Aggregation of Marine Picoplankton

海洋超微型浮游生物的聚集

基本信息

批准号：
1658527
负责人：
Susanne Neuer
金额：
$ 68.75万
依托单位：
Arizona State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-03-15 至 2020-02-29
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1658527&HistoricalAwards=false
关键词：
Aggregation Marine Picoplankton

项目摘要

Marine phytoplankton are microscopic algae that live in the sunlit zone of the ocean. They play an important role in the uptake of carbon dioxide from the atmosphere through photosynthesis, similar to what plants do on land, and are the basis of the marine food web. However, instead of storing this organic carbon in leaf tissue and roots, marine phytoplankton are grazed by planktonic animals, or die and subsequently sink out of the sunlit zone in the form of aggregates, also called "Marine Snow". These particles not only export the organic carbon contained in their cells to the deep ocean, but also serve as food for animals and bacteria that live in the deep. A considerable portion of these phytoplankton are extremely small, among the tiniest of all organisms known. These extremely small cells have not been thought to play an important role in the formation and sinking of marine snow; however, recent findings challenge this view. This project will investigate how the smallest of these phytoplankton contribute to the rain of sinking particles from the sunlit surface to the deep ocean. This research is important because, in some of the largest expanses of the open oceans, these minute cells dominate the phytoplankton community, and larger plankton organisms are very sparse. The project, through a combination of work in the laboratory and at a field station, will shed light on how these tiny phytoplankton cells make aggregates, which ultimately enable them to sink as "Marine Snow". The project also provides unique opportunities for undergraduate students at Arizona State University, a land-locked public university, to gain experience in working with marine research. The project will serve to educate one PhD student, one MS student in an accelerated BS-MS program, and 8-10 undergraduate students/semester in a unique, inquiry based learning effort termed Microbial EducatioN Training and OutReach (MENTOR). The undergraduate students will also participate in Arizona State University (ASU)'s School of Life Sciences, Undergraduate Research Program (SOLUR), which seeks to increase the participation of minorities in science. They will also contribute towards developing web and classroom materials, based on this project, which will then be distributed through a partnership with the award-winning ASU-sponsored Ask A Biologist K-12 web site.The oceanic "biological carbon pump", the photosynthetically mediated transformation of dissolved inorganic carbon into particulate and dissolved organic carbon and its subsequent export to deep water, functions as a significant driver of atmospheric carbon uptake by the oceans. The traditional view of the biological carbon pump in the ocean is that of sinking of large aggregates (marine snow) or fecal pellets, which are made up of large, mineral ballasted cells of phytoplankton. However, recent evidence, stemming from in situ investigations of particulate matter, trap studies and modelling studies, have shown that micron-sized phytoplankton such as picocyanobacteria as well as picoeukaryotes can contribute significantly to the sinking of particulate matter. The specific mechanisms behind the sinking of these micrometer sized cells remain elusive as the cells are too small to sink on their own, and mesozooplankton is likely unable to ingest single cells. Intriguingly, recent research by the investigators has shown that the ubiquitous picocyanobacteria Synechococcus are able to form aggregates and sink at velocities comparable to those of marine snow. They found that the matrix of the Synechococcus aggregates was made of Transparent Exopolymeric Particles (TEP), and that TEP production was enhanced under nutrient limited culture conditions. Interaction with clays and presence of heterotrophic bacteria also enhanced aggregation and sinking velocity. This study aims to further investigate aggregation of other common picoplankton in the laboratory and aggregation occurring in natural settings at an oligotrophic open ocean site, the Bermuda Atlantic Time-series Site (BATS). Ultimately, this project will increase and refine our understanding of the role of the smallest phytoplankton in aggregation and sinking - information vital to understanding carbon cycling processes in the oceans.

海洋浮游植物是生活在海洋阳光区域的微观藻类。它们在通过光合作用的大气中吸收二氧化碳的吸收中起着重要作用，类似于植物在陆地上的作用，并且是海洋食品网的基础。但是，海洋浮游植物没有将这种有机碳储存在叶组织和根部，而是被浮游动物放牧，或者死亡，随后以聚集体的形式沉没，也被称为“海洋雪”。这些颗粒不仅将其细胞中含有的有机碳导出到深海中，而且还可以充当居住在深处的动物和细菌的食物。这些浮游植物中很大一部分非常小，是所有已知生物中最小的。这些极小的细胞没有被认为在海洋雪的形成和下沉中起着重要作用。但是，最近的发现挑战了这一观点。该项目将研究这些浮游植物中最小的如何促进从日光表面到深海的下沉颗粒的降雨。这项研究很重要，因为在开阔海洋的一些最大扩展中，这些微小的细胞主导了浮游植物群落，而较大的浮游生物非常稀疏。该项目通过实验室和现场站的工作结合，将阐明这些微小的浮游植物细胞如何形成聚集体，最终使它们成为“海洋雪”。该项目还为亚利桑那州立大学的本科生提供了独特的机会，该大学是一所陆上锁定的公立大学，以获得从事海洋研究的经验。该项目将在加速的BS-MS计划中教育一名博士学位学生，一名MS学生，以及8至10个本科生/学期，以独特的基于询问的学习努力，称为微生物教育培训和外展（Mentor）。本科生还将参加亚利桑那州立大学（ASU）的生命科学学院，本科研究计划（SOLUR），该计划旨在增加少数群体参与科学的参与。他们还将根据该项目为开发网络和课堂材料做出贡献，然后通过与屡获殊荣的ASU赞助的合作伙伴关系来分配该项目，请询问生物学家K-12网站。海洋的“生物碳泵”，光合作用的，即光合介导的，溶解的无机碳和分解的有机碳的强大驱动器，以使其在颗粒和分解的驱动器中，以实现型有机碳，以实现型号，以使其充满了液体的范围，以实现型号，以实现型号的驱动器，以实现高度的驱动器，以实现高度的碳水化合物，以实现型号的循环量，以实现型号的循环范围，以实现型号的循环范围。在海洋上。海洋生物碳泵的传统视图是大骨料（海洋雪）或粪便颗粒的下沉，这些颗粒由浮游植物的大型矿物压载细胞组成。然而，最近的证据是源于颗粒物，捕获术和建模研究的原位研究，表明微米大小的浮游植物（例如皮基氨基杆菌）以及picoeukaryotes可以显着贡献颗粒物的沉没。这些微米大小的细胞下沉背后的特定机制仍然难以捉摸，因为这些细胞太小而无法自行下沉，而中龙兰克顿很可能无法摄取单个细胞。有趣的是，研究人员的最新研究表明，无处不在的皮基氨基杆菌合子菌能够以与海洋雪相媲美的速度形成聚集体并下沉。他们发现，共菌聚集体的基质是由透明的外聚合颗粒（TEP）制成的，并且在养分有限的培养条件下，TEP的产生得到了增强。与粘土的相互作用以及异养细菌的存在也提高了聚集和下沉的速度。这项研究旨在进一步研究实验室中其他常见的皮科普兰顿的聚集，并在自然环境中发生的聚集在寡头营地的自然环境中，即百慕大大西洋时间系列（BATS）。最终，该项目将增加和完善我们对最小的浮游植物在聚集和沉没中的作用的理解 - 对了解海洋中碳循环过程至关重要的信息。