Marine Diatom-Parasite Relationships in Upwelling Systems

上升流系统中的海洋硅藻与寄生虫的关系

• 批准号: 2149606
• 负责人: Bess Ward
• 金额: $ 39.04万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2149606&HistoricalAwards=false
• 关键词: Marine; Diatom; Parasite; Relationships; Upwelling

A recent global survey of surface ocean waters revealed that microbial parasites comprise half of the eukaryotic plankton diversity and suggested that biological interactions, including parasites, play an important role in the ecology of many types of microscopic algae, which are the base of the ocean food web, but not diatoms. Diatoms are among the most abundant microalgae, particularly in upwelling areas where nutrient-rich deep currents feed the ocean's surface and support the world's greatest fisheries. Yet this survey did not investigate high-productivity regions, leaving a significant knowledge gap. Diatoms may be successful in upwelling regions because they evade predators and parasites, but it seems more reasonable that they, like all other microalgae, also have biological enemies. In this study, the researchers use a large set of available samples from upwelling regions to investigate the effect of parasites on the proliferation of diatom communities and resulting primary production. The project supports a graduate student and provides hands-on research experiences for high school and undergraduate college students. The study data are also integrated into courses taught by the principal investigator. The discovery that half of the eukaryotic diversity in the Tara Oceans sequence database belongs to putatively parasitic microbes implies a revolution in our understanding of biological control of primary production. Ecosystem models are only beginning to incorporate the effect of viruses on production and community composition, but eukaryotic parasites add yet another dimension with potentially vast biogeochemical implications. While viral predation is generally thought to divert material flux away from grazers and into the dissolved organic carbon pool, increasing community diversity and microbial biomass, phytoplankton biomass diverted into parasite biomass becomes available to grazers. Experimental determination of parasite activity is difficult in natural systems, so most of the evidence for diversity, abundance, and host interactions of eukaryotic parasites is based on DNA sequence data. The Tara Oceans database suggests that diatoms have very few biotic interactions, leading to a stronger dependence on bottom-up factors (e.g., nutrients). However, this database did not represent high productivity upwelling regions. This project addresses two hypotheses: 1) diatoms in highly productive episodic upwelling systems are involved in host-parasite interactions that can be identified in co-occurrence networks during blooms; and 2) the community composition and abundance of host-parasite pairs vary over the course of the bloom in a manner consistent with density dependence on the host. In this project, abundance, diversity, and dynamics of parasites in upwelling systems are investigated by tag sequencing, metagenomics, and targeted qPCR of diatom-parasite pairs identified from archived samples from diatom-dominated upwelling systems (California Current, Eastern Tropical Pacific), the North Atlantic Spring bloom, and from two mesocosm experiments of diatom blooms induced by inoculation of surface seawater into nitrate-rich Monterey Bay seawater. Biogeochemical parameters (nutrients, primary production, nitrate assimilation, etc.) for those samples are available. In addition, the research team is using the outputs of the bioinformatics analysis in network and time series analysis to discover links among hosts and parasites.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

最近对地表海水的一项全球调查显示，微生物寄生虫占真核浮游生物多样性的一半，并建议包括寄生虫在内的生物相互作用在许多类型的微观藻类的生态学中起着重要作用，这些藻类是海洋食品网的基础，但不是硅藻。硅藻是最丰富的微藻之一，尤其是在上升的地区，养分丰富的深水流为海洋的表面喂养并支持世界上最大的渔业。然而，这项调查没有调查高生产力区域，留下了很大的知识差距。硅藻在上升地区可能会成功，因为它们逃避了捕食者和寄生虫，但是像所有其他微藻一样，它们也具有生物敌人，似乎更合理。在这项研究中，研究人员使用上升区域的大量可用样本来研究寄生虫对硅藻群落增殖的影响和产生的初级生产。该项目支持研究生，并为高中和大学生提供动手研究经验。研究数据还集成到首席研究人员教授的课程中。塔拉海洋序列数据库中一半的真核多样性属于预核的寄生微生物，这意味着我们对初级生产的生物控制的一场革命。生态系统模型才开始纳入病毒对生产和社区组成的影响，但是真核寄生虫增加了另一个维度，具有潜在的生物地球化学意义。虽然通常认为病毒捕食会使物质通量从放牧者转移到溶解的有机碳池，增加了社区多样性和微生物生物量，但浮游植物生物量转移到寄生虫生物库中。在天然系统中，寄生虫活性的实验性测定很难，因此真核寄生虫的多样性，丰度和宿主相互作用的大多数证据都是基于DNA序列数据的。塔拉海洋数据库表明，硅藻很少有生物相互作用，从而更依赖自下而上的因素（例如，营养素）。但是，该数据库并不代表高生产率上升区域。该项目解决了两个假设：1）高生产性情节上升系统中的硅藻参与宿主 - 寄生虫相互作用，这些相互作用可以在Blooms期间在同时发生的网络中鉴定出来； 2）宿主寄生虫对的社区成分和丰度在绽放过程中以与宿主的密度依赖相一致的方式变化。在该项目中，通过标签测序，宏基因组学和靶向QPCR研究了上升系统中寄生虫的丰度，多样性和动态，这些硅藻寄生虫对的QPCR是从硅藻寄生的样本中鉴定出的硅藻寄生样本中的样本（加利福尼亚州电流，东部热带太平洋的加利福尼亚州，北部的春季春季灌木丛），来自两种繁殖点，以及来自两种味道，并从两种味道实验。将地表海水接种到富含硝酸盐的蒙特利湾海水中。这些样品可用生物地球化学参数（营养，初级生产，硝酸盐同化等）。此外，研究小组正在使用网络和时间序列分析中的生物信息学分析的输出来发现宿主和寄生虫之间的联系。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的智力优点和更广泛影响的审查标准通过评估来获得支持的。