2016 Salt Lake County Watershed Symposium

Do Microbes of the Jordan River, Utah, Yo-Yo Diet?
The Jordan River, a 58-mile, 4th order urban river traversing the Salt Lake Valley from Utah Lake to the Great Salt Lake, suffers from low dissolved oxygen, periods of high water temperature, and loading of organic matter and nutrients. Elevated temperature and abundant energy and nutrients stimulate microbial respiration, which consumes oxygen. We are studying microbial community response to potential variation in temperature and the supply of energy and nutrients at twelve locations along the river in order to better understand whether different management actions are appropriate at certain locations or timepoints. Variation in temperature and resource supply may occur as a result of discharge from from point sources (i.e., water reclamation facilities and tributaries) and seasonal change in hydrology or autotroph production. We are measuring water chemistry and quantifying elemental content ratios, stable isotope signatures, and fluorometry of organic matter from the water column and sediments to infer the source of organic matter and its quality. We also are assessing rates of microbial ecoenzyme expression associated with the acquisition of nutrients or carbon to infer whether microbial communities exhibit maximum rates of activity or if they are limited by energy or nutrients. We present preliminary study results summarized after two of our three sampling campaigns, planned for spring, mid-summer, and late fall of 2016. Our sampling efforts occurred before (late May) and during (early August) the harmful algal bloom (HAB) that afflicted the Jordan River this year.