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Lewis JA, Frost VJ, Heard MJ. Examining the potential impacts of a coastal renourishment project on the presence and abundance of Escherichia coli. PLoS One 2024; 19:e0304061. [PMID: 38787843 PMCID: PMC11125542 DOI: 10.1371/journal.pone.0304061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Accepted: 05/06/2024] [Indexed: 05/26/2024] Open
Abstract
Erosion poses a significant threat to oceanic beaches worldwide. To combat this threat, management agencies often utilize renourishment, which supplements eroded beaches with offsite sand. This process can alter the physical characteristics of the beach and can influence the presence and abundance of microbial communities. In this study, we examined how an oceanic beach renourishment project may have impacted the presence and abundance of Escherichia coli (E. coli), a common bacteria species, and sand grain size, a sediment characteristic that can influence bacterial persistence. Using an observational field approach, we quantified the presence and abundance of E. coli in sand (from sub-tidal, intertidal, and dune zones on the beach) and water samples at study sites in both renourished and non-renourished sections of Folly Beach, South Carolina, USA in 2014 and 2015. In addition, we also measured how renourishment may have impacted sand grain size by quantifying the relative frequency of grain sizes (from sub-tidal, intertidal, and dune zones on the beach) at both renourished and non-renourished sites. Using this approach, we found that E. coli was present in sand samples in all zones of the beach and at each of our study sites in both years of sampling but never in water samples. Additionally, we found that in comparison to non-renourished sections, renourished sites had significantly higher abundances of E. coli and coarser sand grains in the intertidal zone, which is where renourished sand is typically placed. However, these differences were only present in 2014 and were not detected when we resampled the study sites in 2015. Collectively, our findings show that E. coli can be commonly found in this sandy beach microbial community. In addition, our results suggest that renourishment has the potential to alter both the physical structure of the beach and the microbial community but that these impacts may be short-lived.
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Affiliation(s)
- Jordan A. Lewis
- Department of Biology, Winthrop University, Rock Hill, South Carolina, United States of America
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, United States of America
| | - Victoria J. Frost
- Department of Biology, Winthrop University, Rock Hill, South Carolina, United States of America
| | - Matthew J. Heard
- Department of Biology, Belmont University, Nashville, Tennessee, United States of America
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2
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Hill E, Chun CL, Hamilton K, Ishii S. High-Throughput Microfluidic Quantitative PCR Platform for the Simultaneous Quantification of Pathogens, Fecal Indicator Bacteria, and Microbial Source Tracking Markers. ACS ES&T WATER 2023; 3:2647-2658. [PMID: 37593240 PMCID: PMC10428101 DOI: 10.1021/acsestwater.3c00169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 07/03/2023] [Accepted: 07/05/2023] [Indexed: 08/19/2023]
Abstract
Contamination of water with bacterial, viral, and protozoan pathogens can cause human diseases. Both humans and nonhumans can release these pathogens through their feces. To identify the sources of fecal contamination in the water environment, microbial source tracking (MST) approaches have been developed; however, the relationship between MST markers and pathogens is still not well understood most likely due to the lack of comprehensive datasets of pathogens and MST marker concentrations. In this study, we developed a novel microfluidic quantitative PCR (MFQPCR) platform for the simultaneous quantification of 37 previously validated MST markers, two fecal indicator bacteria (FIB), 22 bacterial, 11 viral, and five protozoan pathogens, and three internal amplification/process controls in many samples. The MFQPCR chip was applied to analyze pathogen removal rates during the wastewater treatment processes. In addition, multiple host-specific MST markers, FIB, and pathogens were successfully quantified in human and avian-impacted surface waters. While the genes for pathogens were relatively infrequently detected, positive correlations were observed between some potential pathogens such as Clostridium perfringens and Mycobacterium spp., and human MST markers. The MFQPCR chips developed in this study, therefore, can provide useful information to monitor and improve water quality.
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Affiliation(s)
- Elizabeth
R. Hill
- Water
Resource Science Graduate Program, University
of Minnesota, 173 McNeal
Hall, 1985 Buford Avenue, St. Paul, Minnesota 55108, United States
| | - Chan Lan Chun
- Water
Resource Science Graduate Program, University
of Minnesota, 173 McNeal
Hall, 1985 Buford Avenue, St. Paul, Minnesota 55108, United States
- Natural
Resources Research Institute, University
of Minnesota, 5013 Miller
Trunk Highway, Duluth, Minnesota 55811, United States
- Department
of Civil Engineering, University of Minnesota, 221 Swenson Civil Engineering, 1405
University Drive, Duluth, Minnesota 55812, United States
| | - Kerry Hamilton
- School
of Sustainable Engineering and the Built Environment, Arizona State University, 660 S. College Avenue, Tempe, Arizona 85281, United States
- Biodesign
Center for Environmental Health Engineering, Arizona State University, 727 E. Tyler Street, Tempe, Arizona 85281, United States
| | - Satoshi Ishii
- Water
Resource Science Graduate Program, University
of Minnesota, 173 McNeal
Hall, 1985 Buford Avenue, St. Paul, Minnesota 55108, United States
- BioTechnology
Institute, University of Minnesota, 140 Gortner Laboratory, 1479 Gortner
Avenue, St. Paul, Minnesota 55108, United States
- Department
of Soil, Water, and Climate, University
of Minnesota, 439 Borlaug
Hall, 1991 Upper Buford Circle, St. Paul, Minnesota 55108, United States
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3
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Mathai PP, Dunn HM, Magnone P, Zhang Q, Ishii S, Chun CL, Sadowsky MJ. Association between submerged aquatic vegetation and elevated levels of Escherichia coli and potential bacterial pathogens in freshwater lakes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 657:319-324. [PMID: 30543981 DOI: 10.1016/j.scitotenv.2018.11.484] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 11/30/2018] [Accepted: 11/30/2018] [Indexed: 05/08/2023]
Abstract
Fecal indicator bacteria such as Escherichia coli have been reported to persist and potentially grow in a wide variety of secondary habitats, such as water, beach sand, sediment, periphyton and some algae. However, little is known about their association with submerged macrophytes and how this may influence water quality. In this study, we examined the association of E. coli and potential bacterial pathogens with Eurasian watermilfoil (EWM), an invasive, submerged, macrophyte that has spread across thousands of lakes in North America. EWM samples were collected from 10 lakes in Minnesota, once a month, for six consecutive months from early summer to late fall. Microbiota associated with EWM were examined using membrane filtration, quantitative PCR targeting various bacterial pathogens and host-associated marker genes, and high-throughput DNA sequencing. E. coli densities were generally elevated on EWM samples, and peaked during warmer months. Moreover, our results showed that EWM could serve as a temporal source for transmission of microbiota to the water column. Several potential pathogenic groups, including Aeromonas, Enterobacteriaceae, and Clostridium were present in significantly greater relative abundance on EWM than in water, and waterfowl was predicted to be the major source of fecal contamination. These findings have water quality implications with respect to the potential for submerged macrophytes to harbor and disperse E. coli and other bacterial pathogens in a large number of waterbodies.
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Affiliation(s)
- Prince P Mathai
- BioTechnology Institute, University of Minnesota, St. Paul, MN, USA
| | - Hannah M Dunn
- BioTechnology Institute, University of Minnesota, St. Paul, MN, USA
| | - Paolo Magnone
- BioTechnology Institute, University of Minnesota, St. Paul, MN, USA
| | - Qian Zhang
- BioTechnology Institute, University of Minnesota, St. Paul, MN, USA
| | - Satoshi Ishii
- BioTechnology Institute, University of Minnesota, St. Paul, MN, USA; Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN, USA
| | - Chan Lan Chun
- Department of Civil Engineering and National Resources Research Institute, University of Minnesota, Duluth, MN, USA
| | - Michael J Sadowsky
- BioTechnology Institute, University of Minnesota, St. Paul, MN, USA; Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN, USA; Department of Plant, and Microbial Biology, University of Minnesota, St. Paul, MN, USA.
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4
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Elmberg J, Berg C, Lerner H, Waldenström J, Hessel R. Potential disease transmission from wild geese and swans to livestock, poultry and humans: a review of the scientific literature from a One Health perspective. Infect Ecol Epidemiol 2017; 7:1300450. [PMID: 28567210 PMCID: PMC5443079 DOI: 10.1080/20008686.2017.1300450] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 12/23/2016] [Indexed: 12/16/2022] Open
Abstract
There are more herbivorous waterfowl (swans and geese) close to humans, livestock and poultry than ever before. This creates widespread conflict with agriculture and other human interests, but also debate about the role of swans and geese as potential vectors of disease of relevance for human and animal health. Using a One Health perspective, we provide the first comprehensive review of the scientific literature about the most relevant viral, bacterial, and unicellular pathogens occurring in wild geese and swans. Research thus far suggests that these birds may play a role in transmission of avian influenza virus, Salmonella, Campylobacter, and antibiotic resistance. On the other hand, at present there is no evidence that geese and swans play a role in transmission of Newcastle disease, duck plague, West Nile virus, Vibrio, Yersinia, Clostridium, Chlamydophila, and Borrelia. Finally, based on present knowledge it is not possible to say if geese and swans play a role in transmission of Escherichia coli, Pasteurella, Helicobacter, Brachyspira, Cryptosporidium, Giardia, and Microsporidia. This is largely due to changes in classification and taxonomy, rapid development of identification methods and lack of knowledge about host specificity. Previous research tends to overrate the role of geese and swans as disease vectors; we do not find any evidence that they are significant transmitters to humans or livestock of any of the pathogens considered in this review. Nevertheless, it is wise to keep poultry and livestock separated from small volume waters used by many wild waterfowl, but there is no need to discourage livestock grazing in nature reserves or pastures where geese and swans are present. Under some circumstances it is warranted to discourage swans and geese from using wastewater ponds, drinking water reservoirs, and public beaches. Intensified screening of swans and geese for AIV, West Nile virus and anatid herpesvirus is warranted.
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Affiliation(s)
- Johan Elmberg
- Division of Natural Sciences, Kristianstad University, Kristianstad, Sweden
| | - Charlotte Berg
- Department of Animal Environment and Health, SLU Swedish University of Agricultural Sciences, Skara, Sweden
| | - Henrik Lerner
- Department of Health Care Sciences, Ersta Sköndal Bräcke University College, Stockholm, Sweden
| | - Jonas Waldenström
- Centre for Ecology and Evolution in Microbial Model Systems, Linneaus University, Kalmar, Sweden
| | - Rebecca Hessel
- Division of Natural Sciences, Kristianstad University, Kristianstad, Sweden
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5
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Mika KB, Chavarria KA, Imamura G, Tang C, Torres R, Jay JA. Sources and persistence of fecal indicator bacteria and Bacteroidales in sand as measured by culture-based and culture-independent methods: A case study at Santa Monica Pier, California. WATER, AIR, AND SOIL POLLUTION 2017; 228:124. [PMID: 30853729 PMCID: PMC6404519 DOI: 10.1007/s11270-017-3291-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
This study investigated causes of persistent fecal indicator bacteria (FIB) in beach sand under the pier in Santa Monica, CA. FIB levels were up to 1,000 times higher in sand underneath the pier than that collected from adjacent to the pier, with the highest concentrations under the pier in spring and fall. Escherichia coli (EC) and enterococci (ENT) under the pier were significantly positively correlated with moisture (ρ = 0.61, p < 0.001, n = 59; ρ = 0.43, p < 0.001, n = 59, respectively), and ENT levels measured by qPCR (qENT) were much higher than those measured by membrane filtration (cENT). Microcosm experiments tested the ability of EC, qENT, cENT, and general Bacteroidales (GenBac) to persist under in-situ moisture conditions (10% and 0.1%). Decay rates of qENT, cENT, and GenBac were not significantly different from zero at either moisture level, while decay rates for EC were relatively rapid during the microcosm at 10% moisture (k = 0.7 days-1). Gull/pelican marker was detected at eight of 12 sites and no human-associated markers (TaqHF183 and HumM2) were detected at any site during a one-day site survey. Results from this study indicate that the high levels of FIB observed likely stem from environmental sources combined with high persistence of FIB under the pier.
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Affiliation(s)
- Kathryn B Mika
- Department of Civil and Environmental Engineering, University of California Los Angeles, Los Angeles, CA 90095
| | - Karina A Chavarria
- Department of Civil and Environmental Engineering, University of California Los Angeles, Los Angeles, CA 90095
| | - Greg Imamura
- Department of Civil and Environmental Engineering, University of California Los Angeles, Los Angeles, CA 90095
| | - Chay Tang
- Department of Civil and Environmental Engineering, University of California Los Angeles, Los Angeles, CA 90095
| | - Robert Torres
- Department of Civil and Environmental Engineering, University of California Los Angeles, Los Angeles, CA 90095
| | - Jennifer A. Jay
- Department of Civil and Environmental Engineering, University of California Los Angeles, Los Angeles, CA 90095
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6
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Oster RJ, Wijesinghe RU, Haack SK, Fogarty LR, Tucker TR, Riley SC. Bacterial pathogen gene abundance and relation to recreational water quality at seven Great Lakes beaches. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:14148-14157. [PMID: 25423586 DOI: 10.1021/es5038657] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Quantitative assessment of bacterial pathogens, their geographic variability, and distribution in various matrices at Great Lakes beaches are limited. Quantitative PCR (qPCR) was used to test for genes from E. coli O157:H7 (eaeO157), shiga-toxin producing E. coli (stx2), Campylobacter jejuni (mapA), Shigella spp. (ipaH), and a Salmonella enterica-specific (SE) DNA sequence at seven Great Lakes beaches, in algae, water, and sediment. Overall, detection frequencies were mapA>stx2>ipaH>SE>eaeO157. Results were highly variable among beaches and matrices; some correlations with environmental conditions were observed for mapA, stx2, and ipaH detections. Beach seasonal mean mapA abundance in water was correlated with beach seasonal mean log10 E. coli concentration. At one beach, stx2 gene abundance was positively correlated with concurrent daily E. coli concentrations. Concentration distributions for stx2, ipaH, and mapA within algae, sediment, and water were statistically different (Non-Detect and Data Analysis in R). Assuming 10, 50, or 100% of gene copies represented viable and presumably infective cells, a quantitative microbial risk assessment tool developed by Michigan State University indicated a moderate probability of illness for Campylobacter jejuni at the study beaches, especially where recreational water quality criteria were exceeded. Pathogen gene quantification may be useful for beach water quality management.
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Affiliation(s)
- Ryan J Oster
- U.S. Geological Survey, Michigan Water Science Center , Lansing, Michigan 48911, United States
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Whitman R, Harwood VJ, Edge TA, Nevers M, Byappanahalli M, Vijayavel K, Brandão J, Sadowsky MJ, Alm EW, Crowe A, Ferguson D, Ge Z, Halliday E, Kinzelman J, Kleinheinz G, Przybyla-Kelly K, Staley C, Staley Z, Solo-Gabriele HM. Microbes in Beach Sands: Integrating Environment, Ecology and Public Health. RE/VIEWS IN ENVIRONMENTAL SCIENCE AND BIO/TECHNOLOGY 2014; 13:329-368. [PMID: 25383070 PMCID: PMC4219924 DOI: 10.1007/s11157-014-9340-8] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Beach sand is a habitat that supports many microbes, including viruses, bacteria, fungi and protozoa (micropsammon). The apparently inhospitable conditions of beach sand environments belie the thriving communities found there. Physical factors, such as water availability and protection from insolation; biological factors, such as competition, predation, and biofilm formation; and nutrient availability all contribute to the characteristics of the micropsammon. Sand microbial communities include autochthonous species/phylotypes indigenous to the environment. Allochthonous microbes, including fecal indicator bacteria (FIB) and waterborne pathogens, are deposited via waves, runoff, air, or animals. The fate of these microbes ranges from death, to transient persistence and/or replication, to establishment of thriving populations (naturalization) and integration in the autochthonous community. Transport of the micropsammon within the habitat occurs both horizontally across the beach, and vertically from the sand surface and ground water table, as well as at various scales including interstitial flow within sand pores, sediment transport for particle-associated microbes, and the large-scale processes of wave action and terrestrial runoff. The concept of beach sand as a microbial habitat and reservoir of FIB and pathogens has begun to influence our thinking about human health effects associated with sand exposure and recreational water use. A variety of pathogens have been reported from beach sands, and recent epidemiology studies have found some evidence of health risks associated with sand exposure. Persistent or replicating populations of FIB and enteric pathogens have consequences for watershed/beach management strategies and regulatory standards for safe beaches. This review summarizes our understanding of the community structure, ecology, fate, transport, and public health implications of microbes in beach sand. It concludes with recommendations for future work in this vastly under-studied area.
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Affiliation(s)
- Richard Whitman
- Great Lakes Science Center, United States Geological Survey, 1100 N. Mineral Springs Road, Porter, IN 46304, USA
| | - Valerie J. Harwood
- Department of Integrative Biology, University of South Florida, SCA 110, 4202 E. Fowler Ave. Tampa, FL 33620, USA
| | - Thomas A. Edge
- Canada Centre for Inland Waters, Environment Canada, 867 Lakeshore Road, Burlington, Ontario, Canada L7R 4A6
| | - Meredith Nevers
- Great Lakes Science Center, United States Geological Survey, 1100 N. Mineral Springs Road, Porter, IN 46304, USA
| | - Muruleedhara Byappanahalli
- Great Lakes Science Center, United States Geological Survey, 1100 N. Mineral Springs Road, Porter, IN 46304, USA
| | - Kannappan Vijayavel
- Environmental Health Division, Ottawa County Health Department, 12251 James Street, Suite 200, Holland, MI, 49424, USA
- Remediation and Redevelopment Division, Department of Environmental Quality, State of Michigan, 525 W. Allegan St., Lansing, MI 48909. USA
| | - João Brandão
- Reference Unit for Systemic Infections and Zoonosis, Department of Infectious Diseases, National Institute of Health Dr. Ricardo Jorge, Av. Padre Cruz 1649-016 Lisboa, Portugal
| | - Michael J. Sadowsky
- Department of Soil, Water, and Climate, BioTechnology Institute, University of Minnesota, St Paul, Minnesota 55108, USA
| | - Elizabeth Wheeler Alm
- Department of Biology & Institute for Great Lakes Research, Central Michigan University, Mount Pleasant, MI 48859
| | - Allan Crowe
- Canada Centre for Inland Waters, Environment Canada, 867 Lakeshore Road, Burlington, Ontario, Canada L7R 4A6
| | - Donna Ferguson
- Environmental Health Sciences Department, Fielding School of Public Health, University of California Los Angeles, California 90024, USA
| | - Zhongfu Ge
- Great Lakes Science Center, United States Geological Survey, 1100 N. Mineral Springs Road, Porter, IN 46304, USA
| | | | - Julie Kinzelman
- Department of Public Health, City of Racine, 730 Washington Avenue, Room 109, Racine, WI 53403, USA
| | - Greg Kleinheinz
- Environmental Research and Innovation Centre, University of Wisconsin – Oshkosh, 800 Algoma Boulevard, Oshkosh, WI 54901, USA
| | - Kasia Przybyla-Kelly
- Great Lakes Science Center, United States Geological Survey, 1100 N. Mineral Springs Road, Porter, IN 46304, USA
| | - Christopher Staley
- Department of Soil, Water, and Climate, BioTechnology Institute, University of Minnesota, St Paul, Minnesota 55108, USA
| | - Zachery Staley
- Department of Civil and Environmental Engineering, University of Western Ontario, 1151 Richmond St., London, ON N6A 3K7, Canada
| | - Helena M. Solo-Gabriele
- Department of Civil, Architectural, and Environmental Engineering, University of Miami, 1251 Memorial Drive, McArthur Building Room 252, Coral Gables, FL 33146, USA and, Oceans and Human Health Center, University of Miami Rosenstiel, School of Marine and Atmospheric Science, 4600 Rickenbacker Causeway, Miami, FL 33149, USA
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Haack SK, Fogarty LR, Stelzer EA, Fuller LM, Brennan AK, Isaacs NM, Johnson HE. Geographic setting influences Great Lakes beach microbiological water quality. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:12054-63. [PMID: 24073635 DOI: 10.1021/es402299a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Understanding of factors that influence Escherichia coli (EC) and enterococci (ENT) concentrations, pathogen occurrence, and microbial sources at Great Lakes beaches comes largely from individual beach studies. Using 12 representative beaches, we tested enrichment cultures from 273 beach water and 22 tributary samples for EC, ENT, and genes indicating the bacterial pathogens Shiga-toxin producing E. coli (STEC), Shigella spp. , Salmonella spp , Campylobacter jejuni/coli , and methicillin-resistant Staphylococcus aureus , and 108-145 samples for Bacteroides human, ruminant, and gull source-marker genes. EC/ENT temporal patterns, general Bacteroides concentration, and pathogen types and occurrence were regionally consistent (up to 40 km), but beach catchment variables (drains/creeks, impervious surface, urban land cover) influenced exceedances of EC/ENT standards and detections of Salmonella and STEC. Pathogen detections were more numerous when the EC/ENT Beach Action Value (but not when the Geometric Mean and Statistical Threshold Value) was exceeded. EC, ENT, and pathogens were not necessarily influenced by the same variables. Multiple Bacteroides sources, varying by date, occurred at every beach. Study of multiple beaches in different geographic settings provided new insights on the contrasting influences of regional and local variables, and a broader-scale perspective, on significance of EC/ENT exceedances, bacterial sources, and pathogen occurrence.
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Affiliation(s)
- Sheridan K Haack
- U.S. Geological Survey, Michigan Water Science Center , Lansing, Michigan 48911, United States
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Converse RR, Kinzelman JL, Sams EA, Hudgens E, Dufour AP, Ryu H, Santo-Domingo JW, Kelty CA, Shanks OC, Siefring SD, Haugland RA, Wade TJ. Dramatic improvements in beach water quality following gull removal. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:10206-13. [PMID: 22913457 DOI: 10.1021/es302306b] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Gulls are often cited as important contributors of fecal contamination to surface waters, and some recreational beaches have used gull control measures to improve microbial water quality. In this study, gulls were chased from a Lake Michigan beach using specially trained dogs, and water quality improvements were quantified. Fecal indicator bacteria and potentially pathogenic bacteria were measured before and during gull control using culture methods and quantitative polymerase chain reaction (qPCR). Harassment by dogs was an effective method of gull control: average daily gull populations fell from 665 before to 17 during intervention; and a significant reduction in the density of a gull-associated marker was observed (p < 0.001). Enterococcus spp. and Escherichia coli densities were also significantly reduced during gull control (p < 0.001 and p = 0.012, respectively for culture methods; p = 0.012 and p = 0.034, respectively for qPCR). Linear regression results indicate that a 50% reduction in gulls was associated with a 38% and 29% decrease in Enterococcus spp. and E. coli densities, respectively. Potentially human pathogenic bacteria were detected on 64% of days prior to gull control and absent during gull intervention, a significant reduction (p = 0.005). This study demonstrates that gull removal can be a highly successful beach remedial action to improve microbial water quality.
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Affiliation(s)
- Reagan R Converse
- US Environmental Protection Agency, Chapel Hill, North Carolina 27514, United States.
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