In the last decades, hydromorphological degradation of rivers has gained more attention in river management, stressing the importance of understanding the links between hydromorphology and aquatic assemblages. The present study investigated general patterns in the response of benthic invertebrate assemblages to single morphological features along naturally diversified Slovenian rivers. The whole gradient of local habitat quality (river habitat quality, RHQ) and habitat modification (river habitat modification, RHM) features, according to the Slovenian hydromorphological assessment method, was covered. Regional natural characteristics explained the low share of RHQ and RHM variability, indicating nonregional presence of morphological features. The analysis identified predominant flow and predominant channel substrate as the most important RHQ features. We found that in contrast to RHQ features, RHM features had low explanatory power. These results suggest a weaker response of benthic invertebrate assemblages to the physical alteration itself than to the effect that the alteration exerts on habitat quality features. Variance partitioning among three environmental variable groups revealed predominantly independent effects (69%) on benthic assemblages, mostly on account of regional natural characteristics (30%) and RHQ features (31%). As benthic invertebrate assemblages are adapted to the former natural conditions, a similar modification may result in different effects with regard to regional natural differences. Therefore, the low proportion of variability, explained by RHM features, might be the consequence of joint dataset from different regions. Our study gives general implications for river management, but in order to more clearly define the significance of particular modification features, we suggest further analysis within more homogeneously defined habitats that encompass regional natural characteristics.
COBISS.SI-ID: 3101263
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.
COBISS.SI-ID: 3400527
Due to a long history of human intervention in river ecosystems, pristine conditions hardly exist nowadays and therefore a concept of a "guiding image" defines the present-day potential natural state. Since regional physiographic factors influence the natural habitat features and biota on local level, also guiding images are expected to differ regionally. In this study, the guiding images of rivers of four major regions were defined: alpine, lowland, mediterranean and karst. The habitat features of rivers were studied in four major European regions: the Alps, the Pannonian Lowland, the Submediterranean region and the Dinaric region. For the analysis only those river habitat quality features were used that were proven to be ecologically important. The results showed differences among habitat features of rivers of all investigated regions. On the whole dataset the major gradient among reference sites was observed for habitat features that are in tight relation to water flow and sediment dynamics. For these features the major differences were found between the alpine and the lowland rivers, and on the other hand the similarities were observed between the Mediterranean and the Alpine rivers and between the karst and the lowland rivers. Another important gradient was observed on account of habitat features of riparian and channel vegetation. The highest values of these features were observed for the alpine and the mediterranean rivers and lower in the karst or the lowland rivers. However, the simpler riparian vegetation structure suggested by our results might not be the representative picture of natural vegetation, so the values of these features for a guiding image should be used with caution. In the present study the first step to the guiding images of the rivers in four major regions is proposed. Since the results showed considerable variability of some river habitat features present within regions, we suggest further investigation on even smaller groups. Nevertheless, the recognized differences and similarities among four regions in river habitat features that are ecologically relevant might serve as guidance for more sustainable and cost-effective river management.
COBISS.SI-ID: 7024481