title: Spatial and temporal variation in indicator microbe sampling is influential in beach management decisions.
abstract: Fecal indicator microbes, such as enterococci, are often used to assess potential health risks caused by pathogens at recreational beaches. Microbe levels often vary based on collection time and sampling location. The primary goal of this study was to assess how spatial and temporal variations in sample collection, which are driven by environmental parameters, impact enterococci measurements and beach management decisions. A secondary goal was to assess whether enterococci levels can be predictive of the presence of Staphylococcus aureus, a skin pathogen. Over a ten-day period, hydrometeorologic data, hydrodynamic data, bather densities, enterococci levels, and S. aureus levels including methicillin-resistant S. aureus (MRSA) were measured in both water and sand. Samples were collected hourly for both water and sediment at knee-depth, and every 6 h for water at waist-depth, supratidal sand, intertidal sand, and waterline sand. Results showed that solar radiation, tides, and rainfall events were major environmental factors that impacted enterococci levels. S. aureus levels were associated with bathing load, but did not correlate with enterococci levels or any other measured parameters. The results imply that frequencies of advisories depend heavily upon sample collection policies due to spatial and temporal variation of enterococci levels in response to environmental parameters. Thus, sampling at different times of the day and at different depths can significantly impact beach management decisions. Additionally, the lack of correlation between S. aureus and enterococci suggests that use of fecal indicators may not accurately assess risk for some pathogens.
authors.affiliation: University of Miami, NSF NIEHS Oceans and Human Health Center, Miami, FL 33149, USA.
authors.forename: Amber A
authors.initials: AA
authors.lastname: Enns
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Vogel
authors.forename: Amir M
authors.initials: AM
authors.lastname: Abdelzaher
authors.forename: Helena M
authors.initials: HM
authors.lastname: Solo-Gabriele
authors.forename: Lisa R W
authors.initials: LR
authors.lastname: Plano
authors.forename: Maribeth L
authors.initials: ML
authors.lastname: Gidley
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Phillips
authors.forename: James S
authors.initials: JS
authors.lastname: Klaus
authors.forename: Alan M
authors.initials: AM
authors.lastname: Piggot
authors.forename: Zhixuan
authors.initials: Z
authors.lastname: Feng
authors.forename: Ad J H M
authors.initials: AJ
authors.lastname: Reniers
authors.forename: Brian K
authors.initials: BK
authors.lastname: Haus
authors.forename: Samir M
authors.initials: SM
authors.lastname: Elmir
authors.forename: Yifan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Nasly H
authors.initials: NH
authors.lastname: Jimenez
authors.forename: Noha
authors.initials: N
authors.lastname: Abdel-Mottaleb
authors.forename: Michael E
authors.initials: ME
authors.lastname: Schoor
authors.forename: Alexis
authors.initials: A
authors.lastname: Brown
authors.forename: Sumbul Q
authors.initials: SQ
authors.lastname: Khan
authors.forename: Adrienne S
authors.initials: AS
authors.lastname: Dameron
authors.forename: Norma C
authors.initials: NC
authors.lastname: Salazar
authors.forename: Lora E
authors.initials: LE
authors.lastname: Fleming
mesh_terms: D001493:Bathing Beaches / Q000592:standards*; D016983:Enterococcus; D019015:Geologic Sediments / Q000382:microbiology*; D011156:Population Density; D015980:Public Health Practice / Q000592:standards*; D011891:Rain; D012623:Seawater / Q000382:microbiology*; D013045:Species Specificity; D013211:Staphylococcus aureus / Q000302:isolation & purification*; D013997:Time Factors; D014872:Water Movements