Assessing the ecological status in the context of the European Water Framework Directive: Where do we go now (original) (raw)
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Towards holistic assessment of the functioning of ecosystems under the Water Framework Directive
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The assessment of chemical and ecological status in the context of the Water Framework Directive requires concrete, holistic knowledge about the abiotic and biotic structural properties and processes that determine the functioning of ecosystems. Ecological indicators typically exhibit non-linear responses to anthropogenic pressures together with great spatial and temporal variability, which underpin emerging key characteristics of natural systems. Recent research on the relationships between ecological indicators and anthropogenic pressures reveals several features of these relationships that can be used to predict meaningful changes of community structure and ecosystem functioning. The effective integration of strategies for assessing chemical status, including complementary biological tools, with strategies for assessing ecological status using functional endpoints of ecosystems may reduce the inherent costs of monitoring and increase the level of protection of the environment. ª
Environmental Management
The EU Water Framework Directive requires the development of management responses aimed towards improving water quality as a result of improving ecosystem health (system state). Ecosystems have potential to supply a range of services that are of fundamental importance to human well-being, health, livelihoods and survival, and their capacity to supply these services depends on the ecosystem condition (its structure and processes). According to the WFD, Programmes of Measures should be developed to improve overall water status by reducing anthropogenic catchment pressures to levels compatible with the achievement of the ecological objectives of the directive, and when designed and implemented properly should improve the ecological condition of aquatic ecosystems that the delivery of ecosystem services depends on. Monitoring and evaluation of implemented measures are crucial for assessing their effectiveness and creating the agenda for consecutive planning cycles. Considering the chall...
Science of The Total Environment, 2012
One objective of the European Union (EU)'s Water Framework Directive (WFD: Directive 2000/60/EC) is for all European surface waters to achieve 'good status' by 2015. In support of this objective, the EU has facilitated an intercalibration exercise to ensure harmonized definitions of the status of water bodies, reflecting the deviation of their properties (mainly biotic assemblages) from a minimally disturbed state, termed the "reference condition". One of the major challenges of the WFD has been to find common approaches for defining reference conditions and to define the level of anthropogenic intervention allowed in reference sites. In this paper we describe how river reference sites were selected in the Central-Baltic region of Europe. A list of pressure criteria was provided and 14 Member States (MSs) categorized each criterion according to the method (i.e. measured, field inspection, etc.) used for reference site screening. Additionally, reference landuse and water-chemistry thresholds were agreed among countries in order to base reference site selection on objective criteria. For land-use criteria, a reference threshold and a rejection threshold were established. Sites with all criteria below the reference threshold were considered to be reference sites; sites having most criteria below the reference threshold and only some parameters between the reference and rejection threshold were "possible reference sites". These sites were retained only after carefully checking the cumulative effects of the pressures using local expertise, and a posteriori water-chemistry evaluation was necessary. In general, the most widespread method for defining a reference site was the measurement of pressures, followed by field inspections and expert judgment. However, some major pressures (e.g. hydromorphological alteration) were evaluated in a number of different ways (e.g. measured, field inspection, expert judgment). Our meta-analyses reveal a need to reinforce standardization in the application of pressure criteria by Member States. The pressure criteria identified in this exercise should be refined and tested with biological data to help in the further validation of minimally disturbed sites (i.e. the WFD "reference condition") and to provide a firm foundation for ecological status assessment. This in turn would ensure that there is pan-European comparability when evaluating the achievement of environmental objectives.
Ecological Indicators
According to the Water Framework Directive (WFD), the status of European surface waters is assessed using aquatic organism groups. Here we present an overview of 297 assessment methods, based on a questionnaire survey addressing authorities in all countries implementing the WFD. Twenty-eight countries reported on methods applied to rivers (30%), coastal waters (26%), lakes (25%) and transitional waters (19%). More than half of the methods are based on macroscopic plants (28%) or benthic invertebrates (26%); in addition, phytoplankton (21%), fish (15%) and phytobenthos (10%) were assessed. Countries of Central and Western Europe had developed almost all methods required for the WFD implementation. Two main sampling strategies were discernable: small-scale sampling of the taxonomically diverse groups of benthic invertebrates and phytobenthos that demand elaborate processing, versus large-scale sampling of vast, species-poor plant stands or the mobile fish fauna. About three-quarters of methods identified organisms to species-level while in particular phytoplankton-based methods used classor phylum-level, or included no taxonomic information. Out of nine metric types distinguished, river methods used more sensitivity and trait metrics while for other water categories abundance metrics prevailed. Fish-based methods showed the highest number of metrics. Fifty-six percent of methods focussed on the detection of eutrophication and organic pollution, with shares decreasing from autotrophic to heterotrophic organism groups: phytoplankton > phytobenthos > macroscopic plants > benthic invertebrates > fish fauna. The order was almost reverse for hydrological or morphological deterioration: fish fauna and macroscopic plants > benthic invertebrates > phytoplankton > phytobenthos. These pressures were mainly assessed by methods applied to rivers and transitional waters. The pressure-impact relationship of about one-third of methods was not tested empirically with methods for transitional waters being the least validated. The strength of relationships differed significantly between organism groups and water categories. The correlation coefficients generally covered a broad range (<0.4 to >0.8), but on average with the pattern: phytoplankton > macroscopic plants > benthic invertebrates > phytobenthos and fish fauna. In terms of water categories the following order resulted: coastal waters > lakes > transitional waters > rivers. Status boundaries were mostly defined using statistical approaches. We advocate better reflection of the necessary sampling effort and precision, full validations of pressure-impact relationships and an implementation of more ecological components into classification.
The Water Framework Directive 2000/60/EC sets out strategic and well-defined objectives for water bodies: to prevent further deterioration of aquatic ecosystems and to achieve a "good ecological status" by 2015. However, the Directive itself is fraught with some weaknesses that are likely to jeopardize the achievement of such goals. The main obstacle, in addition to derogations and extensions allowed by the text, lies primarily in the classification system for assessing the ecological status: it is not sufficiently integrated and, in particular, relegates the hydromorphological elements to a very marginal role. Such a "myopia" would potentially (and paradoxically) permit the further alteration of rivers, which could actually still formally reach a "good" ecological status while experiencing heavy impacts. Insufficient integration among biological, physico-chemical and hydromorphological elements also constitutes a barrier to environmental policy integration in Europe, particularly between the WFD and the Floods Directive. The risk is twofold: on the one hand pursuing the traditional flood defences approach would undermine the achievement of WFD objectives, on the other hand, an excellent opportunity may be missed to reduce flood risk through the improvement of hydromorphological conditions of rivers. As a contribution to overcome these limits, we propose an integrated assessment system for the ecological status of rivers (FLEA: FLuvial Ecosystem Assessment), which fully includes also hydromorphological quality elements.