Collaborative Research: From hot to cold in the dark - shifts in seafloor massive sulfide microbial communities as physical and geochemical conditions change after venting ceases

热液喷口沉积海底块状硫化物(Sm)，沿89,000公里的大洋中脊、海底火山和弧后盆地出现，这些盆地出现在海洋中的构造板块边界。活动的热液喷口硫化物烟囱是深海生物多样性和生产力的热点，也是潜在的金属资源。虽然大量的工作集中在了解与积极排泄短信相关的生物群落和地球化学的多样性，但一旦短信停止排泄，人们对与短信相关的生物群落知之甚少。此外，人们对从活动到非活动过渡期间发生的微生物和地球化学变化知之甚少，在此期间，烟囱内流体的微生物群落和地球化学发生了重要的演替。这个跨学科项目将创建和采样这一过渡期，方法是从东太平洋海平面9度的各个喷口收集多个活跃的短信样本，并允许它们在海底过渡到非活跃状态，模拟喷口的结束，同时允许不再知道喷口的确切时间，这在采样自然形成非活跃短信时是不可能的。微生物群落多样性和新陈代谢的分析将与对活性硫化物、过渡硫化物和非活性硫化物的大规模和精细地质测量并行进行。这种海底实验和分析方法将提供有关微生物群落、生物地球化学转化速率和地质条件如何随着SMS从炎热和活跃的喷口向寒冷和不活跃的转变而变化的知识。6-8年级的学生将通过研究邮轮“船到岸”的互动和交流，为教育工作者举办邮轮后研讨会，与通常在STEM领域代表性较低的学生合作，以及与德克萨斯州布赖恩的社区和经济发展项目-科学、工程、艺术和设计画廊(SEAD)的合作，参与该项目。热液喷口对深海的生物和化学在数量上是重要的，但目前的绝大多数知识集中在活跃的喷口沉积上。然而，在喷口停止后，硫化物可以在海底持续数万年，使它们成为全球范围内丰富的长寿微生物底物。近年来，对不活跃的短信息系统的研究发现，微生物群落与活跃沉积物上的微生物群落截然不同，表明微生物群落的演替，因此对深海生物多样性和生物地球化学的影响可能不同于活跃的喷发沉积物。然而，不活动构造的年龄通常是未知的，因此不可能估计这些变化发生的速度，以及硫化物矿物学和微生物群落共同发生变化的速度。这个项目将提供第一次洞察在微生物和矿物学水平上发生的事情，当SMS最初从活跃转变为不活跃时。将对活性短信进行采样和微生物群落组成、功能容量、基因表达和代谢率的分析。将分析位于同一位置的子样品的孔隙度以及大块和精细的矿物学。这些活跃的短信样本的亚样本将留在海底孵化，并在几周后、一年或更长时间后收集，收集时进行相同的分析。这将允许确定在初始过渡期间发生的微生物和矿物学变化，并与来自相同喷口的较早的不活跃的短消息系统进行比较。收集到的数据将综合在一起，以产生一个概念模型，描述喷口矿床从活动到不活动的生物、矿物学、孔隙度和孔隙分布的演替。该项目将填补关于热液生态系统的知识空白，并有可能改变目前对这些重要海底生物多样性和变化率的理解。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。

Hydrothermal vents, which deposit seafloor massive sulfides (SMS), occur along the 89,000 km of mid-ocean ridges, submarine volcanoes, and backarc basins that occur at tectonic plate boundaries in the ocean. Active hydrothermal vent sulfide chimneys are hotspots of biodiversity and productivity in the deep ocean, as well as potential resources for metals. While significant effort has focused on understanding the diversity of biological communities and geochemistry associated with actively venting SMS, relatively little is known about the biological communities associated with SMS once venting ceases. Furthermore, little is known about the microbiological and geochemical changes that occur during the transition period from active to inactive, during which an important succession occurs in the microbial community and geochemistry of fluids within the chimney. This interdisciplinary project will create and sample this transition period by collecting multiple active SMS samples from individual vents at 9 degrees N East Pacific Rise and allowing them to transition to inactive on the seafloor, mimicking the end of venting while allowing for the exact time when venting ceased to be known, something not possible when sampling naturally formed inactive SMS. Microbial community diversity and metabolism will be analyzed in parallel with bulk and fine-scale geological measurements for active, transitioning, and inactive sulfides. This seafloor experimental and analytical approach will provide knowledge of how microbial communities, rates of biogeochemical transformations, and geological conditions change as SMS transition from hot and actively venting to cold and inactive. Students in grades 6-8 will be entrained into the project through research cruise "ship-to-shore" interactions and communications, post-cruise workshops for educators working with students typically underrepresented in STEM fields, and a collaboration with the Science, Engineering, Art and Design Gallery (SEAD), a community and economic development project in Bryan, TX. Hydrothermal vents are quantitatively important to the biology and chemistry of the deep ocean, but the vast majority of current knowledge focuses on actively venting deposits. However, after venting ceases, sulfides can persist on the seafloor for tens of thousands of years, making them long-lived, globally-abundant microbial substrates. In recent years, studies of inactive SMS found drastically different microbial communities than those on active deposits, indicating a succession of the microbial community, and thus a potentially different impact on deep ocean biodiversity and biogeochemistry than actively venting deposits. However, ages of the inactive structures are often not known, so it is impossible to estimate how quickly these changes occur, and how quickly co-occurring changes in sulfide mineralogy and microbiological communities occur. This project will provide the first insight into what happens at the microbial and mineralogical level as SMS initially transition from active to inactive. Active SMS will be sampled and analyzed for microbial community composition, functional capacity, gene expression and metabolic rates. Co-located subsamples will be analyzed for porosity and bulk and fine-scale mineralogy. Subsamples of those active SMS samples will be left on the seafloor to incubate and be collected weeks and a year or more later, with the same analyses conducted upon collection. This will allow for determination of microbiological and mineralogical changes that occur during that initial transition and for comparison with older inactive SMS from the same vent fields. Together, the data collected will be integrated to generate a conceptual model of succession of biology, mineralogy, porosity and pore distribution as vent deposits transition from active to inactive. This project will fill a knowledge gap about hydrothermal ecosystems and has the potential to transform the current understanding of diversity and rates of change in these important seafloor biomes.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.