Spatial variability of E. coli in an urban salt-wedge estuary

Author:

Dusan Jovanovic  Rhys Coleman  Ana Deletic  David McCarthy  

Journal:

Marine Pollution Bulletin

Issue Date:

2017

Abstract(summary):

Abstract This study investigated the spatial variability of a common faecal indicator organism, Escherichia coli , in an urban salt-wedge estuary in Melbourne, Australia. Data were collected through comprehensive depth profiling in the water column at four sites and included measurements of temperature, salinity, pH, dissolved oxygen, turbidity, and E. coli concentrations. Vertical variability of E. coli was closely related to the salt-wedge dynamics; in the presence of a salt-wedge, there was a significant decrease in E. coli concentrations with depth. Transverse variability was low and was most likely dwarfed by the analytical uncertainties of E. coli measurements. Longitudinal variability was also low, potentially reflecting minimal die-off, settling, and additional inputs entering along the estuary. These results were supported by a simple mixing model that predicted E. coli concentrations based on salinity measurements. Additionally, an assessment of a sentinel monitoring station suggested routine monitoring locations may produce conservative estimates of E. coli concentrations in stratified estuaries. Highlights • Vertical variability of E. coli significantly impacted by salt-wedge dynamics. • Lateral variability of E. coli was low and in the range of analytical uncertainty. • Longitudinal variability of E. coli was low. • Routine monitoring stations may be a conservative estimates of water quality.

Page:

114-114