Intercalibrating classifications of ecological status: Europe's quest for common management objectives for aquatic ecosystems
Introduction
Anthropogenic activities cause ecosystem deterioration worldwide, resulting in loss of biodiversity and impoverished ecosystem services (Halpern et al., 2008, Lotze, 2010). Aquatic systems are among the most degraded habitats, yet must fulfil societal demands for food, drinking water, transport, power generation and leisure activities (Gleick, 1998, Costanza et al., 1997). Halting and reversing the process of deterioration is a global challenge requiring concerted action (Palmer et al., 2004). The principal tool for the coordinated protection of aquatic ecosystems is river basin management planning that acts across state boundaries and administrative barriers (Griffiths, 2002). To identify management priorities harmonised information about the condition of an ecosystem is essential (DeBarry, 2004). However, the definition of uniform standards and common quality targets between political units is hampered by the multitude of different biological assessment methods applied (Birk et al., 2012a, Cao and Hawkins, 2011).
In the case of the European Water Framework Directive (WFD; European Commission, 2000) biological assessment results have to be expressed as Ecological Quality Ratios (EQR), by comparing monitoring data (e.g. on river fish) with equivalent data from undisturbed or minimally disturbed “reference sites”. The EQR is divided into five status classes (high, good, moderate, poor, and bad), depending on the scale of deviation from reference conditions where 0 = maximum deviation (bad) and 1 = no deviation (high). The WFD Annex V specifies the characteristics of status classes in terms of normative definitions (e.g. at good status the biota “show low levels of distortion resulting from human activity, but deviate only slightly from … undisturbed conditions.”). The most important distinction is that between good and moderate status, because, when the quality status is less than good (‘failing’ water bodies), countries must take action (referred to as a “programme of measures”) to improve a water body until good status is achieved.
As with any common water policy a consistent level of ambition in the protection and restoration of surface water bodies is required across participating countries or states. However, this presents formidable challenges at a continental scale where the diversities of physical and human geography overlap — in this case across the more than 500 million inhabitants of the 27 Member States of the European Union whose environmental, cultural, political and socio-economic identities influence awareness and attitudes to water resources and the willingness or ability to protect or restore them. Such challenges are magnified when catchments straddle the jurisdictions of several environmental institutions, both nationally (Moss, 2012) and internationally in the case of large rivers, such as the Danube (Birk et al., 2012b), or when the need to consider future uncertainties is accommodated into long term planning for protection of water resources (Carter and White, 2012). To achieve this harmony of ambition the WFD stipulates that countries participate in an intercalibration exercise designed to identify and resolve inconsistencies and incomparability between countries in their interpretation of the normative definitions (European Commission, 2011). In simple terms, the intercalibration exercise ensures that, for instance, an Irish water body classified in good status according to the Irish assessment method would also be classified in good status by the Polish or German methods if that water body was located in Poland or Germany, respectively (Birk and Böhmer, 2007).
The intercalibration process is organized hierarchically for each water category: rivers, lakes, and coastal and transitional waters (i.e. estuaries and lagoons). Within each category countries that share a similar biogeographical region belong to a Geographical Intercalibration Group (GIG) (Table 1). The exercise is performed among those countries in a GIG that support similar types of aquatic ecosystems (termed “common intercalibration types”) and expert groups composed of national specialists deal with each relevant biological quality element (BQE; i.e. phytoplankton, benthic flora and invertebrates, fish). To date, the exercise has involved about 70 expert groups intercalibrating more than 300 biological assessment methods for over 100 common intercalibration types of 27 European countries. As an example of harmonisation of the results of biological assessment methods the intercalibration exercise of the WFD is therefore unparalleled in breadth and scale.
In this publication we (1) outline the key principles of the intercalibration methodology, (2) summarise the achievements of intercalibration after seven years of endeavour, and (3) discuss benefits and drawbacks of Europe's quest for common management objectives for its aquatic ecosystems. Up to now, the intercalibration exercise is mostly documented in technical reports and other grey literature; this paper specifically targets scientists and water managers involved in the interpretation of its results, especially in international river basin management planning.
Section snippets
Intercalibration methodology
Setting a consistent level of ambition among ecological status classifications via intercalibration requires an analytical approach that recognises (i) basic differences between the BQEs, (ii) systematic discrepancies between the national assessment methods, and (iii) biogeographical variation across Europe. These issues were addressed by applying appropriate intercalibration options (see Section 2.1), collating suitable datasets, and standardising the national classifications before testing
Overview of intercalibration achievements
Each individual intercalibration exercise ran through the process steps described above and ideally included all the national classifications of a BQE within a common intercalibration type for a water category. A total of 201 individual exercises (Water category × BQE × Common type) were performed, with the most exercises focussing on coastal waters (39% of the total number of exercises) with, on average, n = 2.5 countries participating, followed by rivers (25%, n = 7.9), lakes (21%, n = 5.1) and
Discussion
Good ecological status is an attractive objective for the management of European surface waters, but the natural and cultural diversity within this continent creates many legitimate interpretations of this ambition (Birk et al., 2012a). Intercalibration is thus a necessary precursor to and guarantor of Europe's harmonised water policy. But does it live up to this expectation? To answer this question we start our discussion with a review of the intercalibration achievements, then evaluate the
Conflict of interest statement
There is no conflict of interest.
Acknowledgements
Many dedicated persons were involved in the intercalibration exercise. A few people deserve particular mentioning for their contribution to the process in general: Jürgen Böhmer (Kirchheim/Teck, DE), John Murray-Bligh (Exeter, UK), Roger Owen (Edinburgh, UK), Isabel Pardo (Vigo, ES), Geoff Phillips (Norwich, UK), Didier Pont (Aix en Provence, FR), Rob Portielje (Lelystad, NL), Marcel van den Berg (Lelystad, NL), the late Jean-Gabriel Wasson (Lyon, FR) and Georg Wolfram (Vienna, AT). We thank
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