Fecal
contamination impairs many streams and rivers in the United
States. In Alabama, close to one third of the impaired water
bodies on the Section 303(d) list cite pathogens as one of
the causes of impairment. A 23-mile segment of Catoma Creek
in Montgomery County has been included on the state Section
303(d) List due to elevated numbers of fecal coliform bacteria
and organic enrichment. Detection of fecal indicator bacteria
such as fecal coliforms or Escherichia coli suggests the
presence of potential human pathogens that may pose health
risks to humans and threaten the integrity of ecosystems.
Fecal contamination in a watershed usually comes from multiple
sources, which cannot be readily determined. In this study,
we used a library-dependent and nucleic acid-based technique
to determine the sources of fecal contamination in the Catoma
Creek watershed. We constructed a rep-PCR DNA fingerprint
library using E. coli isolates obtained from nine host sources,
i.e., human, cattle, dog, horse, chicken, wild turkey, waterfowl,
beaver and deer, in the Catoma Creek watershed. DNA fingerprints
from E. coli isolated from stream water were compared with
those in the known source library. The results indicate that
human, domestic animals, and wildlife all contributed to
the fecal contamination in the Catoma Creek watershed. Identification
of fecal contamination sources is essential for the development
of effective pollution control strategies and ensures that
pollution control efforts are directed at the correct sources.
Bacterial source tracking has the potential to become a critical
component of the TMDL process and enhance watershed management. |
