Patrick Leitner

• BOKU University

Zusammenfassung Kontinuumsunterbrechungen und Restwassersituationen durch Kleinstwasserkraftanlagen stellen wesentliche hydromorphologische Beeinträchtigungen von Fließgewässern in Österreich dar, wobei bereits Möglichkeiten und Vorgaben für Sanierungsmaßnahmen bestehen. Speziell für das hydromorphologische Risiko in Staubereichen fehlen jedoch spe...

Freshwater macroinvertebrates are a diverse group and play key ecological roles, including accelerating nutrient cycling, filtering water, controlling primary producers, and providing food for predators. Their differences in tolerances and short generation times manifest in rapid community responses to change. Macroinvertebrate community compositio...

Zusammenfassung Die Modellierung von aquatischen Lebensräumen gewinnt durch die verschiedenen Zielvorgaben auf europäischer und somit auch nationaler Ebene immer mehr an Bedeutung. Neben den Vorgaben der Wasserrahmenrichtlinie und den Zielen zum Ausbau der erneuerbaren Energieträger, inkl. Wasserkraft, sind es auch die neuen Strategien zur Biodiver...

Humans impact terrestrial, marine and freshwater ecosystems, yet many broad-scale studies have found no systematic, negative biodiversity changes (for example, decreasing abundance or taxon richness). Here we show that mixed biodiversity responses may arise because community metrics show variable responses to anthropogenic impacts across broad spat...

For the stone crayfish, a threatened species listed in the Habitats Directive in Annex II and V, three monitoring methods were evaluated: hand capture by day, hand capture by night and eDNA sampling respectively. The lack of a standardized sampling method in Austria and the simultaneous obligation to monitor and report on the status of protected sp...

Owing to a long history of anthropogenic pressures, freshwater ecosystems are among the most vulnerable to biodiversity loss¹. Mitigation measures, including wastewater treatment and hydromorphological restoration, have aimed to improve environmental quality and foster the recovery of freshwater biodiversity². Here, using 1,816 time series of fresh...

As alien invasive species are a key driver of biodiversity loss, understanding patterns of rapidly changing global species compositions depends upon knowledge of invasive species population dynamics and trends at large scales. Within this context, the Ponto-Caspian region is among the most notable donor regions for aquatic invasive species in Europ...

Aim Invasive alien species are a growing problem worldwide due to their ecological, economic and human health impacts. The “killer shrimp” Dikerogammarus villosus is a notorious invasive alien amphipod from the Ponto‐Caspian region that has invaded many fresh and brackish waters across Europe. Understandings of large‐scale population dynamics of hi...

The Ziller River, a tributary to the Inn in Tyrol, Austria, is affected by hydropower generation. Macroinvertebrate habitat‐preferences were investigated in the field and corresponding habitat suitability curves were applied successfully to a novel integrative assessment method based on hydrodynamic modelling. Here, a reach of the Ziller River is s...

As alien invasive species are a key driver of biodiversity loss, understanding patterns of rapidly changing global species compositions depends upon knowledge of biological invasion dynamics and trends. The Ponto-Caspian region is among the most notable donor regions for aquatic invasive species in Europe. Using macroinvertebrate time series collec...

Globalization has led to the introduction of thousands of alien species worldwide. With growing impacts by invasive species, understanding the invasion process remains critical for predicting adverse effects and informing efficient management. Theoretically, invasion dynamics have been assumed to follow an “invasion curve” (S-shaped curve of availa...

Sediment dynamics and composition in streams are key factors influencing the habitat quality of aquatic organisms, consequently playing an important role in terms of river restoration. The superposition of the river-bed with fine sediments is an increasing global stressor affecting local habitat diversity and leading to changes of benthic communiti...

With the European Water Framework Directive (WFD) in 2000, all European countries committed themselves to restore the good ecological status or a good ecological potential in their water bodies and to prevent further deterioration of the ecological status. In the national water management plan, concrete environmental goals are defined for all water...

A wide knowledge base regarding the ecological preferences of benthic macroinvertebrates is synthesized in public databases. This knowledge can assist in disentangling the influence of multiple environmental factors on the probability of occurrence of macroinvertebrates and in identifying anthropogenic impacts on the macroinvertebrate assemblage. W...

Specific concepts of fluvial ecology are well studied in riverine ecosystems of the temperate zone but poorly investigated in the Afrotropical region. Hence, we examined the longitudinal zonation of fish and adult caddisfly (Trichoptera) assemblages in the endorheic Awash River (1,250 km in length), Ethiopia. We expected that species assemblages ar...

Two factors complicate the ecological status classification of very large rivers in Europe according to the EU Water Framework Directive: First, current assessment methods do not fully consider the specific ecology of very large rivers (such as lateral connectivity and the role of floodplains for ecological status). Second, most of Europe's very la...

Large wood (LW) is an indispensable element in riverine ecosystems, especially in lower river parts. The presence of LW significantly shapes local hydraulics, morphology, the nutrient budget; promotes overall river dynamics; and additionally presents a unique habitat for numerous benthic invertebrate species. Therefore, LW is recognized as valuable...

The present case study deals with a controlled drawdown beyond the operational level of the Gepatsch reservoir (Austria). Based on the awareness of potential ecological consequences, an advanced set of measures was conducted and an integrative monitoring design was implemented. This pre-and post-event monitoring included measurements regarding the...

The sustainable management of very large rivers is based on the assessment of their environmental condition. However, unlike for smaller rivers, this assessment is yet less advanced due to the specific complexities of very large river systems. In Europe, this is reflected by the lack of an international large river typology classifying these ecosys...

We comparatively examined the role of littoral and deep water sampling methods in assessing macroinvertebrate assemblages and in characterizing longitudinal changes in assemblage structure along >2,500‐km–long course of the Danube River, Europe. The effectiveness of detecting taxa corresponded well with an inshore–offshore gradient in sampling (i.e...

Benthic invertebrates were used as bioindicators to document the effect of restoration measures in the backwater Alte Donau in Vienna, a former side-arm of the Danube. The study covers four periods of lake management: (1): the mesotrophic year before eutrophication (1987), (2): the 2 years of chemical iron chloride treatment aimed at the phosphate...

Benthic invertebrates were used as bioindicators to document the effect of restoration measures in the backwater Alte Donau in Vienna, a former side-arm of the Danube. The study covers four periods of lake management: (1): the mesotrophic year before eutrophication (1987), (2): the 2 years of chemical iron chloride treatment aimed at the phosphate...

• Studying interactions among co‐evolved invaders might help us in understanding, predicting, and perhaps mitigating the impact of the invading species on the native biota. The factors of spatial niche differentiation were investigated among invasive Ponto‐Caspian peracarids with the aim of revealing how co‐evolved species can coexist with the ‘kil...

After Chelicorophium curvispinum, two other Ponto-Caspian tube-dwelling, filter feeding amphipod species (C. robustum and C. sowinskyi) have colonized several catchments in Central and Western Europe in recent decades. To reveal the mechanism of niche differentiation among them, we measured the mesh sizes of their filtering apparatus and analyzed m...

A calibration mistake caused systematic error in the microscopic measurements; all filter mesh size values should be divided by a factor of 2.56. As our conclusions were based on the inter- and intraspecific variations of the trait, this systematic error does not influence them in any way. Filter mesh sizes ranged between 2.47 and 7.17 μm in C. cur...

Dredging Austrian Danube harbours becomes necessary to keep the navigation channel free from bed sediment and to insure safe navigation, especially after major floods. In most cases, the excavated substrate is deposited in the free-flowing river section in the vicinity of the mouth of a harbour. The effects of harbour dredging on the biota need to...

In this paper, a monitoring and modelling concept for ecological optimized harbour dredging and fine sediment disposal in large rivers is presented. According to the concept, first a preliminary assessment should be performed previous to the dredging and dumping procedure to derive knowledge about the current status in hydrodynamics, morphology and...

The dynamic component in hydrology, sedimentology, and, consequently, river morphology serves as a backbone for the entire river environment (Maddock 1999). In addition to water pollution, the hydro-morphological/sedimentological degradation is one of the main pressures on river systems (Ward and Stanford 1995; Dudgeon et al. 2006). The EU Water Fr...

Instream large wood (LW) constitutes an indispensable element of natural river ecosystems. It affects local hydraulics, morphology, nutrient budget, overall habitat complexity, and dynamics. Despite numerous studies about LW as a habitat for benthic communities, information on the varying importance along the longitudinal gradient of a river is lac...

Benthic invertebrates were used as bioindicators to document the effect of restoration measures in the backwater Alte Donau in Vienna, a former side-arm of the Danube. The study covers four periods of lake management: (1): the mesotrophic year before eutrophication (1987), (2): the 2 years of chemical iron chloride treatment aimed at the phosphate...

Ponto–Caspian peracarids (amphipods, isopods, mysids and cumaceans) represent one of the most successful groups of aquatic invaders comprising several high-impact species, such as Chelicorophium curvispinum, Dikerogammarus villosus, or Hemimysis anomala. In the present study we made the first attempt to compare biological traits and the environment...

Artificial flow fluctuations due to the operation of hydropower plants, frequently described as hydropeaking, result in a constant decrease of biomass of specific macrozoobenthos (MZB) taxa. For the presented case study, we assessed three reaches in the Ziller River catchment. At each sampling reach we performed the Multi-Habitat-Sampling (MHS) met...

Fauna Aquatica Austriaca, Mayflies (Ephemeroptera)

During research into phytobenthos, macrophytes and macroinvertebrates in Bijela rijeka River in the Plitvice Lakes National Park in 2015, Hydrurus foetidus (Villars) Trevisan was recorded for the first time in Croatia. H. foetidus is a macroalga belonging to the group of golden algae or chrysophytes (Ochrophyta: Chrysophyceae). It is a stenotherm s...

Facilitative interactions among co‐evolved representatives of the endemic Ponto‐Caspian fauna are regarded as a major factor of their invasion success. Nevertheless, the most renowned examples represent interactions between different trophic levels or functional groups, while ecologically similar species can be expected to show competition‐based ni...

Der naturnahe Wasserbau besitzt aufgrund seiner Begrifflichkeit bereits den Anspruch, natürliche und naturnahe Rahmenbedingungen und Prozesse in Planungen von wasserbaulichen Maßnahmen wie Hochwasserschutz oder Ufersicherungen miteinzubeziehen. Hier spielt in einer mittel- bis längerfristigen Betrachtung der Feststoffhaushalt eines Fließgewässers e...

Hydropeaking as a result of peak-load electricity production has been identified as one of the most significant pressures in alpine streams. Scouring of macroinvertebrates leads to downstream transport of aquatic organisms (catastrophic drift). Additionally, invertebrates are affected by periodic drying of wetted area during the dewatering of grave...

A key challenge for the ecological risk assessment of chemicals has been to evaluate the relative contribution of chemical pollution to the variability observed in biological communities, as well as to identify multiple stressor groups. In this study we evaluated the toxic pressure exerted by > 200 contaminants to benthic macroinvertebrates in the...

Anthropogenically induced siltation has serious effects on micro-habitat diversity and thus on aquatic organisms in lotic systems. The present study deals with the impact of siltation on the macroinvertebrate community in the River Lafnitz, south-eastern Austria. Our aim was to examine various ecological parameters in a meandering river stretch. Th...

Large rivers have always been in the focus of human attention. Ancient and modern civilisations have arisen, prospered and dwindled on their banks, leaving us with the myths and legends that their waters provoked. Large rivers are of major economic relevance as providers of substantial services like, most notably drinking water, food, energy and tr...

The River Danube plays a central role in the spread of Ponto-Caspian species as a part of the so-called southern invasion corridor (Danube-Main-Rhine system); therefore, changes in its peracarid fauna (comprising the bulk of invasives) merit special attention. The latest international research expedition (Joint Danube Survey 3, 2013) offered an opp...

The aim of this work is to analyze the importance of Large Woody Debris (LWD) for benthic invertebrates along the longitudinal gradient of a lowland river, the Lafnitz River. The river is located in the southeastern part of Austria and has a near natural character and riparian vegetation, with a high diversity of woody debris structures. Difference...

This article gives a rough overview on the occurrence and distribution of selected benthic invertebrates along the Danube River. The description of the benthic community within typological units of the Danube is based on the results from the Joint Danube Surveys. Species richness and abundance illustrate the structure and dominant groups of the ben...

The current and future use of water power as a cost-effective and renewable energy source are increasingly leading to conflicts of interest between the declared environmental protection goals of the EU Water Framework Directive and the water energy sector. As such, it has become necessary to objectively assess and quantify the potential impacts of...

Mit der Richtlinie 2000/60/EG zur Schaffung eines Ordnungsrahmens für Maßnahmen der Gemeinschaft im Bereich der Wasserpolitik hat die Umweltpolitik der Europäischen Gemeinschaften eine neue Dimension erreicht. Ziel dieser Richtlinie ist (neben anderen Vorgaben) die Schaffung eines Ordnungsrahmens für den Schutz der Binnenoberflächengewässer, der Üb...

Due to the disparate characteristics of Austria’s rivers, streams and surrounding riparian areas, similar anthropogenic impacts on our water systems can spark varying reactions. This is also true in the case of those waters affected by hydropeaking. In this context, the specific geometry of the river in question and the potential for “natural devel...

In Central Europe freshwater ecosystems have to deal with a loss of habitat structures due to channelisation and standardisation. Unimpaired streams and rivers are very rare, which leads to a few, remaining populations of sensitive invertebrate species which are severely fragmented. This progress is mainly noticed in lowland rivers in agricultural...

The majority of studies comparing the response of biotic metrics to environmental stress in rivers are based on relatively small, homogeneous datasets resulting from research projects. Here, we used a large dataset from Austrian and German national river monitoring programmes (2,302 sites) to analyse the response of fish, diatom and macroinvertebra...

Aquatische wirbellose Neozoa Die Datenlage belegt eindeutig, dass sich besonders in den beiden letzten Jahrzehnten die Entdeckungen neuer, nicht heimischer Tierarten in Österreichs Flüssen und Seen häufen. Nach bisherigen Erkenntnissen sind weniger die natürlichen Ausbreitungstendenzen, sondern die menschlichen Aktivitäten daran Schuld. Der Mensch...

Numerical fish-habitat modelling on various scales is considered to be state of the art in river management. However, most of the concepts applied use steady-state hydraulic parameters such as flow velocity and water depth. Herein we present analysis and discussion of the possibility of including a driftfeeding parameter (SIF) into habitat evaluati...