Spatial variability of E. coli in an urban salt-wedge estuary.
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.
Environmental and Public Health Microbiology (EPHM) Laboratory, Monash Infrastructure Institute, Department of Civil Engineering, Monash University, Clayton, Victoria 3800, Australia. Electronic address: dusan.jovanovic@monash.edu.
Dusan
D
Jovanovic
Melbourne Water Corporation, Docklands, Victoria 3008, Australia. Electronic address: rhys.coleman@melbournewater.com.au.
Rhys
R
Coleman
Environmental and Public Health Microbiology (EPHM) Laboratory, Monash Infrastructure Institute, Department of Civil Engineering, Monash University, Clayton, Victoria 3800, Australia. Electronic address: ana.deletic@monash.edu.
Ana
A
Deletic
Environmental and Public Health Microbiology (EPHM) Laboratory, Monash Infrastructure Institute, Department of Civil Engineering, Monash University, Clayton, Victoria 3800, Australia. Electronic address: david.mccarthy@monash.edu.
David
D
McCarthy
D001315:Australia; D004784:Environmental Monitoring; D004926:Escherichia coli / Q000254:growth & development*; D063366:Estuaries; D005243:Feces / Q000737:chemistry; D008962:Models, Theoretical; D010100:Oxygen / Q000032:analysis; D054712:Salinity; D013696:Temperature; D014871:Water Microbiology
D010100:Oxygen
Depth profiling; Faecal contamination; Pathogens; Spatial distribution; Stratified estuary