Toward understanding fecal coliform and Escherichia coli distributions in the Annapolis River
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The Clean Annapolis River Project (CARP) has identified fecal bacterial contamination as the single greatest threat to water quality in the Annapolis River, located in western Nova Scotia. The intense agriculture and use of private wells within the Annapolis River watershed make bacterial contamination an issue of particular concern. This post hoc exploratory study examines the relationships between concentrations of bacterial indicators and a variety of environmental factors. Concentrations of Escherischia coli and fecal coliform bacterial were transformed using the natural logarithm and were compared and contrasted based on differences in sampling location, month, year, rain rates, temperature, and pH, using box-and-whisker plots, analysis of variance (ANOVA), and Student‟s t tests. A step-wise multiple regression was then performed to determine the level of interaction between the predictor variables, which environmental factors had the strongest influence, and the total amount of variation that could be explained by the study. All predictor variables with the exception of pH demonstrated some statistically significant influence on logarithmically transformed bacterial concentrations. The multiple regression analysis indicated that rain a few days prior to sampling, sampling location, month, and water temperature were the strongest predictors of transformed concentrations, and collectively accounted for 21.3% of variability in the transformed concentrations.