Microbial Food Webs in Marine Sediments: Spatial Motives Link Bacterivory and Biogeochemistry

海洋沉积物中的微生物食物网：空间动机将细菌食性和生物地球化学联系起来

• 批准号: 9618135
• 负责人: Slava Epstein
• 金额: --
• 依托单位: Northeastern University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-03-01 至 2002-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9618135&HistoricalAwards=false
• 关键词: Microbial; Food; Webs; Marine; Sediments

*** 9618135 Epstein This project addresses trophic relations between sediment micrograzers and bacteria of particular biogeochemical importance. It is suggested that proto- and micrometazoan grazers balance production of sediment chemo- and photolithotrophs and thus become important players in the dynamics of reduced and oxidized forms of sulfur, nitrogen, and carbon, and possibly Mn and Fe. This idea is supported by the results of previously work, pilot data, and literature information. All these data suggest the following ideas. 1. Major sediment microbacterivores (flagellates, ciliates, nematodes, and others) are concentrated in a specific sediment layer, at and immediately below oxic/anoxic interface. 2. It is exactly in this sediment layer that most sulfide, ammonium, and methane oxidizing chemolithotrophs, as well as anaerobic photosynthesizers, are known to concentrate. 3. In this particular layer, which exhibits increased grazing pressure over bacteria, micrograzers appear to remove daily up to 50% of bacterial standing stock. Based on the above evidence, the following hypothesis is advanced. Proto- and micrometazoan grazing controls bacterial dynamics in a specific sediment layer at and immediately below the oxic/anoxic interface. The hypothesis will be tested by comparing the rates of bacterivory by sediment flagellates, ciliates, nematodes, and other micrograzers, with bacterial standing stock and bacterial production in the identified sediment layer. This will be done by a combination of classical, modern, and novel approaches. Seasonality will be examined by conducting the experiments in two different seasons, which were previously shown to contrast with each other in the microbial food web structure. At each seasonal time point, experiments will account for daily dynamics in grazing activity and vertical migrations of prospective bacterivores. Many key techniques to b e used here have been substantially improved, and supporting evidence collected, under prior NSF support. The model community (fine intertidal sands, Boston Harbor) has been under study for several years and is uniquely suited for the planned research. This work is one of the first to introduce spatial motives into studies of sediment microbial food webs. The target of this research are those functional types of bacteria that are particularly important in sediment biogeochemistry, nutrient recycling, and sediment-water exchange. The significance of studying mechanisms governing these bacteria dynamics goes therefore beyond its intrinsic value for detailing benthic microbial food web structure, and is important in a much larger ecological context. ***

*** 9618135 爱泼斯坦 本项目研究沉积物微型食草动物之间的营养关系 和具有特殊地球化学重要性的细菌。建议 原生动物和微型后生动物的食草动物平衡了沉积物的产生 化学营养菌和营养菌，从而成为 硫、氮和碳的还原和氧化形式的动力学， 以及可能的Mn和Fe。 这一想法得到了以下结果的支持： 以前的工作，试点数据和文献信息。所有这些数据 提出以下想法。 1.主要沉积物食微细菌动物 （鞭毛虫，纤毛虫，线虫等）集中在一个 在好氧/缺氧界面处及其正下方的特定沉积层。 2. 正是在这一沉积层中，大多数硫化物，铵， 和甲烷氧化化学无机营养生物，以及厌氧 光合作用，是众所周知的集中。 3.在这个特定 层，表现出对细菌的放牧压力增加， 微型食草动物似乎每天可以清除多达50%的细菌 车辆. 基于上述证据，以下假设是 先进 原生动物和微型后生动物的摄食控制细菌动力学 在好氧/缺氧层及其正下方的特定沉积层中， 接口. 将通过比较以下各项的噬菌率来检验该假设： 沉积物鞭毛虫、纤毛虫、线虫和其他微型食草动物， 细菌现存量和细菌产量 沉积层这将是一个古典的，现代的， 和新颖的方法。季节性将通过进行 在两个不同季节的实验，这是以前显示， 在微生物食物网结构中相互对比。在每个 季节性时间点，实验将占每日动态， 放牧活动和潜在食细菌动物的垂直迁移。 这里使用的许多关键技术都得到了大幅改进，B e， 并在NSF的支持下收集支持证据。模型 社区（细潮间带砂，波士顿港）一直在研究中 几年来，它非常适合计划中的研究。 这 工作是第一个引入空间动机的研究之一， 沉积微生物食物网。本研究的对象是那些 在沉积物中特别重要的功能型细菌 生物地球化学、营养物再循环和沉积物-水交换。的 研究这些细菌动力学的机制具有重要意义 因此超越了它的内在价值， 微生物食物网结构，在更大的 生态背景。 ***