Collaborative Research: Oceanic diazotroph community structure and activities in a high carbon dioxide world

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。北太平洋副热带环流（NPSG）是地球上最大的海洋生态系统，在全球碳循环中发挥着突出作用，并形成了海洋生物多样性的重要水库。固氮菌（称为固氮菌）为NPSG的贫营养沃茨提供了新氮的主要来源，从而直接控制碳循环。海洋对CO2的吸收导致该生态系统海水中CO2分压（pCO 2）的长期变化。 因此，了解碳系统扰动如何影响海洋生物地球化学是一项重要而及时的任务。在本项目中，研究人员将研究固氮微生物的自然组合如何对海水碳化学扰动作出反应。实验室和实地实验将置于每月时间序列测量的背景下，对固氮微生物丰度的活动和丰度进行测量。总之，该项目将提供深入了解N2固定微生物生理学对CO2变化的依赖性。 本研究的主要目的是：（1）定量分析海水pCO 2变化对海洋固氮生物自然群落生长和群落结构的影响;（2）确定海水pCO 2变化对两种模式海洋固氮生物生长和碳获取策略的影响（束毛藻属和Crocosphaera）;（3）定量ALOHA站固氮生物群落结构和活动的时间变化。更广泛的影响包括提供重要的见解，气候变化情景对海洋生物地球化学的潜在影响，这将是有价值的微生物生态学家，气候变化科学家和海洋生物地球化学家。此外，计划为本科生和研究生提供研究机会，重点是妇女和代表性不足的群体参与科学。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The North Pacific Subtropical Gyre (NPSG) is the largest ocean ecosystem on Earth, playing a prominent role in global carbon cycling and forming an important reservoir of marine biodiversity. Nitrogen (N2) fixing bacteria (termed diazotrophs) provide a major source of new nitrogen to the oligotrophic waters of the NPSG, thereby exerting direct control on the carbon cycle. Oceanic uptake of CO2 causes long-term changes in the partial pressure of CO2 (pCO2) in the seawater of this ecosystem. Therefore, understanding how carbon system perturbations may influence ocean biogeochemistry is an important and timely undertaking.In this project, the investigators will examine how natural assemblages of N2 fixing microorganisms respond to perturbations in seawater carbon chemistry. Laboratory and field-based experiments will be placed in the context of monthly time series measurements on the activities and abundances of N2 fixing microorganism abundances. Together, the project will provide insight into the dependence of N2 fixing microorganism physiology on variations in CO2. The broad objectives of the research are: (1) Quantify the responses and consequences of changes in seawater pCO2 on the growth and community structure of naturally-occurring assemblages of ocean diazotrophs; (2) Identify why and how changes in seawater pCO2 influence the growth and carbon acquisition strategies of two model marine diazotrophs (Trichodesmium and Crocosphaera); and (3) Quantify temporal variability in diazotroph community structure and activities at Station ALOHA. The broader impacts include providing important insights into potential influences of climate change scenarios on ocean biogeochemistry which will be valuable to microbial ecologists, climate change scientists, and biogeochemists. In addition, research opportunities for both undergraduate and graduate students are planned with an emphasis on participation of women and underrepresented groups in science.