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Santa Barbara, CA, United States

Ervin J.S.,University of California at Santa Barbara | Van De Werfhorst L.C.,University of California at Santa Barbara | Murray J.L.S.,City of Santa Barbara | Holden P.A.,University of California at Santa Barbara
Environmental Science and Technology | Year: 2014

Elevated levels of fecal indicator bacteria (FIB), including Escherichia coli and enterococci, trigger coastal beach advisories and signal public health risks. Solving FIB pollution in suburban coastal watersheds is challenging, as there are many potential sources. The Arroyo Burro watershed in Santa Barbara, CA is an example, with its popular, but chronically FIB-contaminated beach. To address, a microbial source tracking study was performed. Surface waters were sampled over 2 years, FIB were quantified, and DNA was analyzed for host-associated fecal markers. Surf zone FIB were only elevated when the coastal lagoon was discharging. Among the fecal sources into the lagoon, including upstream human sources and coastal birds, canines were the most important. Canine sources included input via upstream creek water, which decreased after creek-side residences were educated about proper pet waste disposal, and direct inputs to the lagoon and surf zone, where dog waste could have been tidally exchanged with the lagoon. Based on this study, canine waste can be an influential, yet controllable, fecal source to suburban coastal beaches. © 2014 American Chemical Society. Source


Sercu B.,University of California at Santa Barbara | Van De Werfhorst L.C.,University of California at Santa Barbara | Murray J.L.S.,City of Santa Barbara | Holden P.A.,University of California at Santa Barbara
Environmental Science and Technology | Year: 2011

Separating storm drains and sanitary sewers is expected to control sewage pollution, for example, from combined sewer overflows, and to reduce excessive stormwater flow to wastewater treatment plants. However, sewage contamination has been found in such separated storm drain systems in urban areas during dry-weather flow. To determine whether transmission of sewage is occurring from leaking sanitary sewers directly to leaking separated storm drains, field experiments were performed in three watersheds in Santa Barbara, CA. Areas with high and low risks for sewage exfiltration into storm drains were identified, and rhodamine WT (RWT) dye pulses were added to the sanitary sewers. RWT was monitored in nearby storm drain manholes using optical probes set up for unattended continuous monitoring. Above-background RWT peaks were detected in storm drains in high-risk areas, and multiple locations of sewage contamination were found. Sewage contamination during the field studies was confirmed using the human-specific Bacteroidales HF183 and Methanobrevibacter smithii nifH DNA markers. This study is the first to provide direct evidence that leaking sanitary sewers can directly contaminate nearby leaking storm drains with untreated sewage during dry weather and suggests that chronic sanitary sewer leakage contributes to downstream fecal contamination of coastal beaches. © 2011 American Chemical Society. Source


Sercu B.,University of California at Santa Barbara | van de Werfhorst L.C.,University of California at Santa Barbara | Murray J.L.S.,City of Santa Barbara | Holden P.A.,University of California at Santa Barbara
Microbial Ecology | Year: 2011

Microbiological contamination from runoff is a human health concern in urbanized coastal environments, but the contamination sources are often unknown. This study quantified fecal indicator bacteria and compared the distributions of human-specific genetic markers and bacterial community composition during dry and wet weather in urban creeks draining two neighboring watersheds in Santa Barbara, CA. In a prior study conducted during exclusively dry weather, the creeks were contaminated with human waste as indicated by elevated numbers of the human-specific Bacteroidales marker HF183 (Sercu et al. in Environ Sci Technol 43:293-298, 2009). During the storm, fecal indicator bacterial numbers and loads increased orders of magnitude above dry weather conditions. Moreover, bacterial community composition drastically changed during rainfall and differed from dry weather flow by (1) increased bacterial diversity, (2) reduced spatial heterogeneity within and between watersheds, and (3) clone library sequences more related to terrestrial than freshwater taxa. Finally, the spatial patterns of human-associated genetic markers (HF183 and Methanobrevibacter smithii nifH gene) changed during wet weather, and the contribution of surface soils to M. smithii nifH gene detection was suspected. The increased fecal indicator bacteria numbers during wet weather were likely associated with terrestrial sources, instead of human waste sources that dominated during dry weather flow. © 2011 Springer Science+Business Media, LLC. Source


Sercu B.,University of California at Santa Barbara | Van De Werfhorst L.C.,University of California at Santa Barbara | Murray J.L.S.,City of Santa Barbara | Holden P.A.,University of California at Santa Barbara
Applied and Environmental Microbiology | Year: 2011

Monitoring microbiological water quality is important for protecting water resources and the health of swimmers. Routine monitoring relies on cultivating fecal indicator bacteria (FIB), frequently using defined substrate technology. Defined substrate technology is designed to specifically enrich for FIB, but a complete understanding of the assay microbiology requires culture-independent analysis of the enrichments. This study aimed to identify bacteria in positive wells of Colilert and Enterolert Quanti-Tray/2000 (IDEXX Laboratories) FIB assays in environmental water samples and to quantify the degree of false-positive results for samples from an urban creek by molecular methods. Pooled Escherichia coli- and Enterococcus-positive Quanti-Tray/2000 enrichments, either from urban creek dry weather flow or municipal sewage, harbored diverse bacterial populations based on 16S rRNA gene sequences and terminal restriction fragment length polymorphism analyses. Target taxa (coliforms or enterococci) and nontarget taxa (Vibrio spp., Shewanella spp., Bacteroidetes, and Clostridium spp.) were identified in pooled and individual positive Colilert and Enterolert wells based on terminal restriction fragments that were in common with those generated in silico from clone sequences. False-positive rates of between 4 and 23% occurred for the urban creek samples, based on the absence of target terminal restriction fragments in individual positive wells. This study suggests that increased selective inhibition of nontarget bacteria could improve the accuracy of the Colilert and Enterolert assays. Copyright © 2011, American Society for Microbiology. Source


Cao Y.,Southern California Coastal Water Research Project | Van De Werfhorst L.C.,University of California at Santa Barbara | Sercu B.,University of California at Santa Barbara | Murray J.L.S.,City of Santa Barbara | Holden P.A.,University of California at Santa Barbara
Environmental Science and Technology | Year: 2011

High fecal indicator bacterial (FIB) concentrations signal urban coastal water quality impairments that can threaten public health. However, FIB (total and fecal coliform plus Enterococcus sp.) concentrations are not specific to human waste, and thus, microbial source tracking (MST) is employed to assess public health risks and remediation alternatives. Currently, water quality diagnosis requires several simultaneous MST assays. Relatively unexplored is a community analysis approach for MST where the overall microbial community composition is compared, through multivariate analysis, to link sources and sinks of microbial pollution. In this research, an urban coastal creek and drain sampling transect, previously diagnosed as human-waste-contaminated, were evaluated for bacterial community composition relative to fecal sources; a laboratory spiking study was also performed to assess method sensitivity and specificity. Multivariate statistical analysis of community profiles clearly distinguished different fecal sources, indicated a high sensitivity for sewage spikes, and confirmed creek contamination sources. This work demonstrates that molecular microbial community analysis combined with appropriate multivariate statistical analyses is an effective addition to the MST tool box. © 2011 American Chemical Society. Source

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