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Urbanic G.,University of Ljubljana | Urbanic G.,Institute for Water of the Republic of Slovenia
Ecohydrology | Year: 2014

Lakeshore deterioration is a major threat to the ecological integrity of lakes worldwide. In this study, the relationship between littoral benthic invertebrates and the Lakeshore Modification Index (LMI) was examined. The influence of the taxonomic resolution on littoral benthic invertebrate community response to LMI was assessed using the results of the canonical correspondence analysis and the relationship between the taxa richness, Shannon-Wiener diversity index and the LMI. Benthic invertebrates were sampled in summer between 2006 and 2011 in two natural and two artificial Alpine lakes using a littoral microhabitat type sampling scheme. Ordination analyses show a similar explanation power when the lowest available taxonomic level was used in comparison with the family level. Taxa richness and the Shannon-Wiener diversity index indicate that lakeshore modifications impair littoral biological conditions with a loss of richness and diversity independently of lake type and used taxonomic level. For 64 families, a lakeshore modification indicative value between one and nine were set on the basis of distribution among five lakeshore modification classes. A Littoral Fauna Index (LFI) was then derived by summation of the lakeshore modification indicative values recorded at each site. A validation dataset from natural and artificial lakes confirmed the good relationships between LMI and LFI but revealed some differences in the relationships. The results show that the impacts of lakeshore modifications can be assessed using littoral benthic invertebrate assemblages with a family-level-based LFI, which makes this method cost effective and appropriate for routine monitoring. © 2013 John Wiley & Sons, Ltd. Source

The effects of hydropower dams and, in particular, the impacts of reduced river flows on the periphyton community were assessed in the Soča River, Slovenia. Sampling sites were selected upstream and downstream of the Podsela and Ajba dams. Sampling was carried out in 1998 during a period of low flows. Reaches downstream from the dams experienced prolonged periods of reduced flows, and a corresponding decrease in flow velocity and water depth. The chain of hydropower dams has stopped sediment inflow from the upstream reach. Below the dams, the oscillations of water temperature, dissolved oxygen and oxygen saturation are much larger than at unregulated sites upstream. The impact of prolonged periods of reduced flows, a lack of sediment supply from upstream and changes in physicochemical variables has caused high periphyton biomass, proliferation of green algae and increases in the number of periphytic algae species below the dams. This has significant implications for the design of environmental flow strategies that provide a sediment supply to maintain a healthy periphyton community. Editor Z.W. Kundzewicz; Associate editor M. AcremanCitation Smolar-Žvanut, N. and Mikoš, M., 2014. The impact of flow regulation by hydropower dams on the periphyton community in the Soča River, Slovenia. Hydrological Sciences Journal, 59 (5), 1032-1045. © 2014 IAHS Press. Source

Orlando-Bonaca M.,Slovenian National Institute of Biology | Mavric B.,Slovenian National Institute of Biology | Urbanic G.,Institute for Water of the Republic of Slovenia
Ecological Indicators | Year: 2012

The assessment of the status of coastal waters is required by the European Water Framework Directive. The aim of the present study was to test the response of benthic invertebrates to hydromorphological (HM) alterations and to develop a new index for the assessment of HM alterations of the rocky shore, based on benthic invertebrates. Fifty samples were collected, 10 from pre-classified HM classes 1, 3, 5; 15 from class 2, and 5 from class 4. Seven HM variables describing habitat conditions were used to test the benthic invertebrate response and to develop the HM stressor gradient: material, texture, structure, belt length, sedimentation, water retention and artificially induced mobility. Abundance, some diversity (Shannon-Wiener, Simpson's and Evenness) and richness (number of taxa) metrics showed low correlation values (r < 0.5) against HM variables and HM stressor gradient, indicating that tested metrics have limited value in assessment of the HM degradation impact on coastal benthic invertebrates. On the other hand, significant differences in the structure of benthic invertebrate assemblages among HM classes were observed (One-way ANOSIM global test r = 0.53, P < 0.0001). In the partial canonical correspondence analyses each of seven HM variables statistically significantly (P < 0.05) explained individual portion of the benthic invertebrate taxa variability. HM indicative values ranging from 1 to 9 were defined for each of 229 taxa, according to its distribution along the five HM classes. HM indicative weights (WHM) between 1 and 5 were defined according to the valences distribution among HM classes. HM indicative values, WHM and log 5 abundance classes were combined in a new Benthic Index for Rocky Shore (BIRS), using the weighted average approach. The combination of all three parameters in the BIRS showed a statistically significant (P < 0.05) response of the new developed index to HM stressor gradient, with a high Pearson correlation coefficient (r = 0.97). Further work has to be done in order to develop a WFD compliant method with five classes' boundary values. Nevertheless, the new developed index has a good potential to contribute to existing coastal assessment systems. Especially, as impact of hydromorphological alterations on coastal communities was almost neglected so far, despite being one of the main threats to coastal water integrity. © 2011 Elsevier Ltd. Source

Vrenko D.Z.,Institute for Water of the Republic of Slovenia | Petrovic D.,University of Ljubljana
Cartographic Journal | Year: 2015

Geographical information is connected to everyday life in many ways. Web cartography has made geospatial data more available to the public. In the next few years, the average age of the population will be over 51 years, with more than 15% of the population over the age of 65 years. The fact that the senior population is increasing suggests that online mapping and map viewer design should be aware of the senior population’s visual restrictions, as well as restrictions of other potential map users, including colour-vision-impaired users. This paper describes the senior population’s visual restrictions that can be compared with colour-vision-impaired users and provides guidelines with regard to online mapping and map viewer design for this growing segment of the elderly population. © The British Cartographic Society 2015. Source

Petkovska V.,Institute for Water of the Republic of Slovenia | Urbanic G.,Institute for Water of the Republic of Slovenia | Urbanic G.,University of Ljubljana
Ecohydrology | Year: 2015

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. © 2014 John Wiley & Sons, Ltd. Source

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