Managing shellfish water quality under uncertain climate: Time to adapt?

May 7th, 2013

Carlos J. A. Campos, Centre for Environment, Fisheries & Aquaculture Science, United Kingdom

Shellfish waters provide a variety of ecosystem services and support a diverse array of important economic and cultural activities. In many contexts, shellfish waters can be considered commodities yet they have many characteristics of public goods; they provide shellfish products which are excellent complements of a healthy diet. Molluscan shellfish farming grew steadily from 3 million tonnes in 1990 to nearly 12 million in 2008, making them one of the fastest growing sectors of the world’s aquaculture production.1 However, in Europe this trend was only consistent until the later 1990s, showing a decreasing trend thereafter.2

With stagnant aquaculture production, European markets are increasingly dependent upon imports and will face significant challenges in the long-term, including the capacity to produce affordable, high-quality protein required by a growing human population. On a global scale, three issues will affect seafood security in the immediate future: climate change, increasing demand and competition for high value seafood products, and global financial security.1

Maintenance of high quality coastal waters is of prime importance to maintaining access to shellfish that are safe to eat. Contamination of shellfish waters with pathogenic bacteria and viruses could lead to significant economic costs, such as those associated with shellfish production and marketing, health care, degradation of ecosystem services, reduced tourism activity, and increased water treatment processes. Shellfish borne diseases cause millions of hospitalisations worldwide.3,4,5 Viruses, particularly noroviruses and hepatitis A virus are common causes of shellfish borne infections although most hospitalisations and deaths are due to bacterial agents (Salmonella and Vibrio species).6

Identifying risks and uncertainties

The impacts of pollution on shellfish water resources are controlled by factors both outside and inside the ‘waterbody’. The most common mechanisms of introduction of pathogens in shellfish waters are discharges of sewage from municipal and industrial waste water treatment plants, discharges of stormwater and runoff from agricultural and urban land. Despite significant investment in wastewater treatment in recent decades, vast quantities of insufficiently treated sewage are still discharged directly to European coastal waters.7 Even where wastewater treatment plants exist, their inefficient operation and the dis­posal of waste sludge may contaminate soils, surface water and groundwater. Runoff from agricultural land can also contribute significant loads of microbiological contaminants to shellfish waters, particularly during wet weather.8 Intensive livestock production units often create water contamination hot spots with elevated levels of biological oxygen demand and nutrients. In addition, industrial areas have long been associated with the introduction of hazardous contaminants into shellfisheries.

Human populations are growing and increasingly moving to urban areas on the coast, where many cities with populations exceeding 50,000 are situated in close proximity to shellfish waters. Under these circumstances, enforcement of environmental standards is often challenging, making it difficult to prevent water pollution incidents.

Tourism generally provides a strong incentive to protect the environment and water quality because a healthy environment is what attracts people and trade. However, seasonal variations of human population affect the performance of wastewater treatment plants and the quality of effluent discharges.9 Indeed, tourism and recreational activities have also contributed to compromising the quality of coastal waters.10,11 These activities directly influence contaminating pathways, namely discharges from sewage outfalls, waste discharges from recreational vessels, and faecal pollution from pets and surface water runoff.

Climatic events are becom­ing increasingly erratic and violent12 and will have quite profound impacts in low-lying coastal areas in the future, particularly on the abundance and distribution of marine pathogens, erosion and sedimentation, flooding and distribution of habitats.13 The Intergovernmental Panel on Climate Change predicts serious impacts in coastal areas although it emphasizes that there are still ma­jor uncertainties in its forecasts and significant inter-regional variability.14 Nevertheless, some issues require immedi­ate attention. For instance:

Major floods could affect coastal water quality and the performance of waste-water treatment plants, leaving some shellfish waters potentially exposed to elevated levels of pathogens;

Heavy rains and floods could increase re-suspension of contaminants;

Droughts and extreme low flows in watercourses could reduce the natural capacity of soils to absorb and process contaminants;

Many estuaries could also be affected by increasing saltwater intrusion and this may also influence the distribution of pathogens.

In addition to these factors, climate changes could also affect the shellfish industry in ways that alter the quality, distribution and quantity of shellfish supply and demand.

One of the key findings of regulatory monitoring is the growing understanding that shellfish water quality is determined by complex interacting environmental processes where contaminants often show random and chaotic variability.15 Currently, the scientific understanding of the mechanisms driving this variability relies considerably on process-based, deterministic catchment models that contain significant levels of uncertainty. Whilst these models have provided important evidence towards reducing pollution from sewerage infrastructure and contributed to successful management of shellfisheries in some parts of the world, they do not always allow the resilience necessary to minimise the effects of pollution incidents derived from climate change in the long-term. Therefore, despite the limitations imposed by the current global finan­cial crisis, it is important to continue investments in sewerage systems as well as researching mitigation and adaptation responses. It is also urgent to create more innovative solutions for wastewater treatment and infrastructure within the financial capabilities of governments, potentially incorporating more comprehensive cost-benefit analy­sis.16 In addition, improved emergency responses for rainfall-dependent sewage discharges are urgently required considering their high impact on regulatory non-compliance of shellfish waters,14 particularly in a changing climate.

Towards adaptation thinking

Risk and uncertainty associated with weather events have long been a challenge to shellfish regulators managing shellfish water quality across the world. How can they plan for and adapt to increasingly uncertain future climatic conditions? Science can certainly help articulate where and how to reduce uncertainty associated with climatic predictions. However, scientific understanding and participation of scientists in decision-making can encounter barriers. More effective communication is required between scientists, policy-makers, shellfish industry members and the general public to help expand the range of policy options that are being proposed and implemented.

Finally, a more flexible approach is required to ensure more effective management of shellfish waters and better consumer protection, perhaps replacing the ‘impacts-thinking’ approach that currently dominates this management by an ‘adaptation-thinking’. This will acknowledge the dynamic characteristics of ecosystems and climate change and shift the focus of climate change adaptation from a particular set of impacts to the process of resource management itself.17 The application of an ‘adaptation thinking’ to shellfish water quality issues could offer a more flexible and continuous process of adjustment to changes in society, technologies and climate. Ultimately, it could also bring significant economic benefits to govern­ments and individuals through reduced expenditure on disease treatment.

References:

1. FAO (2010) The state of world fisheries and aquaculture. FAO Fisheries and Aquaculture Circular No. 1061/1, Rome.

2. Váradi, L., Lane, A., Harache, Y., Gyalog, G., Békefi, E. and Lengyel, P. (2011) Regional review on status and trends in aquaculture development in Europe – 2010. FAO Fisheries and Aquaculture Circular No. 1061/1, Rome FIRA/C1061/1 (Bi).

3. Potasman, I., Paz, A. and Odeh, M. (2002) Infectious outbreaks associated with bivalve shellfish consumption: a worldwide perspective. Clin Infect Dis 35: 921-928.

4. Iwamoto, M., Ayers, T., Mahon, B.E. and Swerdlow, D.L. (2010) Epidemiology of seafood-associated infections in the United States. Clin Microbiol Rev 23(2): 399-411.

5. Hall, A.J., Eisenbart, V.G., Etingüe, A.L., Hannah Gould, L., Lopman, B.A. and Parashar, U.D. (2012) Epidemiology of foodborne norovirus outbreaks, United States, 2001-2008. Emerg Infect Dis 18(10): 1566-1573.

6. Butt A.A., Aldridge, K.E. and Sanders, C. (2004) Infections related to the ingestion of seafood. Part I: viral and bacterial infections. Lancet Infect Dis 4: 201-212.

7. European Environment Agency (2010) The European environment. State and outlook 2010. Synthesis. EEA, Copenhagen.

8. Kay, D., Crowther, J., Stapleton, C.M., Wyer, M.D., Fewtrell, L., Anthony, S., Bradford, M., Edwards, A., Francis, C.A., Hopkins, M., Kay, C., McDonald, A.T., Watkins, J. and Wilkinson, J. (2008) Faecal indicator organism concentrations and catchment export coefficients in the UK. Water Res 42: 2649-2661.

9. De Luca-Abbott, S., Lewis, G.D. and Creese, R.G. (2000) Temporal and spatial distribution of enterococcus in sediment, shellfish tissue, and water in a New Zealand harbour. Journal of Shellfish Research 19(1): 423-429.

10. Sobsey, M.D., Perdue, R., Overton, M. and Fisher, J. (2003) Factors influencing faecal contamination in coastal marinas. Water Sci Technol 47(3): 199-204.

11. Campos, C.J.A. and R. Cachola (2007) Faecal coliforms in bivalve harvesting areas of the Alvor Lagoon (Southern Portugal): influence of seasonal variability and urban development. Environmental Monitoring and Assessment 133: 31-41.

12. Royal Commission on Environmental Pollution (2010) Adapting institutions to climate change. Twenty-eighth Report to UK Parliament by Command of Her Majesty, March 2010. http://www.ukcip.org.uk/wordpress/wp-content/PDFs/RCEP_adaptation_final_report.pdf.

13. Lowe, J.A., Howard, T.P., Pardaens, A., Tinker, J., Jenkins, G., Ridley, J., Leake, J., Holt, J., Wakelin, S., Wolf, J., Horsburgh, K., Reeder, T., Milne, G., Bradley, S. and Dye, S. (2009) UK climate change projections science report: marine and coastal projections. Met Office Hadley Centre, Exeter, UK.

14. Kay, D. and Rees, G. (2010) Framework for change. Safe management of shellfish and harvest waters. In: Rees, G., Pond, K., Kay, D., Bartram, J., Santo Domingo, J. (Eds). IWA Publishing, London, UK.

15. Campos, C.J.A., Acornley, R., Morgan, O.C. and Simon Kershaw. In press. Trends in the levels of Escherichia coli in commercially harvested bivalve shellfish from England and Wales, 1999-2008. Marine Pollution Bulletin.

16. Crowther, J., Kay, D., Campos, C.J.A. and O.C. Morgan. 2011. Sanitary profiles of selected shellfish water catchments pre- and post-improvements in sewerage infrastructure. Cefas report to Defra, Project WT1001 – Factors affecting the microbial quality of shellfish.

17. Matthews, J.H. and Wickel, A.J. (2009) Embracing uncertainty in freshwater climate change adaptation: a natural history approach. Climate Dev 1: 269-279.

Carlos Campos is a shellfish water quality scientist at Cefas, UK and can be contacted at: carlos.campos@cefas.co.uk. He has worked on the effects of sewage discharges and meteorological factors affecting the microbiological quality of commercially harvested shellfish. His research currently focuses on the fate of human noroviruses in the marine environment. Carlos is member of the International Water Association.

The views expressed in this article belong to the individual authors and do not represent the views of the Global Water Forum, the UNESCO Chair in Water Economics and Transboundary Water Governance, UNESCO, the Australian National University, or any of the institutions to which the authors are associated. Please see the Global Water Forum terms and conditions here.