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Microbial Source Tracking in Two Southern Maine Watersheds
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Project Title: Microbial Source Tracking in Two Southern Maine Watersheds
Research Locations: Wells Reserve, ME
Last Update: 2-25-04
Microbial contaminants including viruses and bacteria enter coastal waters through wastewater, stormwater and agricultural runoff, posing risks to the environment and to human health. While traditional methods of measuring bacterial contamination, namely counting bacterial colonies, provide information about the amount of contamination in a water body, they do not offer clues about the source of the contaminant. Knowing the source of the bacteria - human, wildlife or domestic animal - is key to making the proper management decisions. This project is employing and evaluating a new microbial tracking technique called ribotyping to assess its utility for routine verification of contaminant sources.
DNA Fingerprinting - The Ribotyping Process
Different bacterial strains carry different genetic information. This fact allows scientists to distinguish, for example, human-specific bacterial strains from cow-specific strains, by looking at their DNA. When genetic material is run through the ribotyping process, it produces an
image such as the one in Figure 2, which shows the unique “fingerprint” of
the material and that of several known source species from a reference
database. This fingerprint is used to classify the bacteria - in this case Escherichia coli - and provides a basis for comparison of unknown contamination sources to known sources.
The Approach
Investigators sampled water in two Maine watersheds and collected fecal material found in each area. A selection of water samples that tested positive for bacterial contaminants, specifically E. coli, was then run through the ribotyping process. The resulting images were compared to regional and watershed-level libraries of bacterial fingerprints to find matches, and identify the sources.
Results
Results of this project showed that in both watersheds, people, pets and livestock account for approximately 40% of contamination (18%, 9% and 11% respectively in the Webhannet watershed, and 3%, 22% and 14% respectively in the Little River watershed). Wild animal sources were also found to be significant contributors, (32% in the Webhannet and 26% in the Little River). Researchers are continuing to develop the libraries of known sources in each area for future microbial source tracking research.
Outreach: A Fundamental Component of Prevention
Investigators are conducting extensive outreach work, teaching managers in the northeast and other areas how to integrate microbial source tracking/ribotyping techniques into their existing monitoring programs. Over the past year, project staff have given over 30 presentations to local, state, regional and national audiences.
Helping to Manage the Webhannet and Little River, ME Watersheds
Since the project's inception, a steering committee representing community, municipal, regional, state and federal interests has worked closely with researchers to guide the project in each watershed. Members of the committee helped to draft remediation strategies best suited to the needs and resources of the communities involved. To implement these strategies, steering committee members and researchers are cooperating with other state agencies, municipalities and state legislators to fill in data gaps, revise local ordinances and discuss future steps in contaminant prevention and control.
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Project Coordinator
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Kristen Whiting-Grant (207) 646-1555 x115 Univ. of Maine Cooperative Extension and Sea Grant kristen.whiting-grant@maine.edu |
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Start -End Date:
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09/01/2001 - 09/01/2004
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NERR Reserve(s):
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Wells Reserve, ME
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| For more information: |
Dolores Jalbert Leonard Phone: (603) 862-3685 Email: dolores.leonard@unh.edu |