Group-Specific Diatom Silica Production in a Coastal Upwelling System

沿海上升流系统中特定族群硅藻二氧化硅的生产

• 批准号: 1155663
• 负责人: Jeffrey Krause
• 金额: $ 45.35万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-01 至 2017-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1155663&HistoricalAwards=false
• 关键词: Group; Specific; Diatom; Silica; Production

This study will examine the distribution of silica production among diatom species, using a novel combination of existing approaches, to evaluate the contributions of specific species or genera to total diatom silica production. Specific hypotheses regarding the distribution of silica production among species of diatoms will be tested by exploiting the strong contrasts in diatom community structure and silica production between a coastal upwelling system and in an oligotrophic subtropical gyre. Several lines of evidence support the idea that the diatoms responsible for the majority of silica production shifts from the most numerically abundant species in coastal systems to relatively rare, but very large, cells in offshore oligotrophic environments. This shift alters the role of diatoms in regional food webs and because many processes determining the role of phytoplankton groups in biogeochemical cycles are a function of cell size, such a shift has strong implications for regional differences in the contribution of diatoms to upper-ocean carbon cycling and the biological pump. This study also seeks to understand of the role of silicon limitation in regulating diatom silica production at the species level. Si limitation of silica production has been detected in every system examined to date, ranging from the high Si waters of the Antarctic, to coastal upwelling systems and the oligotrophic subtropical gyres. Field studies of Si limitation are rarely accompanied by examination of the species present. When studies do have taxonomic data the lack of information on the performance of individual species makes it impossible to allocate the measured rates among cells, potentially leading to erroneous conclusions about the contribution of specific diatom groups to community composite rates.The project will test five hypotheses. Each is related to the general theme of using species-specific data to improve understanding of the factors regulating diatoms' role in marine food webs. By combining bulk measures of silica production using the radioisotope 32Si with quantitative measures of silicon deposition rates by individual cells using the fluorescent probe 2-(4-pyridyl)-5((4-(2-dimethylaminoethyl-aminocarbamoyl)-methoxy)phenyl)oxazole, or PDMPO, the following will be determined: species-specific diatom contributions to total community silica production, regional differences in the distribution of silica production among diatom species as a function of cell size, species-specific kinetic parameters governing the ability of species to compete for dissolved silicon, and whether dominance of a particular diatom group or species can be explained by knowledge of their capacity to utilize Si and their numerical abundance (as opposed to other factors such as grazing or limitation by other nutrients).Broader impacts:Specific-specific knowledge from field assemblages will improve the understanding of the major biological and ecological drivers of organic carbon and silica production by diatoms in the sea. This dataset will also help identify key species for inclusion in food-web and biogeochemical models in coastal and oligotrophic gyre ecosystems, and test whether knowledge of diatom nutrient uptake capacity from laboratory studies are representative of diatoms in mixed communities in the field. This project will also provide research experiences for undergraduates in both the laboratory and field settings, and will include a K-12 outreach program designed in collaboration with scientific-outreach personnel from UCSB's Marine Science Institute's Oceans to Classroom (O2C) program for use in regional elementary schools. O2C currently reaches over 18,000 students in 800 regional K-12 classrooms annually bringing marine science to life for students using real-life examples of marine research by UCSB PIs.

这项研究将使用现有方法的新组合来研究硅藻种类之间二氧化硅生产的分布，以评估特定物种或属对总硅藻二氧化硅产量的贡献。关于在硅藻种类中二氧化硅生产分布的特定假设将通过利用沿海上升流入系统和少亲营养的亚热带的强烈对比来测试。 几条证据支持了这样的想法，即负责大多数二氧化硅生产的硅藻从沿海系统中数值最丰富的物种转变为近海无散性环境中相对较少但非常大的细胞。这种转变改变了硅藻在区域食品网中的作用，并且因为许多过程确定了浮游植物基团在生物地球化学周期中的作用，这是细胞大小的函数，所以这种转移对硅藻对上囊碳循环和生物泵的贡献的区域差异具有很强的影响。这项研究还试图了解硅限制在调节物种水平上的硅藻生产中的作用。迄今为止，在所有检查的系统中都检测到了SI生产的SI限制，从南极的高Si水域到沿海上升流系统和少亲营养的亚热带Gyres。 SI限制的现场研究很少伴有对存在物种的检查。当研究确实有分类数据时，缺乏有关单个物种性能的信息，就无法分配细胞之间的测量率，这可能会导致关于特定硅藻组对社区综合率的贡献的错误结论。该项目将测试五个假设。每个都与使用特定物种数据来提高对调节硅藻中硅藻作用的因素的理解的一般主题有关。通过使用荧光探针2-（4-吡啶基）-5（（4-（4-（4-（2-二甲基氨基氨基 - 氨基氨基氨基酰基） - 甲氧基 - 甲氧基）促进的氧化量为pdmpo，通过荧光探针2-（4-（4-吡啶基） - 5（4-（4-吡啶基）），通过使用荧光探针2-（4-吡啶基） - 5（4-吡啶基） - 5（4-吡啶基） - 5（4-吡啶基） - 5（4-吡啶基） - 二氧化硅生产，硅藻种群分布分布的区域差异与细胞大小的关系，特定物种特异性的动力学参数统治物种竞争竞争能力争夺溶解的硅的能力，以及特定的硅藻群或物种的优势是否可以通过使用其他因素或其他因素（以及其他因素）来解释的，例如其他因素或其他因素）影响：来自现场组合的特定特定知识将改善对海中有机碳和二氧化硅生产的主要生物学和生态驱动因素的理解。该数据集还将有助于鉴定关键物种，以纳入沿海和少亲子循环生态系统中的食品网和生物地球化学模型，并测试实验室研究中对硅藻营养摄取能力的了解是否代表了该领域混合群落的硅藻。该项目还将为实验室和野外环境中的本科生提供研究经验，并将包括与UCSB海洋科学研究所的科学 - 欧特雷奇人员合作设计的K-12外展计划，旨在在区域小学中使用，以便在区域小学中使用。 O2C目前每年在800个区域K-12教室中吸引了18,000多名学生，其中使用UCSB PIS的Marine Research实例将海洋科学栩栩如生。