Options for re-establishing river continuity, with an emphasis on the special solution “fish lift”: examples from Austria.

The European Water Framework Directive (WFD) became a major tool in European water policy. All the member states had to develop River Basin Management Plans (RBMPs). Austria’s first National Water Resource Management Plan was published in 2009 and describes measures to be set. Depending on the catchment size, ecological targets were defined on water body level, to be reached by 2015, 2021 or 2027. A priority goal is the re-establishment of river continuity. Therefore the Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management published a “Guideline for the construction of fish passes” in 2012.We provide an overview on measures to re-establish river continuity that were recently planned or already established at the Inn catchment, a major tributary to the upper Danube River. Planning principles as well as details from the construction phase and monitoring concepts as well as first results are presented.Founded in 1924 TIWAG started its business with the construction of the HPP Achensee, at the time one of Europe’s largest storage facilities. Since then TIWAG expanded its expertise on engineering, constructing and operating hydro power plants in Tyrol. In the first river basin management cycle at three hydropower plants, located in the“priority river network” (HPP Langkampfen, HPP Kirchbichl and HPP Imst - the latter with the weir Runserau and the water intake at Wenns), measures had to be developed to overcome discontinuity. During planning phase it was tried to apply “standard solutions” according to the Austrian guideline. This was possible for three sites, where we planned vertical slot fish passes in combination with natural bypass channels. To enable upstream migration at the weir Runserau, different alternatives were evaluated, but it was not possible to use a “standard solution”. A  review about existing fish lifts was the basis for a promising solution. The chosen design combines a conventional fish migration facility (vertical slot) with a fish lift. Linked together those facilities are offering new, additional possibilities. The characteristics of this new concept and its advantages are presented.</p

The effect of riparian forest on landscape connectivity for the EPT community across European regions

Ephemeroptera, Plecoptera and Trichop- tera are three orders of freshwater macroinvertebrates with a short terrestrial adult life-stage that they use to disperse by flying upstream. This aerial dispersal can be assisted by native riparian forest, but regional variation has not yet been empirically tested. In this study we compared the EPT community of 153 sampling sites located in freshwater streams in four European regions (Central Plains, Central Highlands, Alps, Iberia). In each site, we assessed the EPT com- munity dispersal ability using the Species Flying Pro- pensity index. We also calculated the native decidu- ous forest cover in the riparian buffer and several environmental stressors such as saprobic pollution or catchment anthropization. Finally, we tested which of these parameters have a significant effect on the EPT community. In the Central Highlands and in Iberia, the share of weak dispersers increased with native deciduous forest cover, indicating a positive effect on dispersal of EPTs. In the Central Plains and the Alps, no such effect was found. We conclude that the effect of native deciduous forest depends on regional land- scape characteristics and the regional species pool, but considering the dispersal of the regional EPT communities is needed to create effective river man- agement policies.info:eu-repo/semantics/publishedVersio

Gene flow in a pioneer plant metapopulation (Myricaria germanica) at the catchment scale in a fragmented alpine river system

River alterations for natural hazard mitigation and land reclamation result in habitat decline and fragmentation for riparian plant species. Extreme events such as floods are responsible for additional local species loss or population decline. Tributaries might provide refugia and subsequent source populations for the colonization of downstream sites in connected riverine networks with metapopulations of plant species. In this study, we analyzed the metapopulation structure of the endangered riparian shrub species Myricaria germanica along the river Isel, Austria, which is part of the Natura 2000 network, and its tributaries. The use of 22 microsatellite markers allowed us to assess the role of tributaries and single populations as well as gene flow up- and downstream. The analysis of 1307 individuals from 45 sites shows the influence of tributaries to the genetic diversity at Isel and no overall isolation by distance pattern. Ongoing bidirectional gene flow is revealed by the detection of first-generation migrants in populations of all tributaries as well as the river Isel, supporting upstream dispersal by wind (seeds) or animals (seeds and pollen). However, some populations display significant population declines and high inbreeding, and recent migration rates are non-significant or low. The genetic pattern at the mouth of river Schwarzach into Isel and shortly thereafter river Kalserbach supports the finding that geographically close populations remain connected and that tributaries can form important refugia for M. germanica in the dynamic riverine network. Conservation and mitigation measures should therefore focus on providing sufficient habitat along tributaries of various size allowing pioneer plants to cope with extreme events in the main channel, especially as they are expected to be more frequent under changing climate

Transplantation of an alpine Carex-fen – a mitigation measure related to the construction of a reservoir in the Austrian Alps

Translocations are applied in the context of infrastructure projects to preserve certain vegetation types. Within the EIA of a large hydropower project in the Austrian Alps, manifold mitigation measures were defined. Among those, the transplantation of about 1.4 ha Carex-fen at an altitude of about 2000 m was defined. One year before the start of the construction works in 2021, basic infrastructure (roads) was established and different ecological measures were undertaken, e.g. translocation of amphibians to newly constructed habitats as well as the transplantation of the Carex-fen. The turf was cut from the initial area with an adjusted excavator shovel, delivered to a wheel loader which brought each single turf immediately to the target area, where another excavator mounted the turf in a pre-arranged area. At the donor site more than ½ of the area was based on wet gley, while especially areas in the vicinity of the river were based on fluvial gravel. With the 30 to 70 cm thick turfs also animals, e.g. Odonata, were transferred. Before the translocation a monitoring of the donor sites was carried out. The monitoring concept foresees a detailed monitoring of the newly established sites for 10 years. Herein we provide insights in the applied technology and summarize first results of the monitoring. Overall, our project is unique regarding the vegetation type, the technology, the size and the intensity of monitoring

Digitalization and real-time control to mitigate environmental impacts along rivers: Focus on artificial barriers, hydropower systems and European priorities

Hydropower globally represents the main source of renewable energy, and provides several benefits, e.g., water storage and flexibility; on the other hand, it may cause significant impacts on the environment. Hence sustainable hydropower needs to achieve a balance between electricity generation, impacts on ecosystems and benefits on society, supporting the achievement of the Green Deal targets. The implementation of digital, information, communication and control (DICC) technologies is emerging as an effective strategy to support such a trade-off, especially in the European Union (EU), fostering both the green and the digital transitions. In this study, we show how DICC can foster the environmental integration of hydropower into the Earth spheres, with focus on the hydrosphere (e.g., on water quality and quantity, hydropeaking mitigation, environmental flow control), biosphere (e.g., improvement of riparian vegetation, fish habitat and migration), atmosphere (reduction of methane emissions and evaporation from reservoirs), lithosphere (better sediment management, reduction of seepages), and on the anthroposphere (e.g., reduction of pollution associated to combined sewer overflows, chemicals, plastics and microplastics). With reference to the abovementioned Earth spheres, the main DICC applications, case studies, challenges, Technology Readiness Level (TRL), benefits and limitations, and transversal benefits for energy generation and predictive Operation and Maintenance (O&M), are discussed. The priorities for the European Union are highlighted. Although the paper focuses primarly on hydropower, analogous considerations are valid for any artificial barrier, water reservoir and civil structure which interferes with freshwater systems.Digitalization and real-time control to mitigate environmental impacts along rivers: Focus on artificial barriers, hydropower systems and European prioritiespublishedVersio

Options for re-establishing river continuity, with an emphasis on the special solution “fish lift”: examples from Austria.

The European Water Framework Directive (WFD) became a major tool in European water policy. All the member states had to develop River Basin Management Plans (RBMPs). Austria’s first National Water Resource Management Plan was published in 2009 and describes measures to be set. Depending on the catchment size, ecological targets were defined on water body level, to be reached by 2015, 2021 or 2027. A priority goal is the re-establishment of river continuity. Therefore the Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management published a “Guideline for the construction of fish passes” in 2012.We provide an overview on measures to re-establish river continuity that were recently planned or already established at the Inn catchment, a major tributary to the upper Danube River. Planning principles as well as details from the construction phase and monitoring concepts as well as first results are presented.Founded in 1924 TIWAG started its business with the construction of the HPP Achensee, at the time one of Europe’s largest storage facilities. Since then TIWAG expanded its expertise on engineering, constructing and operating hydro power plants in Tyrol. In the first river basin management cycle at three hydropower plants, located in the“priority river network” (HPP Langkampfen, HPP Kirchbichl and HPP Imst - the latter with the weir Runserau and the water intake at Wenns), measures had to be developed to overcome discontinuity. During planning phase it was tried to apply “standard solutions” according to the Austrian guideline. This was possible for three sites, where we planned vertical slot fish passes in combination with natural bypass channels. To enable upstream migration at the weir Runserau, different alternatives were evaluated, but it was not possible to use a “standard solution”. A  review about existing fish lifts was the basis for a promising solution. The chosen design combines a conventional fish migration facility (vertical slot) with a fish lift. Linked together those facilities are offering new, additional possibilities. The characteristics of this new concept and its advantages are presented.</p

Reference databases, primer choice, and assay sensitivity for environmental metabarcoding: Lessons learnt from a re‐evaluation of an eDNA fish assessment in the Volga headwaters

Biodiversity monitoring via environmental DNA, particularly metabarcoding, isevolving into a powerful assessment tool for riverine systems. However, formetabarcoding to be fully integrated into standardized monitoring programmes, somecurrent challenges concerning sampling design, laboratory workflow, and data analy-sis need to be overcome. Here, we review some of these major challenges and poten-tial solutions. We further illustrate three potential pitfalls, namely the choice ofsuitable metabarcoding primers, the necessity of complete reference databases, andvarying assay sensitivities, by a reappraisal of our-own recently carried outmetabarcoding study in the Volga headwaters. TaqMan qPCRs had detected catfish(Silurus glanis) and European eel (Anguilla anguilla), whereas metabarcoding had not, inthe same samples. Furthermore, after extending the genetic reference database by12 additional species and re-analysing the metabarcoding data, we additionallydetected the Siberian spiny loach (Cobitis sibirica) and Ukrainian brook lamprey(Eudontomyzon mariae) and reassigned the operational taxonomic units previouslyassigned toMisgurnus fossilistoCobitis sibirica. In silico analysis of metabarcodingprimer efficiencies revealed considerable variability among primer pairs and amongtarget species, which could lead to strong primer bias and potential false-negatives inmetabarcoding studies if not properly compensated for. These results highlight someof the pitfalls of eDNA-metabarcoding as a means of monitoring fish biodiversity inlarge rivers, which need to be considered in order to fully unleash the full potential ofthese approaches for freshwater biodiversity monitori