The links between river morphological variables and benthic invertebrate assemblages: comparison among three European ecoregions

Abstract

Understanding the relationship between river natural and degraded habitats and river assemblages is crucial but yet insufficient for the desired sustainable river management. Our paper therefore compares the relation of river natural morphological features and their modification to benthic invertebrate assemblages among European ecoregions Alps, Pannonian lowland, and Dinaric western Balkan with varied natural characteristics. Morphological conditions were assessed using the habitat quality (RHQ) and modification (RHM) variables, according to Slovenian hydromorphological assessment method, and linked to benthic invertebrate assemblages using multivariate analyses. The overall results indicate markedly higher importance of RHQ variables in comparison with RHM variables for structuring benthic invertebrate assemblages, but reveal important differences among ecoregions. Predominant flow and predominant channel substrate were found among the most important RHQ variables across all ecoregions. Beside these, benthic invertebrate assemblages of the Alps were influenced most by bank variables, whereas of the Pannonian lowland by features linked directly to channel conditions. In Dinaric western Balkan a combination of bank and channel variables influenced the assemblages. Among habitat modification features artificial bank profiles appeared important across all ecoregions. However, in the Alps equal explanatory power was observed for variables water impoundment by weir/dam and bank modifications, whereas in the Pannonian lowland only for variable artificial bank material and even for none in Dinaric western Balkan. According to our findings it is important to consider habitat modification in river management, but more weight should be given to habitat quality features. Moreover, the differences among ecoregions emphasize the need for ecoregion-specific approach.