Sources of Escherichia coli in a coastal subtropical environment

Helena M Solo-Gabriele, Melinda A. Wolfert, Timothy R. Desmarais, Carol J. Palmer

Research output: Contribution to journalArticle

325 Citations (Scopus)

Abstract

Sources of Escherichia coli in a coastal waterway located in Ft. Lauderdale, Fla., were evaluated. The study consisted of an extensive program of field measurements designed to capture spatial and temporal variations in E. coli concentrations as well as experiments conducted under laboratory-controlled conditions. E. coli from environmental samples was enumerated by using a defined substrate technology (Colilert-18). Field sampling tasks included sampling the length of the North Fork to identify the river reach contributing high E. coli levels, autosampler experiments at two locations, and spatially intense sampling efforts at hot spots. Laboratory experiments were designed to simulate tidal conditions within the riverbank soils. The results showed that E. coli entered the river in a large pulse during storm conditions. After the storm, E. coli levels returned to baseline levels and varied in a cyclical pattern which correlated with tidal cycles. The highest concentrations were observed during high tide, whereas the lowest were observed at low tide. This peculiar pattern of E. coli concentrations between storm events was caused by the growth of E. coli within riverbank soils which were subsequently washed in during high tide. Laboratory analysis of soil collected from the riverbanks showed increases of several orders of magnitude in soil E. coli concentrations. The ability of E. coli to multiply in the soil was found to be a function of soil moisture content, presumably due to the ability of E. coli to outcompete predators in relatively dry soil. The importance of soil moisture in regulating the multiplication of E. coli was found to be critical in tidally influenced areas due to periodic wetting and drying of soils in contact with water bodies. Given the potential for growth in such systems, E. coli concentrations can be artificially elevated above that expected from fecal impacts alone. Such results challenge the use of E. coli as a suitable indicator of water quality in tidally influenced areas located within tropical and subtropical environments.

Original languageEnglish
Pages (from-to)230-237
Number of pages8
JournalApplied and Environmental Microbiology
Volume66
Issue number1
StatePublished - Jan 1 2000

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Escherichia coli
Soil
soil
tide
sampling
soil moisture
riparian soils
tides
tidal cycle
Rivers
river
wetting
moisture content
temporal variation
spatial variation
experiment
predator
water quality
substrate
rivers

ASJC Scopus subject areas

  • Environmental Science(all)
  • Biotechnology
  • Microbiology

Cite this

Sources of Escherichia coli in a coastal subtropical environment. / Solo-Gabriele, Helena M; Wolfert, Melinda A.; Desmarais, Timothy R.; Palmer, Carol J.

In: Applied and Environmental Microbiology, Vol. 66, No. 1, 01.01.2000, p. 230-237.

Research output: Contribution to journalArticle

Solo-Gabriele, HM, Wolfert, MA, Desmarais, TR & Palmer, CJ 2000, 'Sources of Escherichia coli in a coastal subtropical environment', Applied and Environmental Microbiology, vol. 66, no. 1, pp. 230-237.
Solo-Gabriele, Helena M ; Wolfert, Melinda A. ; Desmarais, Timothy R. ; Palmer, Carol J. / Sources of Escherichia coli in a coastal subtropical environment. In: Applied and Environmental Microbiology. 2000 ; Vol. 66, No. 1. pp. 230-237.
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