Watershed-scale Impacts on Microbial Indicators of Water Quality

Track 4A: Monitoring Water Quality
Friday, October 13, 2017, 10:00 am – 11:50 am

Catie Capplein, Meredith K. Steele, and Brian D. Badgley
Crop and Soil Environmental Services
Virginia Tech

Fecal indicator bacteria (FIB) are regularly used to assess surface water quality but effects of multiple non-point pressures from urbanization on microbial contaminants are not well understood. Our objective was to compare variation in surface water chemistry with general and human-specific microbial fecal indicators in watersheds of varying land use. We took weekly water samples for one year from nine sub-watersheds around Blacksburg, VA and quantified FIB, a genetic marker for human fecal contamination, along with physical and chemical indicators of water quality. In general, concentrations of FIB and the human marker differed markedly across space and time. For example, high FIB were associated with multiple land use types but the human marker was most elevated in urbanized watersheds. The two indicators also differed seasonally, suggesting response to different hydrologic processes. In addition, neither indicator correlated strongly with factors that affect microbial survival, such as nutrients or metals. Instead, each correlated most strongly with different cations, suggesting that salt species may play an important role in persistence and detection of microbial indicators.