A comparison of the European Water Framework Directive physical typology and RIVPACS-type models as alternative methods of establishing reference conditions for benthic macroinvertebrates |
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Authors: | John Davy-Bowker Ralph T Clarke Richard K Johnson Jiri Kokes John F Murphy Svetlana Zahrádková |
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Institution: | (1) Centre for Ecology & Hydrology, Winfrith Technology Centre, Dorchester, Dorset, DT2 8ZD, United Kingdom;(2) Department of Environmental Assessment, Swedish University of Agricultural Sciences, P.O. Box 7050, SE-750 07 Uppsala, Sweden;(3) T.G.M. Water Research Institute, Drevarska 12, 657 57 Brno, Czech Republic;(4) Department of Zoology and Ecology, Faculty of Science, Masaryk University Brno, Kotlářská 2, 611 37 Brno, Czech Republic |
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Abstract: | The EU Water Framework Directive requires European Union Member States to establish ‘type-specific biological reference conditions’
for streams and rivers. Types can be defined by using either a fixed typology (System-A), defined by ecoregions and categories
of altitude, catchment area and geology, or by means of an alternative characterisation (System-B) that can use a variety
of physical and chemical factors. Several European countries also have existing RIVPACS-type models that give site (rather
than stream type) specific predictions of benthic macroinvertebrate communities. In this paper we compare the Water Framework
Directive (WFD) System-A physical typology and three existing European multivariate RIVPACS-type models as alternative methods
of establishing reference conditions. This work is carried out in Great Britain – using RIVPACS, Sweden – using SWEPACSRI and the Czech Republic – using PERLA. We found that in all three countries, all seasons and season combinations, and for
all biotic indices tested, RIVPACS-type models were more effective (lower standard deviations of O/E ratios) than models based
solely on the WFD System-A variables or null models (based on a single expectation for all sites). We also investigated the
explanatory power of whole groups of WFD System-A variables and RIVPACS-type model variables, and the explanatory power of
individual variables. We found that variables used in the RIVPACS-type models were often better correlates of macroinvertebrate
community variation than the WFD System-A variables. We conclude that this is primarily because while the latter use very
broad categories of map-derived variables, the former are based on continuous variables selected for their ecological significance. |
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Keywords: | reference condition physical typology RIVPACS SWEPACSRI PERLA |
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