62 research outputs found
Hydromorphologie der Lausitzer Neiße: Pilotkonzept zur Verbesserung des hydromorphologischen Zustands im Abschnitt Sieniawka/Zittau bis Przewoz/Podrosche
Die Hydromorphologie eines Fließgewässers bestimmt wesentlich sein Abflussverhalten. Angesichts der Bedeutung der Hydromorphologie für ökologischen Funktionen und Leistungen sowie für den ökologischen Zustand von Gewässern ist es sehr wichtig, geeignete Methoden zur Erfassung und Bewertung des hydromorphologischen Zustandes zu entwickeln. Die Publikation widmet sich der Entwicklung und Darstellung eines Pilotkonzepts zur Verbesserung des hydromorphologischen Zustandes in ausgewählten Abschnitten der Lausitzer Neiße im Hinblick auf Niedrigwasser. Die Publikation richtet sich an Angestellte von Wasserbehörden in Sachsen und Polen, Entscheidungstragende von Verbänden, Betrieben und Institutionen aus dem Wassersektor und die interessierte Öffentlichkeit.
Redaktionsschluss: 02.03.202
Niedrigwasser und Mindestwasserabflüsse: Niedrigwasser und Mindestwasserabflüsse in der Lausitzer Neiße – Grenzüberschreitende Ansätze zur Ermittlung und Bewertung
Die Bewirtschaftungspläne der Lausitzer Neiße in Sachsen, Brandenburg und Polen sind nicht in allen Punkten kompatibel, andererseits erfordert sowohl die Umsetzung der Europäischen Wasserrahmenrichtlinie als auch das Hochwasserrisikomanagement und das Management von Niedrigwasser eine Betrachtung des gesamten Einzugsgebietes, sodass sich die Notwendigkeit einer Abstimmung zwischen den zuständigen Behörden ergibt. Regelungen in Bezug auf das Management von Niedrigwasserbedingungen in Polen und Sachsen werden vergleichend gegenübergestellt und eine Reihe von Vorschlägen für eine gemeinsame Betrachtungsweise von Niedrigwasser und der Ermittlung und Festsetzung von Mindestwasserabflüssen formuliert. Die Publikation richtet sich an Angestellte von Wasserbehörden in Sachsen und Polen, Entscheidungstragende von Verbänden, Betrieben und Institutionen aus dem Wassersektor und die interessierte Öffentlichkeit.
Redaktionsschluss: 02.03.202
Two-Dimensional Distance Correlation Maps from Pulsed Triple Electron Resonance (TRIER) on Proteins with Three Paramagnetic Centers
Pribitzer S, Ibanez LF, Gmeiner C, et al. Two-Dimensional Distance Correlation Maps from Pulsed Triple Electron Resonance (TRIER) on Proteins with Three Paramagnetic Centers. APPLIED MAGNETIC RESONANCE. 2018;49(11):1253-1279
Der Einfluss von Klimavariabilität auf aquatische Nahrungsnetze: Der Einfluss von Klimavariabilität auf aquatische Nahrungsnetze
In den gemäßigten Breiten zeigte
sich die allgemeine Erwärmung
der letzten Jahrzehnte
insbesondere im Winter und im
zeitigen Frühjahr. Dementsprechend
traten Veränderungen in
der Phänologie, dem zeitlichen
Verlauf von Populations- und
Entwicklungsprozessen von Organismen
(z. B. Zeitpunkt der
Knospung bei Pflanzen oder der
Laichperiode bei Fischen), vor
allem im Frühjahr auf. Obwohl
generell eine frühere und beschleunigte
Entwicklung als
Reaktion auf die Erwärmung
beobachtet wurde, zeigten sich
doch Unterschiede in der Sensitivität
von Organismen. Dadurch
kann es in Nahrungsnetzen
zu Match- oder Mismatch-
Situationen in Räuber-Beute
Beziehungen kommen. Am
Beispiel der komplexen Interaktionen
im Nahrungsnetz der
Talsperre Saidenbach wird der
Einfluss verschiedener Erwärmungsszenarien
auf Schlüsselorganismen
und deren Interaktionen
im Nahrungsnetz und
letztlich auf die Wassergüte in
dieser Trinkwassertalsperre im
Rahmen des DFG-Schwerpunktprogramms
AQUASHIFT
analysiert.In temperate regions, the warming
trends of the last decades
have been observed primarily in
winter and early spring. Accordingly,
changes in the phenology
of individual species, e.g.
sprouting in plants or spawning
of fish, occurred mainly in
spring. Although the general
pattern is earlier and faster development
in response to
warming, differences in sensitivity
have been apparent between
species, potentially giving
rise to match or mismatch scenarios
in predator-prey relations.
The impact of warming scenarios
on key species, their interactions
and ultimately on the
water quality is studied at Saidenbach
Reservoir within the
framework of the DFG priority
program AQUASHIFT
Population dynamics of Daphnia galeatat in the biomanipulated Bautzen Reservoir: life history strategies against food deficiency and predation
The population dynamics and demography of Daphnia galeata was analysed in a five year study in the biomanipulated Bautzen Reservoir. Samples were taken two times a week during the period May-July in the pelagic zone of this highly eutrophic water. Major bottom-up and top-down factors were determined during the study period and analysed with regard to their influence on Daphnia dynamics and life history. Field data on fecundity and population structure of D. galeata were combined with results from life table and growth experiments performed under approximately in situ conditions to gain insight into the mechanisms leading to a midsummer decline of this cladoceran species which dominates the zooplankton community in Bautzen Reservoir. Two main patterns of Daphnia dynamics emerged: In years without a midsummer decline the population increased slowly in spring, starting from low densities. High water transparency was observed already during the build-up of the population of D. galeata. Despite considerable fluctuations, Daphnia abundance remained on a high level throughout summer. In years with a midsummer decline the population started from relatively high densities in early May and more than doubled during one week. Peak densities were reached before the clear-water stage emerged. At the end of this period the population declined to low values which lasted for the rest of the summer. Fecundity of the Population of D. galeata declined, whereas the mean egg volume increased at the beginning of the clear-water stage as a result of declining food levels. The size at maturity (SAM) remained high during this period. Additionally, juvenile growth was reduced and the age at maturity was retarded. Survival probability was low for those daphnids born shortly before or during the clear-water stage compared to those born later. It can be concluded from these results that recruitment to adult stages is strongly reduced during the clear-water stage. The end of this period is marked by an alternation in generations. Only at that time can SAM be reduced because the new generation of adults matures at a smaller size, carrying small eggs. A high impact of non-predatory adult mortality can be expected when the population is dominated by a strong peak-cohort during the clear-water stage according to recruitment patterns during the build-up of the population. The most drastic decline both of Daphnia abundance and SAM was observed in those years when the biomass of juvenile fish exceeded 20 kg ha-1 at the end of the clear-water stage. Due to gape-size limitation juvenile fish mainly feed on juvenile daphnids during this period and thus, they reinforce bottom-up effects on the Daphnia population. When fish change their size selection towards adult daphnids at the time when the new generation takes over, this seems to represent the worst case for the Daphnia population. Consequently, the timing between bottom-up effects and the feeding pressure of juvenile fish determines the extent of the decline. - (This manuscript is also available - in the form of a book - from Shaker Verlag GmbH, Postfach 101818, 52018 Aachen, Germany world-wide web address: http://www.shaker.de, electronic-mail address: [email protected]. It has been posted on the web sites of Dresden University of Technology with the permission of the publisher
Population dynamics of Daphnia galeatat in the biomanipulated Bautzen Reservoir: life history strategies against food deficiency and predation
The population dynamics and demography of Daphnia galeata was analysed in a five year study in the biomanipulated Bautzen Reservoir. Samples were taken two times a week during the period May-July in the pelagic zone of this highly eutrophic water. Major bottom-up and top-down factors were determined during the study period and analysed with regard to their influence on Daphnia dynamics and life history. Field data on fecundity and population structure of D. galeata were combined with results from life table and growth experiments performed under approximately in situ conditions to gain insight into the mechanisms leading to a midsummer decline of this cladoceran species which dominates the zooplankton community in Bautzen Reservoir. Two main patterns of Daphnia dynamics emerged: In years without a midsummer decline the population increased slowly in spring, starting from low densities. High water transparency was observed already during the build-up of the population of D. galeata. Despite considerable fluctuations, Daphnia abundance remained on a high level throughout summer. In years with a midsummer decline the population started from relatively high densities in early May and more than doubled during one week. Peak densities were reached before the clear-water stage emerged. At the end of this period the population declined to low values which lasted for the rest of the summer. Fecundity of the Population of D. galeata declined, whereas the mean egg volume increased at the beginning of the clear-water stage as a result of declining food levels. The size at maturity (SAM) remained high during this period. Additionally, juvenile growth was reduced and the age at maturity was retarded. Survival probability was low for those daphnids born shortly before or during the clear-water stage compared to those born later. It can be concluded from these results that recruitment to adult stages is strongly reduced during the clear-water stage. The end of this period is marked by an alternation in generations. Only at that time can SAM be reduced because the new generation of adults matures at a smaller size, carrying small eggs. A high impact of non-predatory adult mortality can be expected when the population is dominated by a strong peak-cohort during the clear-water stage according to recruitment patterns during the build-up of the population. The most drastic decline both of Daphnia abundance and SAM was observed in those years when the biomass of juvenile fish exceeded 20 kg ha-1 at the end of the clear-water stage. Due to gape-size limitation juvenile fish mainly feed on juvenile daphnids during this period and thus, they reinforce bottom-up effects on the Daphnia population. When fish change their size selection towards adult daphnids at the time when the new generation takes over, this seems to represent the worst case for the Daphnia population. Consequently, the timing between bottom-up effects and the feeding pressure of juvenile fish determines the extent of the decline. - (This manuscript is also available - in the form of a book - from Shaker Verlag GmbH, Postfach 101818, 52018 Aachen, Germany world-wide web address: http://www.shaker.de, electronic-mail address: [email protected]. It has been posted on the web sites of Dresden University of Technology with the permission of the publisher
Climate change impact assessment on the hydrology of a large river basin in Ethiopia using a local-scale climate modelling approach
Local-scale climate change adaptation is receiving more attention to reduce the adverse effects of climate change. The process of developing adaptation measures at local-scale (e.g., river basins) requires high-quality climate information with higher resolution. Climate projections are available at a coarser spatial resolution from Global Climate Models (GCMs) and require spatial downscaling and bias correction to drive hydrological models. We used the hybrid multiple linear regression and stochastic weather generator model (Statistical Down-Scaling Model, SDSM) to develop a location-based climate projection, equivalent to future station data, from GCMs. Meteorological data from 24 ground stations and the most accurate satellite and reanalysis products identified for the region, such as Climate Hazards Group InfraRed Precipitation with Station Data were used. The Soil Water Assessment Tool (SWAT) was used to assess the impacts of the projected climate on hydrology. Both SDSM and SWAT were calibrated and validated using the observed climate and streamflow data, respectively. Climate projection based on SDSM, in one of the large and agricultural intensive basins in Ethiopia (i.e., Awash), show high variability in precipitation but an increase in maximum (Tmax) and minimum (Tmin) temperature, which agrees with global warming. On average, the projection shows an increase in annual precipitation (>10%), Tmax (>0.4 °C), Tmin (>0.2 °C) and streamflow (>34%) in the 2020s (2011–2040), 2050s (2041–2070), and 2080s (2071–2100) under RCP2.6-RCP8.5. Although no significant trend in precipitation is found, streamflow during March–May and June–September is projected to increase throughout the 21 century by an average of more than 1.1% and 24%, respectively. However, streamflow is projected to decrease during January–February and October–November by more than 6%. Overall, considering the projected warming and changes in seasonal flow, local-scale adaptation measures to limit the impact on agriculture, water and energy sectors are required
Impacts of projected change in climate on water balance in basins of East Africa
In East Africa, climate change and variability have shown a strong impact on sectors such as agriculture, energy, and water. To allow mitigation and adaptation of the possible impacts of the projected change in climate, this study applies a Statistical Downscaling Model (SDSM) to generate a high-resolution climate projection, equivalent to future station data, to drive impact assessment models in selected, agricultural intensive, basins of Ethiopia (EthShed), Kenya (KenShed), and Tanzania (TanShed). Observed and large-scale climate variables (predictors) are obtained from the national meteorological agency of Ethiopia and international databases. BROOK90, a physical-based hydrological model, is used to assess the impacts of the projected change in precipitation and maximum and minimum temperature (T-max, and T-min) on the water balance. Based on SDSM, the results show an increase in precipitation, relative to the baseline period (1961–1990), in EthShed (14% - 50%) and KenShed (15% - 86%) and a decrease in TanShed (1.3% - 6.3%) in the 20s (2011–2040), 50s (2041–2070), and 80s (2071–2100) under the three Representative Concentration Pathways (RCPs; RCP2.6, RCP4.5, and RCP8.5). T-max (anomalies up to 3.7 °C) and T-min (anomalies up to 2.76 °C) will be warmer than the baseline period throughout the 21 century in all three basins. In line with the projected change in precipitation and temperature, an increase (decrease) in seasonal and annual streamflow, soil-water, and evaporation in EthShed and KenShed (TanShed) is projected in the 20s, 50s, and 80s. In general, sustainable adaptation measures are required to be developed in a site-specific manner, considering the projected increase in temperature and evaporation in all three basins and a decrease in soil-water and streamflow in TanShed
Regional climate projections for impact assessment studies in East Africa
In order to overcome limitations of climate projections from Global Climate Models (GCMs), such as coarse spatial resolution and biases, in this study, the Statistical Down-Scaling Model (SDSM) is used to downscale daily precipitation and maximum and minimum temperature (T-max and T-min) required by impact assessment models. We focus on East Africa, a region known to be highly vulnerable to climate change and at the same time facing challenges concerning availability and accessibility of climate data. SDSM is first calibrated and validated using observed daily precipitation, (T-max, and T-min) from 214 stations and predictors derived from the reanalysis data of the National Centers for Environmental Prediction. For projection (2006–2100), the same predictors derived from the second generation Canadian Earth System Model (CanESM2) are used. SDSM projections show an increase in precipitation during the short-rain season (October–December) in large parts of the region in the 2020s (2011–2040), 2050s (2041–2070), and 2080s (2071–2100). During the long-rain season (March–May (MAM)) precipitation is expected to increase (up to 680 mm) in Ethiopia, mainly in the western part, and Kenya and decrease (up to −500 mm) in Tanzania in the 2020s, 2050s, and 2080s. However, the western part of Ethiopia will be much drier than the baseline period (1961–1990) during June–September (JJAS) in the 2020s, 2050s, and 2080s, which indicates a shift in precipitation from JJAS to MAM. Annually, precipitation, T-max, and T-min will be higher than during the baseline period throughout the 21 century in large parts of the region. The projection based on SDSM is in line with the direction of CMIP5 GCMs but differs in magnitude, particularly for T-max and T-min. Overall, we conclude that the downscaled data allow for much more fine-scaled adaptation plans and ultimately better management of the impacts of projected climate in basins of Ethiopia, Kenya, and Tanzania
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