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Maryland Department of the Environment Delaware Department of Natural Resources and Environmental Control Salisbury University Drs. Elichia Venso and Mark Frana Bacterial Source Tracking Laboratory
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To determine levels of fecal indicator organisms ( E. coli & Enterococcus) in beach sediment and water samples at 1 Delaware and 3 Maryland sampling sites To investigate survival and/or regrowth of fecal indicator organisms found in sediment and water samples To determine if an association was present between bacterial density in beach sand and in beach water To select for and identify potential bacterial pathogens in these same water and sediment samples
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4 sampling locations: Maryland Assateague Island (bay side) Granary Creek (Wye River tributary) Sandy Point Delaware Delaware Shore 12 month project: Jan–Dec 2008 Sample collections: Monthly (Jan-Apr; Oct – Dec) Bimonthly (May – Sep) Samples collected at each study site: Water at knee depth Sediment at water sampling location (“wet”) Sediment in foreshore between high tide line and water’s edge (“dry”)
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Collection data sheets included information on: Water Temperature Conductivity Dissolved Oxygen pH Salinity Sediment Temperature Note: Analysis was conducted on one set of samples for nitrogen, phosphorus, pH, etc. Other Air Temperature and Direction Weather Tide Unusual observations
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Water: Analysis of triplicate water samples to enumerate the fecal indicators using Colilert ® -18 Most Probable Number analysis for the detection of E. coli and Enterolert™ for the detection of Enterococci Membrane filtration onto selective media for the isolation of potential pathogens
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Sediment: Determination of moisture content Agitation of 10 grams in 50 ml of extraction buffer for 30 minutes using a wrist-action shaker, then allowed to settle for 30 min Membrane filtration of supernatant for enumeration of E. coli and Enterococci and identification of potential pathogens. Regrowth: Incubation of select sediment and water samples at 4°C, 21°C, and 37 ° C, followed by enumeration of E. coli and Enterococcus
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MacConkey Sorbitol E. coli O157:H7 CIN Yersinia CAMPY CSM Campylobacter XLT4: BG: Salmonella SS Agar Salmonella/Shigella
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Carbon Source Utitilization using Biolog © Polymerase Chain Reaction (PCR)-Midi Labs © DNA amplification Sequence matching
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Density in water versus in wet and dry sediments: E. coli : 72% at AI 49% at SP Enterococci 58% at AI 29% at GC Density in water versus in wet and dry sediments and % moisture: E. coli: 82% at AI 99% at GC 100% at SP Enterococci: 92% at DS61% at GC 50% at SP Density in water versus in dry sediment and % moisture: Enterococci: 92% DS35% at GC 25% at SP
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Percentage of experiments with regrowth in water: E. coli : 47% at AI27% at DS 73% at GC 67% at SP Enterococci: 33% at GC 27% at SP Percentage of experiments with regrowth in wet sediment: E. coli : 67% at GC 20% at SP Enterococci: 33% at GC 20% at SP Percentage of experiments with regrowth in dry sediment: E. coli : 33% at GC 20% at SP Enterococci:27% at GC 20% at AI and SP
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One “potential” pathogen with a definitive ID: Sandy Point Wet Sediment Vibrio furnissii Six additional potential pathogens, but with low confidence ID: Granary Creek Water E. coli O157:H7 (2) Shigella dysenteriae (2) Sandy Point Wet Sediment E. coli O157:H7 Shigella flexneri Other Genera identified: Aeromonas Citrobacter Enterobacter Klebsiella Proteus Pseudomonas Serratia Shewanella
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Detectable indicator bacterial densities were found in 47% of 408 assays. The highest fecal indicator counts were found in sediment samples from Granary Creek. The lowest fecal indicator counts were found at the Delaware Shore site. Regrowth/survivability data was measurable at all four sites, although survival was relatively short-term for samples held at 21 °C and 37 °C as compared to samples held at 4 °C. Only one potential pathogen was definitively identified.
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MDE Kathy Brohawn William Beatty John “Rusty” McKay Heather Morehead Kathy Bassett Sarah Harvey Ann McManus DNREC John Pingree Debbie Rouse Glenn King Salisbury University Lesley Frana Annie Adkins Chris Labe Isha Choudhary Mary Vendetti, Leo Cabrera Cloe Manarinjara Megan Robison
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