Tourism and recreation are the major 

drivers of economic development in 

coastal areas of the United States. 

The annual economic impact of local, 

national, and international visitors 

to marine recreational beaches 

throughout the United States is 

substantial. For example, $150 billion 

was realized just in the States of 

Florida ($57 billion) California ($82 

billion), and Hawaii ($11 billion) in 

2004.

To monitor most of the Nation’s 

public beaches, the microbiological 

quality of beach water is routinely 

analyzed for indicators of human and 

animal fecal pollution (for example, 

fecal coliforms, enterococci, and 

E. coli) by local and state regulatory 

agencies. In addition to these tests, 

microbiologists at the U.S. Geological 

Survey (USGS) Florida Integrated 

Science Center (FISC) have initiated 

programs to perform additional 

sampling for microbial indicators 

and pathogens in coastal waters and 

also in the sands and sediments from 

nearshore sites at public beaches. 

These efforts are in accordance with 

the recommendations outlined in the 

Clean Beaches Council’s 2005 State 

of the Beaches Report: Bacteria and 

Sand, A National Call to Action*, 

in which an integrated approach to 

research was requested, with emphasis 

on the areas of microbiology, 

geochemistry, and physical sciences, 

and how they relate to the presence 

and persistence of bacteria in beach 

sands. The following issues are being 

addressed by FISC scientists and 

academic collaborators:

Indicators and Pathogens in 

Marine Beach Waters and Sands: 

Representing the most extensive 

Microbiology and Public Beach Safety: 

Integrated Science for the Protection of Public Health

Figure 1. Top: FISC microbiologist collecting water and beach sand for analysis. Bottom: the FISC 

mobile laboratory allows scientists to process samples in the field.

U.S. Department of the Interior

U.S. Geological Survey

FS 2006-3045

April 2006
public health microbiology survey 

of coastal marine beaches, a 

monthly bacteriological survey was 

conducted for one year at 10 of the 

most frequented public beaches in 

Pinellas County, Florida. Sands 

and overlying waters were assayed 

for a suite of indicators of human 

fecal contamination, as well as total 

bacteria. The general conclusions 

were:

u Sands harbor greater concentrations 

of indicator bacteria relative to the 

overlying waters. 

u Sands and silts may serve as 

reservoirs of pathogens that can be 

resuspended into the water.

u Beaches in areas with reduced 

water circulation had the highest 

concentrations of all bacterial 

indicators in the sands. 

Development of Methods for the 

Detection of Emerging Pathogens 

in Beach Sands: USGS FISC is 

also developing new methods to 

detect emerging pathogens, such as 

drug-resistant bacteria (for example, 

methicillin-resistant Staphylococcus 

aureus) that are not currently part 

of the routine monitoring at public 

beaches. 

Indicator and Pathogen Survival 

and Persistence in Marine Beach 

Sands: Little is known about bacterial 

survival and persistence in beach 

sands. USGS FISC has been studying 

factors (for example, nutrient and 

metal cycling, temperature, salinity, 

and ultraviolet irradiation) within 

beach sands that contribute to bacterial 

survival and persistence. 

Improvement of Beach Monitoring 

through Research Collaborations: 

FISC microbiologists are currently 

involved in discussions with state and 

local governments, and universities 

to establish long-term collaborations 

for investigations into the causes of 

repeated closing of specific beaches 

due to issues affecting microbiological 

quality. These collaborations include 

the following issues:

Submarine Ground-water Discharge: 

Millions of gallons of fresh ground 

water seep into the coastal waters of 

Florida on a daily basis. Studies will 

provide data on possible microbial 

and nutrient influences into beach 

zones that cannot be accounted for by 

simple measurement of precipitation 

or runoff. 

Beach Sand and Sediment Transport: 

The distance and volume of 

transported beach sands and sediments 

increase as the wave energy increases 

(for example, during storms and 

hurricanes). Bacteria securely attach 

themselves to these particles and can 

move considerable distances, possibly 

spreading a microbiological risk 

from one site to another. Sediment 

transport and hydrodynamic-flow 

models allow predictions of sediment 

movement and might be adapted to 

predict transport of indicators and 

pathogens.

Microbial Source Tracking and Risk 

Assessment: Collaborations with 

academic institutions are aimed at 

determining the source of indicators 

and pathogens that impact beach 

sands and waters. The data from these 

and other studies are being used to 

determine the risk of infection and 

illness in humans who come in contact 

with or consume contaminated waters.

*2005 State of the Beach Report: Bacteria

and Sand, A National Call to Action. 

Clean Beaches Council. July 2005. 

http://www.cleanbeaches.org/

ewebeditpro/items/O31F6450.pdf

Figure 2. Microbiological media and molecular techniques are used in the laboratory to detect 

bacteria in samples.

Figure 3. View through the microscope: bacteria (stained bright green for detection) attached 

to sediment particles.

For more information, please contact:

Christina A. Kellogg

John T. Lisle

U. S. Geological Survey

Florida Integrated Science Center

600 4th Street South

St. Petersburg, FL 33701

Telephone: 727-803-8747

Email: ckellogg@usgs.gov or

jlisle@usgs.gov

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