Patterns of Microbial Community Structure Within and Between Hadal Environments

海洋最深的部分存在于海沟中，海沟的陡峭墙壁从大约4英里向下延伸到深度，在某些情况下，深度接近海水表面以下7英里。在这些地点，地壳被回收利用。也许并不令人惊讶的是，考虑到深海海沟的偏远，它们是海洋中最不为人所知的栖息地。参与该项目的研究人员正在努力确定地球上存在的两个最深海沟中存在的微生物的特征，这两个海沟都位于太平洋，位于新西兰北部的克马迪克海沟，以及位于关岛以东和南部的马里亚纳海沟。马里亚纳海沟的大部分位于美国马里亚纳海沟海洋国家纪念碑内。人们对深海海沟中微生物的多样性和适应能力知之甚少。目前存在的微生物中有一部分是从上面的浅水中下来的，不太可能参与深海的任何营养循环。其他的适应于接近冰点的温度和高于每平方米10e7公斤(每平方英寸16,000磅)的压力。这些后一类微生物在回收有机物方面发挥着重要作用。但他们是谁呢？该项目正在帮助培训参与研究的不同本科生和研究生，在基于网络的课堂上学习栖息在极端环境中的微生物的更多本科生，以及参加在南极洲提供的高级培训课程的更多研究生和博士后科学家。正在进行的实验包括直接计数海水和沉积物中的原核生物和病毒，分析各种压力下可培养异养菌的丰度和系统发育宽度，测量海水和沉积物样品内和跨海水和沉积物样品以及两个海沟系统内和跨两个海沟系统的细菌群落物种多样性和丰富度，测量微生物活动随压力的变化，以及识别高压活性细胞。作为国家科学基金会资助的哈达尔生态系统研究项目的一部分，这些分析产生的数据正在纳入其他人进行的额外化学、地质和生物测量的结果。其中两个可行的假设是，原核生物的数量和多样性通常与表面生产力和海沟轴线附近的位置呈正相关，存在特定海沟特有的细菌分类群，存在于多个海沟，在深海环境中分布更广泛。

The deepest portion of the ocean is present in ocean trenches, whose steep walls descend from approximately 4 miles down to depths that in some cases are close to 7 miles below the seawater surface. At these locations Earth's crust is recycled. Perhaps not surprisingly given their remoteness, deep ocean trenches are the least understood habitats in the ocean. The researchers participating in this project are working to characterize the microbes present in two of the deepest trenches present on Earth, both in the Pacific Ocean, the Kermadec Trench located north of New Zealand, and the Mariana Trench, located east and south of the island of Guam. Most of the Mariana Trench is located within the United States Mariana Trench Marine National Monument. Relatively little is known about the diversity and adaptations of the microorganisms in deep ocean trenches. An unknown fraction of the microbes present have descended from shallow waters above and are unlikely to participate in any nutrient cycles in the deep sea. Others are adapted to near freezing temperatures and up to pressures greater than 10e7 kilograms per square meter (16,000 pounds per square inch). These latter microbes perform important roles recycling organic matter. But who are they? This project is contributing to the training of diverse undergraduate and graduate students participating in research, additional undergraduate students learning about microbes inhabiting extreme environments in a web-based class, and additional graduate students and postdoctoral scientists participating in an advanced training course being offered in Antarctica.Experiments being performed include direct counts of prokaryotes and viruses in seawater and sediments, analyses of the abundance and phylogenetic breadth of culturable heterotrophic bacteria at a range of pressures, measurements of bacterial community species diversity and richness both within and across seawater and sediment samples, as well as within and across the two trench systems, measurements of microbial activity as a function of pressure and the identification of high pressure-active cells. The data generated from these analyses are being integrated into the results of additional chemical, geological and biological measurements performed by others as a part of the National Science Foundation funded Hadal Ecosystems Studies Project. Two of the working hypotheses are that prokaryote numbers and diversity are generally positively correlated with surface productivity and proximity to the trench axis and that bacterial taxa exist which are endemic to specific trenches, present in multiple trenches and more widely distributed in deep-sea environments.