Carpinteria Salt Marsh Reserve

31 Aug, 11 PM - 01 Jul, 02 PM

Fecal pollution, human and non-human, is a major cause of water impairment in coastal areas. However, our understanding fecal pollution in coastal ecosystems, as well as our ability to identify and mitigate its sources, is greatly limited by the uncertainties surrounding its behavior in two major reservoirs: wetlands and beach sediments. Fecal indicator bacteria (FIB) and pathogens can enter coastal creeks and rivers from upland sources, but near-shore beach sources are also significant reservoirs [2-12], and coastal wetlands that have been shown to both increase [8, 13-15] and decrease [16] the levels of FIB in water. This field and laboratory based study has been developed as an ?examination and assessment of sources, levels, and pathways of pathogens?? in coastal wetlands and sediment (CEQI priority area A). Our planned work is comprised of two core focus areas. The first focus area involves conducting field surveys in tandem with laboratory analysis for human specific markers in four coastal wetlands and beaches. The second focus area is a laboratory based, systematic investigation of factors contributing to pathogen and pathogen indicator transport and fate in sediments. Focus Area 1. Sanitary surveys using human Bacteroides markers and a novel rapid tiered approach for source tracking at four chronically impaired beaches. We will study the discharge for four watersheds across a range of geographical conditions and levels of urbanization in which downstream, beach-related chronic water quality problems exist, although from unknown sources. Two watersheds will have a coastal wetland. A tiered approach will be adopted in which typical indicators will first be surveyed, followed by measurement of human specific markers at beach and watershed locations [17, 18] where indicator levels are high. This work will support the development of a sound protocols for conducting sanitary surveys by addressing issues including temporal and spatial variability of FIB and DNA-based fecal indicators in beach sands, sampling effects (including sample size, depth, and handling), variations in DNA or FIB recovery (e.g. due to grain size distributions, variations in bacterial adherence), and influences in tidal cycles plus freshwater discharge on these issues. Seed funding to Walker and Jay from CEQI in 2007-2008 has allowed development of the necessary molecular methods for this work. Specifically, numerous methods for the extraction and purification of DNA from sediment, including gel purification, phenol/chloroform, and various extraction/cleanup kits were tested for DNA purity as well as loss to determine the optimal combination of techniques. In addition, the measurement of Bacteroides by qPCR was conducted successfully on sediment samples from Avalon in 2007 (plasmid kindly provided by Jed Fuhrman at USC as a positive control). Through this work we will test four hypotheses: Hypothesis 1. Application of near-real time FIB sensing can greatly increase the effectiveness of a tiered approach in source tracking. A near-real time assay for enterococci and E. coli based on immunomagnetic separation/ATP quantification will be used to evaluate the freshwater sources in our impaired watersheds. Sites with high levels of these parameters can be identified and resampled for follow up analyses the same day. Hypothesis 2. Identification of human fecal sources can be accomplished via species-specific Bacteroides DNA-based assays coupled with microbial community fingerprinting in water and sand. Inclusion of sand in source tracking studies has not previously been undertaken but may prove important as the sediments can be an important reservoir. Jay?s preliminary work in Bacteroides in sediment at Avalon Beach (Santa Catalina Island) shows a lack of correlation between human-specific Bacteroides and FIB, indicating differential survival in sediments and potential proliferation of non-fecal FIB. Microbial community fingerprinting has been shown by Holden to be effective for comprehensively surveying relatedness of entire bacterial communities in samples to source community DNA. Human-specific and community-based approaches are expected to be complementary for beach source tracking: the first definitively shows the presence of human-specific markers (HSM), but where HSM have differentially attenuated, whole community analysis reveals residual waste signatures if they exist. Hypothesis 3. Levels of FIB and HSM microbial communities in beach sands correlate with adverse health outcomes in populations with increased exposure to sand. Our work at Malibu Beach includes addition of sediment component to a large-scale Southern California Coastal Water Research Project (SCCWRP) epidemiology study. SCCWRP and partners are conducting a major investigation on the relationship between water column FIB and pathogens levels. By collaborating with this study, we will test for correlations with health outcomes for the sediment FIB and HSM levels. Quantitative PCR methods will be used for identifying Bacteroides and Salmonella [19-22]. DNA from the sediment samples collected in the field will be frozen and provide a ?DNA bank? for future investigations. Hypothesis 4. FIB and human specific markers are removed from water as it moves through a wetland (or from a watershed, through to the ocean). Understanding whether there is a relationship between populations of FIB and human specific markers in wetlands is important for determining how wetlands impact human health in coastal bathing waters. Currently, no work has been done investigating the fate of HSM in wetlands. We will evaluate FIB and HSM in water, sediment and suspended sediment during wet and dry weather and different seasonal tidal cycles. Recent work by Ambrose and Myers at Carpinteria Salt Marsh and Santa Ana River suggested that FIB in coastal runoff was largely attenuated in the estuaries [16]. Focus Area 2. Investigation of factors controlling survival and transport of FIB in sediments. Packed bed column experiments will be conducted in saturated and partially saturated sand under a range of conditions identified by field sampling. Model Gram negative (E. coli) and Gram positive (enterococci) will be utilized to test the general hypothesis that deposition and release in sediments occurs as a function of seasonal variations and tidal cycles. Microcosm experiments using pure culture FIB as well as raw sewage will be conducted to fill crucial gaps in our understanding of FIB and Bacteroides fate and survival in sand. Recent work [23] has shown that through beach flow can be an important source of FIB to seawater. Also, a previous partnership between Heal the Bay and Jay showed strong evidence that subsurface migration of stormwater is a likely factor in surf zone water quality at Santa Monica pier. Work proposed here will provide further insight in these processes. Hypothesis 1. Transport of FIB, and the capacity of sediment to retain FIB, is correlated with seasonal variations of salinity and temperature. Recent work by Walker has shown E. coli adhesion to quartz sand and transport through porous media highly sensitive to temperature and IS [24] ? both which would vary seasonally. Hypothesis 2. Transport of FIB, and the capacity of the sediment to serve as a pathogen ?sink? is related to the varying degrees of sediment saturation. Recently Walker and colleagues have demonstrated that varying levels of water saturation in sand, as well as the ionic strength of the pore fluid, influences colloid transport [25]. Few have investigated looking not only at various levels of saturation, let alone the actual process of de-saturating or re-saturating under representative aquatic solution conditions simulating tidal cycles. In testing this hypothesis, it will be demonstrated whether sediments influenced by regular tidal fluctuations have the potential to act as a ?sink? or storage reservoir for FIB. Hypothesis 3. Survival of indicators and pathogens is directly related to the seasonal and tidal variations. Microcosm studies will be conducted exposing sands to the range of conditions tested in the above 2 hypotheses in Focus Area 2. Additionally, the environmental scenarios observed and measured in the field will also be simulated to identify the extent of FIB survival and persistence.

Visit #16748 @Carpinteria Salt Marsh Reserve

Approved

Under Project # 10878 | Research

Fate, Persistence, and Source Identification of Pathogens, Pathogen Indicator Bacteria, and Human Specific Markers in Coastal Beach and Wetland Sediments of Southern California

research_scientist - University of California, Berkeley

Reservation Members(s)

Monique Myers Aug 31, 2008 - Jul 1, 2009 (305 days)
Group of 2 Faculty Aug 31, 2008 - Jul 1, 2009 (305 days)
Group of 2 Research Scientist/Post Doc Aug 31, 2008 - Jul 1, 2009 (305 days)

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