Graduate Thesis Or Dissertation

Source identification of fecal pollution in the Tillamook watershed : antibiotic discriminant analysis

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  • The identification of sources of point and nonpoint fecal pollution is difficult to determine. Understanding the sources of fecal organisms in quality limited waters could greatly enhance our ability to restore and protect the water quality and habitat of these systems. Antibiotic resistance patterns of fecal streptococci bacteria were analyzed using discriminant analysis and these were in turn used to identify sources of fecal pollution in the Tillamook Bay watershed, Oregon. Antibiotic resistance patterns for humans, dairy cattle, and wild animals were established using a database of 830 isolates collected from known sources of feces in the Tillamook watershed. The average rate of correct classification (ARCC) for these three sources was determined to be 83%, with individual rates of 73% for human isolates, 88% for wild isolates, and 89% for dairy isolates. To test the application of this technique, water samples were collected for two independent studies. Samples were collected from a winter rainstorm event, as well as 9 samples over one year at the mouth of the five major rivers flowing into the Tillamook Bay. Results clearly demonstrate that monitoring bacterial sources is complex with results varying on a sample-by-sample, site-bysite, and river-by-river basis. Dairy and human sources contributed a majority of the fecal bacteria in all samples collected while wild sources consistently contribute a small percentage. Fecal coliform bacteria (FCB) and fecal streptococci bacteria (FSB) concentrations were also used in conjunction with source distributions to estimate the magnitude of individual samples and prioritize samples based on their water quality significance. These results demonstrate that antibiotic resistance profiles in fecal streptococci can determine sources of fecal pollution.
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