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

1989年进行的JGOFS野外试验收集的数据表明，即使在北大西洋春季水华的高峰期，细菌也处理了初级生产的很大一部分。对这些比率的重新检查提出了几个问题，自1989年以来的研究发现了许多新的微生物和微生物过程，当时没有考虑到这一点。一些新的微生物似乎是光异养的，例如好氧厌氧光合作用(AAP)细菌，它可以像北大西洋的聚球藻和原氯球菌一样丰富。这些新的发现表明，有必要重新研究细菌(和古生菌)在北大西洋春季水华期间的作用。2005年，美国国家科学基金会支持的调查人员和欧盟碳海洋项目将解决有关北大西洋春季水华期间二氧化碳水平和温度对藻类群落结构和生物地球化学的影响的问题。研究人员将加入这一努力，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，由于使用了高分子质量的溶解有机物，类细胞吞噬细菌在春季水华的高峰期和衰退期大量存在，而SAR11和其他由低分子量DOM支持的α-蛋白细菌群主导着非水华表层水域。研究人员将使用与培养无关的方法来验证这一假设，包括显微放射自显影和FISH(微型鱼类)和流式细胞仪增强的FISH，还将检查SAR11、类细胞吞噬细菌、光异养生物和其他丰富的微生物群体对选定的DOM成分(氨基酸、蛋白质、葡萄糖和多糖)和二氧化碳的吸收。1989年的JGOFS田间实验是对北大西洋春季水华的重要研究。这项研究的结果产生了许多关于细菌在初级产品加工中的作用的假说，这些假说对海洋微生物研究的后续发展产生了很大影响。2005年，研究人员将在一项旨在研究气候变化对海洋过程的影响的国际合作中，重新考察北大西洋春季水华，将春季水华作为长期气候变化的指标。在这个项目中，研究人员将参与并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，使用分子遗传学、生态学和生物地球化学方法相结合的方法。这项工作是对NASB 2005实验和美国/欧盟伙伴关系的重要补充，以确定北美和欧洲共享的生态系统北大西洋可能如何应对下个世纪的气候制度变化。该项目将让研究生和本科生参与研究，并通过一个网站进行公众宣传。

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.