Das Makrozoobenthos als Indikatorgruppe zur Bewertung großer Flüsse unter Einbeziehung auenökologischer Aspekte

With the guideline 2000/60/EG, which called for the creation of a framework on water policy, the environmental policy of the European Community took on a new dimension. The goal of the guideline is (among others) the creation of a framework for the protection of inland surface waters, transitional waters, coastal waters and groundwater in order to avoid their deterioration; and to protect and improve the status of aquatic ecosystems, their associated land ecosystems directly dependent on them, and wetlands in terms of their water budget. Thanks to various forms of use, e.g. hydropower production, flood protection and ship traffic, especially major European rivers like the Danube, Rhine and Elbe have changed massively from their original typological characteristics. Reference conditions are hardly anywhere to be found, many native species are now extinct, and river biotopes are often dominated by invasive species. The size and depth of these rivers also pose challenges in terms of taking samples, and it has also become apparent that all methods currently used to assess rivers’ ecological status focus solely on the main channels; the various habitats to be found in large rivers’ riparian systems aren’t taken into account. However, there is international consensus that these systems are key elements in rivers’ processes and biodiversity, and as such are significant for the continuing functionality of major rivers. In the context of an Austrian Ministry of Life-funded research project, the Institute of Hydrobiology and Aquatic Ecosystem Management’s Working Group on Benthic Ecology and Ecological Status Assessment, together with the University of Vienna and the Environment Agency Austria, is currently working to develop a practice-oriented riparian zone index based on macrozoobenthos as an indicator of quality. To date, Europe has no Water Framework Directive-compliant assessment systems for riparian zones. Given the fact that established methods are limited to river’s main channels, precluding a holistic view of and approach to river ecosystems, this project represents a pioneering work in the field of European water resource management.     

Erfassen von Ursache-Wirkungs-Beziehungen in Flusslandschaften: Vermittlung von Systemwissen in Schulen als Beitrag für ein nachhaltiges Flussgebietsmanagement

A scientific understanding of the processes at work in river landscapes represents an important basis for including the local populace in effective and sustainable river landscape management. By conveying system-based knowledge to students, these future inhabitants and users of river landscapes will be better able to recognize contexts and connections, understand project-related decisions and policies, and support sustainable planning efforts. As such, in October 2012 the Austrian Federal Ministry for Science and Research started the “FlussAu:WOW!” project, part of the “Sparkling Science” research program. In the project, scientists work together with the students from two upper-level high-school classes over a period of two years, investigating research questions on river landscape management. The scientific goal of the project is to create a set of indicators to represent the functionality of floodplains. In the first school year, the researchers worked on key questions together with the students in workshops, performed field surveys and analyzed the results of fieldwork. In the subsequent discussions, the researchers constantly pointed out the complex interrelations at work in river-floodplain systems. Students’ knowledge was evaluated in pre-project and post-project tests. The analysis of the pre-tests revealed major knowledge gaps on questions concerning river landscape management, e.g. on factors that place major pressures on these regions. A comparison between the pre- and post-tests confirmed a significant improvement in the students’ factual knowledge after the first year; however, the post-project tests only showed a coupling of that knowledge with a recognition of cause-and-effect relations in sporadic cases. Beyond factual knowledge, it is above all a grasp of the interconnections between individual system elements that serves as an essential basis of education. Interactive, modern approaches are critical to conveying interdisciplinary knowledge. As part of the “FlussAu:WOW!” project, in the second school year system-based learning is implemented with the help of innovative modeling and simulation software. In both the pre- and post-tests, questions on the students’ interests revealed a high level of motivation to join in the research, and considerable interest in questions concerning nature and the environment. As a result, by the end of the first school year the cooperation between researchers, educators and students had already made a valuable contribution to sustainable river landscape management.     

Die unbekannte dritte Dimension: Geländehöhen,Gewässertiefen und Dynamik österreichischer Donaulandschaften vor der Regulierung

River landscapes are multidimensional ecosystems characterized by diverse spatio-temporal interrelations. Longitudinal interactions along the river continuum and lateral exchange processes between river and floodplain are common focal points in river restoration projects. Vertical interactions, such as between aquatic habitats and river bottom (hyporheic interstitial) or between groundwater and terrestrial habitats, are often only addressed in planning schemes, if the impairments of ecological functions and human uses are already evident. This partly reflects the dearth of well-founded basic data on the configuration of river landscapes prior to regulation in the vertical dimension. Consequently, only few reference data are available for designing adapted restoration measures.     

Integrierte gewässerökologische Modellansätze zur Beurteilung von Gewässervernetzungsvarianten am Beispiel der Unteren Lobau

Floodplains and wetlands are among the most endangered ecosystems worldwide. River-regulation and flood protection measures cut off these formerly highly dynamic systems from their natural water level fluctuations and water exchange conditions leading to siltation processes. Restoration measures to counteract these developments need to be assessed for the effect on currently established habitats and communities in order to estimate their effects, as species with different habitat preferences and different protection status do react distinctly different. This article will present how habitat modelling was used in a case study of the Untere Lobau to assess and predict the effects of potential management measures. The Untere Lobau is a wetland ecosystem of the Danube east of Vienna. It is part of the national park Donau-Auen and a protected area according to the EU habitat-directive. Prior to the river regulation, at the end of the 19^th century, the Untere Lobau was a dynamic floodplain. Today, siltation processes endanger especially the status of the aquatic habitats. Three management options were investigated: 1) business as usual – No implementation of additional hydrological measures, thus siltation processes are not mitigated; 2) a water enhancement scheme – A small amount of water is supplied to preserve the water bodies at the current status quo; 3) partly reconnection – An upstream reconnection of the floodplain to the main channel of the Danube, leading to a more rheophilic characteristic of the system moving towards conditions prior regulation. Based on a model approach and calculating habitat preferences via binary logistic regressions of selected species from different organism groups, an increase or decrease of available suitable habitat area (weighted usable areas) could be estimated. This study proofed clearly that models can assess the effects of hydrological management measures on the biocenosis and that they are a valuable tool for supporting the decision taking process in wetland management.     

Effektivität von Maßnahmen zur Reduktion der Phosphorbelastung der oberösterreichischen Fließgewässer

Assessing the effectiveness of measures to reduce the phosphorus loads in bodies of water in the plains of catchment areas requires a comprehensive grasp of the interactions between human activities, resulting emissions, and their effects on those waters. A quantitative representation of the connection between emissions loads over different pathways and emissions concentrations, and which takes into account the retention in both land and water, is called for as an essential basis. Once this has been established, in the next phase the effects of local emission reduction measures can be evaluated, the suitability of said measures for implementation in a given region on the basis of the predominant local conditions and land use management can be determined, and the effectiveness of the respective models can be represented in the context of overall emissions and retention. The findings of related studies in Upper Austria show that erosion protection measures and/or measures to avoid erosive phosphorus emissions in running water bodies have the best potential for reducing phosphorus loads when they are precisely targeted (used in areas with a high degree of connectedness to bodies of water or adjacent to running waters).     

Was? Wie? Warum? Jugendliche erforschen Flusslandschaften – Förderung des Systemverständnisses als Basis für gelebte Partizipation im Flussgebietsmanagement

River landscape planning and management to promote the positive long-term development of river landscapes must adhere to the principle of sustainability. In this context, the goal is to initiate a development process for river landscapes that successfully reconciles the requirements of nature and water conservation with social and economic aspects, and which actively involves affected citizens in the decision-making process. A systems-based understanding and the opportunity to make ecologically relevant decisions are essential prerequisites for participative processes.     

Grundlegende Erkenntnisse im Rahmen des Pilotprojekt Bad Deutsch-Altenburg – Die Bedeutung der Stromsohle und Uferzonen für ökologische Prozesse und Artengemeinschaften an einem stark regulierten Fluss,der Donau

To ensure a long-term ecological stability, rivers need areas that are available at different discharge situations as highly productive habitats which are connected with the river. These retention areas or biologically active zones are important for the riverine communities as refuge (e.g. benthic macroinvertebrates and fish) or the development of benthic algae communities as basis for the riverine food web as well as retention zones to perform various ecosystem services (e.g. nutrient retention). Especially during low water level situations, the river shorelines and the river bed itself are of significant importance, but highly degraded in intensely regulated river systems such as the Danube River. A basic understanding of the processes and functional correlations is required to avoid negative consequences of engineering measures applied and to improve the ecological conditions. In the framework of the pilot project Bad Deutsch-Altenburg in the Danube River east of Vienna not only monitoring the implementation of engineering measures is required, but also scientific knowledge gained about basic ecological relationships and potential responses of riverine communities. This article presents results of several years of investigations on the distribution and development of three organism groups (benthic algae, benthic macroinvertebrates and fish) along different riparian structures and in the river bed of the Danube River.