Ecology of eukaryote microbes in the deep North Atlantic

北大西洋深处真核微生物的生态学

• 批准号: 1235169
• 负责人: Alexander Bochdansky
• 金额: $ 53.99万
• 依托单位: Old Dominion University Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-15 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1235169&HistoricalAwards=false
• 关键词: Ecology; eukaryote; microbes; deep; North

In the microbial realm, one of the three domains of life -- the Eukarya -- has received little attention in deep-sea research. This stands in contrast to the fact that in all known aquatic environments, and measured by the amount of material and energy transferred, the link between prokaryotic and eukaryotic cells is one of the most significant trophic interactions on Earth. In terms of volume, the deep sea is the largest biome, and despite its tremendous role in long-term biogeochemical cycles, it has largely been neglected. Biological activity in the deep sea is neither negligible nor homogeneous in space and time. Recent data suggest that biological activity in the dark ocean (as evidenced by respiration rates, bacterial secondary production and a variety of other metrics) is much higher than anticipated from all known organic carbon fuel sources combined (i.e., POC flux, DOC convection, in situ production and active transport by zooplankton). Water masses in the deep ocean represent highly-diverse biogeographic regions with distinct communities and particle distributions. Moreover, because of feeding thresholds, cold temperatures, extreme pressures and unique adaptations that deep-sea microbes exhibit, biological activity rules cannot simply be extrapolated from laboratory cultures and from experiments with surface-dwelling microbes. This study focuses on the fundamental role of eukaryotic microbial communities in deep-sea ecology with the overarching hypothesis that protists represent sensitive biological indicators of utilizable organic carbon. There is good reason to believe that microbial eukaryotes and their activities are better indicators of "new" sources of organic carbon than particle inventories, sediment traps, isotope ratios, or models based on surface production and theoretical flux attenuation. For these new biological indicators to work, however, one needs to separate live from the moribund and dead cells, the bacterivores from saprotrophs, the inactive resting stages from those actively feeding on prokaryotes, the gametes and zoospores from vegetative and feeding stages, and those located on particles from the ones freely suspended in the water column. Each of these groups represents different levels of per-cell energy and carbon requirements. Intellectual merit: This study determines the ecological role of eukaryotic microbes in the deep North Atlantic over large geographic regions. The research incorporates two fundamentally different experimental designs that capitalize on different time scales: 1) Short-term incubations (~72 hours) of respiratory activity and bacterivory combined with a high resolution sampling of abundances across large geographic regions performed from a research vessel, and 2) Long-term incubations (=/ 4 weeks) measuring colonization of sinking particles and growth of eukaryotic microbes using free-falling (untethered) vehicles representing the first attempt of physiological rate measurements directly in the deep sea. Methods include new tracers for bacterivory, incubations for single-cell respiration, taxonomic identification using fluorescence in situ hybridization, single-cell genomics, and the first of its kind deep-sea holographic microscope capturing images to a maximum depth of 6000 m at 5 micrometer resolution. Broader Impacts: This project supports undergraduate and graduate research and enhances undergraduate curriculum in biological oceanography courses held by the PI. Workshops for underrepresented groups will be held in Puerto Rico. A permanent exhibit on the role of microbes in the ocean will be installed at a major museum and interpretation center in Hampton Roads. This research contributes significantly to the development of new technology for oceanographic research with emphasis on deep-sea environments and supports international scientific research collaborations.

在微生物领域，生活的三个领域之一 - 真核生物 - 在深海研究中很少关注。这与以下事实相反：在所有已知的水生环境中，并通过转移的材料和能量的量来衡量，原核和真核细胞之间的联系是地球上最重要的营养相互作用之一。在数量方面，深海是最大的生物群落，尽管它在长期生物地球化学周期中具有巨大的作用，但它在很大程度上被忽略了。在深海中的生物活性在时空既不可忽略不相同。最近的数据表明，黑海洋中的生物活性（如呼吸率，细菌二级生产和各种其他指标所证明的那样）要比所有已知的有机碳燃料来源（即POC Flux，doc对流，原位生产和浮游动物的主动运输）所预期的要高得多。深海中的水块代表具有不同社区和颗粒分布的高度多样性的生物地理区域。此外，由于深海微生物所表现出的喂养阈值，寒冷的温度，极端压力和独特的适应性，因此不能简单地从实验室培养物中推断出生物活性规则，以及从实验室培养物中推断出来。这项研究的重点是真核微生物群落在深海生态学中的基本作用，其总体假设是生物代表了可利用的有机碳的敏感生物学指标。有充分的理由相信，与粒子库存，沉积物陷阱，同位素比率或基于基于表面产生和理论通量衰减的模型相比，微生物真核生物及其活性是有机碳的“新”来源更好的指标。但是，要使这些新的生物学指标起作用，需要将生物与垂死和死细胞分离，来自腐生的细菌植物，不活跃的休息阶段，与积极进食的原核生物，配子和动物孢子的植物，与营养和喂食阶段以及来自水列的粒子上的粒子。这些组中的每一个都代表了不同水平的人均能量和碳需求。智力优点：这项研究决定了北大西洋深地理区域中真核微生物的生态作用。这项研究结合了两种基本不同的实验设计，这些设计在不同的时间范围内都有资本：1）短期孵育（〜72小时）的呼吸活动和细菌的孵化（〜72小时），结合了从研究血管中进行的大地理区域进行丰度的高分辨率采样，以及使用长期孵化（=/ 4周）的循环（=/ 4周），以测量良好的成长（=/ 4周）。 （无限制的）车辆，代表了直接在深海中生理速率测量的首次尝试。方法包括新的细菌示踪剂，单细胞呼吸的孵育，使用荧光原位杂交的分类学鉴定，单细胞基因组学以及第一个同类深海全息显微镜将图像捕获至5微米分辨率为6000 m的最大深度。更广泛的影响：该项目支持本科和研究生研究，并增强了PI持有的生物海洋学课程中的本科课程。代表性不足的团体的讲习班将在波多黎各举行。关于微生物在海洋中作用的永久性展览将安装在汉普顿路的一个主要博物馆和解释中心。这项研究为海洋学研究的新技术发展做出了重大贡献，重点是深海环境，并支持国际科学研究合作。