Dramatic Improvements in Beach Water Quality Following Gull Removal

Alternative indicators have been developed that can be used to identify host sources of fecal pollution, yet little is known about how their distribution and fate compare to traditional indicators. Escherichia coli and enterococci were widely distributed at the six beaches studied and were detected in almost 95% of water samples (n ϭ 422) and 100% of sand samples (n ϭ 400). Berm sand contained the largest amount of E. coli (P Ͻ 0.01), whereas levels of enterococci were highest in the backshore (P Ͻ 0.01). E. coli and enterococci were the lowest in water, using a weight-to-volume comparison. The gull-associated Catellicoccus marimammalium (Gull2) marker was found in over 80% of water samples, regardless of E. coli levels, and in 25% of sand samples. Human-associated Bacteroides (HB) and Lachnospiraceae (Lachno2) were detected in only 2.4% of water samples collected under baseflow and post-rain conditions but produced a robust signal after a combined sewage overflow, despite low E. coli concentrations. Burdens of E. coli and enterococci in water and sand were disproportionately high in relation to alternative indicators when comparing environmental samples to source material. In microcosm studies, Gull2, HB, and Lachno2 quantitative PCR (qPCR) signals were reduced twice as quickly as those from E. coli and enterococci and approximately 20% faster than signals from culturable E. coli. High concentrations of alternative indicators in source material illustrated their high sensitivity for the identification of fecal sources; however, differential survival and the potential for long-term persistence of traditional fecal indicators complicate the use of alternative indicator data to account for the levels of E. coli and enterococci in environmental samples. IMPORTANCE E. coli and enterococci are general indicators of fecal pollution and may persist in beach sand, making their use problematic for many applications. This study demonstrates that gull fecal pollution is widespread at Great Lakes beaches, whereas human and ruminant contamination is evident only after major rain events. An exploration of sand as a reservoir for indicators found that E. coli was ubiquitous, while gull host markers were detected in only 25% of samples. In situ sand beach microcosms provided decay rate constants for E. coli and enterococci relative to alternative indicators, which establish comparative benchmarks that would be helpful to distinguish recent from past pollution. Overall, alternative indicators are useful for identifying sources and assessing potentially high health risk contamination events; however, beach managers should be cautious in attempting to directly link their detection to the levels of E. coli or enterococci.KEYWORDS beaches, water quality, human-associated indicators, gull-associated indicators, qPCR F ecal contamination of recreational waters can be a serious threat to public health. Due to the vast diversity of fecal-borne human pathogens, the USEPA has recommended the use of fecal indicator bacteria (FIB),...

Section: Discussionsupporting

confidence: 91%

Distribution and Differential Survival of Traditional and Alternative Indicators of Fecal Pollution at Freshwater Beaches

Cloutier

McLellan

2017

“…For instance, the occurrence of STEC and EPEC has been previously found in some wild birds in Europe, Japan, and the United States, but these studies were limited to only gull and pigeon (15)(16)(17)(18)(19)(20)(21). Moreover, the contribution of fecal bacteria from avian sources and subsequent deterioration of water quality have been demonstrated in a number of studies (22,23), which found a significant correlation between the number of birds and the E. coli concentration (24,25). A direct link between avian STEC isolates causing human illness has also been reported (26).…”

mentioning

confidence: 99%

Occurrence of Diarrheagenic Virulence Genes and Genetic Diversity in Escherichia coli Isolates from Fecal Material of Various Avian Hosts in British Columbia, Canada

Chandran

Mazumder

2014

Contamination of surface water by fecal microorganisms originating from human and nonhuman sources is a public health concern. In the present study, Escherichia coli isolates (n ‫؍‬ 412) from the feces of various avian host sources were screened for various virulence genes: stx 1 and stx 2 (Shiga toxin-producing E. ). None of the isolates were found to be positive for stx 1 , while 23% (n ‫؍‬ 93) were positive for only stx 2 , representing STEC, and 15% (n ‫؍‬ 63) were positive for only eae, representing EPEC. In addition, five strains obtained from pheasant were positive for both stx 2 and eae and were confirmed as non-O157 by using an E. coli O157 rfb (rfb O157 ) TaqMan assay. Isolates positive for the virulence genes associated with ETEC and EIEC were not detected in any of the hosts. The repetitive element palindromic PCR (rep-PCR) fingerprint analysis identified 143 unique fingerprints, with an overall Shannon diversity index of 2.36. Multivariate analysis of variance (MANOVA) showed that the majority of the STEC and EPEC isolates were genotypically distinct from nonpathogenic E. coli and clustered independently. MANOVA analysis also revealed spatial variation among the E. coli isolates, since the majority of the isolates clustered according to the sampling locations. Although the presence of virulence genes alone cannot be used to determine the pathogenicity of strains, results from this study show that potentially pathogenic STEC and EPEC strains can be found in some of the avian hosts studied and may contaminate surface water and potentially impact human health.

“…Microbial source tracking (MST) methodology offers tools to diagnose and identify fecal contamination sources in the environment (1,2). Although it is not a standard environmental monitoring method used for routine regulatory purposes, it has been extensively studied and applied worldwide, especially for deciphering fecal pollution in surface and recreational waters (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14).…”

mentioning

confidence: 99%

Microbial Source Tracking in Adjacent Karst Springs

Ohad

Vaizel-Ohayon

Rom

et al. 2015

cModern man-made environments, including urban, agricultural, and industrial environments, have complex ecological interactions among themselves and with the natural surroundings. Microbial source tracking (MST) offers advanced tools to resolve the host source of fecal contamination beyond indicator monitoring. This study was intended to assess karst spring susceptibilities to different fecal sources using MST quantitative PCR (qPCR) assays targeting human, bovine, and swine markers. It involved a dual-time monitoring frame: (i) monthly throughout the calendar year and (ii) daily during a rainfall event. Data integration was taken from both monthly and daily MST profile monitoring and improved identification of spring susceptibility to host fecal contamination; three springs located in close geographic proximity revealed different MST profiles. The Giach spring showed moderate fluctuations of MST marker quantities amid wet and dry samplings, while the Zuf spring had the highest rise of the GenBac3 marker during the wet event, which was mirrored in other markers as well. The revelation of human fecal contamination during the dry season not connected to incidents of raining leachates suggests a continuous and direct exposure to septic systems. Pigpens were identified in the watersheds of Zuf, Shefa, and Giach springs and on the border of the Gaaton spring watershed. Their impact was correlated with partial detection of the Pig-2-Bac marker in Gaaton spring, which was lower than detection levels in all three of the other springs. Ruminant and swine markers were detected intermittently, and their contamination potential during the wet samplings was exposed. These results emphasized the importance of sampling design to utilize the MST approach to delineate subtleties of fecal contamination in the environment.