Mur River Research Articles

From the Mountain to the Valley - Drivers of Groundwater Prokaryotic Communities along an Alpine River Corridor

Rivers extend into the underlying groundwater which represents the unseen freshwater majority. Understanding microbial community composition and dynamics of shallow groundwater and lotic ecosystems is thus crucial, due to their potential impact on ecosystem processes and functioning. A 300 km section of the Mur river valley, from 2000 m.a.s.l. in the Austrian alps to the flats (200 m.a.s.l.) at the Slovenian border, was followed, analyzing river water from 14 stations and groundwater from 45 wells in early summer and late autumn. The active (RNA derived) and total prokaryotic communities were characterized using high-throughput gene amplicon sequencing. Key physico-chemical parameters and stress indicators were recorded. The groundwater microbiome is analyzed regarding its composition, change with land use, and difference to the river. Community composition and species turnover differed significantly. At high altitudes, dispersal limitation was the main driver of groundwater community assembly, whereas in the lowland, homogeneous selection explained the larger share. Land use was a key determinant of the groundwater microbiome composition. The alpine region was more diverse in prokaryotic taxa, with some early diverging archaeal lineages being highly abundant. This dataset shows a longitudinal change in prokaryotic communities that is dependent on regional differences affected by geomorphology and land use.

From the Mountain to the Valley: Drivers of Groundwater Prokaryotic Communities along an Alpine River Corridor.

Rivers are the "tip of the iceberg", with the underlying groundwater being the unseen freshwater majority. Microbial community composition and the dynamics of shallow groundwater ecosystems are thus crucial, due to their potential impact on ecosystem processes and functioning. In early summer and late autumn, samples of river water from 14 stations and groundwater from 45 wells were analyzed along a 300 km transect of the Mur River valley, from the Austrian alps to the flats at the Slovenian border. The active and total prokaryotic communities were characterized using high-throughput gene amplicon sequencing. Key physico-chemical parameters and stress indicators were recorded. The dataset was used to challenge ecological concepts and assembly processes in shallow aquifers. The groundwater microbiome is analyzed regarding its composition, change with land use, and difference to the river. Community composition and species turnover differed significantly. At high altitudes, dispersal limitation was the main driver of groundwater community assembly, whereas in the lowland, homogeneous selection explained the larger share. Land use was a key determinant of the groundwater microbiome composition. The alpine region was more diverse and richer in prokaryotic taxa, with some early diverging archaeal lineages being highly abundant. This dataset shows a longitudinal change in prokaryotic communities that is dependent on regional differences affected by geomorphology and land use.

Application of the D-A-(C) index as a\xa0simple tool for microbial-ecological characterization and assessment of groundwater ecosystems\u2014a\xa0case study of the Mur River Valley, Austria

The assessment and monitoring of the ecological quality and status of groundwater is a timely issue. At present, various assessment tools have been developed that now await application and validation. One of these, the D‑A‑C index, evaluates the microbiological-ecological quality of groundwater based on of prokaryotic cell counts, microbial activity measurements, and the qualitative characterization of dissolved organic carbon (DOM). The purpose of this paper is to illustrate the different ways of application of the D‑A-(C) index making use of a recently collected data set (n = 61) from the river Mur valley, Austria. First, we present an extension of the D‑A-(C) index by including measurements of dissolved organic matter quality (DOM) derived from fluorescence spectroscopy as additional variables to supplement the analysis of microbial cell density and activity levels. Second, we illustrate how the definition of a reference status for a ‘good’ microbiological-ecological state can improve the analysis and allow for a more sensitive and accurate detection of impacts on groundwater ecosystems. Based on our results, we advocate that the analysis be performed by making use of expert knowledge for the definition of reference sites to which target sites are to be compared.

The Relic Landscapes of the Grazer Bergland: Revisiting the Piedmonttreppen Debate

Abstract The Grazer Bergland is a mountainous region at the eastern end of the Alps that escaped glacial erosion in the Pleistocene and thus preserves low-relief landforms that are relics of the earlier uplift history. These relic landforms may reflect a Piedmonttreppe that formed during a series of stages of a wide-reaching Pliocene uplift event that interacts with the landscape evolution, but this model is not uniquely accepted for the region. In order to test this model and for a future better correlation of the paleosurfaces with those mapped in other regions, it is important to benchmark these relic landforms. We do so by presenting a geomorphic map of the Bergland region over some 600 km2. We describe the well-known levels Stadelberg/Zahrerberg- (at 540 – 700 m a.s.l.), Kalkleiten/Hochstraden- (at 700 – 850 m a.s.l.), Trahütten- (at 950 – 1100 m a.s.l.), Hubenhalt- (at 1200 m a.s.l.), as well as Wolschenegg- and Kor- (at 1200-1720 m a.s.l.) levels and correlate their distribution in space and time. Fluvial channels between segments of the relic surfaces have knickpoints that correlate with the planation surfaces, which is in strong support of the Piedmonttreppe model. Our analysis results in a model that interprets the course of the Mur river to be the product of a river piracy event near Peggau at the time of the planation of the Trahütten level (about 4 Ma), diverting the paleo-Mur from an eastwards course along the Mürz valley in direction Vienna, towards Graz. Thereafter, the Mur remained antecedent with respect to the uplift of the surrounding massifs resulting in massive base level drop for many tributaries, like the Mixnitzbach or Rötschbach. The resulting knickpoints have since migrated upstream to cause successive minor river capture events, for example the Rötschbach capture at Kesselfall. We also show that the presence of lower levels in the Passail Basin is best interpreted in terms of the more efficient erosion of basin sediments that filled a Miocene half graben north of the Schöckl ridge and analyze the two major drainages of the region, the Raab and the Weizbach.

HPLC-ICPMS/MS shows a significant advantage over HPLC-ICPMS for the determination of perchlorate in ground, tap, and river water

Perchlorate is an environmental contaminant that originates from anthropogenic as well as natural sources. The health effects of perchlorate with respect to the thyroid function are well known. The capabilities of the inductively coupled plasma mass spectrometry (ICPMS) has been recently expanded by coupling with tandem mass spectrometry. The advantages of HPLC-ICPMS/MS has not yet been thoroughly assessed for chlorine speciation analysis. We report a rapid and simple method for perchlorate determination in ground, tap, and river water and we show that the ICPMS/MS offers as a chromatographic detector at least 10-fold improvement in the detection limit relative to single quadrupole ICPMS. The achieved limit of detection was 0.3 μg Cl L−1 perchlorate and could be yet improved by simple freeze-drying (down to ca. 50 ng Cl L−1, based on the river water matrix), which is comparable with HPLC-ESIMS/MS, with the advantage of eliminating the need for the 18O-perchlorate isotopically labeled internal standard. The method was validated in the various water matrices in terms of recovery at levels 5.0–250 μg Cl L−1 (±10%), repeatability (RSD<5%), and linearity (r2 = 0.9999), and revealed the presence of trace levels in the Mur river water (0.33 ± 0.04 μg Cl L−1). Carbon was found to significantly decrease signal response for chlorine, and we shed light on the general effects of carbonate on chlorine speciation in hard water analysis.

Romanogobio skywalkeri, a new gudgeon (Teleostei: Gobionidae) from the upper Mur River, Austria

Romanogobio skywalkeri, new species, is described from the upper Mur River in the Austrian Danube drainage. It is related to R. banarescui from the Mediterranean basin. Romanogobio skywalkeri is distinguished from R. banarescui by lacking epithelial crests on the predorsal back, having 12-14 total pectoral-fin rays (vs. 10-11) and usually 8½ branched dorsal-fin rays (vs. 7½). It is distinguished from other Romanogobio species in the Danube drainage by having a very slender body; a moderately long barbel, extending slightly beyond the posterior eye margin; and no epithelial crests on the predorsal back. Romanogobio skywalkeri is distinguished by a minimum net divergence of 6.3% (uncorrected p-distance against R. banarescui) in the COI barcoding region from other European Romanogobio species. A key to the Romanogobio species of the Danube drainage is provided. Romanogobio banarescui from the Vardar drainage and R. carpathorossicus from the Danube drainage are treated as valid species.

Deriving formulas for an unsteady virtual velocity of bedload tracers

AbstractIn a flume experiment with steady flow conditions, H. A. Einstein recognised the transport of bedload particles as consisting of steps of rolling, sliding, or saltation with intermittent rest periods, and introduced the concept of an average, ‘virtual’ transport velocity. This virtual velocity then has also been derived from tracer studies in the field by dividing the travelled distance of a tracer by the duration of competent flow. As a consequence, the virtual velocity in the field is represented by one single value only, despite the unsteady flow variables. Tracer measurements in a river have not been yet used to express transport velocity as a direct function of these actual variables, and insights from tracer measurements into the processes of sediment transport remain limited. In particular, the unsteady conditions for bedload in the field have impeded the derivation of sediment transport characteristics as determined from laboratory experiments, as well as the transfer of laboratory insights to a field setting. We introduce a method of data regression for the derivation of an ‘unsteady’ virtual velocity from repeated surveys of tracer positions. The regression program called graVel (provided as supplementary material) relates the integral of an excess flow variable term to measured travel distances, yielding the most probable threshold value for entrainment and the coefficient of linear and non‐linear formulas. An extended regression allows additional fitting of the exponent in non‐linear formulas. Application to published tracer data from the Mameyes River, Puerto Rico, shows that the unsteady virtual velocity is more likely governed by non‐linear relations to excess Shields stress, similar to bedload transport, than by relations linking the particle velocity linearly to excess shear velocity. Partial agreements with non‐dimensional results derived from the larger, non‐wadeable Mur River encourage the establishment of a generalised formula for the unsteady virtual velocity. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Biometric Traits and Ecology of Sichel, Pelecus cultratus (Linnaeus, 1758) with Notes on its Recent Status in the Middle Flow of the Danube River Tributaries (Slovenia and Croatia)

Available knowledge on the sichel, Pelecus cultratus, from the middle Danube River and its tributaries is insufficient. This study aims to provide new data on the morphology and ecology of sichel from the Mur River, and its distribution in Croatia and Slovenia. In 2009, the schooling of sichel were observed at a high-water level in the Mur River of Slovenia. In total, 14 specimens were sampled by fishermen using sport fishing techniques. The age, condition, length-weight relationship (LWR), 20 morphometric and four meristic traits, were analysed. Fulton condition coefficient and LWR value indicated that sichel specimens’were well adapted to the environmental conditions. Positive allometry in both males and females were observed (W = 0.004 L3.119). This represents the first LWR dataset for sichel. The morphometric and meristic traits values from this research add to the limited data that is presently available. By comparing historical and recent data on sichel distribution, we observed a dramatically declining trend. Therefore, further research and targeted protection of the sichel in the middle Danube River tributaries are urgently required.

Impact of Combined Sewer Overflow on Wastewater Treatment and Microbiological Quality of Rivers for Recreation

Within the framework of a one-year study the treatment capacity of a municipal wastewater treatment plant (WWTP) was evaluated, with regard to fecal indicator bacteria (FIB) and to their influence on the recipient. The logarithmic reduction rates for fecal coliforms (FC), Escherichia coli (EC) and intestinal enterococci (IE) were 2.84, 2.90 and 2.93. In the investigated period of time, the tested treatment plant released 4.3% of the total annual load flow volume as combined sewer overflow (CSO), that is, when the influent into the combined sewer exceeds the capacity of the treatment plant and coarsely cleaned wastewater arrives at the recipient. This CSO discharge increased the number of FIB significantly by 1.2 × 102 MPN/100 mL for EC, and by 1.8 × 101 MPN/100 mL for IE. For the Styrian part of the Mur River (1.6 million inhabitants), a calculation of FIB of all sewage treatment plants estimating the same ratio of CSO (4.3%) and a given mean flow rate (QM) results in a significant increase of the FIB load in the recipient: 3.8 × 103 MPN/100 mL for EC and 5.8 × 102 MPN/100 mL for IE. On the basis of these values the standards of water quality for recreational purposes cannot be met.

Large-scale application of the flood damage model RAilway Infrastructure Loss (RAIL)

Abstract. Experience has shown that river floods can significantly hamper the reliability of railway networks and cause extensive structural damage and disruption. As a result, the national railway operator in Austria had to cope with financial losses of more than EUR 100 million due to flooding in recent years. Comprehensive information on potential flood risk hot spots as well as on expected flood damage in Austria is therefore needed for strategic flood risk management. In view of this, the flood damage model RAIL (RAilway Infrastructure Loss) was applied to estimate (1) the expected structural flood damage and (2) the resulting repair costs of railway infrastructure due to a 30-, 100- and 300-year flood in the Austrian Mur River catchment. The results were then used to calculate the expected annual damage of the railway subnetwork and subsequently analysed in terms of their sensitivity to key model assumptions. Additionally, the impact of risk aversion on the estimates was investigated, and the overall results were briefly discussed against the background of climate change and possibly resulting changes in flood risk. The findings indicate that the RAIL model is capable of supporting decision-making in risk management by providing comprehensive risk information on the catchment level. It is furthermore demonstrated that an increased risk aversion of the railway operator has a marked influence on flood damage estimates for the study area and, hence, should be considered with regard to the development of risk management strategies.

Genetic evaluation of the self-sustaining status of a population of the endangered Danube salmon, Hucho hucho

A new multiplex microsatellite protocol was developed for population screening of the endangered Danube salmon (or huchen) Hucho hucho. Allelic variation was screened at five newly cloned and four previously published loci in 246 samples to help evaluate the self-sustaining status of an urban population of huchen in the framework of a controversial environmental assessment in the Mur River, Austria. The loci revealed 78 alleles (mean = 8.6), and in the Mur River an average expected heterozygosity of 0.668. We inferred that the huchen population in and around the city of Graz is self-sustaining based on the following evidence, which includes both genetic and non-genetic sources of information: (1) there is little to no current stocking; (2) presence of juvenile huchen in multiple year classes; (3) sighting of spawning events; (4) documentation of 14 spawning redds; (5) no deviation from Hardy–Weinberg equilibrium; and (6) limited number of recaptures or parental matches with presumed parent fish of stocking operations. We discuss the potential application of such an analysis in evaluating threatened huchen populations throughout their native distribution.

Post-Miocene landscape rejuvenation at the eastern end of the Alps

In the debate on the causes of uplift and landscape evolution of the Alps, most studies focus on regions that were glaciated at some stage during the last 2 m.y. In these areas, it is difficult to separate glacial-driven versus tectonically driven rates of erosion. Here, we present 10 Be-derived erosion rates from unglaciated catchments in the Koralpe range at the eastern end of the Alps. This region features strong geomorphologic evidence for landscape transience with young valleys incised into a smooth relict landscape. Erosion rates average 49 ± 8 mm/k.y. for catchments located on the relict landscape and 137 ± 15 mm/k.y. for catchments in the incised landscape. From these data, we estimate the onset of incision at 4 ± 1 Ma, the surface uplift at 350 ± 90 m, and a total relative base-level fall of 540 ± 140 m. Our results are in close agreement with both the magnitude and the age of onset of uplift of the Styrian Basin and the northern Molasse Basin, as well as the incision rate of the Mur River into the Styrian karst. The inferred timing of the onset of uplift around 4 Ma relates to interpreted basin inversion in the Pannonian Basin. Since this uplift event appears to have involved both the Pannonian Basin and the entire eastern end of the Alpine mountain range, we suggest that it may have occurred in response to a deep-seated process in the lithosphere. As such, we argue for tectonic drivers for the post-Miocene uplift in the eastern Alps.

Graz, UNESCO City of Design and Historical Heritage

Graz is the second largest town in Austria and the capital of Styria, with a population of about 300,000 inhabitants. This middle-sized European city is an influential industrial, cultural and university center. Its specific geopolitical location within Europe and its mixed ethnic population have influenced the formation of Graz as a city of rich cultural exchange. Its historical center, located at the foot of the Schlossberg castle, became a UNESCO world cultural heritage site in 1999 and is one of the best preserved historical downtowns worldwide. The cultural revival in the second half of the 20th century brought innovative architecture and urban modernization to Graz, and it later gained a wider international reputation as the European Cultural Capital in 2003. For this occasion two important modern city landmarks were built: the new contemporary museum, Kunsthaus, built along the river Mur bank and a multi-purpose object, the Murinsel, located directly in the Mur River. The City of Graz has also been a member of the UNESCO Creative Cities network as a City of Design since 2011. Modern development and the preservation of tradition are both equally present here. This city profile emphasizes the creative industry as one of the economic strategies for the Graz city government.

Young uplift in the non-glaciated parts of the Eastern Alps

We report the first incision rates derived from burial ages of cave sediments from the Mur river catchment at the eastern margin of the Eastern Alps. At the transition zone between the Alpine orogen and the Pannonian basin, this river passes through the Paleozoic of Graz — a region of karstifiable rocks called the Central Styrian Karst. This river dissects the study area in a north–south direction and has left behind an abundance of caves. These caves can be grouped into several distinct levels according to their elevation above the present fluvial base level. Age estimates of abandoned cave levels are constrained by dating fluvial sediments washed into caves during the waning stages of speleogenesis with the terrestrial cosmogenic nuclide method. These ages and the elevations of the cave levels relative to the current valley floor are used to infer a very complex history of 4millionyears of water table position, influenced by the entrenchment and aggradation of the Mur river. We observe rather low rates of bedrock incision over the last 4Ma (in the order of 0.1mm/y) with an e-folding decrease in this trend to lower rates at younger times. We relate this incision history to a tectonic setting where an increase of drainage area of the Mur river due to stream piracy in Late Miocene to Pliocene times is linked to surface uplift. The later decrease in valley lowering rates is attributed to the rise of the base level related to aggradation of sediments within the valley. Sediment transport through the valley from the upstream section of the Mur river limited the erosional potential of the river to a transport limited state at the later stages of the incision history.

Investigating artificial groundwater recharge to ensure the water supply to the city of Graz

Being Austria's fourth largest water-supply company, the Grazer Stadtwerke AG., has ensured the successful water-supply of the Styrian capital with 250.000 inhabitants for many years. The average daily water demand of the area amounts to about 50,000 m3. Approximately 30 % of the total demand is covered by the bulk water supply from the Zentral Wasser Versorgung Hochschwab Süd. The waterworks Friesach and Andritz, which cover the additional 70 % of the water demand, operate by means of artificial groundwater recharge plants where horizontal filter wells serve as drawing shafts. The groundwater recharge systems serve to increase the productivity of the aquifer and to reduce the share of the infiltration from the Mur River. Protection areas have been identified to ensure that the water quality of the aquifer stay at optimal levels. The protection areas are divided into zones indicating various restrictions for usage and planning. Two respective streams serve as the source for the water recharge plants. Different infiltration systems are utilised. Each of the various artificial groundwater recharge systems displays specific advantages and disadvantages in terms of operation as well as maintenance. In order to secure a sustainable drinking water supply the recharge capacity will be increased. Within an experimental setting different mixtures of top soils are investigated with respect to infiltration and retention rates and compared to the characteristics of the existing basins. It can be shown that the current operating sand basin with more than 90% grains in the range between 0.063 and 6.3 mm represents the best combination of infiltration and retention rates. In future experiments the performance of alternative grain size distributions as well as planting the top soil will be tested. Additionally, in order to optimize the additional groundwater recharge structures the composition of the subsurface water regarding its origin is statistically analyzed.

Assessing the impact of a downscaled climate change simulation on the fish fauna in an Inner-Alpine River

This study assesses the impact of a changing climate on fish fauna by comparing the past mean state of fish assemblage to a possible future mean state. It is based on (1) local scale observations along an Inner-Alpine river called Mur, (2) an IPCC emission scenario (IS92a), implemented by atmosphere-ocean global circulation model (AOGCM) ECHAM4/OPYC3, and (3) a model-chain that links climate research to hydrobiology. The Mur River is still in a near-natural condition and water temperature in summer is the most important aquatic ecological constraint for fish distribution. The methodological strategy is (1) to use downscaled air temperature and precipitation scenarios for the first half of the twenty-first century, (2) to establish a model that simulates water temperature by means of air temperature and flow rate in order to generate water temperature scenarios, and (3) to evaluate the impact on fish communities using an ecological model that is driven by water temperature. This methodology links the response of fish fauna to an IPCC emission scenario and is to our knowledge an unprecedented approach. The downscaled IS92a scenarios show increased mean air temperatures during the whole year and increased precipitation totals during summer, but reduced totals for the rest of the annual cycle. These changes result in scenarios of increased water temperatures, an altered annual cycle of flow rate, and, in turn, a 70 m displacement in elevation of fish communities towards the river's head. This would enhance stress on species that rely on low water temperatures and coerce cyprinid species into advancing against retreating salmonids. Hyporhithral river sectors would turn into epipotamal sectors. Grayling (Thymallus thymallus) and Danube salmon (Hucho hucho), presently characteristic for the Mur River, would be superceded by other species. Native brown trout (Salmo trutta), already now under pressure of competition, may be at risk of losing its habitat in favour of invaders like the exotic rainbow trout (Oncorhynchus mykiss), which are better adapted to higher water temperatures. Projected changes in fish communities suggest an adverse influence on salmonid sport fishing and a loss in its high economic value.

Best practise flushing strategy at the Upper Mur River

Durch Stauhaltungen wird der Feststoffhaushalt der Steirischen Oberen Mur beeinflusst und ein Feststoffdefizit im Unterwasser erzeugt. Weiters konnen bei Spulungen von Flusskraftwerken fur die Flussbiozonose schadliche Schwebstoffbelastungen und bei den Abstauvorgangen Schwall- und Sunkerscheinungen auftreten. Durch Spulungen von vier Flusskraftwerken wird den negativen Auswirkungen des Feststoffruckhalts in den Stauraumen entgegengewirkt. Bisher war es unklar, welche Spulabstande an der Oberen Mur zu einem wasserwirtschaftliches Optimum fuhren, um die Stauraume bestmoglich entlanden zu konnen. Mit dem EU Interreg IIIB Projekt ALPRESERV wurde ein wasserwirtschaftliches Konzept entwickelt, das zusammen mit einem umfangreichen okologischen Untersuchungsprogramm Teil eines Spulkonzepts bildet. Im vorliegenden Artikel wird das optimierte, wasserwirtschaftliche Spulprogramm prasentiert und auf einzelne Elemente eingegangen.

BYPASS CHANNELS AT WEIRS AS APPROPRIATE AIDS FOR FISH MIGRATION IN RHITHRAL RIVERS

In most cases, the design of currently deployed migration aids is based on technical concepts, e.g. fish ladders, fish lifts, etc. These systems meet the swimming and migratory requirements of commercially interesting species such as salmonids, but not of smaller fish species and/or juvenile stages. In this context, bypass channels designed to resemble natural stream channels-with a comparatively flat gradient and a high morphological, current and substrate diversity-are a viable alternative. The utility of such systems, in compensating for the interrupted river course and in supporting migrations of various rhithral fish species, has been demonstrated in an investigation of a bypass channel on the Mur River in Styria, Austria. This 200 m long system with a total of 30 pools and riffle-like connections was successfully navigated by all seven existing fish species and was additionally used by juvenile fish as habitat. During the main spawning periods April-June and September-December, a total of 3658 fish ascended the bypass, 94% of which did so in the spring. In the 5.5 km stretch of river below the weir, the grayling (Thymallus thymallus) was the dominant species. From an estimated population of 13 300 adults, 17% migrated through the pass.

A New Footbridge, Austria

At the site selected for a new footbridge, the banks of the Mur River in Graz, Austria, have an elevation difference of about 2.2 m. The designers felt that a simple straight beam inclined across t...

The Mur River Wooden Bridge, Austria

This article describes the design and construction of a bridge across the River Mur, to connect the communities of St. Georgen/Murau and St. Lorenzen/Murau in Austria. The chosen design was a wooden bridge with a parabolic three-hinged arch, which functions as the main girder and is also the principal aesthetic element. The bridge's connection elements are made of steel, and there is a concrete deck. The bridge has length 85m and the arch has chord length 45m. A bracing system handles wind and other lateral loads perpendicular to the long axis of the bridge. At the abutment and pier on each side, anchored and reinforced elastomeric bearings are provided, which can resist the tensile forces. All other bearing points, including those for the V- support and the arch, act as pin bearings in the structural system. The structural elements of the bridge were completed in three phases: (1) completion of steel members; (2) lamination of the wood members; (3) component assembly of the wood members. Phases (2) and (3) were concurrent. To prepare for the assembly work, a sufficiently large joining and assembling area had to be provided on both banks of the river.