|Macrobenthos monitoring at the Belgian coast and the evaluation of the availability of reference data for the Water Framework Directive|
|Van Hoey, G.; Wittoeck, J.; Hillewaert, H.; Van Ginderdeuren, K.; Hostens, K. (2008). Macrobenthos monitoring at the Belgian coast and the evaluation of the availability of reference data for the Water Framework Directive. ILVO: Belgium. 72 pp.|
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- Opdracht met betrekking tot het uitvoeren van de kaderrichtlijn water macrobenthos monitoring van de Belgische Kust voor rekening van FOD Volksgezondheid, veiligheid van de voedselketen en leefmilieu, more
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The Water Framework Directive (2000/60/EG) of the European Parliament and of the Council aims to achieve a good ecological and chemical quality status for all water types by 2015. The quality status of a water body can be determined based on the evaluation of biological, chemical and hydro-morphological quality elements. The evaluation of those quality elements is based on the integration of well defined biological quality criteria. Each of these quality criteria support a classification (bad, poor, moderate, good and high) aiming at measuring the ‘health’ of the system compared to reference conditions. Furthermore, the WFD (Article 8) requires to have monitoring programmes for the quality elements in their waters. This project concerns the quality element macro-invertebrates in the Belgian coastal zone (<1 nautical mile). The evaluation tool for macro-invertebrates is the Benthic Ecosystem Quality Index (BEQI), which aims at providing a signal that is capable of showing significant deviations from a defined reference state. An important aspect within the BEQI is the use of the habitat approach, which presumed that there is a habitat typology within the water body. The habitat typology for the Belgian coast concerns the following main types: (1) Abra alba habitat (muddy fine sand), (2) Nephtys cirrosa habitat (well sorted medium sand), (3) Macoma balthica habitat (mud). A first attempt to assess the ecological quality status of macro-invertebrates in the Belgian coastal waters is done within the REFCOAST project and Van Hoey et al. (2007b). This showed some shortcomings, such as (1) the low amount of reference samples and (2) almost no spatial coverage of the assessment samples within the 1 mile zone of the Belgian coast. Consequently, the ecological status of macro-invertebrates and the reference conditions have to be re-determined. This is done within the current project by monitoring the quality element macro-invertebrates for the Belgian Coastal waters (<1 nautical mile) and secondly to re-determine the reference condition for the macro-invertebrates of the Belgian Coast. Nine sampling locations within the 1 mile zone of the coast were selected, based on the position of possible influences (rivers, harbours), nature conservation areas, knowledge on sedimentology and benthic communities. At those sampling locations, 15 samples were at random taken within an area of 0.6 km². This gives a total of 135 samples. An analysis of the benthos characteristics at those locations showed sometimes a big variation of those characteristics within 1 location. An overall trend is an impoverishment in diversity, density and biomass towards the eastern part of the coast. It was possible to link the samples to one of the three habitat types, based on a detailed community analysis. Due to this, the following conclusions about the sampling strategy could be made: (1) the selection of the 9 sampling locations leads to a good spatial distribution of the samples, except in the central zone; (2) an increase of the number of samples within the Abra alba habitat in the western and central coastal zone is necessary; (3) a strong reduction in the number of samples in the Macoma balthica habitat in the eastern coastal zone and to maintain or slightly reduce the number of samples in the other coastal zones; (4) the Nephtys cirrosa habitat is mainly found in the western coastal zone with enough samples, but the occurrence in the central zone has to be better investigated.
A large amount of data (Belgian (UGent, ILVO), France, The Netherlands) was available for extending the reference data for the different habitats in the Belgian Coastal zone. Finally, it seems that the data taken in the period 1994 - 2004 shows the best temporal and spatial variability in benthos sampling points within the Belgian Coastal zone (< 6 nautical mile) and was selected as reference data. This data could be linked to the 3 main habitat types, based on a detailed community analysis. Due to this, enough samples were available for each habitat type to determine the reference boundary values, which were included in the report.