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There is a growing need to improve our understanding of catchment flow generation processes, especially in alpine watersheds, where the aquatic biodiversity is dependent upon the types of water sources and their seasonal dynamics. In order to identify and quantify the potential sources that contribute to stream runoff, Water samples were collected and discharge was measured. Other physical variables like electric conductivity and water temperature were also collected twice a day, once in the morning and once in the evening. These measurements continued for two to four consecutive days. In situ measurements were done for temperature, electric conductivity and turbidity of water at different temporal scale. Mass spectrometry was done to analyze silica and sulfate along with chlorine. Three different water sources were identified based on their physiochemical characteristics: glacier melt water, quickly routed surface runoff, and slowly routed ground water. Principal component analysis was performed in order to reduce dimensionality of the chemistry data independently in two hydrological years. End member mixing analysis was carried out for morning and afternoon data to describe the daily variation of runoff components. Our study suggests that glacier melt component has a strong daily variation, which influences the magnitude and timing of peak flow. A sign of early melt and accumulation can be seen in this watershed based on the studied years.

Freshwater biodiversity has shown to be highly vulnerable to climate warming, alpine cold stenotherm populations being especially at risk of getting extinct. This paper aims at identifying the environmental factors favouring cold stenotherm species in alpine ponds. This information is required to provide management recommendations for habitats restoration or creation, needed for the mitigation of the effects of climate warming on alpine freshwater biodiversity. Cold stenotherm species richness as well as total (i.e. stenotherm and eurytherm) richness were analyzed for aquatic plants, Coleoptera and Odonata in 26 subalpine and alpine ponds from Switzerland and were related to environmental factors ecologically relevant for pond biodiversity. Our results confirmed that the set of environmental variables governing pond biodiversity in alpine or subalpine ponds is specific to altitude. Altitude and macrophyte presence were important drivers of cold stenotherm and total species richness, whereas connectivity did not show any significant relation. Therefore, the management of pond biodiversity has to be ‘altitude-specific'. Nevertheless, cold stenotherm species from the investigated alpine ponds do not show some specific requirements if compared to the other species inhabiting these ponds. Therefore, both total and cold stenotherm species richness could be favoured by the same management measures.

Deichbau und andere flussbautechnische Maßnahmen haben dazu geführt, dass die Mittlere Elbe ihre ursprünglichen Überschwemmungsgebiete verloren hat. Um die Auswirkungen der alljährlich auftretenden Hochwasserereignisse einzudämmen, wurden große Bereiche der Talniederung durch Deiche vom Überflutungsgeschehen abgetrennt. Diese Eingriffe in den Naturhaushalt ermöglichten gleichfalls eine intensive ackerbauliche Nutzung oder eine hochwassersichere Bebauung der Auen. Die natürliche Auendynamik ist heute weitestgehend auf einen schmalen Bereich entlang der Elbe beschränkt. Hinter den Deichen sind die für die Elbeauen typischen Lebensräume von der lebenswichtigen Auendynamik abgeschnitten. Angepasste Auenarten und -lebensgemeinschaften treten zugunsten von Allerweltsarten zurück. Eine Wiederanbindung von Altauenbereichen an das Überflutungsgeschehen ist deshalb eine der vordringlichsten Maßnahmen zur Revitalisierung gefährdeter Auenlebensräume und stellt eine Chance dar, einen nachhaltigen und modernen Hochwasserschutz mit Naturschutzzielen zu verbinden. An der Elbe entspricht das aktuelle Hochwasserschutzsystem nicht den heutigen Anforderungen an den Hochwasserschutz. Um jedoch jederzeit auf mögliche große Hochwasserereignisse reagieren zu können, entstanden Anfang der 1990er Jahre in den Anliegerländern der Elbe zahlreiche Pläne für Deichrückverlegungen.

Deichrückverlegungsprojekte, wie das im Roßlauer Oberluch an der Mittleren Elbe, stellen für den Naturschutz sowohl Chance als auch Herausforderung dar. Es wird argumentiert, dass solche Maßnahmen einerseits dem Hochwasserschutz, auf der anderen Seite auch dem Arten- und Biotopschutz dienen sollen. Die Auswirkungen von Deichrückbauvorhaben auf Natur und Landschaft sind bisher jedoch nur unzureichend bekannt. Dies ist primär der Tatsache geschuldet, dass für viele Arten die Kenntnisse über die Wechselwirkungen mit ihrer Umwelt noch immer defizitär sind und somit die Auswirkungen von Umweltveränderungen auf Flora und Fauna nicht effektiv quantifiziert werden können. Das gilt auch und gerade für Heuschrecken in Feuchtlebensräumen, wie z. B. in Flussauen. In der vorliegenden Arbeit wurden die Zusammenhänge zwischen wichtigen Umweltvariablen und den Vorkommen von Heuschrecken genauer betrachtet.

Floodplains are characterized by high spatial and temporal heterogeneity. Despite low active mobility, Central European floodplain gastropod communities show a high species diversity. They are supposed to have developed a large range of resistance and/or resilience strategies to survive in the highly variable and frequently disturbed floodplain habitats.Relating gastropod diversity and species traits to hydrological conditions, we tested how different groundwater and flood regimes affect gastropod diversity and identified the main species traits favouring their survival in highly dynamic floodplain grasslands.Species richness, species diversity and functional diversity peaked at intermediate flood disturbance and moisture levels. Harsher environmental conditions in either dryer or frequently flooded habitats restricted the gastropod communities to a few specialized species.Morphological and life-history traits showed significant variations along the hydrological gradient. Shell character and mode of reproduction proved to be important functional determinants for gastropod community composition. Species with strongly calcified shells, which limit the risk of injuries in case of dislodgment, were more often found in flood prone sites. Uniparental reproduction dominated in the driest as well as in highly flood-disturbed habitats, providing reproductive assurance where harsh environmental conditions may reduce the number of potential mates.Intermediate disturbance and moisture levels favoured local gastropod diversity whereas dryer or highly flood-disturbed habitats sheltered specialized species. Therefore, the maintenance of areas with different disturbance and moisture levels is of major importance in favouring taxonomical and functional mollusc diversity across the whole floodplain.

Extreme environmental events are predicted to increase in future due to global climate change. However, their effects on biodiversity still remain insufficiently understood because of the rarity and consequently the difficulty of studying the effects of extreme events. Here, we investigate the impacts on ground beetles of an unpredictable catastrophic flood event of the Elbe River in Germany in the year 2002 using pre- and post-flood data. We analysed the response of grassland communities differentially exposed to flooding and focused on the question of how long their response lagged behind this extreme flood. Ground beetles were sampled from 1998 to 1999 (pre-flood period) and from 2002 to 2006 (post-flood period) on 48 floodplain grassland plots with a stratified randomized sampling design. Community resilience was quantified by calculating changes in species richness, species abundances, Simpson diversity and beta diversity of ground beetle assemblages. Ground beetles showed low resistance but high resilience to the extreme flood. Species richness decreased strongly immediately after the flood but reached pre-flood values 2 years later. However, beta diversity remained relatively high in the subsequent years indicating persistent shifts in species composition and abundances. Contrary to our expectation, assemblages inhabiting plots prone to flooding, expected to be less sensitive to floods, did not recover faster than those on rarely inundated plots. We considered both the timing and the long duration of the flood as main reasons for the low community resistance to the flood. Strategies related to dispersal and habitat generality are identified to be crucial for the quick community recovery following the extreme flood. Our results endorse that extreme floods are integral parts of functioning floodplain ecosystems and that species can cope well even with such unpredictable extreme events, although recovery time tends to be longer than after normal floods.

The ecological reaction of species on environmental factors can differ both, temporally and geographically. Therefore, bioindicator systems must be shown to remain accurate at different places and points of time. Extreme events pose challenges for testing this robustness, which has not yet been explored systematically. The unique opportunity of the extreme flooding of the river Elbe in August 2002 was used for such a test. The bioindicator system for mean groundwater depth during the vegetation period and annual duration of inundation in floodplains studied here was developed with data collected in 1999. Data from 2003 were used to analyse the dependence of the bioindication results on the humidity of the study plots and taxonomic group (plants, molluscs and carabid beetles). For the duration of inundation, the accuracy of bioindication in 2003 was similar to that in 1999, except for the medium-humid and dry plots using molluscs as indicators. For groundwater depth, the accuracy of bioindication in 2003 was similar to that of the reference year except in the dry plots with significantly lower accuracy for all species groups. With a few exceptions, the bioindicator system is shown to be robust and to remain accurate in spite of an extreme flood event. In conclusion, the relevance of extreme events for the robustness of bioindicator systems differs between the indicated parameters and taxonomic groups. The results stress the need to take into account the limits of the working range and the occurrence of extreme events, when testing and applying bioindicator systems.

Deichbau und andere flussbautechnische Maßnahmen haben dazu geführt, dass die Mittlere Elbe ihre ursprünglichen Überschwemmungsgebiete verloren hat. Um die Auswirkungen der alljährlich auftretenden Hochwasserereignisse einzudämmen, wurden große Bereiche der Talniederung durch Deiche vom Überflutungsgeschehen abgetrennt. Diese Eingriffe in den Naturhaushalt ermöglichten gleichfalls eine intensive ackerbauliche Nutzung oder eine hochwassersichere Bebauung der Auen. Die natürliche Auendynamik ist heute weitestgehend auf einen schmalen Bereich entlang der Elbe beschränkt. Hinter den Deichen sind die für die Elbeauen typischen Lebensräume von der lebenswichtigen Auendynamik abgeschnitten. Angepasste Auenarten und -lebensgemeinschaften treten zugunsten von Allerweltsarten zurück. Eine Wiederanbindung von Altauenbereichen an das Überflutungsgeschehen ist deshalb eine der vordringlichsten Maßnahmen zur Revitalisierung gefährdeter Auenlebensräume und stellt eine Chance dar, einen nachhaltigen und modernen Hochwasserschutz mit Naturschutzzielen zu verbinden. An der Elbe entspricht das aktuelle Hochwasserschutzsystem nicht den heutigen Anforderungen an den Hochwasserschutz. Um jedoch jederzeit auf mögliche große Hochwasserereignisse reagieren zu können, entstanden Anfang der 1990er Jahre in den Anliegerländern der Elbe zahlreiche Pläne für Deichrückverlegungen.

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Deichrückverlegungsprojekte, wie das im Roßlauer Oberluch an der Mittleren Elbe, stellen für den Naturschutz sowohl Chance als auch Herausforderung dar. Es wird argumentiert, dass solche Maßnahmen einerseits dem Hochwasserschutz, auf der anderen Seite auch dem Arten- und Biotopschutz dienen sollen. Die Auswirkungen von Deichrückbauvorhaben auf Natur und Landschaft sind bisher jedoch nur unzureichend bekannt. Dies ist primär der Tatsache geschuldet, dass für viele Arten die Kenntnisse über die Wechselwirkungen mit ihrer Umwelt noch immer defizitär sind und somit die Auswirkungen von Umweltveränderungen auf Flora und Fauna nicht effektiv quantifiziert werden können. Das gilt auch und gerade für Heuschrecken in Feuchtlebensräumen, wie z. B. in Flussauen. In der vorliegenden Arbeit wurden die Zusammenhänge zwischen wichtigen Umweltvariablen und den Vorkommen von Heuschrecken genauer betrachtet.

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In contrast to the northern hemisphere where species of Chironomidae are usually the dominant benthic invertebrates in the coldest upper reaches of glacial streams, mayflies (Deleatidium spp.: Leptophlebiidae) predominate in equivalent conditions in New Zealand. We examined the life histories and annual production of Deleatidium spp. at two sites on the Matukituki River (South Island, New Zealand) and at three sites in its glacier-fed tributary, Rob Roy Stream. Mean annual water temperature at the five sites ranged from 2.1 to 7.0°C. Monthly sampling showed that mayfly populations were poorly synchronised at all sites but were probably univoltine. The large Deleatidium cornutum was the dominant mayfly species found at the upper sites (Sites 1 and 2) on Rob Roy Stream, whereas above the confluence with Matukituki River (Site 3) it co-existed with a complex of smaller species we refer to as D. "angustum". Deleatidium "angustum" also dominated at the Matukituki sites. Deleatidium production calculated for the five sites, assuming an 11-month nymphal life, ranged from 0.48 g dry weight/m2/year (Site 1) to 3.07 g dry weight/m2/year (Site 3). The values for D. cornutum at Sites 2 and 3 are high for a species of Deleatidium and reflect its large size. This species appears to be strongly adapted for growth at low temperatures. Climate change scenarios for New Zealand predict the gradual and ultimate loss of small South Island glaciers and a consequent warming of streams as runoff from rainfall and snow melt becomes more dominant in spring. As a result, suitable habitats will be lost for cold-water specialists such as D. cornutum, and they are likely to suffer reductions in their distributional range and local extinction. In contrast, species such as those in the D. "angustum" complex may extend their ranges into streams formerly dominated by glacial meltwater. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which

1. Glacier-fed streams are characterised by low spatial but high temporal heterogeneity, manifested in seasonal and diurnal discharge and suspended sediment peaks induced by glacial runoff. These streams shelter macroinvertebrate communities adapted to such harsh environmental conditions. Studies relating macroinvertebrate traits to environmental conditions in glacial streams could provide important insights into the structure and function of glacial stream communities.2. From data collected in three glacial streams from the central Swiss and southern French Alps, we analysed the relationships among six biological traits to define five groups of macroinvertebrate taxa with similar suites of traits.3. The longitudinal distribution of the five groups and of individual traits was analysed, as well as their variation according to a glaciality index combining water temperature, conductivity, suspended solids and substrate stability.4. The trait diversity along the three streams showed a strong upstream-downstream gradient. The upper reaches were dominated by a single group of taxa characterised by small, crawling, deposit feeders. The other trait-based groups appeared progressively downstream.5. Changes in the relative frequency of trait-based groups along the glaciality gradient highlighted the dominance of all-rounder resistant/resilient traits in the three streams and confirmed that environmental conditions in the glacial streams are too harsh or uniform to allow macroinvertebrate communities to develop alternative suites of traits. The findings are discussed in relation to the question of trait coding in the available literature.

1. Benthic macroinvertebrate distribution was examined in relation to channel characteristics (including stability), substratum, hydraulic variables, primary production (chlorophyll a) and coarse particular organic matter (CPOM) in an alpine glacial stream, the Mutt (Upper Rhône valley, Switzerland). Co-inertia analysis and canonical correspondence analysis were used to identify the major environmental gradients influencing community variations.2. The Mutt (length: 3.6 km, altitudinal range: 1800–3099 m a.s.l.) exhibited typical characteristics of a kryal stream. Average summer temperature remained below 2 °C immediately downstream from the snout but was on average 5 °C higher 1700 m downstream. Seasonal variations in water sources were evidenced by the high late-summer (September) contribution of groundwater with increased conductivity.3. Sixty-six taxa were recorded from the five reaches sampled at three periods (snowmelt, ice melt and low water in late summer) in 1996 and 1997, of which 29 were Chironomidae. Three taxa of Diamesinae were the first colonizers of the stream below the glacier, but 16 taxa, including Ephemeroptera, Plecoptera and Trichoptera, were already recorded 200 m downstream. Water depth, channel slope and Pfankuch’s Index of channel stability were strongly correlated with the longitudinal faunal gradient. Maximum temperature, current velocity and water conductivity were also correlated, but to a lesser extent.4. The rapid incorporation of non-chironomid taxa into the stream community represented a departure from Milner & Petts’s (1994) conceptual model of invertebrate succession downstream of glacial margins. The results confirmed that glacial stream communities are primarily driven by physical determinants.

The study of the invertebrate assemblages in a small glacial catchment of the Swiss Alps (the Mutt) was designed to categorise sites in relation to their water sources and assess the contribution of small headwater tributaries to the biodiversity of such Alpine catchments. Physico-chemical characteristics and macroinvertebrate drift were monitored in seven streams during three contrasting hydrological periods in June, August and September 1997. Physico-chemical characteristics clearly differentiated kryal (glacial) and krenal (groundwater-fed) streams. The glacial waters showed a broader amplitude in environmental variation, depending on altitude, geology and season. Macroinvertebrate drift composition was significantly correlated with the environmental conditions. In kryal streams, where harsh conditions prevailed, diversity and abundance were low, while the krenal streams showed highly diversified and dense macroinvertebrate communities. favoured by physico-chemical constancy. However, the low number of taxa found at the same time in these groundwater-fed tributaries and in the main Mutt stream indicated a low contribution from these small streams to the communities of the main stream. Nevertheless, the habitat heterogeneity generated by different water origins in the tributaries favoured the coexistence of diversified macroinvertebrate communities in a rather small catchment area. Therefore these tributaries played an important part in the biodiversity of the glacial catchment.