Sanitary surveys in England and Wales

Sanitary surveys in England and Wales: implementation and future perspectives Kershaw Simon 1*, Campos Carlos J. A.1, Hargin Kevin2 1

Centre for Environment, Fisheries & Aquaculture Science (Cefas), Aquatic Health and Hygiene Division, Food Safety Group, Weymouth Laboratory, Weymouth, Dorset, DT4 8UB, UK, *Corresponding author: [email protected] 2 Food Standards Agency (FSA), 125 Kingsway, London, WC2B 6NH, UK

In England and Wales (E&W), fish and shellfish constitute one of the most reported food items causing infectious disease outbreaks in humans. The risk of contamination of bivalve molluscan shellfish with pathogens is assessed through monitoring of the bacterial indicator species Escherichia coli and classification of bivalve mollusc production and relay areas (BMPAs), which in turn determines the level of treatment required before bivalves can be sold for human consumption. Regulation (EC) No 854/2004 introduced additional requirements for competent authorities intending to classify BMPAs. These requirements, which are collectively known in E&W as the “sanitary survey”, aim to inform the sampling plans for the microbiological monitoring programme. In E&W, sanitary surveys are undertaken by Cefas on behalf of the competent authority, the Food Standards Agency. This paper describes the approach taken to date in prioritising and undertaking these surveys in E&W. This includes the identification of sources of microbiological pollution of human and animal origin, pathways of pollution transport, assessment of the potential risk of microbiological contamination in bivalves and the development of a sampling plan. It is concluded that sanitary surveys have contributed to improve the identification of pollution events and the sources of those events such that, remedial action can be taken to the benefit of public health and the sustainable development of the fisheries. Keywords: Bivalve mollusc, Contamination, Official controls, E. coli, Microbiological monitoring, Regulation, Sanitary survey, Shellfish.

Introduction In England and Wales (E&W), fish and shellfish are the food vehicle (after poultry, red meat and desserts) of humans (Hughes et al. 2007). Statutory controls aimed diseases within the European Union have been based monitoring and

fourth most commonly reported infectious intestinal disease in at minimising the risk of these on the use of microbiological

classification of bivalve mollusc production or relaying areas (BMPAs) and postharvesting treatments, which may be required before bivalves can be sold for human 1 ICMSS09 – Nantes, France – June 2009 www.symposcience.org

consumption. Following entry into force of Regulation (EC) No 854/2004, additional requirements on the organisation of official controls for live bivalve molluscs intended for human consumption were introduced in the United Kingdom legislative framework in 2006. Annex II of the regulation stipulates that competent authorities deciding to classify BMPAs should “(a) make an inventory of the sources of pollution of human and animal origin likely to be a source of contamination for the production area; (b) examine the quantities of organic pollutants which are released during the different periods of the year, according to seasonal variations of both human and animal populations in the catchment area, rainfall readings, waste-water treatment, etc.;” and “(c) determine the characteristics of the circulation of pollutants by virtue of current patterns, bathymetry and the tidal cycle in the production area;”. Collectively, these tasks are equivalent to what has been termed in other countries undertaking such controls as the “sanitary survey”. The main purpose of these surveys is to inform sampling plans for the microbiological monitoring of BMPAs. The Regulation further specifies that these plans should be “based on the examination of established data, and with a number of samples, a geographical distribution of the sampling points and a sampling frequency which must ensure that the results of the analysis are as representative as possible for the area considered”. In this paper, we describe the current practice on the implementation of sanitary surveys for new BMPAs in E&W, which Cefas is undertaking on behalf of the competent authority - the Food Standards Agency (FSA).

1. The sanitary survey process 1.1. Receipt and validation of applications for new production areas Since April 2007, sanitary survey requirements have been implemented for new beds, extensions to classified beds or entirely new BMPAs newly classified after 1 January 2006. These are identified to Cefas or the FSA by means of an official ‘new harvesting area’ application form. The form: includes details of the the proposed operation and the production area requiring classification, evidence of permission to fish, conservation controls; annual production and date by which the classification is required and a map detailing the perimeter of the area to be harvested. The details of the operation need to include the growing method, harvesting method and seasonality of harvest. Upon receipt, validation and acknowledgement of the application form a sanitary survey is initiated. The sanitary survey involves three main stages: desk-based study, shoreline survey and, if necessary, a bacteriological survey (Figure 1). The desk study analyses the relevant available information necessary to produce an assessment of pollution sources on the microbiological contamination of BMPAs.

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Figure 1. Process summary for sanitary surveys in England and Wales.

To complete this study, Cefas liaises with the shellfish industry, Local Enforcement Authority (LEA), Environment Agency (EA), water companies, Department for Environment, Food and Rural Affairs (Defra), Meteorological Office, United Kingdom Hydrographic Office, Office for National Statistics, Sea Fisheries Committees (SFCs), marina offices/harbour masters, tourist boards, academic institutions, the Royal Society for the Protection of Birds, British Trust for Ornithology and environmental consultants, as appropriate together with other local organisations and individuals. The shoreline survey is the physical inspection of the shoreline and adjacent areas to confirm the presence of sources of contamination identified during the desk study and to identify any additional sources of contamination impacting the BMPA (Figure 2). Shoreline surveys are usually carried out with the participation of LEAs, the applicant and, occasionally, with officers from SFCs or the EA. A bacteriological survey may be carried out to help assess spatial variation in contamination within the proposed harvesting area.


Figure 2. Example map showing types of information obtained during shoreline surveys: (A) pollution source; (B, C) fishing practices; (D) sewage related debris; (E) freshwater inputs.

The outcomes of the sanitary survey consist of an overall assessment of sanitary survey data and a recommended sampling plan for the monitoring programme. The results are disseminated in the form of a technical report, which undergoes a period of consultation with relevant parties. Following identification of representative monitoring points (RMPs), implementation of monitoring towards provisional classification can take place in accordance with Cefas protocols. Currently, a minimum of six months is anticipated as the time between an accepted application and recommendation for provisional classification of the new BMPA. This period allows approximately three months to undertake the sanitary survey and to produce the sampling plan followed by three months of microbiological monitoring to derive the classification. During this process, the competent authority, the applicant and the LEA are kept informed on the progress of the survey.

1.2. Inventory of pollution sources Pollution sources of human and animal origin that could give rise to faecal contamination of bivalve molluscs have been thoroughly discussed in the literature (e.g. Garreis 1994; Lee et al. 2003; Sobsey et al. 2003). The EU Working Group on the Microbiological Monitoring of Bivalve Mollusc Harvesting Areas considers that as much information as possible on continuous discharges, rainfall-dependent sewage discharges (combined sewer overflows, storm overflows), emergency discharges, land use, farm animals, wildlife and ships and boats should be obtained and recorded (Cefas 2007). In E&W, it has been shown that a significant proportion of the variation of E. coli in bivalve molluscs commercially harvested in E&W could be explained by the size of discharge and distance discharge-sampling point (Lee and Glover 1998). However, coastal areas which have been subject to significant improvement schemes to continuous and intermittent discharges have shown noteworthy differences in overall microbiological qualities of commercially harvested bivalves (Kershaw and Younger 2004; Acornley and Kershaw 2008). Therefore, 4 ICMSS09 – Nantes, France – June 2009 www.symposcience.org

particular consideration is given to the identification of those sewage discharges likely to represent higher risk of contamination. The Cefas Shellfish Hygiene System, a Microsoft SQL 7.0 database running in a Citrix client server environment that integrates geographically referenced data on consented sewage discharges and shellfisheries (production areas, sampling points, sampling authorities and laboratories and results of microbiological testing), has been a valuable source of information for these purposes. Figure 3 shows an example thematic map by discharge type and periodicity.

Figure 3. Example map of significant sewage discharges and watercourses in a catchment draining to bivalve mollusc production areas.

The effects of diffuse pollution from agricultural land on the water quality of riverine systems and coastal waters have gained particular attention in recent years (Campbell et al. 2004). Despite the increased awareness in best management practices to control microorganism pollution in many parts of the UK, farm animal waste is still a potentially significant source of microbiological contamination impacting many estuaries and bays where aquaculture operations are established. Considerable effort has been made to collate information on farming practices (e.g. storage sites and spreading regimes for manures and slurries; livestock densities and grazing patterns) in order to identify areas at risk of diffuse pollution. At catchment level, some information has been obtained from programmes aimed at reducing diffuse water pollution (e.g. catchment sensitive farming delivery initiatives, and European demonstration projects (e.g. Cycleau and ICREWResolving Diffuse Pollution). Literature review is complemented with on-site observations undertaken during shoreline surveys. Information on the existence of livestock access to watercourses, buffer strips aimed at protecting watercourses, existence of wetlands, manure storage sites, farmyard dirty areas and bird roosting areas is recorded. Water samples are collected from watercourses draining from farmland or from impervious surfaces in urbanised areas and 5 ICMSS09 – Nantes, France – June 2009 www.symposcience.org

samples of bivalve molluscs are also collected from the area requiring classification. These samples are quantified for Escherichia coli (E. coli) the statutory indicator of contamination of faecal origin (European Communities, 2005).

1.3. Quantities of microbiological pollutants and their seasonality Time series analyses of the microbiological content of rainfall-dependent discharges, daily rainfall totals and levels of E. coli in bivalves (Figure 4) has contributed to assessments of whether the frequency and magnitude of periods of deteriorated microbiological water quality has affected bivalves. The study of seasonal variations of microbiological loads from continuous discharges have also contributed to understand the extent to which seasonal variations in human population (due to tourism, for example) result in deteriorated water quality in receiving waters. Liaison with the EA and water companies has allowed identification of those discharges that have the potential to affect the BMPA.

Figure 4. Example time series plot of daily rainfall totals, sewage spill events and levels of E. coli in Pacific oysters from a bivalve mollusc production area showing: (i) Elevated results are not restricted to periods of prolonged or high rainfall associated with this gauging station; (ii) Spills events do not always coincide with rainfall events from the gauging station selected; (iii) No consistent pattern is seen in relative E. coli contamination between these sites.

Consideration has also been given to collating information from bacteriological surveys undertaken as part of pollution prevention/reduction programmes. A restricted amount of data has been available from catchment-scale studies. In some cases, the value of this information is limited, for example when these surveys are carried out in periods when there is no bivalve harvesting activity (e.g. due to seasonal conservation controls). When more detailed studies are not available, typical concentrations/loads of bacteria associated with animal and human sources have been used. Rainfall-runoff responses have been studied by describing catchment characteristics (e.g. geology, land uses and land cover) and analysing hydrographs and hyetographs. These studies have shown that, in some areas, levels of E. coli in bivalves are highly influenced by river catchment hydrological characteristics; usually, the duration and intensity of rainfall are important in determining peak levels of bacteria in bivalves, particularly in watercourses with “flashy” responses in water levels. However, heavy rainfall does not 6 ICMSS09 – Nantes, France – June 2009 www.symposcience.org

always determine high levels of bacteria in coastal waters. In some areas, the rainfall levels could actually help maintain low levels of bacteria in watercourses due to washout from the catchment.

1.4.Circulation of pollutants Coastal circulation is very complex and subject to a variety of mixing and transport processes. The legislation cites tides and currents as the factors that should be studied for sanitary survey purposes. Information on tidal elevation characteristics and tidal streams has been obtained from Admiralty charts and tidal prediction programmes and summarised in sanitary survey reports. This helps the assessment of the capability of tidal currents to move sediments (see Dyer et al. 1994) and other contaminated suspended matter. Information from dye tracing studies and mathematical models simulating the movement and dispersion of contaminants (Figure 5) has helped to inform assessments of spatial variations in levels of contamination between and across BMPAs, particularly when model grid resolutions are adequate to the extent of areas being assessed. More complex models involving advection, dispersion and decay of bacterial concentrations over tidal cycles have been developed for some areas for the purpose in the scope of sewage improvement schemes or marina/port management and development plans. Cefas has also undertaken simple analyses of salinity differences and relationships with concentrations of microbiological indicators.

Figure 5. Example dye dispersion study. Figure reproduced with the consent of HR Wallingford Ltd, the copyright owner. HR Wallingford Ltd will accept no liability for the use by third parties of information contained within this figure.

1.5. Overall assessment and sampling plan All analyses of sanitary survey data in E&W contribute to an overall assessment of the effects of pollution sources on the microbiological contamination of BMPAs. The rationale is to consider, for each source, the microbiological load, its relationship with other sources and the potential transport mechanisms determining the impact on bivalve molluscs. These considerations determine a sampling plan (Figure 6) detailing the location of sampling points and sampling frequency, as required by the legislation.


Figure 6. Example sampling plan map showing boundaries of classification zones and locations of representative monitoring points (RMPs).

In E&W, sampling plans constitute a formal document containing the following information: • Name and contact of sampling authority; • Species, growing methods and harvesting techniques; • Location of bivalves; • Sampling point coordinates; • Depth of sampling; • Geographic tolerance of sampling around fixed point; • Delineation of classification zones/production areas; • Frequency of sampling; and • Time of next review of the sanitary survey. Liaison with LEAs during the Sanitary Survey allows discussion on practicalities associated with the implementation of sampling plan recommendations. Constraints associated with collection, transporting and analysing samples together with associated costs may arise. In these cases, further rationalisation of the sampling plan may be recommended.

2. Recent progress and major constraints To date significant progress has been made in analysing the contamination status of BMPAs, discriminating levels of contamination between species of bivalves and studying the effect of environmental factors on the levels of contamination in BMPAs. Progress has also been made at identifying gradients of contamination between beds. This has been possible due to the availability of long-term and quality assured data from the Shellfish Hygiene monitoring programme. Consideration has been given to incorporating analyses of microbiological data from other monitoring programmes (e.g. Shellfish Waters, Bathing Waters) in order to clarify spatial and temporal variations in levels of contamination within production areas. 8 ICMSS09 – Nantes, France – June 2009 www.symposcience.org

Cefas has liaised closely with the EA and water companies and industry on the identification of sewage discharges that could represent high risk to shellfisheries. Shoreline surveys have provided the opportunity to verify and update information on fishery limits and activities. Water samples collected during these surveys from watercourses and sewage discharges and shellfish samples from areas requiring classification have been particularly valuable in putting the potential effects of these sources into context. Potentially significant localised sources such as bird roosting areas or areas where livestock is observed to access watercourses have been informative. Several constraints have been identified during the implementation of sanitary surveys in E&W. Some of these arise from the level of detail given in the legislation. Up to date information on the extent and location of bivalve mollusc beds is not always available for wild shellfisheries as the frequency and extent of stock assessments differ from area to area according to resources available to fishery management authorities. Poor business planning for development of aquaculture operations can result in false expectations with respect to areas to be classified, particularly in the first years of investment. When this occurs, the assessment of the effects of pollution sources on bivalve molluscs, the delimitation of classification zones and implementation of the sampling plan could be delayed or even compromised. To date, it has not been possible to obtain field level information on animal and human “biosolids” spreading. Bacteriological studies determining microbiological loads to coastal areas which could be used to determine which catchment areas are likely to mostly contribute to high microbiological loads are not necessarily available. Undertaking such studies would be beyond the scope of the programme and available resources as are the commissioning of detailed hydrographic studies. Absence of detailed hydrographic data in some coastal areas including limited information on density flows, bathymetric variation and atmospheric forcing which could affect residual circulation patterns have been recognised as significant impediments to wellinformed assessments of contaminant transport to and across BMPAs. Cefas has relied on water movement studies from third party institutions and supplemented these data with field observations and limited measurements of water quality parameters during shoreline surveys. Finally, overall assessments of sanitary survey data have contributed to the identification of worst-case sampling conditions. However, it has been recognised that sampling authorities could have difficulties in implementing recommendations for worst-case sampling. A discussion of the potential implications of these recommendations for monitoring programmes is given by Campos et al. (submitted) in this volume.

3. Future perspectives Obvious benefits to the Shellfish Hygiene Monitoring Programme have been recognised following the implementation of sanitary surveys in E&W. Ultimately, the programme has contributed to improve public health control mechanisms and therefore the sustainability of shellfisheries. The role of sanitary surveys in identifying microbiological pollution sources can be used to inform future water quality investment programmes. New remote sensing techniques for high resolution bathymetric data acquisition coupled with sensors to assimilate water quality parameters could reduce the uncertainty of predictions from more “traditional” models and offer identification and enhanced resolution of small-scale hydrodynamic processes. 9 ICMSS09 – Nantes, France – June 2009 www.symposcience.org

Outcomes of sanitary surveys could be considered in the scope of local environmental management plans and studies on site suitability for the establishment of new aquaculture operations. For further information the following site can de visited: http://www.nrlcefas.org/Content/Statutory%20procedures/Leaflet_on_Sanitary_Surveys.pdf.

Acknowledgements. Cefas would like to thank the large number of people who have collaborated with the implementation of the sanitary survey requirements in England and Wales. References Acornley, R.and Kershaw, S., 2008, Assessment of the effects of improvements to wastewater pipeline discharges on bacterial contamination of shellfisheries in England and Wales. In: Proceedings of the MWWD 5th International Conference on Marine Waste Water Discharges and Coastal Environment. October 27-31 2008. Catvat (Dubrovnik), Croatia. (Available on DVD from MWWD website). Campbell, N., D’Arcy, B., Frost, A., Novotny, V. and Sansom, A., 2004, Diffuse pollution. An introduction to the problems and solutions, London, IWA Publishing. 322pp. Campos, C.J.A., Hargin, K., Kershaw, S., Lee, R. J., Morgan, O. C., (in prep). Notes on worst-case scenario of microbiological contamination in bivalve mollusc harvesting areas. Proceedings of the 7th International Conference on Molluscan Shellfish Safety, Nantes, France. 14-19 June 2009. Aquat. Living Resour. VV (2010) ppp-ppp Centre for Environment, Fisheries & Aquaculture Science (Cefas), 2007, Microbiological monitoring of bivalve mollusc harvesting areas, guide to good practice: technical application. Issue 3, EU Working Group on the Microbiological Monitoring of Bivalve Mollusc Harvesting Areas. 67pp Dyer, K.R., 1994, Estuarine sediment transport and deposition. In: Pye, K. (Ed.) Sediment Transport and Depositional Processes, Oxford, Blackwell Scientific Publications, 193–218. European Communities, 2004. Regulation (EC) No 854/2004 of the European Parliament and of the Council of 29 April 2004 laying down specific rules for the organisation of official controls on products of animal origin intended for human consumption. Off. J. Eur. Communities L226, 25.06.04, 83–127. European Communities, 2005. Regulation (EC) No 2073/2005 of 15 November 2005 on microbiological criteria for foodstuffs. Official Journal of the European Union L338: 1-26. Garreis, M.J., 1994, Sanitary surveys of growing waters. In: Hackney, C.R., Pierson, M.D. (Eds.). Environmental Indicators and Shellfish Safety. Chapman and Hall, New York, 289-330. Hughes, C., Gillespie, I.A., O’Brien, S.J., The Breakdowns in Food Safety Group, 2007, Foodborne transmission of infectious intestinal disease in England and Wales, 1992-2003. Food Control 18, 766–772. Kershaw, S. and Younger A., 2004, Evaluation of the effects of improvements to wastewater pipeline discharges on bacterial contamination of shellfisheries in England and Wales. In: Proceedings of the 3rd International Conference on Marine Waste Water Discharges and Marine Environment. Sept. 27-Oct. 2, 2004. Catania, Sicily (Available on DVD from MWWD website). Lee, R.J., Glover, R.J.O., 1998, Evaluation of the impact of different sewage treatment processes on shellfishery pollution using a Geographic Information System (GIS). Wat. Sci. Technol. 38(12), 15–22. Lee, R., Kay, D., Wilkinson, R.J., Fewtrell, L., Stapleton, C., 2003, Impact of intermittent discharges on the microbial quality of shellfish. Environment Agency R&D Technical Report P2266/TR. 48pp. Sobsey, M.D., Perdue, R., Overton, M., Fisher, J., 2003, Factors influencing faecal contamination in coastal marinas. Water Sci. Technol. 47(3), 199–204.
