HCNSO Student Theses and Dissertations

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Defense Date


Document Type

Thesis - NSU Access Only

Degree Name

M.S. Marine Biology


Oceanographic Center

First Advisor

Andrew Rogerson

Second Advisor

Donald S. McCorquodale

Third Advisor

Harold E. Laubach


Traditionally, the hygienic quality of beaches has been determined by monitoring the water for microbial indicators of fecal pollution. Beach sand, which may also be an important medium for the transmission of fecal borne pathogens, has rarely been examined. The aims of this study where to examine the prevalence of fecal indicator organisms in tidally affected beach sand and in dryer upper beach sand, relative to water; identify the potential sources of indicator organisms in beach sand; examine the prevalence of selected eukaryotic microbes at sandy beaches; and investigate the potential health risks related to beach use. Three south Florida Beaches (Ft. Lauderdale Beach, Hollywood Beach, Hobe Beach) were sampled bimonthly for a I year period. Significantly, enterococci, fecal coliform, and E. coli levels were consistently present at higher concentrations in beach sand compared to the seawater at all 3 study beaches. Levels of somatic and F-specific coliphages were also present at higher concentrations in beach sand. Microbial- source tracking analysis by carbon utilization profiling suggested that the predominate sources of enterococci in beach sand were seagulls, and transiently replicating indigenous populations. Acanthamoeba spp. was the most commonly isolated free-living naked amoeba in this study and molecular analysis revealed that 19 of the 20 beach sand clones were genotype T4, the Acanthamoeba keratitis-associated genotype. With respect to salinity, the growth characteristics of beach sand Acanthamoeba isolates were similar to Acanthamoeba isolated from corneal scrapings. Results from the beach survey indicated that beach goers may have an increased risk for acquiring contact related ailments at Hobe Beach. Accordingly, bacterial and viral fecal indicator microbes were detected at the highest frequency and greatest average concentrations from Robe Beach. Reports of enteric and respiratory related symptoms were not higher in beach goers compared to the control cohort.

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