Date of this Version
Speicher, Allison, "AN INVESTIGATION INTO BACTERIAL CONTAMINATION IN AN URBAN NEBRASKA STREAM USING MICROBIAL SOURCE TRACKING" (2015). Civil Engineering M.S. Theses, Dissertations, and Student Research.
High levels of fecal bacteria in surface waters are a public health concern due to the enteric illnesses caused by primary contact with these waters. Shortcomings in the current fecal indicator bacteria (FIB) monitoring approach and the ubiquity of pathogen-impaired water bodies has led to the development of microbial source tracking (MST), a molecular tool that can identify potential fecal contamination sources. In this study we use a bacterial community based approach examining the V4 region of the 16S rRNA gene to elucidate sources of fecal bacteria in Antelope Creek, an urban creek in Lincoln Nebraska.
We hypothesized that sediment from the bed of Antelope Creek and animal wastes near the stream were major sources of the fecal bacteria in dry and wet weather water samples. To test the hypothesis, water from three dry weather events and three storm events was collected in addition to streambed sediment, sanitary sewage, and fecal waste from birds, dogs, small mammals, and horses. A UniFrac multi-variative principal coordinate analysis (PCoA) revealed differences in bacterial communities from sediment and water samples, indicating that sediment is not likely a major contributor of bacteria to dry and wet weather flows. PCoA analysis on the Bacteroidetes phylum revealed strong differences in community composition between water samples and fecal waste from horses, sanitary sewage, geese and dogs. The closest fecal community compositions were found for wastes from small mammals, pigeons, and ducks.
Statistical differences were seen in the overall bacterial community and the Bacteroidetes population by sampling date for both dry and wet weather water, while no statistical differences were seen by sampling location. This distinction suggests that environmental or source changes throughout the recreational season (e.g. temperature, sunlight, seasonal animal migration) were the major drivers of the shifts in the bacterial community in Antelope Creek. The absence of a location with consistently high E. coli counts suggests no major point source contribution.
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