RUI: Collaborative Research: MIP : Lake Huron Sinkholes - Microbial Composition and Processes in Biogeochemical Hotspots

微生物在决定我们生活质量的生态系统过程中起着至关重要的作用。尽管它们对人类健康和福祉很重要，但微生物种类及其在地下环境中的活动在很大程度上是未知的。这个为期两年的项目将描述居住在休伦湖桑德湾国家海洋保护区（NMS）新发现的地下水供应湖底生态系统（淹没天坑）中的微生物群落。由于水化学差异造成的陡峭环境梯度，天坑生境具有微生物量大、生物活性强的特点。这些淹没的天坑似乎是生物地球化学的“热点”，淡水类似于海洋喷口生态系统，为发现新的微生物和群落过程提供了机会。为了更好地理解群落的功能，我们将沿着深度梯度对三个天坑群落的地下水排放产生的物理和化学环境进行表征；浅层（悲惨湾天坑5米）、中层（中岛天坑18米）及深层（孤立天坑93米）。微生物群落将使用针对不同标记的分子技术进行表征。首先，膜脂分析将与稳定碳同位素融入单个脂肪酸的测量相结合，以提供群落组成和活性的综合视图。其次，遗传多样性概况和DNA序列数据将提供高分辨率的群落组成视图。第三，荧光显微镜和放射性同位素示踪剂将用于直接评估微生物丰度和生长速度。综合起来，这些分析将为劳伦森五大湖淹没的天坑生态系统中的微生物生命和过程提供第一张详细的图片。这项研究开创了一条新的研究路线，将五大湖的土地和水资源联系起来。它还描述了新的生物和独特的栖息地，招募和培训代表性不足的学生，在两所主要的本科院校（大峡谷州立大学和威斯康星大学斯托特分校）的大学研究人员之间建立了强有力的合作，将研究和教育整合到这两所院校的课程中，与现有的外展项目合作培训K-12教育工作者，并通过将新创建的休伦湖天坑网站与NOAA大湖环境研究实验室和NSF北温带湖泊微生物观测站的现有数据网络连接起来，建立数据共享基础设施。我们的发现将为继续保护桑德湾国家海洋保护区提供额外的理由，这是唯一一个位于淡水生态系统中的国家海洋保护区。最终，这些研究将提供对生物圈中微生物生命的更好理解，这是确保经济和环境可持续未来的关键一步。

Microorganisms play vital roles in the ecosystem processes that determine our quality of life. Despite their importance to human health and welfare, the microbial species and their activities in subsurface environments are largely unknown. This 2-year project will describe the microbial communities inhabiting newly discovered groundwater-supplied lake floor ecosystems (submerged sinkholes) in the Thunder Bay National Marine Sanctuary (NMS), Lake Huron. Due to the steep environmental gradients created by differences in water chemistry, sinkhole habitats are characterized by high microbial biomass and intense biological activity. These submerged sinkholes appear to be biogeochemical "hot spots" freshwater analogs to marine vent ecosystems that offer opportunities for discovering novel microorganisms and community processes. To better understand community function, the physical and chemical environments created by groundwater discharge into the lake floor will be characterized for three sinkhole communities located along a depth gradient; shallow (Misery Bay Sinkholes at 5 m), intermediate (Middle Island Sinkhole at 18 m) and deep (Isolated Sinkhole at 93 m). Microbial communities will be characterized using molecular techniques that target different markers. First, membrane lipid profiling will be combined with measurements of stable carbon isotope incorporation into individual fatty acids to provide an integrated view of community composition and activity. Second, genetic diversity profiles and DNA sequence data will provide a high-resolution view of community composition. Third, fluorescence microscopy and radioisotopic tracers will be used to directly assess microbial abundance and growth rates. Combined, these analyses will provide the first detailed picture of microbial life and processes in the submerged sinkhole ecosystems of the Laurentian Great Lakes.This study initiates a new line of research linking land and water resources in the Great Lakes. It also describes novel organisms and unique habitats, recruits and trains underrepresented students, forges a strong collaboration between university researchers at two predominantly undergraduate institutions (Grand Valley StateUniversity and University of Wisconsin-Stout), integrates research and education into the curriculum at both institutions, trains K-12 educators in partnership with existing outreach programs, and builds data sharing infrastructure by linking a newly created Lake Huron sinkholes website to existing data networks at NOAA's Great Lakes Environmental Research Laboratory and NSF's North Temperate Lakes Microbial Observatory. Our findings will provide additional rationale for the continued protection of Thunder Bay National Marine Sanctuary, the only NMS located in a freshwater ecosystem. Ultimately, these studies will provide a better understanding of microbial life in the biosphere, a critical step in ensuring an economically and environmentally sustainable future.