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

Abstract

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),...

Fecal pollution: new trends and challenges in microbial source tracking using next‐generation sequencing

“…have been used to estimate fecal pollution in the past (Savichtcheva and Okabe, ). Recently, Cloutier and McLellan () reported that molecular markers from these fecal anaerobes, such as human‐associated Bacteroides and gull‐associated Catellicoccus marimammalium , accurately detected fecal pollution and correctly identified sources after a combined sewer overflow, while quantification of E. coli alone failed to indicate pollution.…”

“…have been used to estimate fecal pollution in the past (Savichtcheva and Okabe, 2006). Recently, Cloutier and McLellan (2017) reported that molecular markers from these fecal anaerobes, such as human-associated Bacteroides and gullassociated Catellicoccus marimammalium, accurately detected fecal pollution and correctly identified sources after a combined sewer overflow, while quantification of E. coli alone failed to indicate pollution. Despite these successes, drawbacks of fecal anaerobic indicators include geographically consistent distribution (ubiquitous presence in the feces of animal species, globally) and cross-reactivity (present in the feces of multiple animal species) (Boehm et al, 2013;Yahya et al, 2017).…”

Austria-wide survey on resistant, potentially pathogenic bacteria at Austrian bathing sites, 2017

“…These findings indicate that antibiotic resistance genes were acquired by multiple separate acquisition events mediated by plasmids (Villa et al, 2012;Voulgari et al, 2014). The occurrence of plasmids raises concerns about the possibility of the detected strains contributing to the dissemination of resistance genes among bacterial species in the water environment (Cloutier and McLellan, 2017;Rothenheber and Jones, 2018;Schang et al, 2016). Vancomycin-resistant enterococci were not detected in any of the water samples.…”

Kū Hou Kuapā: Cultural Restoration Improves Water Budget and Water Quality Dynamics in Heʻeia Fishpond

“…We also evaluated an internal source of fecal pollution deriving from a large colony of B. ibis residing on the mangrove island on the loko i'a interior. In order to quantify B. ibis fecal contamination, we optimized primers to C. marimammalium (GFC, Table 2), an uncharacterized Gram-positive facultative anaerobe in the order of Lactobacillales (Fusobacterium) [54] originally developed to detect fecal contamination from gulls in coastal environments [41,[55][56][57] for cattle egret fecal material ( Figure S1). Unlike Bacteroidales and Enterococcus, we found a significant decrease in egret fecal bacteria post-restoration, suggesting that increased flushing and decreased residence times had a positive impact on water quality.…”