Collaborative Research: Quantifying competing loss rates of viral lysis and microzooplankton grazing on Emiliania huxleyi mortality

合作研究：量化病毒裂解和微型浮游动物放牧对艾米利亚赫胥黎死亡率的竞争损失率

• 批准号: 1459190
• 负责人: Matthew Johnson
• 金额: $ 60.3万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-05-01 至 2018-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1459190&HistoricalAwards=false
• 关键词: Collaborative; Research; Quantifying; competing; loss

Processes that either promote growth or cause mortality drive the abundance of all organisms. For microbes such as phytoplankton, that have a lifespan measured in hours to days, small changes in these processes can have significant impacts. Phytoplankton are the central currency in the flow of material and nutrients throughout the marine environment. Even small shifts in their growth and mortality rates will have large-scale implications for ecosystem structure and biogeochemical cycling. While factors that influence growth are often examined, less is known regarding the regulation of phytoplankton mortality. This project will focus on quantifying competing modes of mortality on the bloom-forming coccolithophore, Emiliania huxleyi, a globally important phytoplankton species that contributes significantly to ocean carbon and sulfur cycles. Mortality due to grazing by single-celled microzooplankton is the largest contributor to phytoplankton loss in the marine environment. However, E. huxleyi also has a well-characterized relationship with a virus that can result in mass mortality. Therefore, E. huxleyi serves as a good model organism for examining how mortality is partitioned between grazing by microzooplankton predators and lysis due to viral infection. Quantifying these mortality mechanisms will help to inform mathematical models for the accurate prediction of shifts in E. huxleyi population dynamics and ultimately, primary production and biogeochemical cycling. This work will involve collaboration with a high school science teacher in a school system with a large proportion of students from underrepresented groups, in the creation and implementation of short film clips that depict important ecological interactions. These film clips will then be incorporated into laboratory activities to communicate these concepts to students. Further, undergraduate students from underrepresented groups will be trained at both Woods Hole Oceanographic Institute and Rutgers University, to perform laboratory research on mortality processes on phytoplankton. This research will also provide training and career development for a postdoctoral scientist.Mortality mechanisms in phytoplankton have generally been studied independent from one another, however in nature, these processes act concurrently. The relative proportion that microzooplankton grazing and viral lysis contribute to overall E. huxleyi loss and how they may interact to shape bloom dynamics is largely unknown. Understanding the relative importance of these processes, as well as their interaction, is critical due to their contrasting influence on the structure and function of marine food webs and biogeochemical cycles. While grazing tends to channel phytoplankton biomass to higher trophic levels, viral lysis stimulates microbial loop activity and vertical particle export flux. This research will determine the effect of one mortality process on the other, as well as their net effect on E. huxleyi population dynamics and export in both laboratory and field mesocosm experiments. This integrated approach will provide a unique mechanistic perspective of multi-trophic microbial interactions, thereby increasing the potential for accurate predictions of E. huxleyi population dynamics and biogeochemical cycling. The outcomes of this research have the potential to yield broadly applicable insights into how microbial interactions can drive ecological and biogeochemical dynamics in the marine environment.

促进生长或导致死亡的过程推动了所有生物体的丰富。对于诸如浮游植物之类的微生物来说，它们的寿命以小时到几天为单位，这些过程中的微小变化可能会产生重大影响。浮游植物是整个海洋环境物质和营养物质流动的中心货币。即使它们的生长和死亡率发生微小变化，也会对生态系统结构和生物地球化学循环产生大规模影响。虽然经常检查影响生长的因素，但对于浮游植物死亡率的调节却知之甚少。该项目将重点量化形成水华的球石藻（Emiliania huxleyi）的竞争死亡率模式，赫胥黎艾米利亚藻是一种全球重要的浮游植物物种，对海洋碳和硫循环做出了重大贡献。单细胞微型浮游动物的放牧造成的死亡是海洋环境中浮游植物损失的最大原因。然而，赫胥氏艾美耳球虫也与一种可导致大规模死亡的病毒有密切的关系。因此，E. huxleyi 是一个很好的模型生物，用于研究死亡率如何在微型浮游动物捕食者的放牧和病毒感染引起的裂解之间分配。量化这些死亡率机制将有助于为数学模型提供信息，以准确预测赫胥黎大肠杆菌种群动态的变化，并最终预测初级生产和生物地球化学循环。这项工作将涉及与学校系统中的一名高中科学教师合作，该学校系统中有很大一部分学生来自弱势群体，创作和实施描绘重要生态相互作用的短片剪辑。然后，这些电影剪辑将被纳入实验室活动中，向学生传达这些概念。此外，来自代表性不足群体的本科生将在伍兹霍尔海洋研究所和罗格斯大学接受培训，对浮游植物的死亡过程进行实验室研究。这项研究还将为博士后科学家提供培训和职业发展。浮游植物的死亡机制通常是相互独立的，但在自然界中，这些过程是同时发生的。微型浮游动物的放牧和病毒裂解对赫胥氏巨蜥总体损失的相对比例以及它们如何相互作用以塑造水华动态在很大程度上尚不清楚。了解这些过程的相对重要性及其相互作用至关重要，因为它们对海洋食物网和生物地球化学循环的结构和功能具有截然不同的影响。虽然放牧往往会将浮游植物生物量引导至更高的营养水平，但病毒裂解会刺激微生物循环活动和垂直颗粒输出通量。这项研究将确定一种死亡过程对另一种死亡过程的影响，以及它们对实验室和野外中生态实验中赫胥黎桉种群动态和出口的净影响。这种综合方法将为多营养微生物相互作用提供独特的机制视角，从而增加准确预测赫胥氏菌种群动态和生物地球化学循环的潜力。这项研究的结果有可能对微生物相互作用如何驱动海洋环境中的生态和生物地球化学动力学产生广泛适用的见解。