Overview of available methods and data

European countries currently use nearly 300 different methods to classify the ecological status of their surface waters. The methods mainly consider species abundance and sensitivity and focus on the impacts of organic pollution and eutrophication. The intercalibration exercise aimed at harmonising the national classifications in order to provide common denominators for the comparison of individual national results within a European context of ecological status classification.

The WISER project reviewed 297 assessment methods, based on a questionnaire survey sent to water authorities in all Member States and additional countries that are being implementing the Water Framework Directive. Twenty-eight countries reported on methods applied to rivers (30% of all assessment methods), coastal waters (26%), lakes (25%) and transitional waters (19%). More than half of the methods are based on either macroscopic plants (28%) or benthic invertebrates (26%); in addition, phytoplankton (21%), fish (15%) and phytobenthos (10%) were assessed (Figure 1).

About three-quarters of the methods identified organisms to species-level while in particular phytoplankton-based methods used class- or 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 were the most common. Fish-based methods had the highest number of different metrics. Fifty-six percent of the methods focussed on the detection of impacts of eutrophication and organic pollution pressures. The most commonly used organism groups in decreasing order were phytoplankton > phytobenthos > macroscopic plants > benthic invertebrates > fish. The order was almost reverse for the detection of the impact of hydrological or morphological deterioration mainly targeted in rivers and transitional waters: fish and macroscopic plants > benthic invertebrates > phytoplankton > phytobenthos.

  Figure 1

The pressure-impact relationships were tested empirically for two-third of the methods, mostly for rivers, lakes and coastal waters, while the methods for transitional waters were least validated. The strength of the relationships differed significantly between organism groups and water categories. The correlation coefficients generally covered a broad range (<0.4 to >0.8). The strength of the relationships decreased in order: Phytoplankton > macroscopic plants > benthic invertebrates > phytobenthos and fish fauna, and for the water categories in order: Coastal waters > lakes > transitional waters > rivers. Status boundaries were mostly defined using statistical approaches.

The pressure-impact relationships were tested empirically for two-third of the methods, mostly for rivers, lakes and coastal waters, while the methods for transitional waters were least validated. The strength of the relationships differed significantly between organism groups and water categories. The correlation coefficients generally covered a broad range (<0.4 to >0.8). The strength of the relationships decreased in order: Phytoplankton > macroscopic plants > benthic invertebrates > phytobenthos and fish fauna, and for the water categories in order: Coastal waters > lakes > transitional waters > rivers. Status boundaries were mostly defined using statistical approaches.

The multitude of aquatic bioassessment methods used for the assessment of the European surface waters is perplexing. It is questionable if the methodological patchwork allows for comparable ecological status classification across Europe. Nevertheless, the WFD intercalibration exercise has provided methodology to check the comparability of results and consistency in classifications. However, despite of more than 10 years of development, there are not fully set of methods for all quality elements in all categories of surface waters. Also the intercalibration still need to be continued in the future to ensure comparability of new methods and improvements of the existing methods.

The multitude of aquatic bioassessment methods used for the assessment of the European surface waters is perplexing. It is questionable if the methodological patchwork allows for comparable ecological status classification across Europe. Nevertheless, the WFD intercalibration exercise has provided methodology to check the comparability of results and consistency in classifications. However, despite of more than 10 years of development, there are not fully set of methods for all quality elements in all categories of surface waters. Also the intercalibration still need to be continued in the future to ensure comparability of new methods and improvements of the existing methods.

The boundaries in the ecological classifications were not often based on ecological principles. The ecological targets are generally based on statistical distributions rather than on meaningful ecological changes in ecosystem functions and in the biological communities. The challenge remains to incorporate ecological components and functions into the national systems of ecological water quality classifications.

Birk, S., Bonne, W., Borja, A., Brucet, S., Courrat, A., Poikane, S., Solimini, A. G., van de Bund, W., Zampoukas, N., Hering, D. (2012). Three hundred ways to assess Europe's surface waters: an almost complete overview of biological methods to implement the Water Framework Directive. Ecological Indicators, 18, 31-41.

Birk, S., Bonne, W., van de Bund, W., Poikane, S., Zampoukas, N. (2012). Europe's quest for common management objectives of aquatic ecosystems. In: Schmidt-Kloiber, A., Hartmann, A., Strackbein, J., Feld, C.K., Hering, D.: Current questions in water management. Book of abstracts to the WISER final conference - Tallinn, Estonia, 25-26 January 2012: 28-29. (download publication)

A large number of datasets from rivers, lakes and coastal waters have been compiled and stored in the WISER Central Database (CDB). Data for all biological quality elements and all water categories are available from the CDB in a harmonised format. More specifically, the CDB can be used to combine (1) biological data with environmental pressure data (chemistry etc.), (2) data for different biological quality elements, (3) data from different water categories. These data are accessible both for WISER partners and for other scientists. The conditions for use of WISER data depend on the intellectual property rights (IPRs) stated by each data owner. Detailed information on all WISER datasets, including IPR information, is available in the WISER metadatabase.

The WISER Central Database contains biological and other environmental data from 26 European countries (Figure 2). The WISER field campaign in 2009/2010 resulted in ca. 8,000 biological samples from ca. 1,000 sampling stations in lakes and coastal/transitional waters from 14 countries, containing altogether 40,000 records of species abundance. In addition, the CDB contains existing datasets from previous research projects, national monitoring etc., containing more than 1,500,000 records of species abundance and 900,000 other environmental observations from ca. 75,000 sampling stations in rivers, lakes and coastal/transitional waters. This extensive database can be very useful also for future research related to river basin management, as well as more general research in e.g. aquatic ecology, biodiversity and environmental stressors.

  Figure 2

Data from the WISER CDB has been used for the many publications as well as for the lake load response tool (LLR website) for planning of river basin management, and for comparison of responses to stressor gradients across different biological quality elements in rivers and lakes. Because of close collaboration between WISER scientists and GIGs (Geographical Intercalibration Groups), WISER data have also been used extensively in the WFD intercalibration exercise.

However, the WISER data may have limited usability for some purposes due to uneven representation of the different countries, water categories and biological quality elements. Due to the intellectual property rights stated by the data owners, only the project partners can download the WISER data. Other persons who are interested in using these data are encouraged to contact the WISER Data service (wp2.1@wiser.eu) or other WISER partners for scientific collaboration.

The publicly available WISER metadata search tool will provide contact information to the relevant WISER partners for each dataset.

Moe, S. J., B. Dudley, R. Ptacnik (2008). REBECCA databases: experiences from compilation and analyses of monitoring data from 5000 lakes in 20 European countries. Aquatic Ecology 42:183-201 (and references within).