Collaborative Research: Microbial Dynamics on Marine Snow Particles

海洋雪通量将碳封存到深海，显著地缓冲了温室效应。为了应对持续的全球变暖，人们提出了大规模海洋施肥，以此来增加海洋雪通量和消除大气中额外的二氧化碳。海洋雪粒含有高密度的细菌和其他微生物，它们的活动改变了雪粒的物理和化学特征。了解这些过程对于预测海洋雪通量的命运至关重要。该项目旨在采用实验、观察和建模相结合的创新方法，从机理上理解海洋雪粒上的微生物动力学。该项目是1)表征海洋雪粒上随时间变化的微生物动力学，2)研究不同的生物和非生物因素是如何改变这种动力学的，以及3)发展数学模型来定量描述这种动力学。实验室产生的硅藻聚集体正被用来测试预测细菌在海洋雪中定居的速度的相遇模型。琼脂聚集体被用来检测细菌对海洋雪化学物质的化学传感反应，以及细菌生理状态对定植过程的影响。通过与食菌原生动物的放牧实验，研究了雪粒上的捕食者-猎物动力学。实地研究正在跟踪藻类大量繁殖过程中天然海洋雪和相关微生物的细菌定植行为、大小和形态的变化。正在利用实验室和实地观察来测试和扩展定殖化模型，以便根据水动力学、微生物行为、生长和种间相互作用来描述海洋雪上的微生物动力学。这些模型正在与混凝模型相结合，以研究海洋雪的形成与微生物动力学如何影响海洋雪和水柱中的碳通量。该项目正在扩展VIMS、TAMU和三个杰出的欧洲研究机构之间的现有合作。研究生研究、培训和教育是该项目的组成部分。为了促进种族多样性和海洋科学领域的领导力培训，正在通过一个新的实习计划招募少数族裔本科生参加该项目，并获得实践研究经验。私人投资机构正在为公众编写教育材料，重点是全球变暖、海洋-气候相互作用和海洋肥力。这些材料正由梦想实习生在其针对小学学生和教师的外展活动中实施，使他们能够在气候问题上确立自己作为未来领导者的地位。

Marine snow fluxes sequester carbon to the deep ocean, significantly buffering the greenhouse effect. In response to continuing global warming, large-scale ocean fertilization has been proposed as a way to enhance marine snow fluxes and remove extra atmospheric CO2. Marine snow particles harbor high densities of bacteria and other microbes, whose activities modify the physical and chemical characteristics of the particles. Understanding these processes is critical to predicting the fate of marine snow fluxes in the ocean. This project is aimed at a mechanistic understanding of the microbial dynamics on marine snow particles, using an innovative approach of combining experiments, observations and modeling. This project is 1) characterizing the time-dependent microbial dynamics on marine snow particles, 2) investigating how different biotic and abiotic factors modify the dynamics, and 3) developing mathematical models to quantitatively describe such dynamics. Lab-generated diatom aggregates are being used to test encounter models for predicting the rate at which bacteria colonize marine snow. Agar-aggregates are being used to examine bacterial chemosensory response to marine snow chemicals, and the effects of the bacterial physiological status on the colonization process. Predator-prey dynamics on snow particles are being investigated by grazing experiments with bacterivorous protists. Field studies are following the changes in bacterial colonization behavior, size and morphology of natural marine snow and the associated microbes during the course of an algal bloom. Laboratory and field observations are being used to test and expand colonization models in order to describe microbial dynamics on marine snow based on hydrodynamics, microbial behavior, growth and interspecific interactions. These models are being integrated with coagulation models to study how marine snow formation coupled with microbial dynamics affects marine snow and carbon fluxes in the water column. This project is extending the existing collaborations between VIMS, TAMU and three outstanding European research institutions. Graduate research training and education are integral parts of the project. To promote ethnic diversity and leadership training in marine sciences, minority undergraduates are being recruited through a new internship program DREAMS to participate in the project and gains hands-on research experience. The PIs are developing education materials for the general public with focus on global warming, ocean-climate interactions and ocean fertilization. These materials are being implemented by DREAMS interns in their outreach activities that target grade school students and teachers, allowing them to establish themselves as future leaders in climate issues.