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

微生物观测站的重点是在莫诺湖发现的微生物，莫诺湖是一个碱性、高盐度、目前为半混合型（较轻、含盐量较低的水常年覆盖在较重、含盐量较高的水之上）的湖，位于加州的内华达州山脉以东。莫诺湖是微生物观测站的理想地点有很多原因。这是一个明确的，生态简单，微生物占主导地位的生态系统，长期的生态和湖沼学数据存在。莫诺湖是一个水文简单的系统，这使得建模易于处理，但它包含复杂的梯度的化学和物理变量作为meromixis的结果。该湖靠近一个主要的野外观测站（由圣巴巴拉的加州大学管理的Sierra内华达州水产研究实验室）。目前正在对湖泊的物理学、浮游生物生态学和生物地球化学进行研究，为微生物研究提供一个全面的框架。莫诺湖目前正在经历一个人类引起的（因此是可预测的）湖沼过渡，赋予一个可预测的时间轨迹的物理，地球化学和生态过程。这种变化反映了过去，大盆地湖泊的自然事件造成的气候振荡和类似的，如果不那么极端，在物理湖沼学的变化可能会在其他湖泊。 莫诺湖代表了一个极端的环境，很可能窝藏独特的微生物。然而，对莫诺湖微生物的类型、系统发育多样性、分类学、生态学或生理生态学知之甚少。例如，最近对一种重要浮游植物的系统发育分析表明，它是一类新的藻类，具有不寻常的生理特性和生化组成。虽然丰富的细菌种群和明显的细菌板的存在已经注意到之前在莫诺湖，细菌群落的多样性的时间和空间变化，直到最近才开始调查。本研究的主要目标是研究莫诺湖微生物的分布，并了解微生物组合的响应与流体动力学驱动的时间变化的物理和化学变量的梯度。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)确定莫诺湖微生物组合的空间和时间变化，特别是在参考不断发展的meromixis。3)确定微生物群落对物理过程的反应，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/化学结构和微生物组合之间的相互作用的机械理解，作为微生物过程，湖泊生态化学和初级生产之间关系的预测（长期）建模的基础。该项目提供了一个独特的机会，以确定新的微生物和定义微生物之间的相互作用，在复杂的梯度的物理/化学条件下，通常只遇到在沉积物-水界面。这是一个合作项目，涉及格鲁吉亚大学的James Hollibaugh博士和Samantha Joye博士，奖项#9977886，加州大学圣巴巴拉分校的Robert Jellison博士（#9977901）和圣克鲁斯的加州大学的Jonathan Zehr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).