Environmental ecology of human pathogens at the beach

Understanding the challenges for clean safe beach environments and their wider ecosystem services is central to the aims of the Marine Strategy Framework Directive (MSFD), and is vital for the sustainability and economic viability of designated bathing waters. Knowledge of how bathing waters and beach environments, together with local economies might respond to shifts in management decisions is critical in order to inform reliable decision-making and to evaluate future benefits and risks to human health. Maintaining and improving the microbial quality of EU bathing waters is regulated by the Bathing Water Directive (BWD), which uses faecal indicator organisms (FIOs) such as Escherichia coli as a measure of infection risk to humans. Epidemiological studies have established that exposure to FIOs in bathing waters is significantly linked to a decrease in public health. Whilst the BWD was developed to limit human exposure to potential pathogenic diseases, it is only relevant for the small proportion of beach users who actually go into the water. In contrast however, every single beach user is exposed to the sand on the beach, and there is overwhelming data from around the world demonstrating that FIOs and human pathogens are able to survive in beach sand for considerable periods of time. The source of these pathogens could include direct faecal loading from dogs and birds such as gulls, human shedding from skin, and both urban and rural run-off and (more frequently) sewage discharges together with continual replenishment in the intertidal zone from potentially polluted water. Therefore, exposure to beach sand could be a far more significant human exposure route for pathogens and disease than the bathing water itself. Crucially however, there is currently no regulatory requirement for the testing of beach sand at designated bathing waters, which is ultimately driven by a lack of empirical studies demonstrating the potential risk of exposure to pathogens during recreational use of beaches. Therefore, the aim of this studentship is to produce an analytical framework of the risks associated with the whole beach environment, including beach sand, at designated bathing waters, and provide the evidence for a step-change in regulatory public health policy to minimise exposure to pathogens in the beach environment.

Key Research Questions:

1. What are the spatial and temporal dynamics of FIOs and human pathogens at the beach, e.g., from sewage discharge, dog fouling, seagulls?
2. Do sand-borne pathogens present a greater exposure risk than water-borne pathogens at designated bathing waters?
3. What are the policy implications for currently un-explored hotspots of FIOs and pathogens, and what regulatory control strategies need to be developed?


This interdisciplinary project will link environmental microbiology and disease ecology with policy development and public health. To ensure the impact of the science case, sampling methodology will be the same as that used within projects informing environmental policy for the UK Government. During fieldwork at designated UK bathing waters, the student will isolate FIOs (e.g., E. coli) and microbial human pathogens (e.g., bacteria, protozoans & yeasts) from the sand and water and characterise their spatial and temporal dynamics over the bathing water season. In addition, a set of controlled microcosm experiments will be conducted to further understand the dynamics of environmental isolates of E. coil and human pathogens in sand and seawater and their potential for persistence and dispersal, under a range of environmental and anthropogenic variables. The project will also employ qualitative and participatory approaches to complement the quantitative laboratory experiments and field monitoring. Stakeholder engagement strategies will be used to capture the breadth of attitudinal responses surrounding risks of exposure to pathogens at the beach, together with engaging with visitors to beach environments. In parallel to the work on disease ecology and environmental microbiology, the student will carry out a policy-relevant analysis to develop a complementary analytical framework of the risks associated with beach sand at designated bathing waters. This will be driven by a public health agenda and will be central for exploring the development of regulatory policy to minimise risk of exposure to human pathogens at the beach environment.

Project Timeline

Year 1

Phase 1: Following a critical review of the literature (months: 0-4), the student will undertake an intensive field monitoring programme in both Scotland and England during the bathing season to determine spatial and temporal patterns of FIOs and pathogens at the beach (months: 9-12 & 21-24). This will run in parallel with a series of controlled laboratory-based studies to determine microbial dynamics in beach sand and seawater (months 5-24).

Year 2

Phase 2: This phase of the studentship will combine both quantitative and qualitative aspects to produce a conceptual model of the exposure risks associated with human pathogens in beach sand.

Year 3

Phase 3: Integration of environmental and socio-economic data to develop an underlying framework to identify risks of exposure to human pathogens from a visit to the beach.

Year 3.5

The three overlapping experimental phases of this project will take 36 months to complete, with the remaining time being allocated to writing the thesis & papers for publication, attending conferences and networking with stakeholders.

& Skills

This studentship will provide a platform to build an interdisciplinary research career in environmental public health and policy. Extensive skill development in field work will include comprehensive training in environmental sampling and monitoring techniques. The studentship will broaden the scope of the applicant’s skills base by providing specialist training in the safe handling of microorganisms (e.g., Biohazard Group 2 bacteria) together with a wide range of microbiological techniques, and by developing expertise in a range of skills in applied geography. This CASE project will be carried out in close partnership with the environmental regulator SEPA (Scottish Environment Protection Agency), which will allow the student to develop a strong understanding of relevant regulatory and policy agendas.

References & further reading

Metcalf R, White H, Moresco V, Ormsby M, Oliver DM, Quilliam RS. (2022). Sewage-associated plastic waste washed up on beaches can act as a reservoir for faecal bacteria, potential human pathogens, and genes for antimicrobial resistance. Marine Pollution Bulletin 180, 113766

Brandão, J. et al. (2021). Mycosands: Fungal diversity and abundance in beach sand and recreational waters – Relevance to human health. Science of The Total Environment, 781, 146598.

World Health Organization (2021). WHO guidelines on recreational water quality, Volume 1: coastal and fresh waters. World Health Organization.

Quilliam RS, Taylor J, Oliver DM (2019). The disparity between regulatory measurements of E. coli in public bathing waters and the public expectation of bathing water quality. Journal of Environmental Management 232, 868-874

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