LE3 .A278 2005

2005

Bell, Colin

Acadia University

Bachelor of Science

Honours

Biology

Biology

The study of the survival of Escherichia coli in marine water and sediment is important as E.coli is commonly used as an indicator of fecal contamination which can pose a major public health threat. If E.coli is able to persist or even grow in an aquatic system then it would not be an accurate measure of fecal pollution. In this study a microcosm system was used to investigate the survival of E.coli in marine sediment and water over a two week period. The effects of several different variables on E.coli survival in this system were tested over 11 trials. These variables included using four different strains of E.coli, three different salinity levels, and two different water cycling designs. A general successional pattern of E.coli in the microcosm system was determined to consist of E.coli disappearing from the water at high tide much faster than it did from the sediment. By comparing the four different strains of E.coli it was determined that the aquatic E.coli fared better in the marine environment than the animal isolate. When observing the effects of salinity on E.coli it was determined that E.coli fared better at a salinity of 5ppt. Deep sediment samples were taken which confirmed that E.coli was able to penetrate the sediment at a depth of at least 6cm. Two water cycling patterns were compared to find that the observed amount of E.coli only rose above the predicted E.coli level in trial 2 which used marine E.coli. It was determined that E.coli levels rose above the predicted level throughout the trials where the systems water was drained and replaced on a 12h tidal cycle. This result indicated that E.coli is able to persist and possibly grow in a marine microcosm system suggesting that it may not be an accurate measure of fecal pollution in a marine environment.

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