Naturnahe Fliessgewässer sind dynamische Systeme: Gewässersohle und Ufer werden regelmässig durchHochwasser umgestaltet, wodurch neue Lebensräume entstehen. In den letzten Jahrzehnten wurde diese Dynamik vielerorts eingeschränkt, weil zahlreiche Fliessgewässer verbaut wurden. Ein wichtiges Ziel von Revitalisierungen ist, sie wiederherzustellen. Das vorliegende Merkblatt präsentiert Grundlagen für die Förderung der Dynamik.

Vielfältige, naturnahe und dynamische Lebensräume sind eine wichtige Voraussetzung dafür, die Biodiversität in Fliessgewässern zu erhalten und zu fördern. Das vorliegende Merkblatt stellt die wichtigsten Faktoren für die Lebensraum- und Artenvielfalt vor und präsentiert Empfehlungen, mit welchen Massnahmen die Biodiversität erhöht werden kann.

Lake Victoria, in East Africa, provides resources and services to millions of lakeshore inhabitants. The dynamics of these resources and services are variable, complex and poorly understood. Additionally, some of the perspectives of different lake scientists, users and stakeholders appear to be in disagreement as to the state of Lake Victoria’s ecosystem and fisheries, thus creating a barrier to constructive discussion regarding this system’s future. We here provide a social-ecological description of Lake Victoria’s system using three different approaches: in a first step, we describe past and present trends in elements of the socio economic and ecological subsystems. We then derive interactions between these elements, combine all subsystems into an interaction diagram and carry out a loop analysis on it to get a better grasp of the cascading chain of effects throughout the system as a whole and of how – conceptually at least – certain feedbacks in the system can be disrupted. In a final step, we bring together experts in all fields of study of Lake Victoria and ask them 10 critical questions regarding the state of the system, the answers of which we use to understand trends and drivers of resilience of Lake Victoria. We find that the social-economic subsystem is increasingly resilient to the collapse of contributing markets, but that it still is vulnerable to fishery collapses. The spatial heterogeneity and variability of Lake Victoria, as well as the biological diversity in central areas of the lake could increase the resilience of fisheries to harvesting. However, this resilience is reduced by eutrophication that causes irreversible loss of biodiversity to the system.

Scientists expect an increase in heavy rainfalls in Switzerland in the future because of climate change. During heavy rainfall, the wastewater system might not be able to cope with all the rainwater anymore, leading to surcharges of wastewater in combined sewer systems. Untreated wastewater can therefore reach surface waters, which is known as combined sewer overflows (CSOs). Wastewater can also overflow from manholes or sewers, thus flooding streets or cellars. With climate change, these events are expected to occur more often. It is possible to improve the wastewater system with structural measures to cope with such events, but the costs are high. Ultimately, this would result in an increase of the wastewater taxes paid by the population. The aim of our study was to elicit the willingness to pay of the Swiss population for improving the wastewater system in the context of climate change. We implemented an online survey representative of the Swiss population and interviewed 1’022 individuals from the three linguistic regions of Switzerland. We elicited the willingness to pay of the respondents using a conjoint choice analysis. Conjoint choice analysis entails the description of hypothetical scenarios where respondents are shown alternative representations of a policy and are asked to pick their most preferred option. In our study, respondents first received information on the wastewater system and on climate change to help them choosing between the different policy options. We focused on the following events: a) wastewater overflows in rivers and lakes; b) street flooding; or c) cellar flooding with wastewater. The results show that the Swiss people are concerned about the consequences of wastewater surcharges on the environment and on human health. Overall, 56% of the respondents would be willing to pay additional annual local taxes to reduce the risk of wastewater flooding or combined sewer overflows (CSOs). The average willingness to pay is about 240 CHF per person and year. This is in the same order of magnitude of the wastewater taxes they are paying today. On average, respondents would be willing to pay more to prevent CSOs (302 CHF, 71% of the respondents). The willingness to pay to prevent street flooding is about 237 CHF (with 53% of the respondents willing to pay). The willingness to pay to prevent wastewater flooding in cellars is about 184 CHF (with 43% of the respondents). One-to-one interviews indicated that the lower willingness to pay related to cellar flooding might be due to the fact that respondents think that measures against cellar floodings are rather a personal than a public responsibility. We want to emphasize that the estimation of the willingness to pay is based on hypothetical scenarios. For different reasons it is possible that the method over-estimates the absolute values of the willingness to pay. However, concretely for policy makers, our results clearly show that the population strongly values the protection of water bodies. Measures that reduce the effects of climate change on the wastewater system would likely be well perceived by the majority of the Swiss population, especially if ecological and health risks are reduced and accordingly communicated.

Dieses Fachgutachten ist Teil des Umweltverträglichkeitsberichts (UVB) 1. Stufe (Beilage 2 zum Hauptbericht) für ein Projekt von Repower, in welchem geplant ist, die beiden Seen Lago Bianco und Lago di Poschiavo als Speicherbecken für den Betrieb eines Pumpspeicherkraftwerkes mit einer in-stallierten Leistung von 1000 MW zu nutzen (Projekt Lagobianco). Die zu erwartenden Auswirkungen auf die Temperatur und die Partikelkonzentrationen in den beiden Seen wurden vorgängig im Rahmen der Machbarkeitsstudie mit Hilfe von Modellrechnungen mit einem gekoppelten zweidimensionalen Modell der beiden Seen berechnet und in zwei Berichten (Schmid et al., 2008; Schmid und Wüest, 2009) dokumentiert. In der vorliegenden Arbeit werden diese Berechnungen weiter vertieft und zusätzlich mit vier verschiedenen hydrologischen Szenarien und Wetterbedingungen von 29 Jahren durchgeführt. Dies erlaubt, einen Überblick über die zu erwartende Variabilität der verursachten Ver-änderungen zu gewinnen, und zu analysieren, unter welchen hydrologischen und meteorologischen Bedingungen die grössten Veränderungen zu erwarten sind.

The ultimate goal of the ESRISS Project is the development of a wide-scale replicable model for small-scale sanitation in the Nile Delta. By "small-scale" we refer to “settlements or groups of settlements of up to 5,000 inhabitants”. In our approach, the whole sanitation system, including management schemes, is considered. Cost-effectiveness and context-appropriateness are key targets. This document synthesises the main findings detailed in the ESRISS report entitled “Small-scale sanitation in Egypt: challenges and ways forward”.

ESRISS is a SECO-funded research project at Sandec. It deals with the sanitation planning gap of Nile Delta villages where the main challenges are organisational and institutional, more than technical. The five-year research project, in partnership with the Egyptian Holding Company for Water and Wastewater (HCWW), tries to bring together local competencies and experiences to develop, implement and monitor an innovative decentralised sanitation system. As a parallel research component of the Integrated Sanitation & Sewerage Infrastructure Project (ISSIP), launched by the Government of Egypt in cooperation with the World Bank, it complements the establishment of centralised treatment plants in three Governorates of the Nile Delta region.

The extent and severity of Arsenic (As) contamination in groundwater throughout Bangladesh and its detrimental effects on human health are well known. While various mitigation measures have been undertaken by various organizations, most of them have not achieved their expected outcomes due to associated technical, spatial and socio-economic challenges. In this study, institutional stakeholders’ opinions on various aspects of As mitigation were elicited to identify their preferences for and reservations on specific mitigation measures. The current status of As mitigation activities and the factors influencing the success of As mitigation were also explored. While institutional weakness, lack of accountability and a latency period were the major factors hindering sustainable As mitigation, stakeholders’ understanding of the As problem and their preferences for the different mitigation measures also had a significant impact on mitigation effectiveness. Mitigation of As contamination was a complex issue that required coordinated effort from various levels of stakeholders and the concept of “paying for water”, which is currently unknown in Bangladesh, needs to be developed to create a greater sense of user ownership of As safe water and thus better water management.

In a field study in Jessore District, Bangladesh, we investigated arsenic (As) porewater dynamics and As uptake by monsoon rice (aman) grown under continuously and intermittently flooded conditions, respectively. As porewater concentrations above the plough pan reached up to 500 ug/L under continuous flooding, but remained below 200 ug/L As under intermittently flooded conditions. Compared to continuous flooding, intermittent flooding thus reduced the As content of aman straw and grain by factors of 3 and 2.5, respectively. Our results corroborate previous evidence that intermittent flooding of paddy fields may be a promising means of reducing As input to paddy soils and As uptake by rice plants.

Tamiflu<SUP>®</SUP> (oseltamivir ethylester) is an antiviral agent for the treatment of influenza A and B. The pro-drug Tamiflu<SUP>®</SUP> is converted in the human body to the pharmacologically active metabolite, oseltamivir acid, with a yield of 75%. Oseltamivir acid is indirectly photodegradable and slowly biodegradable in sewage works and sediment/water systems. A previous environmental risk assessment has concluded that there is no bioaccumulation potential of either of the compounds. However, little was known about the ecotoxicity of the metabolite. Ester hydrolysis typically reduces the hydrophobicity and thus the toxicity of a compound. In this case, a zwitterionic, but overall neutral species is formed from the charged parent compound. If the speciation and predicted partitioning into biological membranes is considered, the metabolite may have a relevant contribution to the overall toxicity. These theoretical considerations triggered a study to investigate the toxicity of oseltamivir acid (OA), alone and in binary mixtures with its parent compound oseltamivir ethylester (OE). OE and OA were found to be baseline toxicants in the bioluminescence inhibition test with <I>Vibrio fischeri</I>. Their mixture effect lay between predictions for concentration addition and independent action for the mixture ratio excreted in urine and nine additional mixture ratios of OE and OA. In contrast, OE was an order of magnitude more toxic than OA towards algae, with a more pronounced effect when the direct inhibition of photosystem II was used as toxicity endpoint opposed to the 24 h growth rate endpoint. The binary mixtures in this assay yielded experimental mixture effects that agreed with predictions for independent action. This is consistent with the finding that OE exhibits slightly enhanced toxicity, while OA acts as baseline toxicant. Therefore, with respect to mixture classification, the two compounds can be considered as acting according to different modes of toxic action, although there are indications that the difference is a toxicokinetic effect, not a true difference of mechanism of toxicity. The general mixture results illustrate the need to consider the role of metabolites in the risk assessment of pharmaceuticals. However, in the concentration ratio of parent to metabolite excreted by humans, the experimental results confirm that the active metabolite does not significantly contribute to the risk quotient of the mixture.

Accumulation of cadmium in periphyton was investigated under field conditions while Cd concentration and speciation were dynamically varying in a small stream during rain events. Speciation in water was determined <I>in situ</I> by diffusion gradient in thin-films (DGT) and by modeling of complexation with fulvic acids. During the rain events, dissolved Cd concentrations increased from 0.17 nM to 0.27-0.36 nM, and 70-97% were DGT-labile. Cd content in periphyton closely followed Cd concentrations in water, despite higher concentrations of Zn and Mn, and may be controlled by either free or DGT-labile Cd concentrations. Decrease of Cd content in periphyton after the rain events was slower than the decrease of Cd concentration in water. Concentrations of Zn, Mn, Cu, Pb and Fe in periphyton also followed the dynamic variations of metal concentrations in water. Repeated exposure of periphyton to elevated dissolved Cd may lead to Cd accumulation.

Migrierende Fische sind stark eingeschränkt in der Schweiz, da die Fliessgewässer durch unzählige Querbauwerke fragmentiert sind. Umgehungsgewässer (UG) stellen eine Möglichkeit dar, um die Konnektivität unserer Gewässer wieder herzustellen. Im Rahmen dieser Masterarbeit wurde Literatur über Umgehungsgewässer zusammengefasst. Zusätzlich ist für die Schweiz eine Übersicht mit bestehenden UG erstellt worden. Im Rahmen eines Feldexperimentes wurden 462 von 715 gefangenen Fischen im UG Ruppoldingen an der Aare bei Boningen, Schweiz, mit Pit-Tags markiert. Das 1200 m lange UG wurde an allen Ausgängen mit fix installierten Antennen ausgestattet. Anschliessend wurden drei Experimente durchgeführt. Im ersten wurden 248 Fische im UG gefangen, markiert und wieder ausgesetzt. Im zweiten wurden 183 Fische im UG/Fischpass gefangen und in die Aare versetzt. Im dritten Experiment wurden 21 Fische in der Aare gefangen und 160 m oberhalb der Staumauer ausgesetzt. Das Umgehungsgewässer weist mit 22 Fischarten eine hohe Artenvielfalt auf, wobei Alet (<em>Squalius cephalus</em>) und Barbe (<em>Barbus barbus</em>) klar dominieren. Der Diversitätsindex nach Shannon ist tief (1.9), da viele Arten nur in sehr geringer Anzahl vorkommen. Die Häufigkeit der verschiedenen Fischarten widerspiegelt die Zusammensetzung der Fischarten der Aare. Alle im UG markierten Individuen wurden in residente, teilweise residente und wandernde Fische eingeteilt. Adulte Alet und Barben verwenden das UG als Laichhabitat und sind im Verlauf des Sommers daraus ausgewandert. Daher konnte ein signifikanter Rückgang grosser Barben im UG nachgewiesen werden. Von den als wandernd klassierten Alet sind signifikant mehr flussabwärts (23) als flussaufwärts (7) aus dem UG ausgewandert, Barben wanderten hauptsächlich in der Nacht. Wandernde Barben waren signifikant grösser als residente Barben. Von 183 in die Aare oberhalb des Kraftwerkes translozierten Fischen sind 14% (25) innerhalb eines Monates zurückgekehrt. Zwölf von 25 Fischen sind dabei über die Turbine abgestiegen. Im zweiten Monat nach der Translokation ist nur noch ein weiteres Egli (<em>Perca fluviatilis</em>) über die obere Antenne eingewandert. Keiner der 21 in der Aare 160 m oberhalb des Kraftwerkes markierten Fische ist ins UG eingewandert.<br /><br /> Migratory fish species are strongly affected by a number of barriers in rivers. Near natural bypass channels are an alternative to reestablish the connectivity of our riverine ecosystems. The following work consists of two parts. The first part is an overview of existing literature concerning near-natural bypass channels in Switzerland. The second part consists of a field experiment, where 462 fish were marked with pit-tags in the nearnatural bypass channel in the Aare River at Boningen, Switzerland. Three stationary antennas, used to record passing marked fish, were installed at the entrance and exits of the 1200m long near-natural bypass channel. The following three independent experiments were conducted. In the first experiment, 248 fish were captured, marked, and released in the bypass channel. In the second experiment, 183 fish were captured in the bypass channel and translocated into the main channel (Aare). In the third experiment, 21 fish were caught and released 160m above the hydropower plant. Results of this study show that the species within the bypass channel have a low diversity (Shannon index of 1.9) even though the number of species caught is very high (22) and comparable with the fish composition in the main river (Aare). This can be attributed to the fact that many species were only recorded once. Barbel (<em>Barbus barbus</em>) and Chub (<em>Squalius cephalus</em>) dominated the sampled fish. All fish that were caught in the bypass channel were grouped into resident, partly resident and migrating categories. It was observed that adult Barbel and Chub used the bypass as a spawning habitat and left it throughout the summer, thus resulting in a significant decrease in the abundance of long Barbel. Significantly more Chub migrated downstream (23) than upstream (7) out of the bypass channel after spawning. Barbel migrated significantly more at night and migrating Barbel were significantly bigger than resident Barbel. Out of the 183 fish that were translocated in the main river above the hydropower plant, 25 (14%) returned within one month. Twelve out of the 25 returning fish passed through the turbine. In the second month after the translocation, one European Perch (<em>Perca fluviatilis</em>) returned passing the upper antenna. None of the 21 fish that were caught and released in the main river above the bypass channel migrated into the bypass channel.

Acoustic signals often have a significant role in pair formation and in species recognition. Determining the genetic basis of signal divergence will help to understand signal evolution by sexual selection and its role in the speciation process. An earlier study investigated quantitative trait locus for male courtship song carrier frequency (FRE) in <I>Drosophila montana</I> using microsatellite markers. We refined this study by adding to the linkage map markers for 10 candidate genes known to affect song production in <I>Drosophila melanogaster.</I> We also extended the analyses to additional song characters (pulse train length (PTL), pulse number (PN), interpulse interval, pulse length (PL) and cycle number (CN)). Our results indicate that loci in two different regions of the genome control distinct features of the courtship song. Pulse train traits (PTL and PN) mapped to the X chromosome, showing significant linkage with the <I>period</I> gene. In contrast, characters related to song pulse properties (PL, CN and carrier FRE) mapped to the region of chromosome 2 near the candidate gene <I>fruitless</I>, identifying these genes as suitable loci for further investigations. In previous studies, the pulse train traits have been found to vary substantially between <I>Drosophila</I> species, and so are potential species recognition signals, while the pulse traits may be more important in intra-specific mate choice.

Long-term research on freshwater ecosystems provides insights that can be difficult to obtain from other approaches. Widespread monitoring of ecologically relevant water-quality parameters spanning decades can facilitate important tests of ecological principles. Unique long-term data sets and analytical tools are increasingly available, allowing for powerful and synthetic analyses across sites. Long-term measurements or experiments in aquatic systems can catch rare events, changes in highly variable systems, time-lagged responses, cumulative effects of stressors, and biotic responses that encompass multiple generations. Data are available from formal networks, local to international agencies, private organizations, various institutions, and paleontological and historic records; brief literature surveys suggest much existing data are not synthesized. Ecological sciences will benefit from careful maintenance and analyses of existing long-term programs, and subsequent insights can aid in the design of effective future long-term experimental and observational efforts. long-term research on freshwaters is particularly important because of their value to humanity.

The Cape Verdean islands form a distinct aquatic freshwater ecoregion characterized mainly by temporal water bodies with an adapted invertebrate community. Freshwater fish were not previously recorded from the archipelago. During a non-exhaustive survey of freshwater bodies on five islands of the archipelago, the first presence of a freshwater fish was recorded. Using barcoding sequences, the species was identified as the guppy (<em>Poecilia reticulata</em>), a highly invasive species alien to the Cape Verdean Islands.

The assessment and validation of sewer deterioration models is difficult because reliable data are missing. This makes it hard to find the most suitable model for a particular application. A network condition simulator (NetCoS) is used to generate synthetic sewer data for defined test scenarios. Thereby, the deterioration and replacement of pipes, the expansion of the sewer network, and classification errors are considered. Based on such synthetic data, deterioration models are calibrated and their results compared with the predefined scenario. While this approach is not capable of proving that a model performs correctly on a real application, it highlights the strengths and weaknesses of a model. The influence of condition classification errors and the age of the sewer system is investigated for two deterioration models. The results show, that classification errors can introduce substantial biases in the parameter estimation of the Markov model while in comparison the applied cohort model is fairly robust. Young sewer systems with fewer pipes in bad condition states on the other hand, have a very strong influence on the parameter uncertainties of the cohort model while the Markov model proved to be less sensitive.

An integrated framework that is comprised of field surveys of groundwater, surface water and soils, laboratory process experiments and hydrologic and geochemical modeling is used to identify the origin (anthropogenic versus geogenic sources), fate and transport of hexavalent Cr in Tertiary and Quaternary deposits of Oropos plain in Greece. Groundwater and soils were analyzed in May 2008 and exhibited considerable Cr concentrations. Mineralogical analysis and micro-XRF analysis of the heavy soil fractions (metallic components) showed Cr bearing phases like chromites, Cr-silicate phases with positive correlation between Si, Al, Fe and Cr soil concentrations. Column experiments showed the Cr(VI) desorption ability of soils, e.g. concentration of 20 μg L<SUP>−1</SUP> was detected after the application of 50 mm of rain. The groundwater model simulated the variability of Cr concentrations emanating from both anthropogenic and geogenic sources, successfully using rate constants obtained from the laboratory experiments, e.g. 4.24 nM h<SUP>−1</SUP> for serpentine soil and 0.77 nM h<SUP>−1</SUP> for soil in alluvial deposits. The mineralogical and geochemical results support a geogenic origin for Cr in soils and groundwater of Oropos plain while modeling results suggest that contaminants transported by Asopos River have affected only the upper layers of the subsurface in the vicinity of the river. The framework can be used to establish background concentrations or clean up levels of Cr-contaminated soils and groundwater.

Lake sediment records are underrepresented in comprehensive, quantitative, high-resolution (sub-decadal), multi-proxy climate reconstructions for the past millennium. This is largely a consequence of the difficulty of calibrating biogeochemical lake sediment proxies to meteorological time series (calibration-in-time). Thanks to recent methodological advances, it is now possible. This paper outlines a step-by-step, specifically tailored methodology, with practical suggestions for calibrating and validating biogeochemical proxies from lake sediments to meteorological data. This approach includes: (1) regional climate data; (2) site selection; (3) coring and core selection; (4) core chronology; (5) data acquisition; and (6) data analysis and statistical methods. We present three case studies that used non-varved lake sediments from remote areas in the Central Chilean Andes, where little a priori information was available on the local climate and lakes, or their responses to climate variability. These case studies illustrate the potential value and application of a calibration-in-time approach to non-varved lake sediments for developing quantitative, high-resolution climate reconstructions.

High-resolution climate reconstructions from a range of natural archives across the world are fundamental to place current climate change into perspective. Paleoclimate records for the Southern Hemisphere are scarce and only a few quantitative high-resolution reconstructions exist for the past millennium. We present a record of annually laminated sediments of Lago Plomo (46°59′S, 72°52′W,203 m a.s.l.) located east of the Northern Patagonian Ice Field (NPI). Radiometric dating (<SUP>210</SUP>Pb, <SUP>137</SUP>Cs, <SUP>14</SUP>C AMS) is consistent with counts of millimetre-scale laminae, confirming the annual nature of the laminae couplets with a light summer and a dark winter layer. The varves were analyzed for thickness, mass accumulation rate (MAR), scanning x-ray fluorescence (XRF) and scanning reflectance spectroscopy in the visible range (VIS-RS). MAR data were calibrated against austral winter (JJA) precipitation data (CRU TS 3.0) for the period ad 1930–2002 (<I>r</I> = 0.67, <I>p</I> <SUB>(aut)</SUB> < 0.05). Using a linear inverse regression model we reconstructed winter precipitation for Lago Plomo back to ad 1530. The root mean squared error of prediction (RMSEP) is small (13.3 mm/month; 12% of the average precipitation) compared with the pronounced decadal and multidecadal variability, suggesting that most of the reconstructed variability is significant. Wetter phases (reference ad 1930–2002) were observed around ad 1600, ad 1630–1690 and ad 1780–1850, and a prolonged drier period ad 1690–1780 with a multidecadal minimum centered on ad 1770. The spatial correlation for South America suggests that the JJA precipitation record from Lago Plomo is representative for large areas in the southwest between <I>c</I>. 41°S and 51°S.

SWAT (Soil and Water Assessment Tool) is a comprehensive, semi-distributed river basin model that requires a large number of input parameters, which complicates model parameterization and calibration. Several calibration techniques have been developed for SWAT, including manual calibration procedures and automated procedures using the shuffled complex evolution method and other common methods. In addition, SWAT-CUP was recently developed and provides a decision-making framework that incorporates a semi-automated approach (SUFI2) using both manual and automated calibration and incorporating sensitivity and uncertainty analysis. In SWAT-CUP, users can manually adjust parameters and ranges iteratively between autocalibration runs. Parameter sensitivity analysis helps focus the calibration and uncertainty analysis and is used to provide statistics for goodness-of-fit. The user interaction or manual component of the SWAT-CUP calibration forces the user to obtain a better understanding of the overall hydrologic processes (e.g., baseflow ratios, ET, sediment sources and sinks, crop yields, and nutrient balances) and of parameter sensitivity. It is important for future calibration developments to spatially account for hydrologic processes; improve model run time efficiency; include the impact of uncertainty in the conceptual model, model parameters, and measured variables used in calibration; and assist users in checking for model errors. When calibrating a physically based model like SWAT, it is important to remember that all model input parameters must be kept within a realistic uncertainty range and that no automatic procedure can substitute for actual physical knowledge of the watershed.

Negative relationships between species richness and the rate of compositional turnover are common, suggesting that diverse communities have greater stability than depauperate ones; however, the mechanistic basis for this pattern is still widely debated. Species richness and turnover can covary either because they are mechanistically linked or because they share common environmental drivers. Few empirical studies have combined long-term changes in community composition with multiple drivers of environmental change, and so little is known about how the underlying mechanisms of species coexistence interact with changes in the mean and variability of environmental conditions. Here, we use a 33 year long time series (1976–2008) of phytoplankton community composition from Lake Zurich, to examine how environmental variation influences the relationship between richness and annual turnover. We find that the relationship between richness and annual turnover reverses midway through the time series (1992–1993), leading to a hump-shaped relationship between species richness and annual turnover. Using structural equation modeling we show that annual turnover and diversity are independently associated with different drivers of environmental change. Furthermore, we find that the observed annual sequences of community assembly give rise to rates of species accumulation that are more heterogeneous through time than expected by chance, likely owing to a high proportion of species showing significant autocorrelation and to strong positive covariation in the occurrences of species.

Understanding genetic specificity in factors determining the outcome of host-parasite interactions is especially important as it contributes to parasite epidemiology, virulence, and maintenance of genetic variation. Such specificity, however, is still generally poorly understood. We examined genetic specificity in interactions among coinfecting parasites. In natural populations, individual hosts are often simultaneously infected by multiple parasite species and genotypes that interact. Such interactions could maintain genetic variation in parasite populations if they are genetically specific so that the relative fitness of parasite genotypes varies across host individuals depending on (1) the presence/absence of coinfections and/or (2) the genetic composition of the coinfecting parasite community. We tested these predictions using clones of fish eye flukes <I>Diplostomum pseudospathaceum</I> and <I>Diplostomum gasterostei</I>. We found that interactions among parasites had a strong genetic basis and that this modified genetic variation in infection success of <I>D. pseudospathaceum</I> between single and multiple infections as well as across multiply infected host individuals depending on the genetic identity of the coinfecting <I>D. gasterostei</I>. The relative magnitude of these effects, however, depended on the exposure dose, suggesting that ecological factors can modify genetic interactions between parasites.

Environmental factors can interact with the effects of chemical pollutants on natural systems by inducing multiple stressor effects in individual organisms as well as by altering selection pressure on tolerant strains in heterogeneous populations. Predation is a stressful environmental factor relevant for many species. Therefore, the impact of predation by the rotifer <I>Brachionus calyciflorus</I> on tolerance of eight genetically different strains of the green alga <I>Chlamydomonas reinhardtii</I> to simultaneous exposure to each of the three herbicides (diuron, paraquat, and S-metolachlor) was tested. Interactions of combined stressors were analyzed based on the independent action model; additive, synergistic, and antagonistic effects of the combined exposure could be etected depending on the herbicide and strain tested. If cultures were acclimated (pre-exposed) to one stressor, tolerance to the second stressor could be increased. This indicates that physiological changes can induce cotolerance of predation-exposed algae to herbicides and of herbicide-treated algae to predation depending on the combination of stressors. The strain-specific differences in multiple stressor effects also changed the correlation of strains' tolerances to individual stressors determined during combined and single-stressor exposure. Changes in cotolerance to stressors affect selection pressure and population dynamics during long-term exposure. This shows that predation stress can have adverse effects on the toxicity of chemical pollutants to microalgae on the organism and population levels.

Hormonaktive Stoffe, die vor allem über das Abwasser in Oberflächengewässer gelangen, können die Gesundheit von Wassertieren beeinträchtigen. Ökotoxikologische Testmethoden verbessern die Messbarkeit und Bewertung dieser Substanzen. Sie liefern wichtige Entscheidungshilfen für Massnahmen zur Verminderung des Eintrags der Stoffe. So lässt sich mit ihnen die Wirkung zusätzlicher Reinigungsstufen in den Kläranlagen evaluieren.

The zebrafish embryo toxicity test has been proposed as an alternative for the acute fish toxicity test, which is required by various regulations for environmental risk assessment of chemicals. We investigated the reliability of the embryo test by probing organic industrial chemicals with a wide range of physicochemical properties, toxicities, and modes of toxic action. Moreover, the relevance of using measured versus nominal (intended) exposure concentrations, inclusion of sublethal endpoints, and different exposure durations for the comparability with reported fish acute toxicity was explored. Our results confirm a very strong correlation of zebrafish embryo to fish acute toxicity. When toxicity values were calculated based on measured exposure concentrations, the slope of the type II regression line was 1 and nearly passed through the origin (1 to 1 correlation). Measured concentrations also explained several apparent outliers. Neither prolonged exposure (up to 120 h) nor consideration of sublethal effects led to a reduced number of outliers. Yet, two types of compounds were less lethal to embryos than to adult fish: a neurotoxic compound acting via sodium channels (permethrin) and a compound requiring metabolic activation (allyl alcohol).

Der Rhein ist einer der bedeutendsten Flüsse Europas. Sein Verlauf ist geprägt durch einen dicht besiedelten Kulturraum, intensiv geführte Landwirtschaft und hochtechnisierte Industrieanlagen. Sein Wasser bietet zahlreichen spezialisierten Tierund Pflanzenarten ein Zuhause und rund 20 Millionen Menschen täglich Trinkwasser zumeist aus Uferfiltrat. Daneben transportiert sein Wasser beträchtliche Mengen an häuslichen und industriellen Abwässern und entwässert intensiv genutzte Landwirtschaftsflächen. Um eine hohe Qualität des Trinkwassers gewährleisten und den Lebensraum für aquatische Organismen erhalten zu können, ist eine umfassende Kenntnis der aktuellen Wasserqualität des Rheinwassers unerlässlich. Nachdem sich 1986 ein Unfall im Industriegebiet Schweizerhalle bei Basel ereignet hatte, wobei große Mengen Chemikalien in den Rhein gelangten und dessen Ökosystem empfindlich aus dem Gleichgewicht brachten, wurde 1992 die internationale Rheinüberwachungsstation Weil am Rhein (RÜS) in Betrieb genommen. Die Hauptaufgaben der vom Land Baden-Württemberg und der Schweizerischen Eidgenossenschaft zu gleichen Anteilen betriebenen RÜS bestehen in einer langfristigen Trendüberwachung einer Vielzahl von Parametern und in der zeitnahen Detektion von Fehleinleitungen und Havarien. Ein internationaler Warn- und Alarmplan wurde eingerichtet, um flussabwärts liegende Behörden und Trinkwasserwerke im Fall bedenklicher Verunreinigungen informieren zu können.

There is increasing evidence that many maternally transmitted symbionts protect their hosts against parasites, thus ensuring their own persistence. Despite the protection they provide, such symbionts are typically found in only a fraction of the host population. This suggests that symbiont-conferred resistance is costly or that the maternal inheritance of symbionts is not perfect. To investigate these hypotheses and other properties of this complex ecological system, we develop a mathematical model based on the example of bacterial endosymbionts that protect aphids against parasitoid wasps. Simulations show that in the absence of more complex effects, a very fine balance between the costs of harboring symbionts and the strength of protection they provide is required to maintain coexistence of protected and unprotected hosts. These constraints are significantly relaxed and coexistence becomes a common outcome if deployment of symbiont-provided defenses upon a parasite attack entails an additional (induced) cost. Transmission rates of symbionts also affect coexistence, which is more frequently observed under high (but not perfect) fidelity of vertical transfer and low rates of horizontal transfer. Finally, we show that the prevalence of defensive symbionts has a strong influence on the population dynamics of hosts and parasites: population sizes are stable if and only if protected hosts dominate.

Heritable bacterial endosymbionts play an important role in aphid ecology. Sequence-based evidence suggests that facultative symbionts such as <I>Hamiltonella defensa</I> or <I>Regiella insecticola</I> also undergo horizontal transmission. Other than through male-to-female transfer during the sexual generation in autumn, the routes by which this occurs remain largely unknown. Here, we tested if parasitoids or ectoparasitic mites can act as vectors for horizontal transfer of facultative symbionts. Using symbiont-specific primers for diagnostic PCR, we demonstrate for the first time, to our knowledge, that parasitoids can indeed transfer <I>H. defensa</I> and <I>R. insecticola</I> by sequentially stabbing infected and uninfected individuals of their host, <I>Aphis fabae</I>, establishing new, heritable infections. Thus, a natural route of horizontal symbiont transmission is also available during the many clonal generations of the aphid life cycle. No transmissions by ectoparasitic mites were observed, nor did parasitoids that emerged from symbiont-infected aphids transfer any symbionts in our experiments.

The melon aphid, <I>Aphis gossypii</I> Glover (Hem., Aphididae), is one of the most important pests of cucumber throughout the world. This aphid has a short generation time and high fecundity that result in an enormous reproductive potential, especially in cucumber-growing greenhouses. Vermicomposts, which are produced by exploiting interactions between earthworms and microorganisms, may enhance plant growth and plant resistance against some pests and disease. In this study, the effects of vermicompost and cucumber cultivar (<I>Cucumis sativus</I> L.) on infestation levels with <I>A. gossypii</I> were evaluated. We conducted a factorial experiment with two cucumber cultivars (Royal and Storm) and five concentrations of vermicompost in the soil, including 0% (control), 10%, 20%, 30% and 50%, employing a randomized complete block design with four replicates. The experiment was conducted in a growth chamber at 25±2°C, 65±10% RH and a photoperiod of 14L: 10Dh. The number of aphids was counted 3, 5, 7, 9, 12, 15, 18 and 21days after infestation of cucumber seedlings by aphids. We found that in all vermicompost-amended treatments, aphid numbers were lower than when plants were grown in soil without any vermicompost. The highest and lowest aphid counts occurred in the control treatment on cucumbers of the Royal cultivar and in the 30% and 50% vermicompost treatments on the storm cultivar, respectively. Overall, our study showed that the application of vermicompost has a high potential for reducing <I>A. gossypii</I> populations in cucumber cultures.

Global change is associated with fast and severe alterations of environmental conditions. Superimposed onto existing salinity variations in a semi-enclosed brackish water body such as the Baltic Sea, a decrease in salinity is predicted due to increased precipitation and freshwater inflow. Moreover, we predict that heavy precipitation events will accentuate salinity fluctuations near shore.<BR/> Here, we investigated how the immune function of the broad-nosed pipefish (<I>Syngnathus typhle</I>), an ecologically important teleost with sex-role reversal, is influenced by experimentally altered salinities (control: 18 PSU, lowered: 6 PSU, increased: 30 PSU) upon infection with bacteria of the genus <I>Vibrio</I>.<BR/> Salinity changes resulted in increased activity and proliferation of immune cells. However, upon <I>Vibrio</I> infection, individuals at low salinity were unable to mount specific immune response components, both in terms of monocyte and lymphocyte cell proliferation and immune gene expression compared to pipefish kept at ambient salinities. We interpret this as resource allocation trade-off, implying that resources needed for osmoregulation under salinity stress are lacking for subsequent activation of the immune defence upon infection.<BR/> Our data suggest that composition of small coastal fish communities may change due to elevated environmental stress levels and the incorporated consequences thereof.

Struvite precipitation is a simple technology for phosphorus recovery from source-separated urine. However, production costs can be high if expensive magnesium salts are used as precipitants. Therefore, waste products can be interesting alternatives to industrially-produced magnesium salts. We investigated the technical and financial feasibility of wood ash as a magnesium source in India. In batch experiments with source-separated urine, we could precipitate 99% of the phosphate with a magnesium dosage of 2.7 mol Mg mol P<SUP>− 1</SUP>. The availability of the magnesium from the wood ash used in our experiment was only about 50% but this could be increased by burning the wood at temperatures well above 600 °C. Depending on the wood ash used, the precipitate can contain high concentrations of heavy metals. This could be problematic if the precipitate were used as fertilizer depending on the applicable fertilizer regulations. The financial study revealed that wood ash is considerably cheaper than industrially-produced magnesium sources and even cheaper than bittern. However, the solid precipitated with wood ash is not pure struvite. Due to the high calcite and the low phosphorus content (3%), the precipitate would be better used as a phosphorus-enhanced conditioner for acidic soils. The estimated fertilizer value of the precipitate was actually slightly lower than wood ash, because 60% of the potassium dissolved into solution during precipitation and was not present in the final product. From a financial point of view and due to the high heavy metal content, wood ash is not a very suitable precipitant for struvite production. Phosphate precipitation from urine with wood ash can be useful if (1) a strong need for a soil conditioner that also contains phosphate exists, (2) potassium is abundant in the soil and (3) no other cheap precipitant, such as bittern or magnesium oxide, is available.

The implementation of strict environmental quality standards for polar organic priority pollutants poses a challenge for monitoring programs. The polar organic chemical integrative sampler (POCIS) may help to address the challenge of measuring low and fluctuating trace concentrations of such organic contaminants, offering significant advantages over traditional sampling. In the present review, the authors evaluate POCIS calibration methods and factors affecting sampling rates together with reported environmental applications. Over 300 compounds have been shown to accumulate in POCIS, including pesticides, pharmaceuticals, hormones, and industrial chemicals. Polar organic chemical integrative sampler extracts have been used for both chemical and biological analyses. Several different calibration methods have been described, which makes it difficult to directly compare sampling rates. In addition, despite the fact that some attempts to correlate sampling rates with the properties of target compounds such as log <I>K</I><SUB>OW</SUB> have been met with varying success, an overall model that can predict uptake is lacking. Furthermore, temperature, water flow rates, salinity, pH, and fouling have all been shown to affect uptake; however, there is currently no robust method available for adjusting for these differences. Overall, POCIS has been applied to a wide range of sampling environments and scenarios and has been proven to be a useful screening tool. However, based on the existing literature, a more mechanistic approach is required to increase understanding and thus improve the quantitative nature of the measurements.

Fungi are important decomposers of leaf litter in streams and may have knock-on effects on other microbes and carbon cycling. To elucidate such potential effects, we designed an experiment in outdoor experimental channels simulating sand-bottom streams in an early-successional state. We hypothesized that the presence of fungi would enhance overall microbial activity, accompanied by shifts in the microbial communities associated not only with leaf litter but also with sediments. Fifteen experimental channels received sterile sandy sediment, minimal amounts of leaf litter, and one of four inocula containing either (i) fungi and bacteria, or (ii) bacteria only, or (iii) no microorganisms, or (iv) killed microorganisms. Subsequently, we let water from an early-successional catchment circulate through the channels for 5 weeks. Whole-stream metabolism and microbial respiration associated with leaf litter were higher in the channels inoculated with fungi, reflecting higher fungal activity on leaves. Bacterial communities on leaves were also significantly affected. Similarly, increases in net primary production, sediment microbial respiration and chlorophyll <I>a</I> content on the sediment surface were greatest in the channels receiving a fungal inoculum. These results point to a major role of fungal communities in stream ecosystems beyond the well-established direct involvement in leaf litter decomposition.

We show that the nitrate storing vacuole of the sulfide-oxidizing bacterium <I>Candidatus</I> Allobeggiatoa halophila has an electron transport chain (ETC), which generates a proton motive force (PMF) used for cellular energy conservation. Immunostaining by antibodies showed that cytochrome <I>c</I> oxidase, an ETC protein and a vacuolar ATPase are present in the vacuolar membrane and cytochrome <I>c</I> in the vacuolar lumen. The effect of different inhibitors on the vacuolar pH was studied by pH imaging. Inhibition of vacuolar ATPases and pyrophosphatases resulted in a pH decrease in the vacuole, showing that the proton gradient over the vacuolar membrane is used for ATP and pyrophosphate generation. Blockage of the ETC decreased the vacuolar PMF, indicating that the proton gradient is build up by an ETC. Furthermore, addition of nitrate resulted in an increase of the vacuolar PMF. Inhibition of nitrate reduction, led to a decreased PMF. Nitric oxide was detected in vacuoles of cells exposed to nitrate showing that nitrite, the product of nitrate reduction, is reduced inside the vacuole. These findings show consistently that nitrate respiration contributes to the high proton concentration within the vacuole and the PMF over the vacuolar membrane is actively used for energy conservation.

The Household-Centered Environmental Sanitation (HCES) planning approach was tested for the first time in Nepal in a peri-urban setting during 2009/2011, in order to validate the novel planning approach, identify challenges and improve the process. The participatory multi-stakeholder process involved household mapping and surveys, user needs identification and prioritization and a stakeholder assessment. Following an expert's assessment of potential sanitation options, community sensitization campaigns through exposure visits, a sanitation bazaar and focused community interactions were conducted. Among the three sanitation alternatives, users showed strong preference to set up a simplified sewerage system with a decentralized wastewater treatment. The paper critically discusses the key challenges faced when developing environmental sanitation plans. Setting the right balance between empowering people to take informed decisions and keeping the participation process intact until the final stage was a major challenge. Although participatory planning is time consuming, it is worth investing as it builds local ownership and assists in informed decision-making processes for selecting affordable sanitation options that best meet user's needs.

Social interactions have been shown to play an important role in bacterial evolution and virulence. The majority of empirical studies conducted have only considered social traits in isolation, yet numerous social traits, such as the production of spiteful bacteriocins (anticompetitor toxins) and iron-scavenging siderophores (a public good) by the opportunistic pathogen <I>Pseudomonas aeruginosa</I>, are frequently expressed simultaneously. Crucially, both bacteriocin production and siderophore cheating can be favored under the same competitive conditions, and we develop theory and carry out experiments to determine how the success of a bacteriocin-producing genotype is influenced by social cheating of susceptible competitors and the resultant impact on disease severity (virulence). Consistent with our theoretical predictions, we find that the spiteful genotype is favored at higher local frequencies when competing against public good cheats. Furthermore, the relationship between spite frequency and virulence is significantly altered when the spiteful genotype is competed against cheats compared with cooperators. These results confirm the ecological and evolutionary importance of considering multiple social traits simultaneously. Moreover, our results are consistent with recent theory regarding the invasion conditions for strong reciprocity (helping cooperators and harming noncooperators).

Combined acid catalysis was employed as a pretreatment alternative with combined acid catalysts blending sulfuric acid with two biomimetic acids, trifluoroacetic acid (TFA) and maleic acid (MA), respectively. The influences of acid blending ratio, temperature, and acid dosage on pretreatment performance were investigated. A synergistic effect on hemicellulose decomposition was observed in the combined acid hydrolysis, which greatly increased xylose yield, although TFA/MA would induce more total phenols. Besides, combined TFA pretreatment could efficiently prevent xylose degradation. Fermentation tests of the acid-catalyzed hydrolysates with overliming showed that compared to H<SUB>2</SUB>SO<SUB>4</SUB> pretreatment, TFA and MA pretreatments improved overall ethanol yield with an increase by 27–54%. Combined acid catalysis was shown as a feasible pretreatment method for its improved sugar yield, reduced phenols production and catalyst costs.

A laboratory-scale anaerobic sequencing batch reactor was used to evaluate treatment of a synthetic substrate mixture representing petrochemical wastewater containing methyl tert-butyl ether (MTBE), ethanol and acetic acid. Influent MTBE concentrations were 5, 10 and 50 mg/l (corresponding to MTBE loading rates of 0.2, 0.4 and 2 mg/l.d) with overall organic loading rates (OLRs) of 1.51, 3.23 and 3.25 g COD/l.d, respectively. These OLRs resulted in removal efficiencies for MTBE of 78%, 98% and 88%. Removal efficiencies for chemical oxygen demand were 85% and 90% with influent MTBE concentrations of 5 and 10 mg/l, but were significantly reduced to 72% with influent MTBE concentrations of 50 mg/l. During all reactor runs, effluent concentrations of tert-butyl alcohol (TBA) were below the detection limit. Batch degradation of the organic substrate mixture demonstrated initial inhibitory effects when exposed to MTBE concentrations of 50 mg/l and complete inhibition with MTBE concentrations above 2000 mg/l. It is interesting to note that in batch tests using MTBE as the sole organic substrate (initial MTBE concentrations of 50, 100 and 200 mg/l), the specific methanogenic activity decreased to below detection within the first 96 hours, but following a 72-hour lag phase the methane production increased again. Based on low volatile fatty acid (VFA) concentration, disappearance of TBA peaks and no findings of any other intermediate via gas chromatography/mass spectrometry, while the MTBE concentration is still high, it can be suggested that during the batch tests the breakdown of gas production and the following lag phase were the direct effect of higher MTBE concentrations (more than 50 mg/l) and not because of the TBA or VFA accumulations.

Linkages among bioreactor operation and performance and microbial community structure were investigated for a fixed-bed biofilm system designed to remove perchlorate from drinking water. Perchlorate removal was monitored to evaluate reactor performance during and after the frequency and intensity of the backwash procedure were changed, while the microbial community structure was studied using clone libraries and quantitative PCR targeting the 16S rRNA gene. When backwash frequency was increased from once per month to once per day, perchlorate removal initially deteriorated and then recovered, and the relative abundance of perchlorate-reducing bacteria (PRB) initially increased and then decreased. This apparent discrepancy suggested that bacterial populations other than PRB played an indirect role in perchlorate removal, likely by consuming dissolved oxygen, a competing electron acceptor. When backwash intensity was increased, the reactor gradually lost its ability to remove perchlorate, and concurrently the relative abundance of PRB decreased. The results indicated that changes in reactor operation had a profound impact on reactor performance through altering the microbial community structure. Backwashing is an important yet poorly characterized procedure when operating fixed-bed biofilm reactors. Compared to backwash intensity, changes in backwash frequency exerted less disturbance on the microbial community in the current study. If this finding can be confirmed in future work, backwash frequency may serve as the primary parameter when optimizing backwash procedures.

Water-quality standards requiring simultaneous low level effluent N and P concentrations are increasingly common in Europe and the United States of America. Moving bed biofilm reactors (MBBRs) and biologically active filters (BAFs) have been used as post-denitrification biofilm reactors in processes designed and operated for this purpose (Boltz et al., 2010a). There is a paucity of information describing systematic design and operational protocols that will minimize the potential for phosphorus rate-limited conditions as well as a lack of information describing the interaction between these post-denitrification biofilm reactors and unit processes that substantially alter phosphorus speciation (e.g., chemically enhanced clarification). In this paper, a simple mathematical model for estimating the threshold below which P becomes rate-limiting, and the model is presented and evaluated by comparing its predictions with operational data from post-denitrification MBBRs and BAFs. Ortho-phosphorus (PO<SUB>4</SUB>–P), which is the dissolved reactive component of total phosphorus, was a primary indicator of P rate-limiting conditions in the evaluated post-denitrification biofilm reactors. The threshold below which PO<SUB>4</SUB>–P becomes the rate-limiting substrate is defined: S<SUB>PO<SUB>4</SUB>–P</SUB>:S<SUB>NO<SUB>x–N</SUB></SUB> = 0.0086 g P/g N and S<SUB>PO<SUB>4</SUB>–P</SUB> : S<SUB>M</SUB> = 0.0013 g P/g COD. Additional analyses indicate J<SUP>avg</SUP><SUB>NO<SUB>x</SUB>-N</SUB> =0.48g/m<SUP>2</SUP>/d when S<SUB>PO<SUB>4</SUB>–P</SUB>:S<SUB>NO<SUB>x</SUB>–N</SUB> > 0.0086, and J<SUP>avg</SUP><SUB>NO<SUB>x</SUB>-N</SUB>=0.06g/m<SUP>2</SUP>/d when S<SUB>PO<SUB>4</SUB>–P</SUB>:S<SUB>NO<SUB>x</SUB>–N</SUB> < 0.0086. Effluent nitrate–nitrogen plus nitrite–nitrogen concentration (S<SUB>NO<SUB>x</SUB>–N</SUB>)(S<SUB>NO<SUB>x</SUB>–N</SUB>) from the evaluated post-denitrification biofilm reactors began to rapidly increase when S<SUB>PO<SUB>4</SUB>–P</SUB>:S<SUB>NO<SUB>x</SUB>–N</SUB>:S<SUB>NO<SUB>x</SUB>–N</SUB> was 0.01, approximately (consistent with the rate-limitation threshold of S<SUB>PO<SUB>4</SUB>–P</SUB>:S<SUB>NO<SUB>x</SUB>–N</SUB> < 0.0086 predicted by the mathematical model described in this paper). Depending on the processes used at a given WWTP, optimizing chemically enhanced clarification to increase the amount of PO<SUB>4</SUB>–P that remains in the clarifiers effluent stream, dosing phosphoric acid in the MBBR or BAF influent stream, and/or optimizing secondary process EBPR may overcome phosphorus rate-limitations in the biofilm-based post-denitrification process.

To study the potential of <SUP>220</SUP>Rn as a groundwater tracer, we analyzed different groundwater systems with a laboratory-proven radon-in-water detection system. However, with one single exception, no <SUP>220</SUP>Rn was detected in the groundwater, although <SUP>222</SUP>Rn was always present at high concentrations. Field observations of <SUP>220</SUP>Rn and <SUP>222</SUP>Rn in soil gas revealed soil water content to be the crucial control for <SUP>220</SUP>Rn release from soil grains to soil pores. We identified water films around and water menisci between the soil grains to impede the diffusive transport of <SUP>220</SUP>Rn. This finding was confirmed by the results of laboratory experiments with monazite pebbles and manganese sand, which both are <SUP>220</SUP>Rn sources. Besides the water content, the laboratory experiments also identified the water flow (turbulent in the experiment versus laminar in groundwater) to control the <SUP>220</SUP>Rn emanation. The laminar flow condition in groundwater, together with the soil water content, set a conceptual frame to explain why <SUP>220</SUP>Rn can be detected in unsaturated soil but not in groundwater.