Bacterial production and community structure during the North Atlantic Spring Bloom [NASB 2005]

在1989年进行的JGOFS实地试验中收集的数据表明，即使在北大西洋春季水华的高峰期，细菌也处理了大部分初级产品。对这些比率的重新检查提出了几个问题，自1989年以来的工作发现了许多当时没有考虑到的新微生物和微生物过程。一些新的微生物似乎是光异养的，如好氧无氧光合作用（AAP）细菌，它可以像北大西洋的聚藻球菌和原绿球藻一样丰富。这些新发现表明，有必要重新审视细菌（和古细菌）在北大西洋春季繁盛期间的作用。2005年，美国国家科学基金会支持的研究人员和欧盟碳海洋项目将研究北大西洋春季水华期间二氧化碳分数和温度对藻类群落结构和生物地球化学的影响。研究人员将加入这项工作，并将探索细菌群落结构如何随着浮游植物生物量、生长和群落结构的变化而变化。他们的工作假设是，由于使用了高分子量溶解有机物，在春季水华的高峰和低谷阶段，类细胞吞噬细菌大量存在，而由低分子量DOM支持的SAR11和其他α -变形菌群在非水华的地表水中占主导地位。研究人员将使用与培养无关的方法来验证这一假设，包括微放射自显影和流式细胞术增强的FISH (Micro-FISH)，并将检查SAR11、细胞吞噬样细菌、光异养生物和其他丰富的微生物群对选定DOM成分（氨基酸、蛋白质、葡萄糖和多糖）和CO2的摄取。1989年JGOFS野外试验是对北大西洋春华现象的一次重要研究。研究结果产生了许多关于细菌在初级产品加工中的作用的假设，这些假设对海洋微生物研究的后续发展产生了重大影响。2005年，研究人员将在一项国际合作中重新审视北大西洋春华现象，该合作旨在研究气候变化对海洋过程的影响，利用春华现象作为长期气候变化的代表。在本项目中，研究人员将结合分子遗传学、生态学和生物地球化学方法，研究细菌群落结构如何随着浮游植物生物量、生长和群落结构的变化而变化。这项工作是NASB 2005实验和美国/欧盟伙伴关系的重要补充，以确定北大西洋是北美和欧洲共享的生态系统，在未来一个世纪如何应对气候制度变化。该项目将涉及研究生和本科生的研究，并通过网站向公众宣传。

Data collected in the JGOFS field experiment conducted in 1989 indicated that bacteria process a large fraction of primary production even at the height of the North Atlantic spring bloom. Re-examination of those rates has raised several questions, and work since 1989 has discovered many new microbes and microbial processes not considered at the time. Some of the new microbes appear to be photoheterotrophic, such as the aerobic anoxygenic photosynthesizing (AAP) bacteria, which can be as abundant as Synechococcus and Prochlorococcus in the North Atlantic. These new findings indicate that it is essential to re-examine the role of bacteria (and archaea) during the North Atlantic spring bloom. In 2005, NSF-supported investigators and the EU CarboOcean project will address questions about the impact of pCO2 levels and temperature on algal community structure and biogeochemistry during the North Atlantic spring bloom. The investigators will join this effort and will explore how bacterial community structure changes in response to variation in phytoplankton biomass, growth, and community structure. Their working hypothesis is that Cytophaga-like bacteria are abundant during the height and waning stages of the spring bloom because of the use of high molecular weight dissolved organic matter, whereas SAR11 and other alpha-proteobacterial groups supported by low molecular weight DOM dominate non-bloom surface waters. The investigators will test this hypothesis using culture-independent methods, including microautoradiography and FISH (Micro-FISH) augmented by flow cytometry, and will also examine the uptake of select DOM components (amino acids, protein, glucose and polysaccharides) and CO2 by SAR11, Cytophaga-like bacteria, photoheterotrophs, and other abundant microbial groups.The 1989 JGOFS field experiment was an important study of the North Atlantic Spring Bloom. The results of the study generated numerous hypotheses regarding the roles of bacteria in processing primary production, and these hypotheses have had a great influence on the subsequent development of marine microbial research. In 2005, researchers will revisit the North Atlantic Spring Bloom in an international collaboration designed to examine the influence of climate change on ocean processes, using the spring bloom as a proxy for longer-term climate change. In this project, the investigators will participate and examine explore how bacterial community structure changes in response to variation in phytoplankton biomass, growth, and community structure, using a combination of molecular genetic, ecological and biogeochemical approaches. The work is an essential addition to the NASB 2005 experiment and to the US/EU partnership to determine how the North Atlantic, an ecosystem that is shared by both North America and Europe, may react to climate regime changes during the coming century. The project will involve graduate and undergraduate students in research, and public outreach through a website.