant level of detail, including the resolution of physical space, that must be incorporated in nonlinear systems to capture the dynamics of a global 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。该研究以重18酶营养（氮固定）微生物为中心，作为基石物种。地质，物理，生物学，化学甚至社会因素都对WEQAT中的重18酶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。亚马逊河通过变化盐度并从而通过引入铁和硅酸盐来对区域进行物理影响，从而在地球化学上可以在生物学上刺激含有N2固定内菌的Richelia richelia richelia richelia ellacellularis的硅藻的生长。此外，该地区从非洲萨赫勒地区获得了尘埃中的大量季节性大气输入，这可以促进重要的N2固定蓝细菌的生长。这种大气铁源直接沉积在生物活性最大的地表水上。对于毛状体，物理环境（例如，高风速）也可以抑制活动和开花的形成。重18zotrophs可能会受到亚马逊盆地和非洲萨赫勒地区土地利用实践的影响，而由Marine Plankton固定的​​N2可以通过刺激初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物营养群体的复杂过程，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。将直接参考FE和SI的主要投入途径以及关于物理环境的主要投入途径，并在物理环境中直接研究毛d和半木 / richelia关联的季节性和空间关系。一组合作的科学家将检查与每个重18酶营养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和异养浮游生物种群。这些数据将用于开发和验证生物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，这些模型将用于检查以下假设：物理强迫通过其对重18酶群体的影响和食物网的结构影响N2固定，并部分决定了WEQAT的高生产率。该作品结合了观测和模型的结合来解决生物复杂性的三个基本问题：1）在非线性和高维度的系统中，生态系统结构与功能之间的关系； 2）非线性生态系统对环境强迫的反应； 3）相关的细节级别，包括分辨物理空间的分辨率，必须将其纳入非线性系统，以捕获全球生态系统属性的动态（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。