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

世界各地的生态系统都受到气候人为变化的威胁。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。在几米厚的永久冰层和液态水之下，许多南极湖泊包含复杂的微生物群落，这些群落已经因气候变化而发生变化。这些微生物创造的结构复杂的空间模式为研究空间生态学提供了机会，这些问题在其他地方是无法解决的。该项目的重点是促进对南极湖泊底栖生物群落的空间结构、它们与环境条件的关系以及对未来可能变化的预测的研究。该项目还将推进将现代微生物群落的形态和空间模式与其生物物理和生化环境的关系结合起来的方法。正在开发的量化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老的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和未来的关键问题。南极麦克默多干谷的万达湖湖底覆盖着现代微生物尖峰。利用来自万达湖底37个地点的现有海底群落空间结构数据集，项目组将应用空间生态学的最新理论来研究底栖微生物形成尖顶的空间模式的产生机制。这项工作解决了两个问题：(1)尖顶的形态和空间模式是什么，它们在发育阶段、环境梯度和2013-2023年之间是如何变化的？以及(2)是什么机制导致了各个尖峰的几何形状及其空间分布？万达湖为解决这些问题提供了一个难得的机会。它在沉积、营养物质、光照、传输机制和殖民史等方面具有很好的特征。湖中不同位置的底栖生物群落由于经历了不同的条件，表现出不同的空间格局。在过去的几十年里，湖面上升了10米，通过比较相对较新的淹没底板(1-15年的尖顶)和更深的、发育良好的垫子(70年)，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反应迅速，分析可以表征相隔9年(2013年12月和2023年1月)收集的顶峰空间数据的模式变化，从而提供了直接评估空间自组织生态系统对环境变化的响应的机会。因此，万达湖是一个天然实验室，它允许研究(1)有效地找出影响居住在那里的底栖微生物群落的格局形成机制；以及(2)测试空间自组织理论：适用于世界各地生态系统的格局形成机制和对扰动的反应。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NSF的法定使命，并通过使用基金会的智力优势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.