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

促进生长或导致死亡的过程驱动着所有生物的丰度。对于浮游植物这样的微生物来说，它们的生命周期是几小时到几天，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中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。虽然影响生长的因素经常被检查，但对浮游植物死亡率的调节知之甚少。该项目将侧重于量化水华形成颗石藻Emiliania huxleyi的竞争性死亡模式，Emiliania huxleyi是一种全球重要的浮游植物物种，对海洋碳和硫循环有重大贡献。单细胞微型浮游动物的摄食造成的死亡是海洋环境中浮游植物损失的最大原因。而E. huxleyi还与一种可导致大规模死亡的病毒有明确的关系。因此，E. huxleyi作为一个很好的模式生物，用于研究死亡率如何在微型浮游动物捕食者的摄食和病毒感染引起的溶解之间分配。量化这些死亡机制将有助于为精确预测E。huxleyi种群动态，并最终，初级生产力和地球化学循环。这项工作将涉及与学校系统中的一名高中科学教师合作，其中大部分学生来自代表性不足的群体，创作和执行描述重要生态相互作用的短片。这些电影片段将被纳入实验室活动，以传达这些概念给学生。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，以进行浮游植物死亡过程的实验室研究。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研究的，但在自然界中，这些过程同时起作用。微型浮游动物摄食和病毒裂解对总E.赫胥黎损失以及它们如何相互作用以形成水华动态在很大程度上是未知的。了解这些过程的相对重要性以及它们之间的相互作用至关重要，因为它们对海洋食物网和海洋地球化学循环的结构和功能产生了截然不同的影响。虽然放牧倾向于引导浮游植物生物量到更高的营养水平，病毒裂解刺激微生物循环活动和垂直颗粒输出通量。这项研究将确定一个死亡过程对另一个死亡过程的影响，以及它们对E。huxleyi种群动态和输出在实验室和现场围隔实验。这种综合的方法将提供一个独特的多营养微生物相互作用的机制的角度来看，从而增加了准确预测的可能性。huxleyi种群动态和地球化学循环。这项研究的结果有可能产生广泛适用的见解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。

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.