Zhixuan Feng, Ad Reniers, Brian Haus, Helena Solo-Gabriele, Laura Fiorentino, Maria Olascoaga, Jamie MacMahan


Monitoring microbial water quality is essential for recreational beaches in order to protect human health. To evaluate the relative importance and impacts of various types of non-point microbial sources at a subtropical beach (Hobie Beach, Miami, USA), we utilized a coastal ocean circulation model (Delft3D) with a microbe transport-fate model. Those non-point sources include beach sediment, dog feces, bather shedding, and rainfall runoff. The hydrodynamic model results agreed well with tidal elevations recorded by a nearby NOAA tidal station and also field data collected by pressure sensors, acoustic Doppler current profiler (ADCP). We modeled enterococci levels from four different types of non-point sources on the beach and Staphylococcus aureus levels from only the bather shedding. Model results suggest that dog feces are spotty sources of enterococci and can result in transient spikes of enterococci levels for hours. Beach sands are pervasive sources of enterococci and may explain observed persistent elevations of enterococci levels at this site. Runoff may also significantly increase enterococci levels during rainfall events while bather shedding contribution of enterococci is almost negligible. Bather is the only Staphylococcus aureus source considered in the study and simulated levels are in the same order as prior field measurements.


water quality; recreational beach; enterococci; Staphylococcus aureus; non-point source; Delft3D

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Elmir, S.M., 2006. Development of a Water Quality Model which Incorporates Non-point Microbial Sources. PhD dissertation, University of Miami, Coral Gables, Florida, USA, 185pp.

Elmir, S.M., Wright, M.E., Abdelzaher, A., Solo-Gabriele, H.M., Fleming, L.E., Miller, G., Rybolowik, M., Shih, M-T.P., Pillai, S.P., Cooper, J.A., and Quaye, E.A., 2007. Quantitative evaluation of bacteria released by bathers in a marine water. Water Research, 41, 3-10.

PMid:17113123 PMCid:2633726

Elmir, S.M., Shibata, T., Solo-Gabriele, H.M., Sinigalliano, C.D., Gidley, M.L., Miller, G., Plano, L.R.W., Kish J., Withum, K., and Fleming, L.E., 2009. Quantitative evaluation of enterococci and Bacteroidales released by adults and toddlers in marine water. Water Research, 43, 4610-4616.

PMid:19646730 PMCid:2761526

Enns, A.A., Vogel, L.J., Abdelzaher, A.M., Solo-Gabriele, H.M., Plano L.R.W., Gidley, M.L., Phillips, M.C., Klaus, J.S., Piggot, A.M, Feng, Z., Reniers A., Haus, B.K., Elmir S.M., Zhang, Y., Jimenez, N.H., Abdel-Mottaleb, N., Schoor, M.E., Brown, A., Khan, S.Q., Dameron, A.S., Salazar, N.C., and, Fleming, L.E., 2012. Spatial and temporal variation in indicator microbe sampling is Influential in beach management decisions. Water Research, doi:10.1016/j.watres.2012.01.040

Feng Z., A. Reniers, B.K. Haus, H.M. Solo-Gabriele, 2012. Modeling enterococci release, transport and inactivation at an embayed non-point source beach, Water Resources Research (in revision).

Fujioka, R.S., and T.M. Unutoa, 2006. Comparative stability and growth requirements of S. aureus and fecal indicator bacteria in seawater. Water Science & Technology, 54(3), 169-175.


Ge Z., Whitman, R.L., Nevers, M.B., Phanikumar, S., and Byappanahalli, M.N., 2012. Nearshore hydrodynamics as loading and forcing factors for Escherichia coli contamination at an embayed beach. Limnol. Oceanogr. 57(1), 362-381.

Hsu, S.A., 1988. Coastal Meteorology. San Diego, California: Academic Press, Inc., 260pp.

Lesser, G.R., Roelvink, J.A., van Kester, J.A.T.M., and Stelling, G.S., 2004. Development and validation of a three-dimensional morphological model. Coastal Engineering, 51, 883-915.

Liu, L., Phanikumar, M.S., Molloy, S.L., Whitman, R.L., Shively, D.A., Nevers, M.B., Schwab, D.J., and Rose, J.B., 2006. Modeling the transport and inactivation of E. coli and enterococci in the near-shore region of Lake Michigan. Environmental Science & Technology, 40 (16), 5022-5028.


MacMahan J., R. Vennell, R. Beatson, J. Brown, and A. Reniers, 2012. Divergence-free spatial velocity flow field interpolator for improving measurements from ADCP-equipped small unmanned underwater vehicle. Journal of Atmospheric and Oceanic Technology, 29, 478-484. DOI: 10.1175/JTECH-D-11-00084.1.

Pawlowicz, R., Beardsley, B., and Lentz, S., 2002. Classical tidal harmonic analysis including error estimates in MATLAB using T_TIDE. Computers & Geosciences, 28, 929-937.

Peng, G., C. Moore, and H.C. Graber, 1999. Coastal winds in south Florida, Journal of Applied Meteorology, 38, 1740-1757.<1740:CWISF>2.0.CO;2

Piggot, A.M., Klaus, J.S., Johnson, S., Philips, M., and Solo-Gabriel, H.M., 2012. Relationship between enterococci levels and sediment biofilms at recreational beaches in south Florida, Applied and Environmental Microbiology, 78(17):5973-5982. DOI: 10.1128/AEM.00603-12.

Plano, L.R., Garza, A.C., Shibata, T., Elmir, S.M., Kish, J., Sinigalliano, C.D., Gidley, M.L., Miller, G., Withum, K., Fleming, L.E., Solo-Gabriele, H.M., 2011. Shedding of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus from adult and pediatric bathers in marine waters. BMC Microbiology, 11(5): 1-10.

Sanders, B.F., Arega, F., and Sutula, M., 2005. Modeling the dry-weather tidal cycle of fecal indicator bacteria in surface waters of an intertidal wetland. Water Research, 39, 3394-3408.


Shah, A.H., Abdelzher, A.M., Phillips, M., Hernandez, R., Solo-Gabriele, H.M., Kish, J., Scorzetti, G., Fell, J.W., Diaz, M.R., Scott, T.M., Lukasik, J., Harwood, V.J., McQuaig, S., Sinigalliano, C.D., Gidley, M.L., Wanless, D., Ager, A., Lui, J., Stewart, J.R., Plano, L.R.W., and Fleming, L.E., 2011. Indicator microbes correlate with pathogenic bacteria, yeasts and helminthes in sand at a subtropical recreational beach site. Journal of Applied Microbiology, 110(6), 1571-1583.


Shibata, T., Solo-Gabriele, H.M., Fleming, L.E., and Elmir, S., 2004. Monitoring marine recreational water quality using multiple microbial indicators in an urban tropical environment. Water Research, 38, 3119-3131.

PMid:15261551 PMCid:2548301

Sinton, L.W., Hall, C.H., Lynch, P.A., and Davies-Colley, R.J., 2002. Sunlight inactivation of fecal indicator bacteria and bacteriophages from waste stabilization pond effluent in fresh and saline waters. Applied and Environmental Microbiology, 68 (3), 1122-1131.

PMid:11872459 PMCid:123754

Shuval H., 2003. Estimating the global burden of thalassogenic diseases: human infectious diseases caused by wastewater pollution of the marine environment. Journal of Water and Health, 2, 53-64.

USEPA, 1986. Ambient water quality criteria for bacteria. EPA 440/5-84-002. Washington D.C.

Wang, J.D, Luo, J., and Ault.J.S. 2003. Flows, salinity, and some implications for larval transport in south Biscayne Bay, Florida. Bulletin of Marine Science, 72, 695-723.

Wang, J.D., Solo-Gabriele, H.M., Abdelzaher, A.M., and Fleming, L.E., 2010. Estimation of enterococci input from bathers and animals on a recreational beach using camera images. Marine Pollution Bulletin, 60, 1270-1278.

PMid:20381094 PMCid:3417289

Wright, M.E., Solo-Gabriele, H.M., Elmir, S., and Fleming, L.E., 2009. Microbial load from animal feces at a recreational beach. Marine Pollution Bulletin, 58, 1649-1656.

PMid:19664785 PMCid:2771205

Wright, M.E., Abdelzaher, A.M., Solo-Gabriele, H.M., Elmir, S., and Fleming, L.E., 2011. The inter-tidal zone is the pathway of input of enterococci to a subtropical recreational marine beach. Water Science & Technology, 63.3, 542-549.


Yamahara K.M., Walters, S.P., and Boehm, A.B., 2009. Growth of enterococci in unaltered, unseeded beach sands subjected to tidal wetting. Applied and Environmental Microbiology, 75 (6), 1517-1524.

PMid:19151188 PMCid:2655449

Zhu, X., Wang, J.D., Solo-Gabriele, H.M., and Fleming, L.E., 2011. A water quality modeling study of non-point sources at recreational marine beaches. Water Research, 45, 2985-2995.