2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

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5/21/2019 | 9:45 AM - 10:00 AM | MICROBIAL COMMUNITY RESPONSE TO SHIFTING WATER QUALITY AND QUANTITY IN AN ARID URBAN ECOSYSTEM | 251 AB

MICROBIAL COMMUNITY RESPONSE TO SHIFTING WATER QUALITY AND QUANTITY IN AN ARID URBAN ECOSYSTEM

Hydrologic complexity in urban rivers presents challenges for mitigating impairments on water quality. We conducted synoptic surveys at 18 sites over three seasons in one year within an episodically hypoxic urban river. We quantified the relative contribution of ‘natural’ (lake, groundwater, tributary) and ‘urban’ (effluent, canals) sources of water to the river using a Bayesian mixing model analysis of water isotopes (18O and 2H) combined with a hydrologic mass balance model. Major contributors to streamflow varied both spatially and seasonally. Patterns of dissolved oxygen, nutrient (NO3-N, PO4-P) concentrations, and microbial ecoenzyme expression associated with carbon (C), nitrogen (N), and phosphorus (P) acquisition reflected shifts in dominant water sources. Ratios of dissolved organic and inorganic C, N, and P in the water column indicated C and P co-limitation, based on thresholds required to sustain microbial biomass. Paradoxically, ecoenzyme activity rate ratios indicated microbial communities were N limited, despite high N loads. These results suggest planktonic microbes are reliant on particulate substrates rich in N, such as protein and chitin found in algae and effluent-derived organic matter. Actions to reduce algal production combined with tertiary treatment of effluent might thus alleviate hypoxia.

Biogeochemistry
Connectivity
Hydrology

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Presenters/Authors

Jennifer Follstad Shah (), University of Utah, jennifer.shah@envst.utah.edu;