title: Relationships between sand and water quality at recreational beaches.
abstract: Enterococci are used to assess the risk of negative human health impacts from recreational waters. Studies have shown sustained populations of enterococci within sediments of beaches but comprehensive surveys of multiple tidal zones on beaches in a regional area and their relationship to beach management decisions are limited. We sampled three tidal zones on eight South Florida beaches in Miami-Dade and Broward counties and found that enterococci were ubiquitous within South Florida beach sands although their levels varied greatly both among the beaches and between the supratidal, intertidal and subtidal zones. The supratidal sands consistently had significantly higher (p < 0.003) levels of enterococci (average 40 CFU/g dry sand) than the other two zones. Levels of enterococci within the subtidal sand correlated with the average level of enterococci in the water (CFU/100mL) for the season during which samples were collected (r(s) = 0.73). The average sand enterococci content over all the zones on each beach correlated with the average water enterococci levels of the year prior to sand samplings (r(s) = 0.64) as well as the average water enterococci levels for the month after sand samplings (r(s) = 0.54). Results indicate a connection between levels of enterococci in beach water and sands throughout South Florida's beaches and suggest that the sands are one of the predominant reservoirs of enterococci impacting beach water quality. As a result, beaches with lower levels of enterococci in the sand had fewer exceedences relative to beaches with higher levels of sand enterococci. More research should focus on evaluating beach sand quality as a means to predict and regulate marine recreational water quality.
authors.affiliation: University of Miami, NSF NIEHS Oceans and Human Health Center, Miami, FL 33149, USA.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Phillips
authors.forename: Helena M
authors.initials: HM
authors.lastname: Solo-Gabriele
authors.forename: Alan M
authors.initials: AM
authors.lastname: Piggot
authors.forename: James S
authors.initials: JS
authors.lastname: Klaus
authors.forename: Yifan
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D001493:Bathing Beaches / Q000592:standards*; D016983:Enterococcus / Q000302:isolation & purification; D005431:Florida; D005843:Geography; D006801:Humans; D011998:Recreation; D012822:Silicon Dioxide / Q000737:chemistry*; D012988:Soil Microbiology; D014481:United States; D014483:United States Dept. of Health and Human Services; D014871:Water Microbiology; D014872:Water Movements; D060753:Water Quality / Q000592:standards*
chemical_list: D012822:Silicon Dioxide
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