Microbial
Source Tracking in Two Southern Maine Watersheds
Project
Abstract
The
intent of the project, Microbial Source Tracking in Two Southern Maine
Watersheds is to further explore the use of microbial tracking to more closely
identify the bacteria found in pollution source samples, and attempt to
validate a tool that has been developed for differentiating the sources of
fecal pollution in coastal ecosystems. Specifically, isolates of Escherichia
coli will be selected from fecal coliform positive samples and analyzed using
microbial tracking (ribotyping) techniques. The primary goal is to provide
resource managers in two southern Maine coastal watersheds (Webhannet and
Little Rivers) with information as to the microbial source(s) of fecal coliform
bacteria contamination in their region. This goal will be achieved through the
design and implementation of water sampling, lab analysis and watershed
surveying programs using prior data to specifically tailor experimental
methods. Environmental samples of watershed-specific fecal material from
targeted mammalian species will also be collected to develop a local reference
library. We shall then employ innovative methods to track sources of microbial
contamination (ribotyping) in selected water samples from each of the
watersheds. In this process, isolate DNA is extracted and cut by restriction
enzymes, separated by gel electrophoresis and then probed for detection of
highly conserved rRNA genes. The resulting 'fingerprint' for each unknown
isolate is compared to library fingerprints to determine likeness and for
identifying sources of fecal contaminants in environmental waters. As one of
the initial watershed studies applying the ribotyping method newly acquired by
Jackson Lab at UNH, this project also seeks to validate this lab method through
trials with environmental samples that may contain wild-type fecal coliform
bacteria from multiple animal sources. Once microbial source results are
available, we shall report (locally and at the state-level) results specific to
each watershed. A second goal is to educate community members living within the
Webhannet and Little River watersheds regarding the watershed-specific results
of this project by conducting community outreach efforts. The final goal is to
disseminate the project results to other watersheds in the Northeast region and
the US to share recommendations associated with the utilization of this method
and feasibility of mitigating pollution problems at the community level.
We
anticipate that a significant outcome of this project will be that coastal
decision makers in the Webhannet and Little River watersheds will possess the
research-based information that they require to guide action planning for
contaminant reduction. Reduction and/or elimination of contamination sources in
these two watersheds is likely to lower fecal coliform bacteria counts in
estuarine waters where commercially-valuable soft-shelled clams feed; possibly
resulting in the re-opening of clam harvesting areas that have been long
closed, thereby positively impacting the local economy. This project could also
have important economic and public health benefits in these particular
watersheds, which are home to several of the region’s most popular swimming
beaches. Contaminant reduction could result in improved swim beach water
quality, averting the possibility of beach closures that can impact the
public’s positive perception of that beach thereby reducing its appeal as a
tourist destination and decreasing the flow of tourist dollars to the region.
This project would also contribute to the development and validation of the
ribotyping method and its suitability for application to coastal/estuarine
management issues. Projects such as Microbial Source Tracking in Two Southern
Maine Watersheds are need to field test this method and explore its development
as a standard tool. Until such project validate the method, it will be unclear
exactly how useful it will be in addressing coastal/estuarine management
issues.