Collaborative Research: Investigating Iron-inding Ligands in Southern Ocean Diatom Communities: The Role of Diatom-Bacteria Associations

合作研究：调查南大洋硅藻群落中的铁配体：硅藻-细菌协会的作用

• 批准号: 1443483
• 负责人: Kristen Buck
• 金额: $ 27.66万
• 依托单位: University of South Florida
• 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: 2015-07-15 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1443483&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; Iron; inding

This project focuses on an important group of photosynthetic algae in the Southern Ocean (SO), diatoms, and the roles associated bacterial communities play in modulating their growth. Diatom growth fuels the SO food web and balances atmospheric carbon dioxide by sequestering the carbon used for growth to the deep ocean on long time scales as cells sink below the surface. The diatom growth is limited by the available iron in the seawater, most of which is not freely available to the diatoms but instead is tightly bound to other compounds. The nature of these compounds and how phytoplankton acquire iron from them is critical to understanding productivity in this region and globally. The investigators will conduct experiments to characterize the relationship between diatoms, their associated bacteria, and iron in open ocean and inshore waters. Experiments will involve supplying nutrients at varying nutrient ratios to natural phytoplankton assemblages to determine how diatoms and their associated bacteria respond to different conditions. This will provide valuable data that can be used by climate and food web modelers and it will help us better understand the relationship between iron, a key nutrient in the ocean, and the organisms at the base of the food web that use iron for photosynthetic growth and carbon uptake. The project will also further the NSF goals of training new generations of scientists and of making scientific discoveries available to the general public. The project supports early career senior investigators and the training of graduate and undergraduate students as well as outreach activities with middle school Girl Scouts in Rhode Island, inner city middle and high school age girls in Virginia, and middle school girls in Florida.The project combines trace metal biogeochemistry, phytoplankton cultivation, and molecular biology to address questions regarding the production of iron-binding compounds and the role of diatom-bacterial interactions in this iron-limited region. Iron is an essential micronutrient for marine phytoplankton. Phytoplankton growth in the SO is limited by a lack of sufficient iron, with important consequences for carbon cycling and climate in this high latitude regime. Some of the major outstanding questions in iron biogeochemistry relate to the organic compounds that bind 99.9% of dissolved iron in surface oceans. The investigators' prior research in this region suggests that production of strong iron-binding compounds in the SO is linked to diatom blooms in waters with high nitrate to iron ratios. The sources of these compounds are unknown but the investigators hypothesize that they may be from bacteria, which are known to produce such compounds for their own use. The project will test three hypotheses concerning the production of these iron-binding compounds, limitations on the biological availability of iron even if present in high concentrations, and the roles of diatom-associated bacteria in these processes. Results from this project will provide fundamental information about the biogeochemical trigger, and biological sources and function, of natural strong iron-binding compound production in the SO, where iron plays a critical role in phytoplankton productivity, carbon cycling, and climate regulation.

该项目着重于南大洋（SO），硅藻以及相关细菌群落的角色在调节其生长时发挥作用的重要一组光合藻类。硅藻生长通过将用于生长的碳在长时间尺度上延迟到深海时，为大气中的二氧化碳增添了SO网络，并平衡了大气中的二氧化碳。硅藻的生长受海水中可用的铁的限制，其中大多数不能免费提供给硅藻，而是与其他化合物紧密结合。这些化合物的性质以及浮游植物如何从中获取铁对于了解该地区和全球生产力至关重要。研究人员将进行实验，以表征硅藻，其相关细菌以及在开阔水域和近海水域中的铁之间的关系。实验将涉及以不同的养分比与天然浮游植物组合的不同养分，以确定硅藻及其相关细菌对不同条件的反应。这将提供有价值的数据，可以由气候和食品网络建模者使用，这将有助于我们更好地了解铁，海洋中的关键营养素以及食物网底部的生物之间的关系，这些生物使用铁来用于光合作用的生长和碳吸收。该项目还将进一步培训新一代科学家的目标，并为公众提供科学发现。该项目支持早期的职业高级调查人员，研究生和本科生的培训，以及在罗德岛州，内城中学和弗吉尼亚州内部和高中时代的女孩以及佛罗里达州的中学女孩的中学女童子军，以及佛罗里达州的中学女孩。铁限制区域。铁是海洋浮游植物的必不可少的微量营养素。 SO中的浮游植物生长受到缺乏足够的铁的限制，对这种高纬度状态下的碳循环和气候产生了重要影响。铁生物地球化学的一些主要问题与结合99.9％溶解铁在地面海洋中的有机化合物有关。研究人员在该地区的先前研究表明，SO中强大的铁结合化合物的产生与硝酸盐与铁比高的水域中的硅藻开花有关。这些化合物的来源尚不清楚，但研究人员假设它们可能来自细菌，众所周知，这些细菌会生产出这种化合物的使用。该项目将检验有关这些铁结合化合物产生的三个假设，即使以高浓度存在的铁的生物可用性局限性以及与硅藻相关细菌在这些过程中的作用。该项目的结果将提供有关天然强壮的铁结合化合物生产的生物地球化学触发器以及生物学来源和功能的基本信息，在此，铁在浮游植物生产率，碳循环和气候调节中起着至关重要的作用。