IWA Publishing
 IWA Publishing Journals   Subscriptions   Authors   Users   Librarians   FAQs 

Water Science & Technology Vol 63 No 3 pp 542–549 © IWA Publishing 2011 doi:10.2166/wst.2011.255

The inter-tidal zone is the pathway of input of enterococci to a subtropical recreational marine beach

M. E. Wright, A. M. Abdelzaher, H. M. Solo-Gabriele, S. Elmir and L. E. Fleming

National Science Foundation (NSF)-National Institute of Environmental Health Sciences (NIEHS) Oceans and Human Health Center, University of Miami Rosenstiel School of Marine and Atmospheric Science, 4600 Rickenbacker Causeway, EG 211 Key Biscayne, FL 33149, USA
Department of Civil, Architectural, and Environmental Engineering University of Miami, P.O. Box 248294, Coral Gables, Florida 33124-0630, USA E-mail: hmsolo@miami.edu
Miami-Dade County Health Department, 1725 NW 167 Street Miami, Florida 33056, USA
Department of Epidemiology and Public Health University of Miami Miller School of Medicine, 1120 14th Street 10th Floor, Miami, Florida 33136
Marine Biology and Fisheries University of Miami Rosenstiel School of Marine and Atmospheric Sciences, 4600 Rickenbacker Causeway, Miami, Florida 33149


Efforts were made to evaluate the source of enterococci levels at a recreational beach. Four monitoring efforts were implemented which included tidal studies, hourly sampling, runoff sampling, and spatially intensive sediment sampling. Spatially intensive sediment sampling indicated that enterococci concentrations consistently decreased away from the inter-tidal zone, both seaward and landward. During dry conditions, the highest concentrations in the water were observed during high tide (71±48 CFU/100 mL) and lower concentrations were observed during low tide (4±3 CFU/100 mL). Runoff was characterised by very high levels (11,700 CFU/100 mL). Results from these monitoring efforts collectively showed that the source of enterococci to the study beach is geographically located within the inter-tidal zone. Wash-in from the inter-tidal zone through tidal action and runoff plays a major role in controlling enterococci levels within the water column. Such results are significant in identifying the source and transport mechanisms of enterococci, which can subsequently be used as part of a modelling effort aimed at predicting enterococci levels at recreational beaches.

Keywords: enterococci; inter-tidal zone; marine beach; recreational beach; water quality indicators

Full article (PDF Format)

eProduct: Buy this article for £24.00 (IWA MEMBER PRICE: £18.00)
All prices include VAT. For customers where VAT should not be applied, the VAT amount will be removed upon payment