Collaborative Research: Quantifying the impact of oxylipin chemical signaling on microbial community dynamics and biogeochemical cycling

硅藻是真核浮游植物，负责全球约25%的光合作用。许多种类的硅藻在压力环境下产生称为氧脂素的化学信号，例如营养限制，放牧造成的伤害和病毒感染。这些化学信号对海洋中构成微生物食物网的许多生物有害，如其他真核浮游植物，微型浮游动物和以浮游植物为食的桡足类，以及自由生活的细菌。然而，与颗粒相关的细菌群落受到低剂量氧脂素的刺激，硅藻可以使用这些化学信号来相互交流即将到来的压力。由于这些微生物食物网在地球的碳循环中发挥着关键作用，这些生态系统最终支持渔业，因此了解硅藻水华在生产性上升流区域旋转和崩溃时化学信号的作用非常重要。在这里，研究人员提出了一个实地考察与一系列甲板孵化，以研究在加州当前生态系统的群落动态的氧化脂的影响。该团队还提出了一系列基于实验室的捕食者-猎物研究，通过用显微摄像记录行为来量化氧化脂对微型浮游动物食草动物的影响。主要的问题，将解决包括：1）如何浓度和多样性的氧脂素变化的过程中，一个盛开？2)氧脂素信号对群落动态的净影响是什么？3)氧脂素如何影响碳输出和养分循环（N、P、Si）？在该赠款的生命周期内开展的外联活动的主要目标是向年轻人介绍微生物海洋学，培训多样化的海洋学工作人员，并创建可以在该赠款的生命周期后查询的内容。为了实现这一目标，本科生和研究生科学家在该项目期间通过直接参与计划的巡航，在实验室和教室中通过虚拟直播巡航活动和亲自教学进行培训。其中一些学生是专门从增加代表性不足群体参与的项目中招募的。该项目还利用巡航数据设计数据分析教程和讲习班，以吸引更广泛的科学界参与。来自当地城市地区的初中和高中学生也在科德角周围沿海沃茨接受教育一日游培训。正在为8-12年级的教室编制与该项目工作有关的课程。这是第一项研究，以概况的完整多样性的氧化脂质产生的溶解，细胞，和碎屑（即，海洋雪）分数。这是第一项同时评估生态系统内氧脂素生产（营养胁迫，放牧和病毒感染）的原位驱动因素的研究。该项目也是第一个全面描述东部边界流内水华过程中氧脂素浓度和多样性的项目。该项目的最终目标是了解氧脂素介导的信号传导如何影响碳的命运，因此该团队将在整个实地活动中监测出口效率，净初级生产力，细菌生产力和营养循环。该项目增加了相对较少的元转录组数据集，这些数据集来自公共存储库中可用的下沉颗粒群落和海洋脂质组学数据集。拉格朗日研究产生的数据可用于询问有关表层和深海之间的连通性、群落演替以及水华的地球化学演化等更一般性的问题。最后，拟议的研究改变了我们对化学信号如何影响放牧行为和oxylipin放牧威慑机制的集体理解，同时评估放牧率，选择和行为的微型浮游动物在外源oxylipins的存在下，当提供高和低oxylipin生产的猎物。最先进的显微摄像技术可以可视化和量化微型浮游动物的摄食行为，该系统将适用于测量海上自然群落。 该项目由海洋科学部的生物和化学海洋学项目资助。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Diatoms are eukaryotic phytoplankton that are responsible for ~25% of photosynthesis globally. Many species of diatoms produce chemical signals called oxylipins under stressful circumstances such as nutrient limitation, wounding due to grazing, and viral infection. These chemical signals are detrimental to many organisms that make up microbial food webs in the ocean, like other eukaryotic phytoplankton, microzooplankton and copepods that graze on phytoplankton, and free-living bacteria. However, particle-associated bacterial communities are stimulated by low doses of oxylipins, and diatoms can use these chemical signals to communicate amongst themselves about impending stress. Because these microbial food webs play a critical role in the Earth’s carbon cycle and these ecosystems ultimately support fisheries, it is important to understand the role chemical signaling plays as diatom blooms spin up and crash in productive upwelling regions. Here the investigators propose a field expedition with a series of deck-board incubations to study the effects of oxylipins on community dynamics in the California Current Ecosystem. The team also proposes a series of laboratory-based predator-prey studies to quantify the effects of oxylipins on microzooplankton grazers by documenting behavior with microvideography. The major questions that will be addressed include: 1) how does the concentration and diversity of oxylipins change over the course of a bloom? 2) what is the net impact of oxylipin signaling on community dynamics? 3) how do oxylipins impact carbon export and nutrient recycling (N, P, Si)? Outreach activities undertaken during the lifetime of this grant have the primary goals of introducing young people to microbial oceanography, training a diverse oceanographic workforce, and creating content that can be accessed by inquiring minds after the lifetime of this grant. To accomplish this, undergraduate and graduate scientists are being trained during this project through direct participation on the planned cruise, in the lab, and in classrooms through virtual live-streaming cruise activities and in-person teaching. Some of these students are recruited specifically from programs that increase participation from underrepresented groups. This project also uses cruise data to design data-analysis tutorials and workshops in order to engage the broader science community. Middle and high school students from local urban areas are also being trained on educational day trips in the coastal waters around Cape Cod. A curriculum is being developed for grade 8-12 classrooms related to the work of this project. This is the first study to profile the full diversity of oxylipins produced across dissolved, cellular, and detrital (i.e., marine snow) fractions. It is the first study to simultaneously assess in situ drivers of oxylipin production (nutrient stress, grazing, and viral infection) within an ecosystem. The project is also be the first to fully characterize oxylipin concentrations and diversity over the course of a bloom within an Eastern Boundary Current. The ultimate goal of this project is to understand how oxylipin-mediated signaling impacts the fate of carbon, so the team will be monitoring export efficiency, net primary productivity, bacterial productivity, and nutrient recycling throughout the field campaign. This project adds to the relatively small number of metatranscriptomic datasets from sinking particle communities and marine lipidomic datasets available in public repositories. The data generated by the Lagrangian Study can be used to ask more general questions about connectivity between the surface and deep ocean, community succession, and the geochemical evolution of blooms. Finally, the proposed research transforms our collective understanding of how chemical signaling impacts grazing behavior and the mechanism of oxylipin grazing deterrence by simultaneously assessing grazing rates, selection, and behavior of microzooplankton in the presence of exogenous oxylipins and when offered high and low oxylipin-producing prey. State-of-the-art microvideography visualizes and quantifies microzooplankton grazing behaviors, and the system will be adapted for measurements of natural communities at sea. This project is funded by the Biological and Chemical Oceanography Programs in the Division of Ocean Sciences.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.