Stanford University

ESS Ph.D. Defense:Molecular Ecology and Biogeochemical Activity of Nitrifying Archaea-Anna Rasmussen

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Faculty/Staff, Students, Alumni/Friends
Department of Earth System Science


San Francisco Bay (SFB) is a large and heavily nitrogen-polluted estuary on the west coast of the United States. SFB receives large inputs of nitrate and ammonia from agricultural runoff, urban runoff, and wastewater treatment plants (WWTPs). Although SFB is considered one of the best studied estuaries in the world due in part to a 50-year time series of water quality data, the ecology of bacterioplankton and archaeoplankton in SFB is grossly unexplored.  The community dynamics of nitrogen-cycling microorganisms, especially the bacteria and archaea responsible for nitrification (the oxidation of ammonia to nitrite and then nitrate), are particularly relevant in the ammonia-rich waters of SFB. Despite the critical role of pelagic nitrifiers in transforming ammonia within SFB waters, they have received little attention.  

In this dissertation, I explore the ecology of pelagic microorganisms in the water column using several time series of microbial data and further focus on the distribution and activity of nitrifying guilds.

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