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

点击翻译按钮获取中文摘要

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.