Collaborative Research: Microbial Observatory at an Alkaline, Hypersaline, Meromictic Lake (Mono Lake, California)

微生物观测站关注的是莫诺湖（Mono Lake）中发现的微生物。莫诺湖位于加州内华达山脉以东，是一个碱性高盐湖泊，目前是分生湖泊（全年较轻、含盐量较低的水覆盖在较重、含盐量较高的水上）。莫诺湖之所以是微生物观测站的理想地点，有很多原因。它是一个定义明确，生态简单，微生物主导的生态系统，长期的生态和湖泊数据存在。Mono湖是一个水文简单的系统，这使得建模易于处理，但由于混合作用，它包含复杂的化学和物理变量梯度。这个湖靠近一个主要的野外观测站（内华达山脉水生研究实验室，由加州大学圣巴巴拉分校管理）。目前正在进行的湖泊物理、浮游生物生态学和生物地球化学研究为微生物研究提供了一个全面的框架。莫诺湖目前正在经历人类引起的（因此是可预测的）湖泊过渡，这为物理、生物地球化学和生态过程提供了可预测的时间轨迹。这一变化反映了大盆地湖泊过去因气候波动而发生的自然事件，其他湖泊的自然湖沼学也可能发生类似的变化，如果不那么极端的话。莫诺湖的极端环境很可能孕育着独特的微生物。然而，对于居住在Mono湖的微生物类型、系统发育多样性、分类、生态学或生态生理学的了解相对较少。例如，最近对一种重要的浮游植物的系统发育分析表明，它是一类新的藻类，具有不同寻常的生理特性和生化成分。虽然Mono湖丰富的细菌种群和明显的细菌板的存在已经被注意到，但细菌群落多样性的时空变化直到最近才开始被研究。本研究的主要目的是研究Mono湖微生物的分布，了解微生物组合对水动力驱动的时间变化的物理和化学变量梯度的响应。该项目的具体目标是：1)识别和表征独特的莫诺湖生态系统中的微生物组合。2)确定Mono湖微生物组合的时空变化，特别是参考进化的混生。3)确定微生物群落对物理过程的响应，特别是混合的短期和小规模变化（例如，由于边界混合或局部重力环流而增强的垂直扩散）。4)提供物理/化学结构与微生物组合之间相互作用的机制理解，作为微生物过程，湖泊生物地球化学和初级生产之间关系的预测（长期）建模的基础。这个项目提供了一个独特的机会来识别新的微生物，并定义微生物之间的相互作用在复杂的物理/化学条件梯度通常只遇到在沉积物-水界面。这是一个合作项目，包括博士。乔治亚大学的詹姆斯·霍利博和萨曼莎·乔伊，获奖#9977886，加州大学圣巴巴拉分校的罗伯特·杰利森博士（#9977901）和加州大学圣克鲁兹分校的乔纳森·泽尔博士（#9977892）。

The Microbial Observatory focuses on the microbes found in Mono Lake, an alkaline, hypersaline, currently meromictic (lighter, less saline water overlies heavier, more saline water throughout the year) lake located east of the Sierra Nevada in California. There are a number of reasons why Mono Lake is an ideal site for a Microbial Observatory. It is a well-defined, ecologically simple, microbially dominated ecosystem for which long-term ecological and limnological data exist. Mono Lake is a hydrologically simple system, which makes modeling tractable, yet it contains complex gradients of chemical and physical variables as a result of meromixis. The lake is located close to a major field station (the Sierra Nevada Aquatic Research Laboratory, administered by the University of California, Santa Barbara). There are ongoing studies of the lake's physics, plankton ecology and biogeochemistry that provide a comprehensive framework for the microbial studies. Mono Lake is currently undergoing a human-induced (and thus predictable) limnological transition which imparts a predictable temporal trajectory to physical, biogeochemical and ecological processes. This change mirrors past, natural events in Great Basin lakes resulting from climate oscillations and similar, if less extreme, changes in physical limnology might be expected in other lakes. Mono Lake represents an extreme environment that is likely to harbor unique microbes. However, relatively little is known about the types of microorganisms dwelling in Mono Lake, their phylogenetic diversity, taxonomy, ecology or ecophysiology. For example, recent phylogenetic analysis of an important phytoplankton demonstrates it to be a new class of algae with unusual physiological properties and biochemical composition. While abundant bacterial populations and the existence of pronounced bacterial plates have been noted before in Mono Lake, the temporal and spatial variation in diversity of the bacterial community has only recently begun to be investigated. The primary goal of this research is to examine the distributions of Mono Lake microbes and to understand the response of microbial assemblages to the gradients of physical and chemical variables in relation to temporal changes driven by hydrodynamics. The specific objectives of the project are to: 1) Identify and characterize the microbial assemblages in the unique Mono Lake ecosystem. 2) Determine the spatial and temporal variation of the Mono Lake microbial assemblage, particularly in reference to evolving meromixis. 3) Determine the response of the microbial community to physical processes, especially short-term and small-scale variation in mixing (for example, enhanced vertical diffusion as a result of boundary mixing or localized gravitational circulation). 4) Provide a mechanistic understanding of the interactions between the physical/chemical structure and microbial assemblages as the basis for predictive (long-term) modeling of the relationship between microbial processes, lake biogeochemistryand primary production. This project provides a unique opportunity to identify novel microorganisms and define interactions among microorganisms in complex gradients of physical/chemical conditions usually only encountered at sediment-water interfaces. This is a collaborative project involving Drs. James Hollibaugh and Samantha Joye, University of Georgia, award #9977886, Dr. Robert Jellison, University of California, Santa Barbara (#9977901) and Dr. Jonathan Zehr, University of California, Santa Cruz (#9977892).