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

微生物观测站专注于在Mono Lake中发现的微生物，Mono Lake是一个碱性、高盐度的湖泊，目前处于分相(较轻、较少的咸水覆盖着较重的、全年较多的咸水)湖，位于加利福尼亚州内华达山脉以东。莫诺湖是一个理想的微生物观测站，原因有很多。它是一个定义明确、生态简单、以微生物为主的生态系统，有长期的生态和湖沼学数据。莫诺湖是一个水文简单的系统，这使得建模变得容易，但由于分集作用，它包含了复杂的化学和物理变量梯度。该湖位于一个主要的野外站(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)附近。对该湖的物理、浮游生物生态和生物地球化学的研究正在进行中，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(因此也是可预测的)湖沼学转变，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振荡而发生的自然事件，其他湖泊可能会发生类似的物理湖泊学变化，如果不那么极端的话。莫诺湖代表着一种极端的环境，可能蕴藏着独特的微生物。然而，关于栖息在莫诺湖的微生物的类型、它们的系统发育多样性、分类学、生态学或生态生理学知之甚少。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。虽然在莫诺湖以前就注意到了丰富的细菌种群和明显的细菌板块的存在，但细菌群落多样性的时空变化直到最近才开始被研究。这项研究的主要目标是检查Mono Lake微生物的分布，并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)确定和描述独一无二的莫诺湖生态系统中的微生物组合。2)确定Mono Lake微生物组合的空间和时间变化，特别是参照进化的分体融合。3)确定微生物群落对物理过程的反应，特别是混合过程中的短期和小规模变化(例如，边界混合或局部重力循环导致的垂直扩散增强)。4)从机理上理解物理/化学结构和微生物组合之间的相互作用，以此为基础对微生物过程、湖泊生物地球化学和初级生产之间的关系进行预测性(长期)建模。该项目提供了一个独特的机会来确定新的微生物，并确定在通常只在沉积物-水界面遇到的复杂的物理/化学条件梯度中微生物之间的相互作用。这是一个合作项目，涉及佐治亚大学的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)；加州大学圣克鲁斯分校的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).