Little is known about the distribution of bacterial indicators and pathogens in biofilms on different surface types in natural aquatic environments. This study was conducted to examine the distribution of pathogens and indicator bacteria in biofilms in an agricultural watershed. The study particularly focused on whether biofilms can act as sinks for pathogenic organisms and could be monitored to protect public health. To do so, we monitored the presence of faecal contamination indicators (heterotrophic plate counts, faecal coliforms, enterococci, and E. coli) and particular pathogens (E. coli 0157, Campylobacter sp. and Salmonella sp.) in water, sediment, and in biofilms on river and slate rock, wood, sandpaper, and Lexan™ in Elk Creek (British Columbia, Canada) from December 2005 to April 2007. Faecal indicator concentrations and pathogen presence were evaluated using standard culturing and isolation methods. The results showed that both faecal indicators and pathogens were present at the headwaters and that the use of water column grab samples underestimated faecal indicator numbers. Also, water column grab samples during the dry season were not representative of pathogens present in the creek. This indicates that biofilms might be the main reservoir of Salmonella sp. and pathogenic E. coli O157 in the summer when rainfall (which results in flow changes and sloughing) is limited. Campylobacter sp. was not retrieved in the dry season. Campylobacter on sediment, slate rock and wood showed high correlations with nitrates and enterococci, which could be used as faecal contamination surrogates. Numbers of indicator organisms and pathogens in one-month biofilms were compared to those in long-term biofilms (colonized 12 and 24 weeks) and short-term biofilms (colonized one to three weeks). The comparison showed that surface type, colonization period and water quality all affected the concentration of indicator organisms and pathogens present in biofilms. Finally, results showed high levels of phenotypic antibiotic resistance of E. coli and pathogenic E. coli O157 isolated from the watershed (even at the headwaters), particularly to tetracycline, ampicillin and streptomycin. This study highlights the potential biofilms could play in prediction of water quality changes, the improvement of sampling methods, and the study of aquatic environments.

Little is known about the distribution of bacterial indicators and pathogens in biofilms on different surface types in natural aquatic environments. This study was conducted to examine the distribution of pathogens and indicator bacteria in biofilms in an agricultural watershed. The study particularly focused on whether biofilms can act as sinks for pathogenic organisms and could be monitored to protect public health. To do so, we monitored the presence of faecal contamination indicators (heterotrophic plate counts, faecal coliforms, enterococci, and E. coli) and particular pathogens (E. coli 0157, Campylobacter sp. and Salmonella sp.) in water, sediment, and in biofilms on river and slate rock, wood, sandpaper, and Lexan™ in Elk Creek (British Columbia, Canada) from December 2005 to April 2007. Faecal indicator concentrations and pathogen presence were evaluated using standard culturing and isolation methods. The results showed that both faecal indicators and pathogens were present at the headwaters and that the use of water column grab samples underestimated faecal indicator numbers. Also, water column grab samples during the dry season were not representative of pathogens present in the creek. This indicates that biofilms might be the main reservoir of Salmonella sp. and pathogenic E. coli O157 in the summer when rainfall (which results in flow changes and sloughing) is limited. Campylobacter sp. was not retrieved in the dry season. Campylobacter on sediment, slate rock and wood showed high correlations with nitrates and enterococci, which could be used as faecal contamination surrogates. Numbers of indicator organisms and pathogens in one-month biofilms were compared to those in long-term biofilms (colonized 12 and 24 weeks) and short-term biofilms (colonized one to three weeks). The comparison showed that surface type, colonization period and water quality all affected the concentration of indicator organisms and pathogens present in biofilms. Finally, results showed high levels of phenotypic antibiotic resistance of E. coli and pathogenic E. coli O157 isolated from the watershed (even at the headwaters), particularly to tetracycline, ampicillin and streptomycin. This study highlights the potential biofilms could play in prediction of water quality changes, the improvement of sampling methods, and the study of aquatic environments.

Little is known about the distribution of bacterial indicators and pathogens in biofilms on different surface types in natural aquatic environments. This study was conducted to examine the distribution of pathogens and indicator bacteria in biofilms in an agricultural watershed. The study particularly focused on whether biofilms can act as sinks for pathogenic organisms and could be monitored to protect public health. To do so, we monitored the presence of faecal contamination indicators (heterotrophic plate counts, faecal coliforms, enterococci, and E. coli) and particular pathogens (E. coli 0157, Campylobacter sp. and Salmonella sp.) in water, sediment, and in biofilms on river and slate rock, wood, sandpaper, and Lexan™ in Elk Creek (British Columbia, Canada) from December 2005 to April 2007. Faecal indicator concentrations and pathogen presence were evaluated using standard culturing and isolation methods. The results showed that both faecal indicators and pathogens were present at the headwaters and that the use of water column grab samples underestimated faecal indicator numbers. Also, water column grab samples during the dry season were not representative of pathogens present in the creek. This indicates that biofilms might be the main reservoir of Salmonella sp. and pathogenic E. coli O157 in the summer when rainfall (which results in flow changes and sloughing) is limited. Campylobacter sp. was not retrieved in the dry season. Campylobacter on sediment, slate rock and wood showed high correlations with nitrates and enterococci, which could be used as faecal contamination surrogates. Numbers of indicator organisms and pathogens in one-month biofilms were compared to those in long-term biofilms (colonized 12 and 24 weeks) and short-term biofilms (colonized one to three weeks). The comparison showed that surface type, colonization period and water quality all affected the concentration of indicator organisms and pathogens present in biofilms. Finally, results showed high levels of phenotypic antibiotic resistance of E. coli and pathogenic E. coli O157 isolated from the watershed (even at the headwaters), particularly to tetracycline, ampicillin and streptomycin. This study highlights the potential biofilms could play in prediction of water quality changes, the improvement of sampling methods, and the study of aquatic environments. / Science, Faculty of / Resources, Environment and Sustainability (IRES), Institute for / Graduate

Yes / The intrinsic fluorescence of aquatic organic matter emitted at 350 nm when excited at 280 nm correlates widely with water quality parameters such as biochemical oxygen demand. Hence, in sewage-impacted rivers and groundwater, it might be expected that fluorescence at these wavelengths will also correlate with the microbial water quality. In this paper we use a portable fluorimeter to assess the relationship between fluorescence intensity at this wavelength pair and Escherichia coli enumeration in contrasting river catchments of poor water quality: in KwaZulu-Natal, S. Africa and the West Midlands, UK. Across all catchments we demonstrate a log correlation (r = 0.74) between fluorescence intensity and E. coli over a seven-log range in E. coli enumerations on non-perturbed (unfiltered) samples. Within specific catchments, the relationship between fluorescence intensity and E. coli is more variable, demonstrating the importance of catchment-specific interference. Our research demonstrates the potential of using a portable fluorimeter as an initial screening tool for indicative microbial water quality, and one that is ideally suited to simple pollution scenarios such as assessing the impact of faecal contamination in river or groundwater at specific sites. / This research was funded by the UK EPSRC Grant EP/H003061/1.

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The Water Framework Directive requires reduced environmental impacts from human activities and for the assessment of the non-market benefits of pollution remediation schemes. This policy shift has exacerbated the research problems surrounding the physical, social and economic consequences of the relationship between land use and water quality. This research seeks to quantify the major socio-economic and environmental benefits for people which may arise as riverine pollution is reduced. To achieve these aims this research integrates primary data analyses combining choice experiment techniques with geographical information system based analyses of secondary data concerning the spatial distributions of riverine pollution. Current knowledge on the microbial quality of river water, measured by faecal indicator organism (FIO) concentrations and assessed at catchment scale, is inadequate. This research develops generic regression models to predict base- and high-flow faecal coliform (FC) and enterococci (EN) concentrations, using land cover and population (human and livestock) variables. The resulting models are then used both to predict FIO concentrations in unmonitored watercourses and to evaluate the likely impacts of different land use scenarios, enabling insights into the optimal locations and cost-effective mix of implementation strategies. Valuation experiments frequently conflate respondents’ preferences for different aspects of water quality. This analysis uses stated preference techniques to disaggregate the values of recreation and ecological attributes of water quality, thereby allowing decision makers to better understand the consequences of adopting alternative investment strategies which favour either ecological, recreational or a mix of benefits. The results reveal heterogeneous preferences across society; specifically, latent class analysis identifies three distinct groups, holding significantly different preferences for water quality. From a methodological perspective this research greatly enhances the ongoing synthesis of geographic and economic social sciences and addresses important policy questions which are of interest to a variety of stakeholders, including government departments and the water industry.