Laurie C. Van De Werfhorst

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The Pacific Estuarine Ecosystem Indicators Research Consortium seeks to develop bioindicators of toxicant-induced stress and bioavailability for wetland biota. Within this framework, the effects of environmental and pollutant variables on microbial communities were studied at different spatial scales over a 2-year period. Six salt marshes along the(More)
BACKGROUND Microbial communities in aquatic environments are spatially and temporally dynamic due to environmental fluctuations and varied external input sources. A large percentage of the urban watersheds in the United States are affected by fecal pollution, including human pathogens, thus warranting comprehensive monitoring. METHODOLOGY/PRINCIPAL(More)
Coastal urbanized areas in Southern California experience frequent beach water quality warnings in summer due to high concentrations of fecal indicator bacteria (FIB). Remediation can be difficult, as sources are often unknown. During two summers, we sampled three urbanized watersheds in Santa Barbara, CA at sites with historically high FIB concentrations(More)
Bacterial biofilms, i.e. surface-associated cells covered in hydrated extracellular polymeric substances (EPS), are often studied with high-resolution electron microscopy (EM). However, conventional desiccation and high vacuum EM protocols collapse EPS matrices which, in turn, deform biofilm appearances. Alternatively, wet-mode environmental scanning(More)
The last decade has seen development of numerous new microbial source tracking (MST) methodologies, but many of these have been tested in just a few laboratories with a limited number of fecal samples. This method evaluation study examined the specificity and sensitivity of 41 MST methodologies by analyzing data generated in 27 laboratories. MST(More)
A number of PCR-based methods for detecting human fecal material in environmental waters have been developed over the past decade, but these methods have rarely received independent comparative testing in large multi-laboratory studies. Here, we evaluated ten of these methods (BacH, BacHum-UCD, Bacteroides thetaiotaomicron (BtH), BsteriF1, gyrB, HF183(More)
Marine seeps introduce significant amounts of hydrocarbons into oceans and create unusual habitats for microfauna and -flora. In the vicinity of chronic seeps, microbes likely exert control on carbon quality entering the marine food chain and, in turn, hydrocarbons could influence microbial community composition and diversity. To determine the effects of(More)
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(More)
Here we report results from a multi-laboratory (n = 11) evaluation of four different PCR methods targeting the 16S rRNA gene of Catellicoccus marimammalium originally developed to detect gull fecal contamination in coastal environments. The methods included a conventional end-point PCR method, a SYBR(®) Green qPCR method, and two TaqMan(®) qPCR methods.(More)
The decay of sewage-sourced Escherichia coli and enterococci was measured at multiple depths in a freshwater marsh, a brackish water lagoon, and a marine site, all located in California. The marine site had very clear water, while the waters from the marsh and lagoon contained colored dissolved organic matter that not only blocked light but also produced(More)