Dimensions: Collaborative research: Biological controls of the ocean C:N:P ratios

维度：合作研究：海洋 C:N:P 比率的生物控制

• 批准号: 1046368
• 负责人: Kun Zhang
• 金额: $ 57.25万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1046368&HistoricalAwards=false
• 关键词: Dimensions; Collaborative; research; Biological; controls

Intellectual merit. One of the fundamental patterns of ocean biogeochemistry is the Redfield ratio, linking the stoichiometry of surface plankton with the chemistry of the deep ocean. There is no obvious mechanism for the globally consistent C:N:P ratio of 106:16:1 (Redfield ratio), especially as there is substantial elemental variation among plankton communities in different ocean regions. Thus, knowing how biodiversity regulates the elemental composition of the ocean is important for understanding the ocean and climate as a whole -- now and in the future. The conceptual hypotheses for this study are as follows:1. The C:N:P ratio of a cell is constrained by its broad taxonomic group, which determines, for example, whether it has an outer shell, its size, functional metabolism, membrane lipid composition.2. Within a taxon, there is high genetic diversity. Some of this genetic diversity is potentially laterally transferred, or can be lost within taxa, and confers various functional abilities (organic phosphate assimilation, nitrate assimilation, photoheterotrophy, etc.). Functional diversity provides the cell with further flexibility, such as the ability to respond to varying nutrient supply rates/ratios, and affects a cell's C:N:P ratio within the range specified by the taxon.3. Given these taxonomic and genetic constraints, a cell is physiologically plastic and modifies how it allocates cellular resources in response to nutrient supply rates/ratios in the environment.4. The microbial diversity (taxonomic, genetic, and functional) of the surface ocean varies over time and space, driven by many factors in addition to nutrients. The sum of this mixture composes the ecosystem C:N:P, the ratio that Redfield described. Based on this framework, the CoPIs will make field observations of taxon-specific stoichiometry and growth rates, genomic analyses, and conduct laboratory chemostat experiments to improve understanding of how ocean taxonomic, genetic, and functional biodiversity control the stoichiometry of the surface ocean plankton. Their analyses of these data would lead to a mechanistic understanding of variations in the Redfield ratio, both spatially and temporally.Broader impacts. This study will greatly expand knowledge of the genomic diversity among ocean microbes and how this diversity affects biogeochemistry. The stoichiometry of the ocean's microbes is a parameter that nearly every chemical or biological oceanographer uses, from converting measurements made in one element to another, to estimating regional and global nitrogen budgets. The research also has important implications for the global carbon budget and any changes that might result from climate change. Beyond training three postdoctoral scholars and two graduate students, a Gateway Mentoring Program will be established to recruit undergraduates (total of 12) transferring from community colleges in the Southern California area, training and preparing them for careers in research-oriented science. The program will consist of extensive mentoring, research experiences at UCI, internships at BIOS, Princeton, or UCSD, and presentations at national conferences. This intensive mentoring and research experience prepares students well for a career in science, and enhances acceptance to post-graduate schools. The Program will have a very high proportion of underrepresented groups as reflected in the targeted colleges.Integration. To understand mechanistically temporal and spatial variability of the plankton C:N:P ratio, biodiversity must be studied not only at the traditional taxonomic level, but at the genetic and functional levels which dictate organism response to their environment. Data will be integrated into a combined ocean ecological, evolutionary, and biogeochemical model, with flexible stoichiometry, including cellular biochemical allocations. Seeding a coupled physical-biological model of the oceans with multiple competing genotypes enables the exploration of ecological and evolutionary patterns of resource acquisition and C:N:P ratios. Developing a more mechanistic examination of the course of ecology and evolution, in which laboratory and field data define tradeoffs between different growth and nutrient acquisition strategies, would estabblish the framework of adaptive dynamics for determining "evolutionarily convergence". Finally, model outcomes will be evaluated against field data.

知识价值。海洋生物地球化学的基本模式之一是雷德菲尔德比率，它将表层浮游生物的化学计量与深海的化学计量联系起来。全球一致的106:16:1 (Redfield ratio) C:N:P没有明显的机制，特别是不同海洋区域浮游生物群落之间存在较大的元素差异。因此，了解生物多样性如何调节海洋的元素组成，对于从整体上理解海洋和气候非常重要——无论是现在还是将来。本研究的概念假设如下：1。细胞的C:N:P比值受其广泛的分类群的限制，这决定了，例如，它是否有外壳，它的大小，功能代谢，膜脂组成。在一个分类单元内，具有高度的遗传多样性。其中一些遗传多样性可能横向转移，或在分类群内丢失，并赋予各种功能能力（有机磷酸盐同化，硝酸盐同化，光异养等）。功能多样性为细胞提供了进一步的灵活性，例如对不同营养供应速率/比率的反应能力，并在分类指定的范围内影响细胞的C:N:P比率。考虑到这些分类学和遗传上的限制，细胞在生理上是可塑的，并且会根据环境中的营养供应速率/比率调整其分配细胞资源的方式。海洋表面的微生物多样性（分类、遗传和功能）随着时间和空间的变化而变化，除了营养物外，还受到许多因素的影响。这些混合物的总和构成了生态系统的C:N:P，即雷德菲尔德所描述的比率。在此框架下，CoPIs将进行分类群特异性化学计量和生长速率的实地观察、基因组分析和实验室化学平衡实验，以提高对海洋分类、遗传和功能生物多样性如何控制表层海洋浮游生物化学计量的认识。他们对这些数据的分析将导致对雷德菲尔德比值在空间和时间上变化的机制理解。更广泛的影响。这项研究将极大地扩展对海洋微生物基因组多样性以及这种多样性如何影响生物地球化学的认识。海洋微生物的化学计量学是几乎每个化学或生物海洋学家都会使用的一个参数，从将一种元素的测量值转换为另一种元素，到估计区域和全球的氮收支。这项研究还对全球碳预算和气候变化可能导致的任何变化具有重要意义。除了培养三名博士后学者和两名研究生外，还将建立一个“门户指导计划”，招收南加州地区社区学院转学的本科生（共12人），为他们从事研究型科学工作提供培训和准备。该计划将包括广泛的指导，在UCI的研究经历，在BIOS，普林斯顿或UCSD的实习，以及在国家会议上的演讲。这种密集的指导和研究经验为学生在科学领域的职业生涯做好了准备，并提高了研究生院的接受度。从目标大学的情况来看，该项目将有很高比例的未被充分代表的群体。为了从机制上理解浮游生物C:N:P比值的时空变异性，生物多样性不仅要在传统的分类学水平上进行研究，而且要在生物对环境的反应的遗传和功能水平上进行研究。数据将被整合到一个综合的海洋生态、进化和生物地球化学模型中，具有灵活的化学计量学，包括细胞生化分配。建立具有多种竞争基因型的海洋物理-生物耦合模型，可以探索资源获取和C:N:P比率的生态和进化模式。对生态和进化过程进行更机械的检查，利用实验室和实地数据确定不同生长和营养获取策略之间的权衡，将建立确定“进化趋同”的适应动力学框架。最后，模型结果将根据现场数据进行评估。