Effects of Environmental Change on Microbial Self-organized Patterns in Antarctic Lakes

全球生态系统受到人为气候变化的威胁。湖泊被广泛认为是气候变化的哨兵，其中，极地湖泊是最敏感的。在几米深的永久冰和液态水下面，许多南极湖泊包含着复杂的微生物群落，这些微生物群落已经被气候变化所改变。这些微生物创造的结构复杂的空间模式提供了机会来追求空间生态学的研究问题，这些问题在其他地方无法解决。该项目的重点研究将促进对南极湖泊底栖生物群落空间结构的理解，它们与环境条件的关系，以及对未来可能变化的预测。该项目还将推进将现代微生物群落的形态和空间格局与其生物物理和生化环境相结合的方法。正在开发的定量框架有可能完善对微生物群落模式控制的理解，从而解释气候变化和地质记录中古代化石微生物群落的影响。这样的理解将解决有关地球进化和环境历史及未来的关键问题。南极麦克默多干谷的万达湖的湖底覆盖着现代微生物的尖峰。利用现有的万达湖37个地点底栖生物群落空间结构数据集，项目团队将运用空间生态学的最新理论，研究底栖微生物形成尖峰的空间格局的机制。该研究解决了两个问题：(1)尖峰的形态和空间模式是什么？它们在不同的发育阶段、沿环境梯度和2013年至2023年之间是如何变化的？(2)单个尖峰的几何形状及其空间分布的形成机制是什么？万达湖为解决这些问题提供了绝佳的机会。它在沉积、营养、辐照度、运输机制和殖民历史等方面具有很好的梯度特征。不同位置的底栖生物群落经历不同的环境，表现出不同的空间格局。在过去的几十年里，湖泊水位增加了10米，通过比较相对较新淹没的基质（1至15岁的尖峰）和较深、发育良好的垫层（70岁），为模式发展的“自然实验”创造了额外的机会。由于微生物群落对环境变化的响应非常迅速，分析可以描述间隔9年（2013年12月和2023年1月）的顶峰空间数据的变化模式，为直接评估空间自组织生态系统对环境变化的响应提供了机会。因此，万达湖是一个天然的实验室，可以让研究(1)有效地梳理影响居住在那里的底栖微生物群落的模式形成机制；(2)验证空间自组织理论：模式形成和扰动响应机制，适用于全球生态系统。研究问题将通过整合现有的数据集、空间模式分析、贝叶斯统计模型和基于过程的数值模型来解决。该奖项反映了美国国家科学基金会的法定使命，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。

Ecosystems worldwide are threatened by anthropogenic changes in climate. Lakes are widely regarded as sentinels of climate change and, among these, polar lakes are the most sensitive. Beneath meters of permanent ice and liquid water, many Antarctic lakes contain complex microbial communities that are already being transformed by climate change. The structurally complex spatial patterns that these microbes create provide the opportunity to pursue research questions about spatial ecology that cannot be addressed elsewhere. This project focuses on research that will advance understanding of the spatial structure of benthic communities in Antarctic lakes, their relationships with environmental conditions, and predictions for likely changes in the future. This project will also advance methods in integrating the morphology and spatial patterning of modern microbial communities in relationship to their biophysical and biochemical environments. The quantitative framework being developed has potential to refine understanding of controls on microbial community patterning and thus interpretation of both the effects of climate change and ancient fossil microbial communities in the geologic record. Such understanding will address key questions about Earth’s evolutionary and environmental history and future.Lake Vanda in the McMurdo Dry Valleys, Antarctic, has modern microbial pinnacles covering its lake floor. Using existing datasets on spatial structure of benthic communities from 37 sites on the floor of Lake Vanda, the project team will apply recent theories from Spatial Ecology to investigate the mechanisms that give rise to spatial patterns of pinnacles formed by benthic microbes. The work addresses two questions: (1) What are the morphological and spatial patterns of pinnacles and how do they vary over developmental stages, along environment gradients, and from 2013 to 2023? And (2) what mechanisms give rise to the geometry of individual pinnacles and their spatial distribution? Lake Vanda provides an exceptional opportunity to address these questions. It features well characterized gradients in sedimentation, nutrients, irradiance, transport mechanism, and colonization history. Benthic communities at different locations in the lake manifest distinct spatial patterns, as they experience distinct conditions. Lake level has increased 10 m in the past few decades, creating additional opportunities for a “natural experiment” on pattern development by comparing relatively newly flooded substrates (pinnacles of 1 to 15 years old) with deeper, well-developed mats ( 70 years old). Since microbial communities respond to environmental change rapidly, analyses can characterize changes in patterns in pinnacle spatial data collected 9 years apart (Dec 2013 and Jan 2023), providing the opportunity to directly assess responses of spatially self-organized ecosystems to environmental change. As such, Lake Vanda is a natural laboratory that allows research (1) to effectively sort out mechanisms of pattern formation affecting benthic microbial communities residing there; and (2) to test the theory of spatial self-organization: mechanisms of pattern formation and responses to perturbations, applicable to ecosystems worldwide. Research questions will be addressed by integrating existing datasets, spatial pattern analyses, Bayesian statistical models, and process-based numerical models.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.