✍ Scribed by David M. Oliver; A. Louise Heathwaite; Philip M. Haygarth
No coin nor oath required. For personal study only.
The development of a robust evidence base to inform policy and practice related to catchment microbial dynamics, water quality and human health must be grounded on proven techniques used for microbial water quality analysis. Currently, water regulators are in an exciting transition period with new techniques borne out of the 'molecular revolution' beginning to offer a means of characterising microbial watercourse pollution that challenge 'tried and tested' culture-based reference methods. In this commentary we advocate caution regarding the reliability of quantitative molecular tools and stress the need to continue programmes of cross-validation between enumeration approaches. In turn, novel detection (molecular) methodologies can be validated over time at the larger landscape scale (i.e. the scale at which the policy is implemented) against well-established 'tried and tested' (culture-based) reference methods. This will ensure that hydrologically relevant research and policy questions under consideration still deliver a demonstrable impact for regulators. Indeed, the current European Union (EU) legislation for the microbial quality of bathing and shellfish harvesting waters demands that specific standards are derived from culture-based criteria, highlighting the need to sustain such approaches without their complete abandonment in the face of emerging molecular detection techniques (CEC, 2006a,b). Thus, paradoxically, new molecular technology may compromise the development of the existing, and rather immature, evidence base of catchment microbial dynamics if cross-validation is not properly undertaken. The danger then is that molecular approaches could move on to become the 'gold-standard' without a thorough understanding of the implications for regulation and aspects of modelling and applied research required to meet current water policy frameworks.
Meeting these challenges has clear relevance to those working in the multi-disciplinary field of soil and water science. In this field, there is a drive to understand better the processes and impacts of land management on aquatic and terrestrial systems, and possible impacts on human health (McKergow and Davies-Colley, 2010). Critical to human health is the knowledge of how biological agents such as pathogens, or more commonly surrogate indicators of their presence [e.g. faecal indicator organisms (FIOs)], behave within catchments (Geldreich, 1996;Oliver et al., 2005). For example, how do they persist within or become mobilised from different environmental matrices (such as faeces, manures, soils, stream sediments and waters)? How do FIOs transfer through and across landscapes following rainfall and what is the magnitude of their delivery from land to water? The EU Water Framework Directive (WFD) stipulates that the member states must implement 'programmes of measures' (PoMs) within river basins to protect water quality from microbial impairment. However, fundamental to protecting valuable ecosystem services such as clean and safe recreational and drinking water is a comprehensive understanding of FIO behavioural characteristics in the environment. This will ensure that PoMs can be designed for the greatest effect and decision-making undertaken with the best possible view for sustainable land and water
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