Fecal contamination in shallow temperate estuarine lagoon: Source of the pollution and environmental factors.

In inner coastal waters such as lagoons, which are very turbid and rich in suspended particles, the survival of fecal pollution microorganisms may find favorable environments. In order to better characterize the sources and dynamics of fecal pollution in a strongly turbid environment, in situ observations were made in the Curonian Lagoon. A combination of traditional monitoring and molecular methods were used. To monitor the water quality, the indicator Escherichia coli (EC) was selected as a proxy for fecal contamination. E. coli concentration correlated with environmental parameters as pH, oxygen and turbidity. The main pollution sources are the sewage outlets in the lagoon area, while the pollution coming via rivers did not play a significant role. Still the human associated E. coli consisted only of 0 up to 20% of analyzed isolates, and did not correlate with the E. coli concentrations in the study sites. The role of birds, especially for potentially virulent E. coli may be underestimated in the lagoon.