Collaborative Research: Is nitrogen fixation widespread in the Chukchi and Beaufort Seas?

合作研究：固氮作用在楚科奇海和波弗特海广泛存在吗？

• 批准号: 1503614
• 负责人: Jonathan Zehr
• 金额: $ 24.15万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-12-01 至 2020-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1503614&HistoricalAwards=false
• 关键词: Collaborative; Research; nitrogen; fixation; widespread

The extent of summer Arctic sea ice loss is increasing and now occurs earlier in the year. As a result, it is predicted that the rate of growth of phytoplankton, the base of the marine food web that sustains subsistence marine harvests by native populations, will increase within the Arctic seas. The limited amount of available nitrogen, a required nutrient for phytoplankton, eventually will restrict the level of growth. Nitrogen gas dissolved in the ocean can be converted to a form readily utilizable by phytoplankton, but this has been considered primarily a warm-water process. The principal investigators of this project recently have observed this process in the Arctic Ocean, but there is so little data that its extent remains highly speculative. If it is widespread, it will change the way we think about future scenarios for the changing Arctic marine ecosystem, subsistence fishing, and, potentially, commercial fishing in the Arctic. The project will also contribute to workforce development. The principal investigator is an early-career, female scientist. She will use the project as a mechanism to entrain an undergraduate student into research. She will also use the project to sustain an existing educational collaboration between the Virginia Institute of Marine Sciences and Hampton University, a historically black university.It is hypothesized that microorganisms capable of fixing N2 (diazotrophs) are present in the Chukchi and Beaufort Seas, that they produce measurable rates of N2 fixation in near shore and offshore Arctic marine waters and that diazotroph community composition will differ between coastal sites, which are influenced by terrestrial inputs, versus open water sites. The Chukchi and Beaufort Seas will be sampled during a cruise in late summer 2016, when hydrographic and nutrient conditions are likely to favor diazotrophic populations. The impact that N2 fixation will have on Arctic ecosystems is dependent on its rate, spatial extent and the conditions that favor it. As a consequence, on each cruise the PIs propose to determine diazotroph community composition, examine their distributions based on the presence of the nitrogenase gene (nifH), measure rates of primary productivity and uptake of inorganic and organic N and C substrates using 15N and 13C tracer techniques, and to compare these to hydrographic, nutrient, and overall microbial community composition profiles made along cruise transects. The proposed work will determine the extent of active N2 fixation within the region in the context of other key biogeochemical and microbial community parameters.

夏季北极海冰损失的程度正在增加，现在发生在今年早些时候。 结果，可以预测，浮游植物的生长速率是北极海洋内部维持生存海洋收获的海洋食品网的基础，在北极海域内会增加。 有限的可用氮，这是浮游植物的所需养分，最终将限制生长水平。 溶解在海洋中的氮气可以被浮游植物转化为可容易利用的形式，但这主要是一种温暖的水过程。 该项目的主要研究人员最近在北极海洋中观察到了这一过程，但是数据的程度很少，以至于其范围仍然高度投机。 如果它是广泛的，它将改变我们考虑不断变化的北极海洋生态系统，生存捕鱼以及可能在北极商业捕鱼的方式的方式。 该项目还将有助于劳动力发展。 首席研究员是一位早期的女性科学家。 她将使用该项目作为一种机制，将一名本科生纳入研究。 She will also use the project to sustain an existing educational collaboration between the Virginia Institute of Marine Sciences and Hampton University, a historically black university.It is hypothesized that microorganisms capable of fixing N2 (diazotrophs) are present in the Chukchi and Beaufort Seas, that they produce measurable rates of N2 fixation in near shore and offshore Arctic marine waters and that diazotroph community composition will沿海地区之间的不同，这些沿海地区受陆地投入的影响，与开放水位相比。 Chukchi和Beaufort海域将在2016年夏末的一次巡游中进行采样，当时水文和营养条件可能有利于重生营养性种群。 N2固定对北极生态系统的影响取决于其速率，空间范围和有利于它的条件。结果，在每次巡游中，PIS建议确定重分营养群落组成，根据氮酶基因（NIFH）的存在检查其分布，使用15N和13C轨道器技术的无机N和有机N和C底物的量度和无机N和有机N和C基质的吸收，以及与这些水文相比，并将其与整体，整体培养物相比，并将其与整体，整体，整体培训相比。拟议的工作将在其他关键的生物地球化学和微生物社区参数的背景下确定该区域内主动N2固定的程度。