Dissertation Research: Microbial Responses to Variation in Dissolved Organic Carbon (DOC) Quality and Quantity in the Hyporheic Zone of Stream Ecosystems

9411844豪沃思在过去的十年中，河流生态系统研究的范围已经大大扩展到包括位于河床下方和邻近河床的饱和沉积物。最近的工作表明，在调节流代谢，改变流化学，并支持流食物网的潜流带的重要性。尽管潜流带包含多种微生物和无脊椎动物群落，但底栖细菌是潜流食物网的基础，并被认为控制着其大部分生态系统功能。底栖细菌的主要能量来源是溶解有机碳（DOC）。本论文的研究将确定DOC质量和数量的变化在多大程度上影响了河流潜流区的微生物群落。研究将解决溪流内部和溪流之间不同来源的DOC如何影响低渗区的细菌群落，这些来源被认为在DOC质量和数量上存在差异。将研究细菌丰度和生产力的变化，以响应DOC的变化，以及随后的水化学变化。这项研究还将确定是否hyporheic微生物作为一个碳汇或一个重要的环节，以更高的营养水平在流食物网。 这项研究的目标将导致更好地了解河流生态系统功能和微生物循环动力学。这项研究将提供一个很好的论坛，将生态系统水平的功能与以前知之甚少的微生物过程联系起来。

9411844 Howarth The dimensions of stream ecosystem studies have been greatly expanded within the last decade to include saturated sediments that lie beneath and adjacent to the streambed. Recent work indicates the hyporheic zone's importance in regulating stream metabolism, altering stream chemistry, and supporting stream food webs. Although the hyporheic zone contains diverse microbial and invertebrate communities, benthic bacteria are at the base of the hyporheic food web and thought to control much of its ecosystem function. The primary energy source for benthic bacteria is dissolved organic carbon (DOC). This dissertation research will determine the extent to which variation in DOC quality and quantity affects the microbial community in stream hyporheic zones. Research will address how DOC from contrasting sources within and among streams that are thought to vary in DOC quality and quantity affect the bacterial community in the hyporheic zone. Changes in bacterial abundance and productivity in response to changes in DOC, as well as subsequent changes in water chemistry will be studied. This research will also determine if hyporheic microbes serve as a carbon sink or an important link to higher trophic levels in stream food webs. %%% The objectives of this research will lead to a greater understanding of both stream ecosystem function and microbial loop dynamics. This study will provide an excellent forum to link ecosystem-level function with previously poorly understood microbial processes.