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Invasive species often have a significant impact on the biodiversity of ecosystems and the species native to it. One of the worst invaders worldwide is Aphanomyces astaci, the causative agent of the crayfish plague, an often fatal disease to crayfish species not native to North America. Aphanomyces astaci originates from North America and was introduced to Europe in the midst of the 19th century. Since then, it spread throughout Europe diminishing the European crayfish populations. The overall aim of this thesis was to evaluate the threat that A. astaci still poses to European crayfish species more than 150 years after its introduction to Europe. In the first part of the thesis, crayfish specimens, which are available in the German pet trade, were tested for infections with A. astaci. Around 13% of the tested crayfish were clearly infected with A. astaci. The study demonstrated the potential danger the pet trade poses for biodiversity through the import of alien species and their potential pathogens, in general. In the second part of the thesis, the A. astaci infection prevalence of crayfish species in wild populations in Europe was tested. While the stone crayfish, Austropotamobius torrentium, showed high susceptibility to different haplogroups of A. astaci, the narrow-clawed crayfish, Astacus leptodactylus, was able to survive infections, even by haplogroup B, which is considered to be highly virulent. In the last part of the thesis, A. astaci was traced back to its original distribution area of North America. While the crayfish plague never had such a devastating effect on crayfish in North America as it had in Europe, the reasons for the success of invasive crayfish within North America are not yet fully understood. It is possible that A. astaci increases the invasion success of some crayfish species. Several populations of the rusty crayfish, Orconectes rusticus, in the Midwest of North America were confirmed to be infected with A. astaci and a new genotype was identified, possibly indicating that each crayfish host is vector of a unique A. astaci genotype, even in North America. Overall, the present thesis provides evidence that A. astaci is still a major threat to the crayfish species indigenous to Europe. Crayfish mass mortalities still occur in susceptible crayfish species like A. torrentium even 150 years after the first introduction of A. astaci. While there are some indications for increased resistances through processes of co-evolution, the continuous introduction of crayfish species to Europe threatens to cause new outbreaks of the crayfish plague through the parallel introduction of new, highly virulent A. astaci strains.
Das Grundwasser unterliegt zahlreichen Nutzungen, gleichzeitig ist es Lebensraum einer artenreichen, hoch angepaßten Fauna. Verunreinigungen des Grundwassers mit Kontaminationen unterschiedlichsten Ursprungs stellen eine wachsende Problematik dar. Für das Monitoring von Altlastflächen werden bisher überwiegend physiko-chemische Methoden eingesetzt. Als weitere Möglichkeit bietet sich ein grundwasserfaunistisch begründetes Monitoring an. Da Freilanduntersuchungen über das Auftreten und die Verteilung von Grundwasserfauna in Altlastflächen bisher fehlen, widmet sich die vorliegende Dissertation dieser Thematik. Ein grundsätzliches Problem grundwasserfaunistischer Untersuchungen ist das Fehlen standardisierter Sammelmethoden. Daher erwies es sich als notwendig, die für die Untersuchung der Altlastflächen optimale Sammelmethode zu identifizieren. Insoweit liefert ein vorangehender Methodenvergleich die Grundlage für das Altlasten-Projekt. Ziel des Methodenvergleichs war es herauszufinden, ob die in Kluftgrundwasserleitern im Vergleich mit Lockergesteinsleitern festgestellte Artenarmut und die meist niedrigen Abundanzen habitat- oder auch methodenbedingt sind. Unter Verwendung eines phreatobiologischen Netzsammlers, einer pneumatischen Kolbenhubpumpe (System NIEDERREITER) und eines Quellnetzes wurden im Naturraum Pfälzerwald 16 Grundwasser-meßstellen (je 8 in den Kluftaquiferen des Buntsandsteins und den sandig-kiesigen Aquiferen der Talauen) und 8 Quellen, sowie 4 Grundwassermeßstellen in der pfälzischen Rheinebene hydrochemisch und faunistisch beprobt. Die Grundwässer beider Naturräume unterschieden sich sowohl hydrochemisch wie auch in ihrer faunistischen Zusammensetzung signifikant voneinander. Aus methodischer Sicht zeigten alle Sammeltechniken, mit Ausnahme der Quellbeprobung, trotz gewisser Unterschiede, qualitativ vergleichbare Ergebnisse. Ziel des Hauptteils der Arbeit " dem Altlasten-Projekt " war die Gewinnung erster empirischer Daten über das Vorkommen und die Verteilung von Grundwasserfauna in Abhängigkeit von Altlasten. Des weiteren sollten über die Korrelation der Grundwasserfauna mit hydrochemischen Parametern und den Koloniezahlen erste Ansätze für eine bioindikative Eignung gefunden werden. Basierend auf den Ergebnissen des methodischen Teils wurden unter Verwendung des phreatobiologischen Netzsammlers fünf in der pfälzischen Rheinebene liegende Untersuchungsstandorte (sechs Einzelschäden), die Kontaminationen unterschiedlicher Art aufwiesen, untersucht. Dabei handelte es sich um drei militärische und zwei industrielle Altlasten sowie eine Hausmülldeponie. Insgesamt wurden 91 Meßstellen, die sich im Zustrom, direkt im Schaden sowie im Abstrom befanden, zweimalig beprobt. Trotz der ausgeprägten Heterogenität der untersuchten Altlaststandorte sowie geringer Arten- und Taxazahlen und Abundanzen weisen die Verteilungsmuster auf Sensitivitäten der Fauna gegenüber Grundwasserverunreinigungen hin. In bezug auf einzelne Schadstoffe (LCKW, PCE, AKW) deuten sich schadstoffspezifische Verteilungsmuster der Fauna an. Das abundanteste Taxon der Untersuchung - die Nematoda - traten an den LCKW / PCE- kontaminierten Standorten nur in geringsten Abundanzen auf, ebenso wie die Parastenocaridae (Crustacea). Oligochaeta und einzelne Cyclopoida-Arten (Crustacea) scheinen hingegen deutlich höhere Konzentrationen dieses Schadstoffs zu tolerieren. Eine gegensätzliche Faunenverteilung wurde an den AKW- kontaminierten Standorten beobachtet. Hier zeigten sich die Nematoda wesentlich toleranter als alle anderen Taxa, ebenso wie die Parastenocaridae. Hingegen traten die Oligochaeta und Cyclopoida oberhalb geringer Konzentrationen nur noch sporadisch auf. Die abundanteste Cyclopoida-Art der gesamten Untersuchung, Diacyclops languidoides, konnte in Anwesenheit von AKW nicht nachgewiesen werden.
Flowering habitats to enhance biodiversity and pest control services in agricultural landscapes
(2015)
Meeting growing demands for agricultural products requires management solutions that enhance food production, whilst minimizing negative environmental impacts. Conventional agricultural intensification jeopardizes farmland biodiversity and associated ecosystem services through excessive anthropogenic inputs and landscape simplification. Agri-environment schemes (AES) are commonly implemented to mitigate the adverse effects of conventional intensification on biodiversity. However the moderate success of such schemes thus far would strongly benefit from more explicit goals regarding ecosystem service provisioning. Providing key resources to beneficial organisms may improve their abundance, fitness, diversity and the ecosystem services they provide. With targeted habitat management, AES may synergistically enhance biodiversity and agricultural production and thus contribute to ecological intensification. We demonstrate that sown perennial wildflower strips, as implemented in current AES focusing on biodiversity conservation also benefit biological pest control in nearby crops (Chapter 2).
Comparing winter wheat fields adjacent to wildflower strips with fields without wildflower strips we found strongly reduced cereal leaf beetle (Oulema sp.) density and plant damage near wildflower strips. In addition, winter wheat yield was 10 % higher when fields adjoined wildflower strips. This confirms previous assumptions that wildflower strips, known for positive effects on farmland biodiversity, can also enhance ecosystem services such as pest control and the positive correlation of yield with flower abundance and diversity suggests that floral resources are key. Refining sown flower strips for enhanced service provision requires mechanistic understanding of how organisms benefit from floral resources. In climate chamber experiments investigating the impact of single and multiple flowering plant species on fitness components of three key arthropod natural enemies of aphids, we demonstrate that different natural enemies benefit differently from the offered resources (Chapter 3).
Some flower species were hereby more valuable to natural enemies than others overall. Additionally, the mixture with all flowers generally performed better than monocultures, yet with no transgressive overyielding. By explicitly tailoring flower strips to the requirements of key natural enemies of crop pests we aimed to maximise natural enemy mediated pest control in winter wheat (Chapter 4)and potato (Chapter 5) crops.
Respecting the manifold requirements of diverse natural enemies but not pests, in terms of temporal and spatial provisioning of floral, extra floral and structural resources, we designed targeted annual flower strips that can be included in crop rotation to support key arthropods at the place and time they are needed. Indeed, field experiments revealed that cereal leaf beetle density and plant damage in winter wheat can be reduced by 40 % to 61 % and aphid densities in potatoes even by 77 %, if a targeted flower strip is sown into the field. These effects were not restricted to the vicinity of flower strips and, in contrast to fields without flower strip, often prevented action thresholds from being reached. This suggests that targeted flower strips could replace insecticides. All adult natural enemies were enhanced inside targeted flower strips when compared to control strips. Yet, spillover to the field was restricted to key natural enemies such as ground beetles (winter wheat), hoverflies (potato) and lacewings (winter wheat and potato), suggesting their dominant role in biological control. In potatoes, targeted flower strips also enhanced hoverfly species richness in strips and crop, highlighting their additional benefits for diversity.
The present results provide more insights into the mechanisms underlying conservation biological control and highlight the potential of tailored habitat management for ecological intensification.
In the new epoch of Anthropocene, global freshwater resources are experiencing extensive degradation from a multitude of stressors. Consequently, freshwater ecosystems are threatened by a considerable loss of biodiversity as well as substantial decrease in adequate and secured freshwater supply for human usage, not only on local scales, but also on regional to global scales. Large scale assessments of human and ecological impacts of freshwater degradation enable an integrated freshwater management as well as complement small scale approaches. Geographic information systems (GIS) and spatial statistics (SS) have shown considerable potential in ecological and ecotoxicological research to quantify stressor impacts on humans and ecological entitles, and disentangle the relationships between drivers and ecological entities on large scales through an integrated spatial-ecological approach. However, integration of GIS and SS with ecological and ecotoxicological models are scarce and hence the large scale spatial picture of the extent and magnitude of freshwater stressors as well as their human and ecological impacts is still opaque. This Ph.D. thesis contributes novel GIS and SS tools as well as adapts and advances available spatial models and integrates them with ecological models to enable large scale human and ecological impacts identification from freshwater degradation. The main aim was to identify and quantify the effects of stressors, i.e climate change and trace metals, on the freshwater assemblage structure and trait composition, and human health, respectively, on large scales, i.e. European and Asian freshwater networks. The thesis starts with an introduction to the conceptual framework and objectives (chapter 1). It proceeds with outlining two novel open-source algorithms for quantification of the magnitude and effects of catchment scale stressors (chapter 2). The algorithms, i.e. jointly called ATRIC, automatically select an accumulation threshold for stream network extraction from digital elevation models (DEM) by assuring the highest concordance between DEM-derived and traditionally mapped stream networks. Moreover, they delineate catchments and upstream riparian corridors for given stream sampling points after snapping them to the DEM-derived stream network. ATRIC showed similar or better performance than the available comparable algorithms, and is capable of processing large scale datasets. It enables an integrated and transboundary management of freshwater resources by quantifying the magnitude of effects of catchment scale stressors. Spatially shifting temporal points (SSTP), outlined in chapter 3, estimates pooled within-time series (PTS) variograms by spatializing temporal data points and shifting them. Data were pooled by ensuring consistency of spatial structure and temporal stationarity within a time series, while pooling sufficient number of data points and increasing data density for a reliable variogram estimation. SSTP estimated PTS variograms showed higher precision than the available method. The method enables regional scale stressors quantification by filling spatial data gaps integrating temporal information in data scarce regions. In chapter 4, responses of the assumed climate-associated traits from six grouping features to 35 bioclimatic indices for five insect orders were compared, their potential for changing distribution pattern under future climate change was evaluated and the most influential climatic aspects were identified (chapter 4). Traits of temperature preference grouping feature and the insect order Ephemeroptera exhibited the strongest response to climate as well as the highest potential for changing distribution pattern, while seasonal radiation and moisture were the most influential climatic aspects that may drive a change in insect distribution pattern. The results contribute to the trait based freshwater monitoring and change prediction. In chapter 5, the concentrations of 10 trace metals in the drinking water sources were predicted and were compared with guideline values. In more than 53% of the total area of Pakistan, inhabited by more than 74 million people, the drinking water was predicted to be at risk from multiple trace metal contamination. The results inform freshwater management by identifying potential hot spots. The last chapter (6) synthesizes the results and provides a comprehensive discussion on the four studies and on their relevance for freshwater resources conservation and management.
Factors triggering the ecotoxicity of metal-based nanoparticles towards aquatic invertebrates
(2015)
Nanoparticles are produced and used in huge amounts increasing their probability to end up in surface waters. There, they are subject to environmentally driven modification processes. Consequently, aquatic life may be exposed to different nanoparticle agglomerate sizes, while after sedimentation benthic organisms are more likely to be affected.
However, most ecotoxicity studies with nanoparticles exclusively investigated implications of their characteristics (e.g. size) on pelagic organisms, ignoring environmentally modified nanoparticles. Therefore, a systematic assessment of factors triggering the fate and toxicity of nanoparticles under environmentally relevant conditions is needed. The present thesis, therefore, investigates the implications of nanoparticle related factors (i.e., inherent material-properties and nanoparticle characteristics) as well as environmental conditions towards the pelagic living organism Daphnia magna and the benthic species Gammarus fossarum. In detail, inert titanium dioxide (nTiO2) and ion-releasing silver nanoparticles (nAg), both of varying particle characteristics (e.g. initial size), were tested for their toxicity under different environmental conditions (e.g. ultraviolet-light (UV-light)).
The results indicate that the toxicity of nTiO2 and nAg is mainly determined by: their adsorption potential onto biota, and their fate in terms of reactive oxygen species or Ag+ ion release. Thus, inherent material-properties, nanoparticle characteristics and environmental conditions promoting or inhibiting these aspects revealed significant implications in the toxicity of nTiO2 and nAg towards daphnids.
Furthermore, the presence of ambient UV-light, for example, adversely affected gammarids at 0.20 mg nTiO2/L, while under darkness no effects occurred even at 5.00 mg nTiO2/L. Hence, the currently associated risk of nanoparticles might be underestimated if disregarding their interaction with environmental parameters
Change of ecosystems and the associated loss of biodiversity is among the most important environmental issues. Climate change, pollution, and impoundments are considered as major drivers of biodiversity loss. Organism traits are an appealing tool for the assessment of these three stressors, due to their ability to provide mechanistic links between organism responses and stressors, and consistency over wide geographical areas.
Additionally, traits such as feeding habits influence organismal performance and ecosystem processes. Although the response of traits of specific taxonomic groups to stressors is known, little is known about the response of traits of different taxonomic groups to stressors. Additionally, little is known about the effects of small impoundments on stream ecosystem processes, such as leaf litter decomposition, and food webs.
After briefly introducing the theoretical background and objectives of the studies, this thesis begins by synthesizing the responses of traits of different taxonomic groups to climate change and pollution. Based on 558 peer-reviewed studies, the uniformity (i.e., convergence) in trait response across taxonomic groups was evaluated through meta-analysis (Chapter 2). Convergence was primarily limited to traits related to tolerance.
In Chapter 3, the hypothesis that small impoundments would modify leaf litter decomposition rates at the sites located within the vicinity of impoundments, by altering habitat variables and invertebrate functional feeding groups (FFGs) (i.e., shredders), was tested. Leaf litter decomposition rates were significantly reduced at the study sites located immediately upstream (IU) of impoundments, and were significantly related to the abundance of invertebrate shredders.
In Chapter 4, the invertebrate FFGs were used to evaluate the effect of small impoundments on stream ecosystem attributes. The results showed that heterotrophic production was significantly reduced at the sites IU. With regard to food webs, the contribution of methane gas derived carbon to the biomass of chironomid larvae was evaluated through correlation of stable carbon isotope values of chironomid larvae and methane gas concentrations.
The results indicated that the contribution of methane gas derived carbon into stream benthic food web is low. In conclusion, traits are a useful tool in detecting ecological responses to stressors across taxonomic groups, and the effects of small impoundments on stream ecological integrity and food web are limited.
For decades a worldwide decline of biological diversity has been reported. Landscapes are influenced by several kinds of anthropogenic disturbances. Agricultural land use, application of fertilizers and pesticides and the removal of corridors simplify and homogenize a landscape whereas others like road constructions lead to fragmentation. Both kinds lead to a constraint of habitats, reduce living environment and gene pool, hinder gene flow and change the functional characteristics of species. Furthermore, it facilitates the introduction of alien species. On the other hand, disturbances of different temporal and spatial dimensions lead to a more diverse landscape because they prevent competitive exclusion and create niches where species are able to coexist.
This study focuses on the complexity of disturbance regimes and its influence on phytodiversity. It differs from other studies that mostly select one or few disturbance types in including all identifiable disturbances. Data were derived from three study sites in the north of Bavaria and are subject to different land-use intensities. Two landscapes underlie agriculture and forestry, of which one is intensively used and the second one rather moderate and small-scaled. The third dataset was collected on an actively used military training area. The first part of the study deals with the influence of disturbance regimes on phytodiversity, first with the focus on military disturbances, afterwards in comparison with the agricultural landscapes. The second part examines the influence of disturbance regimes on red-listed species, the distribution of neophytes and generalist plant species and the homogenization of the landscape. All analyses were conducted on landscape and local scale.
A decisive role was played by the variety of disturbance types, especially in different temporal and spatial dimensions and not by single kinds of disturbances, which significantly was proven in the military training area with its multiple and undirected disturbance regime. Homogeneous disturbance regimes that typically are found in agricultural landscapes led to a reduced species number. On local scale, the abiotic heterogeneity which originated of recent and historical disturbances superimposed the positive effects of disturbance regimes, whereas dry and nutrient-poor sites showed a negative effect. Due to a low tree density and moderate treatment species numbers were significantly higher in forest in the training area than in the two agricultural landscapes.
Numbers of red-listed species were positively correlated to the total number of species in all three sites. However, the military training area showed a significantly higher abundance within the area in comparison to the agricultural landscapes where rare species were mostly found on marginal strips. Furthermore, numbers of neophytes and generalist species were lower and consequently homogenization.
In conclusion, the military training area is an ideal landscape from a nature conservation point of view. The moderately used agricultural area showed high species numbers and agricultural productivity. However, yield is too low to withstand either abandonment or land-use intensification.
Global crop production increased substantially in recent decades due to agricultural intensification and expansion and today agricultural areas occupy about 38% of Earth’s terrestrial surface - the largest use of land on the planet. However, current high-intensity agricultural practices fostered in the context of the Green Revolution led to serious consequences for the global environment. Pesticides, in particular, are highly biologically active substances that can threaten the ecological integrity of aquatic and terrestrial ecosystems. Although the global pesticide use increases steadily, our field-data based knowledge regarding exposure of non-target ecosystems such as surface waters is very restricted. Available studies have by now been limited to spatially restricted geographical areas or had rather specific objectives rendering the extrapolation to larger spatial scales questionable.
Consequently, this thesis evaluated based on four scientific publications the exposure, effects, and regulatory implications of particularly toxic insecticides` concentrations detected in global agricultural surface waters. FOCUS exposure modelling was used to characterise the highly specific insecticide exposure patterns and to analyse the resulting implications for both monitoring and risk assessment (publication I). Based on more than 200,000 scientific database entries, 838 peer-reviewed studies finally included, and more than 2,500 sites in 73 countries, the risks of agricultural insecticides to global surface waters were analysed by means of a comprehensive meta-analysis (publication II). This meta-analysis evaluated whether insecticide field concentrations exceed legally accepted regulatory threshold levels (RTLs) derived from official EU and US pesticide registration documents and, amongst others, how risks depend on insecticide development over time and stringency of environmental regulation. In addition, an in-depth analysis of the current EU pesticide regulations provided insights into the level of protection and field relevance of highly elaborated environmental regulatory risk assessment schemes (publications III and IV).
The results of this thesis show that insecticide surface water exposure is characterized by infrequent and highly transient concentration peaks of high ecotoxicological relevance. We thus argue in publication I that sampling based on regular intervals is inadequate for the detection of insecticide surface water concentrations and that traditional risk assessment concepts based on all insecticide concentrations including non-detects lead to severely biased results and critical underestimations of risks. Based on these considerations, publication II demonstrates that out of 11,300 measured insecticide concentrations (MICs; i.e., those actually detected and quantified), 52.4% (5,915 cases; 68.5%) exceeded the RTL for either water (RTLSW) or sediments. This indicates a substantial risk for the biological integrity of global water resources as additional analyses on pesticide effects in the field clearly evidence that the regional aquatic biodiversity is reduced by approximately 30% at pesticide concentrations equalling the RTLs. In addition, publication II shows that there is a complete lack of scientific monitoring data for ~90% of global cropland and that both the actual insecticide contamination of surface waters and the resulting ecological risks are most likely even greater due to, for example, inadequate sampling methods employed in the studies and the common occurrence of pesticide mixtures. A linear model analysis identified that RTLSW exceedances depend on the catchment size, sampling regime, sampling date, insecticide substance class, and stringency of countries` environmental regulations, as well as on the interactions of these factors. Importantly, the risks are significantly higher for newer-generation insecticides (i.e., pyrethroids) and are high even in countries with stringent environmental regulations. Regarding the latter, an analysis of the EU pesticide regulations revealed critical deficiencies and the lack of protectiveness and field-relevance for current presumed highly elaborated FOCUS exposure assessment (publication IV) and overall risk assessment schemes (publication III). Based on these findings, essential risk assessment amendments are proposed.
In essence, this thesis analyses the agriculture–environment linkages for pesticides at the global scale and it thereby contributes to a new research frontier in global ecotoxicology. The overall findings substantiate that agricultural insecticides are potential key drivers for the global freshwater biodiversity crisis and that the current regulatory risk assessment approaches for highly toxic anthropogenic chemicals fail to protect the global environment. This thesis provides an integrated view on the environmental side effects of global high-intensity agriculture and alerts that beside worldwide improvements to current pesticide regulations and agricultural pesticide application practices, the fundamental reformation of conventional agricultural systems is urgently needed to meet the twin challenges of providing sufficient food for a growing human population without destroying the ecological integrity of global ecosystems essential to human existence.
Aquatic macrophytes can contribute to the retention of organic contaminants in streams, whereas knowledge on the dynamics and the interaction of the determining processes is very limited. The objective of the present study was thus to assess how aquatic macrophytes influence the distribution and the fate of organic contaminants in small vegetated streams. In a first study that was performed in vegetated stream mesocosms, the peak reductions of five compounds were significantly higher in four vegetated stream mesocosms compared to a stream mesocosm without vegetation. Compound specific sorption to macrophytes was determined, the mass retention in the vegetated streams, however, did not explain the relationship between the mitigation of contaminant peaks and macrophyte coverage. A subsequent mesocosm study revealed that the mitigation of peak concentrations in the stream mesocosms was governed by two fundamentally different processes: dispersion and sorption. Again, the reductions of the peak concentrations of three different compounds were in the same order of magnitude in a sparsely and a densely vegetated stream mesocosm, respectively, but higher compared to an unvegetated stream mesocosm. The mitigation of the peak reduction in the sparsely vegetated stream mesocosm was found to be fostered by longitudinal dispersion as a result of the spatial distribution of the macrophytes in the aqueous phase. The peak reduction attributable to longitudinal dispersion was, however, reduced in the densely vegetated stream mesocosm, which was compensated by compound-specific but time-limited and reversible sorption to macrophytes. The observations on the reversibility of sorption processes were subsequently confirmed by laboratory experiments. The experiments revealed that sorption to macrophytes lead to compound specific elimination from the aqueous phase during the presence of transient contaminant peaks in streams. After all, these sorption processes were found to be fully reversible, which results in the release of the primarily adsorbed compounds, once the concentrations in the aqueous phase starts to decrease. Nevertheless, the results of the present thesis demonstrate that the processes governing the mitigation of contaminant loads in streams are fundamentally different to those already described for non-flowing systems. In addition, the present thesis provides knowledge on how the interaction of macrophyte-induced processes in streams contributes to mitigate loads of organic contaminants and the related risk for aquatic environments.
Agriculture covers one third of the world land area and has become a major source of water pollution due to its heavy reliance on chemical inputs, namely fertilisers and pesticides. Several thousands of tonnes of these chemicals are applied worldwide annually and partly reach freshwaters. Despite their widespread use and relatively unspecific modes of action, fungicides are the least studied group of pesticides. It remains unclear whether the taxonomic groups used in pesticide risk assessment are protective for non-target freshwater fungi. Fungi and bacteria are the main microbial decomposers converting allochthonous organic matter (litter) into a more nutritious food resource for leaf-shredding macroinvertebrates. This process of litter decomposition (LD) is central for aquatic ecosystem because it fuels local and downstream food webs with energy and nutrients. Effects of fungicides on decomposer communities and LD have been mainly analysed under laboratory conditions with limited representation of the multiple factors that may moderate effects in the field.
In this thesis a field study was conducted in a German vineyard area to characterise recurrent episodic exposure to fungicides in agricultural streams (chapter 2) and its effects on decomposer communities and LD (chapter 3). Additionally, potential interaction effects of nutrient enrichment and fungicides on decomposer communities and LD were analysed in a mesocosm experiment (chapter 4).
In the field study event-driven water sampling (EDS) and passive sampling with EmporeTM styrene-divinylbenzene reverse phase sulfonated disks (SDB disks) were used to assess exposure to 15 fungicides and 4 insecticides. A total of 17 streams were monitored during 4 rainfall events within the local application period of fungicides in 2012. EDS exceeded the time-weighted average concentrations provided by the SDB disks by a factor of 3, though high variability among compounds was observed. Most compounds were detected in more than half of the sites and mean and maximum peak (EDS) concentrations were under 1 and 3 µg/l, respectively. Besides, SDB disk-sampling rates and a free-software solution to derive sampling rates under time-variable exposure were provided.
Several biotic endpoints related to decomposers and LD were measured in the same sampling sites as the fungicide monitoring, coinciding with the major litter input period. Our results suggest that polar organic fungicides in streams change the structure of the fungal community. Causality of this finding was supported by a subsequent microcosm experiment. Whether other effects observed in the field study, such as reduced fungal biomass, increased bacterial density or reduced microbial LD can be attributed to fungicides remains speculative and requires further investigation. By contrast, neither the invertebrate LD nor in-situ measured gammarid feeding rates correlated with water-borne fungicide toxicity, but both were negatively associated with sediment copper concentrations. The mesocosm experiment showed that fungicides and nutrients affect microbial decomposers differently and that they can alter community structure, though longer experiments are needed to determine whether these changes may propagate to invertebrate communities and LD. Overall, further studies should include representative field surveys in terms of fungicide pollution and physical, chemical and biological conditions. This should be combined with experiments under controlled conditions to test for the causality of field observations.
The work presented in this thesis investigated interactions of selected biophysical processes that affect zooplankton ecology at smaller scales. In this endeavour, the extent of changes in swimming behaviour and fluid disturbances produced by swimming Daphnia in response to changing physical environments were quantified. In the first research question addressed within this context, size and energetics of hydrodynamic trails produced by Daphnia swimming in non-stratified still waters were characterized and quantified as a function of organisms’ size and their swimming patterns.
The results revealed that neither size nor the swimming pattern of Daphnia affects the width of induced trails or dissipation rates. Nevertheless, as the size and swimming velocity of the organisms increased, trail volume increased in proportional to the cubic power of Reynolds number, and the biggest trail volume was about 500 times the body volume of the largest daphnids. Larger spatial extent of fluid perturbation and prolonged period to decay caused by bigger trail volumes would play a significant role in zooplankton ecology, e.g. increasing the risk of predation.
The study also found that increased trail volume brought about significantly enhanced total dissipated power at higher Reynolds number, and the magnitudes of total dissipated power observed varied in the range of (1.3-10)X10-9 W.
Furthermore, this study provided strong evidence that swimming speed of Daphnia and total dissipated power in Daphnia trails exceeded those of some other selected zooplankton species.
In recognizing turbulence as an intrinsic environmental perturbation in aquatic habitats, this thesis also examined the response of Daphnia to a range of turbulence flows, which correspond to turbu-lence levels that zooplankton generally encounter in their habitats. Results indicated that within the range of turbulent intensities to which the Daphnia are likely to be exposed in their natural habitats, increasing turbulence compelled the organisms to enhance their swimming activity and swim-ming speed. However, as the turbulence increased to extremely high values (10-4 m2s-3), Daphnia began to withdraw from their active swimming behaviour. Findings of this work also demonstrated that the threshold level of turbulence at which animals start to alleviate from largely active swimming is about 10-6 m2s-3. The study further illustrated that during the intermediate range of turbu-lence; 10-7 - 10-6 m2s-3, kinetic energy dissipation rates in the vicinity of the organisms is consistently one order of magnitude higher than that of the background turbulent flow.
Swarming, a common conspicuous behavioural trait observed in many zooplankton species, is considered to play a significant role in defining freshwater ecology of their habitats from food exploitation, mate encountering to avoiding predators through hydrodynamic flow structures produced by them, therefore, this thesis also investigated implications of Daphnia swarms at varied abundance & swarm densities on their swimming kinematics and induced flow field.
The results showed that Daphnia aggregated in swarms with swarm densities of (1.1-2.3)x103 L-1, which exceeded the abundance densities by two orders of magnitude (i.e. 1.7 - 6.7 L-1). The estimated swarm volume decreased from 52 cm3 to 6.5 cm3, and the mean neighbouring distance dropped from 9.9 to 6.4 body lengths. The findings of this work also showed that mean swimming trajectories were primarily horizontal concentric circles around the light source. Mean flow speeds found to be one order of magnitude lower than the corresponding swimming speeds of Daphnia. Furthermore, this study provided evidences that the flow fields produced by swarming Daphnia differed considerably between unidirectional vortex swarming and bidirectional swimming at low and high abundances respectively.
During olive oil production, large amounts of olive mill wastewater (OMW) are generated within a short period of time. OMW has a high nutrient content and could serve as fertilizer when applied on land. However, its fatty and phenolic constituents have adverse effects on soil properties. It is still unknown how seasonal fluctuations in temperature and precipitation influence the fate and effect of OMW components on soil properties in a long-term perspective. An appropriate application season could mitigate negative consequences of OMW while preserving its beneficial effects. In order to investigate this, 14 L OMW m-2 were applied to different plots of an olive plantation in winter, spring, and summer respectively. Hydrological soil properties (water drop penetration time, hydraulic conductivity, dynamic contact angle), physicochemical parameters (pH, EC, soluble ions, phenolic compounds, organic matter), and biological degradation (bait-lamina test) were measured to assess the soil state after OMW application. After one rainy season following OMW application, the soil quality of summer treatments significantly decreased compared to the control. This was particularly apparent in a three-times lower biodegradation performance, ten-fold higher soil water repellency, and a four-fold higher content of phenolic compounds. The soil properties of winter treatments were comparable to the control, which demonstrated the recovery potential of the soil ecosystem. Spring treatments resulted in an intermediate response compared to summer and winter treatments, but without any precipitation following OMW application. Significant accumulation or leaching effects to deeper soil were not observed. Therefore, the direct application of legally restricted OMW amounts to soil is considered acceptable during the moist seasons. Further research is needed to quantify the effect of spring treatments and to gain further insight into the composition and kinetics of organic OMW constituents in the soil.
Conversion of natural vegetation into cattle pastures and croplands results in altered emissions of greenhouse gases (GHG), such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Their atmospheric concentration increase is attributed the main driver of climate change. Despite of successful private initiatives, e.g. the Soy Moratorium and the Cattle Agreement, Brazil was ranked the worldwide second largest emitter of GHG from land use change and forestry, and the third largest emitter from agriculture in 2012. N2O is the major GHG, in particular for the agricultural sector, as its natural emissions are strongly enhanced by human activities (e.g. fertilization and land use changes). Given denitrification the main process for N2O production and its sensitivity to external changes (e.g. precipitation events) makes Brazil particularly predestined for high soil-derived N2O fluxes.
In this study, we followed a bottom-up approach based on a country-wide literature research, own measurement campaigns, and modeling on the plot and regional scale, in order to quantify the scenario-specific development of GHG emissions from soils in the two Federal States Mato Grosso and Pará. In general, N2O fluxes from Brazilian soils were found to be low and not particularly dynamic. In addition to that, expected reactions to precipitation events stayed away. These findings emphasized elaborate model simulations in daily time steps too sophisticated for regional applications. Hence, an extrapolation approach was used to first estimate the influence of four different land use scenarios (alternative futures) on GHG emissions and then set up mitigation strategies for Southern Amazonia. The results suggested intensification of agricultural areas (mainly cattle pastures) and, consequently, avoided deforestation essential for GHG mitigation.
The outcomes of this study provide a very good basis for (a) further research on the understanding of underlying processes causing low N2O fluxes from Brazilian soils and (b) political attempts to avoid new deforestation and keep GHG emissions low.
The global problematic issue of the olive oil industry is in its generation of large amounts of olive mill wastewater (OMW). The direct discharge of OMW to the soil is very common which presents environmental problems for olive oil producing countries. Both, positive as well as negative effects on soil have been found in earlier studies. Therefore, the current study hypothesized that whether beneficial effects or negative effects dominate depends on the prevailing conditions before and after OMW discharge to soil. As such, a better understanding of the OMW-soil interaction mechanisms becomes essential for sustainable safe disposal of OMW on soil and sustainable soil quality.
A field experiment was carried out in an olive orchard in Palestine, over a period of 24 months, in which the OMW was applied to the soil as a single application of 14 L m-2 under four different environmental conditions: in winter (WI), spring (SP), and summer with and without irrigation (SUmoist and SUdry). The current study investigated the effects of seasonal conditions on the olive mill wastewater (OMW) soil interaction in the short-term and the long-term. The degree and persistence of soil salinization, acidification, accumulation of phenolic compounds and soil water repellency were investigated as a function of soil depth and time elapsed after the OMW application. Moreover, the OMW impacts on soil organic matter SOM quality and quantity, total organic carbon (SOC), water-extractable soil organic carbon (DOC), as well as specific ultraviolet absorbance analysis (SUVA254) were also investigated for each seasonal application in order to assess the degree of OMW-OM decomposition or accumulation in soil, and therefore, the persisting effects of OMW disposal to soil.
The results of the current study demonstrate that the degree and persistence of relevant effects due to OMW application on soil varied significantly between the different seasonal OMW applications both in the short-term and the long-term. The negative effects of the potentially hazardous OMW residuals in the soil were highly dependent on the dominant transport mechanisms and transformation mechanisms, triggered by the ambient soil moisture and temperature which either intensified or diminished negative effects of OMW in the soil during and after the application season. The negative effects of OMW disposal to the soil decreased by increasing the retention time of OMW in soil under conditions favoring biological activity. The moderate conditions of soil moisture and temperature allowed for a considerable amount of applied OMW to be biologically degraded, while the prolonged application time under dry conditions and high temperature resulted in a less degradable organic fraction of the OMW, causing the OMW constituents to accumulate and polymerize without being degraded. Further, the rainfall during winter season diminished negative effects of OMW in the soil; therefore, the risk of groundwater contamination by non-degraded constituents of OMW can be highly probable during the winter season.
The (un-)controlled application of olive oil mill wastewater (OMW) has positive and negative effects on soil quality. On the one hand it can be used as fertilizer, on the other hand especially the occurrence of soil water repellency is problematic. Due to this fact the objective of this study was to characterize the effects of OMW application on soil and to investigate the mechanisms that are in combination with changes of soil organic matter quality responsible for soil water repellency depending on the climatic conditions.
At first several locations of uncontrolled OMW disposal were screened for positive and negative im-pacts. Then, laboratory incubation experiments and finally a field experiment in Israel were conducted in order to determine the influence of climatic conditions. Besides standard soil parameters (pH, elec-tric conductivity, total carbon, dissolved organic carbon , specific UV-Absorption) it was focused on the determination of phenolic compounds, the carbon isotope ratio, the water drop penetration time and the contact angle as well as the thermal analysis.
This thesis shows that soil water repellency of OMW-polluted soils depends on the climatic conditions, i.e. the application season. In the laboratory as well as in the field the wettability of the soil was strongly reduced under hot and dry conditions. It was observed, that the stable carbon fraction characterized by a high calorific value is responsible for soil water repellency. In particular, amphiphilic substances, e.g. fatty acids, may interact with soil particles as a consequence of drying. On the contrary, no reduc-tion of the wettability of the soil was determined under moist conditions and degradation of organic matter of the OMW was enhanced. Nevertheless, too strong irrigation or rainfall, e.g. in winter, may leach phenolic ingredients of the OMW into the groundwater.
At the same time the application led to an increase of organic and inorganic nutrients, which should be emphasized as a positive effect. Due to these results, a controlled application of olive oil mill wastewater as alternative, low-cost and sustainable treatment option is recommended. But, instead of the current application season winter, the olive mill wastewater should be stored and not be spread before spring in order to avoid negative impacts on the soil.
Recent estimates have confirmed that inland waters emit a considerable amount of CH4 and CO2 to the atmosphere at the regional and global scale. But these estimates are based on extrapolated measured data and lack of data from inland waters in arid and semi-arid regions and carbon sources from wastewater treatment plants (WWTPs) as well insufficient resolution of the spatiotemporal variability of these emissions.
Through this study, we analyzed monthly hydrological, meteorological and water quality data from three irrigation and drinking water reservoirs in the lower Jordan River basin and estimated the atmospheric emission rates of CO2. We investigated the effect of WWTPs on surrounding aquatic systems in term of CH4 and CO2 emission by presenting seasonally resolved data for dissolved concentrations of both gases in the effluents and in the receiving streams at nine WWTPs in Germany.
We investigated spatiotemporal variability of CH4 and CO2 emission from aquatic ecosystems by using of simple low-cost tools for measuring CO2 flux and bubble release rate from freshwater systems. Our estimates showed that reservoirs in semi-arid regions are oversaturated with CO2 and acted as net sources to the atmosphere. The magnitude of observed fluxes at the three water reservoirs in Jordan is comparable to those from tropical reservoirs (3.3 g CO2 m-2 d-1). The CO2 emission rate from these reservoirs is linked to changes of water surface area, which is the result of water management practices. WWTPs have been shown to discharge a considerable amount of CH4 (30.9±40.7 kg yr-1) and CO2 (0.06±0.05 Gg yr-1) to their surrounding streams, and emission rates of CH4 and CO2 from these streams are significantly enhanced by effluents of WWTPs up to 1.2 and 8.6 times, respectively.
Our results showed that both diffusive flux and bubble release rate varied in time and space, and both of emission pathways should be included and variability should be resolved adequately in further sampling and measuring strategies. We conclude that future emission measurements and estimates from inland waters may consider water management practices, carbon sources from WWTPs as well spatial and temporal variability of emission.
Die vorliegende Arbeit beschäftigt sich mit der Fragestellung, wie eine repräsentative und aussagekräftige Vergleichbarkeit hinsichtlich der Nachhaltigkeitsleistung (Ökoeffizienz) von Unternehmen branchenunabhängig gewährleistet werden kann trotz der Problematik der Definition repräsentativer Bewertungskriterien der Nachhaltigkeit, sowie der Heterogenität der zu bewertenden Branchen. Bisherige Konzepte zu Umwelt- und Nachhaltigkeitsmanagementsystemen (z.B. EMAS, ISO 14000, ISO 26000, EMASplus), zur Umweltleistungsmessung sowie zur Nachhaltigkeitsbewertung und -berichterstattung (z.B. DNK, GRI) sind mit ihren branchenunabhängigen Formulierung zu allgemein gehalten, um für eine konkrete effizienzorientierte Messung nachhaltigen Wirtschaftens von Unternehmen geeignet zu sein.
Folglich besteht kein System zur Messung der Umweltleistung, um den Forschungsbedarf der Herstellung einer aussagekräftigen Vergleichbarkeit der Ressourcen- und Energieverbräuche der Betriebe einer heterogenen Branche zu begegnen. Angesichts dessen wurde im Rahmen der Arbeit eine allgemeine und branchenunabhängig anwendbare aber dennoch –spezifische Methodik zur Herstellung der Vergleichbarkeit von Unternehmen einer Branche hinsichtlich der Ressourcen- und Energieeffizienz entwickelt. Dabei stellt der Kern der Methodik die Generierung eines betriebsindividuellen Gesamtgewichtungsfaktors dar (GGF-Konzept), welcher als Operationalisierung der Vergleichbarkeit angesehen werden kann und damit der Problematik der Heterogenität begegnet. Die Ermittlung von Kriteriengewichtungen im Rahmen des GGF-Konzeptes kann in Analogie zu einem Entscheidungsproblem bei Mehrfachzielsetzung (Multi Criteria Decision Making – MCDM) gesehen werden, da mehrere Kriterien und Sub-Kriterien zueinander in Relation gesetzt werden mussten. Infolgedessen stellte sich der Analytische-Hierarchie-Prozess als das geeignete Verfahren im Rahmen der Methodikentwicklung heraus. Anwendung fand die Methodik in einem ersten empirischen Test anhand einer ausgewählten Stichprobe von 40 Wäschereibetrieben. Dabei zeigten die Ergebnisse auf, dass repräsentatives sowie aussagekräftiges betriebsindividuelles Benchmarking der Ressourcen- und Energieverbräuche völlig unterschiedlicher und bislang nicht vergleichbarer Betriebe möglich wurde. Hierfür mussten zunächst branchenspezifische repräsentative Bewertungskriterien der Ressourcen- und Energieeffizienz bestimmt werden. Abschließend konnten betriebsspezifische Brennpunkte identifiziert und somit Handlungsempfehlungen zur Optimierung der Ressourcen- und Energieeffizienz der Wäschereibetriebe abgeleitet werden, sodass eine zielorientierte Reduzierung des Ressourcen- und Energieverbrauchs folgen kann.
Grassland management has been increasingly intensified throughout centuries since mankind started to control and modify the landscape. Species communities were always shaped alongside management changes leading to huge alterations in species richness and diversity up to the point where land use intensity exceeded the threshold. Since then biodiversity became increasingly lost. Today, global biodiversity and especially grassland biodiversity is pushed beyond its boundaries. Policymakers and conservationists seek for management options which fulfill the requirements of agronomic interests as well as biodiversity conservation alongside with the maintenance of ecosystem processes. However, there is and will always be a trade-off.
Earlier in history, natural circumstances in a landscape mainly determined regionally adapted land use. These regional adaptions shaped islands for many specialist species, and thus diverse species communities, favoring the establishment of a high β-diversity. With the raising food demand, these regional and traditional management regimes became widely unprofitable, and the invention of mineral fertilizers ultimately led to a wide homogenization of grassland management and, as follows, the loss of biotic heterogeneity. In the course of the green revolution, this immediate coherence and the dependency between grassland biodiversity and traditional land use practices becomes increasingly noticed. Indeed, some traditional forms of management such as meadow irrigation have been preserved in a few regions and thus give us the opportunity to directly investigate their long-term relevance for the species communities and ecosystem processes. Traditional meadow irrigation was a common management practice to improve productivity in lowland, but also alpine hay meadows throughout Europe until the 20th century. Nowadays, meadow irrigation is only practiced as a relic in a few remnant areas. In parts of the Queichwiesen meadows flood irrigation goes back to the Middle Ages, which makes them a predestined as a model region to study the long- and short-term effects of lowland meadow irrigation on the biodiversity and ecosystem processes.
Our study pointed out the conservation value of traditional meadow irrigation for the preservation of local species communities as well as the plant diversity at the landscape scale. The structurally more complex irrigated meadows lead to the assumption of a higher arthropod diversity (Orthodoptera, Carabidae, Araneae), which could not be detected. However, irrigated meadows are a significant habitat for moisture dependent arthropod species. In the light of the agronomic potential, flood irrigation could be a way to at least reduce fertilizer costs to a certain degree and possibly prevent overfertilization pulses which are necessarily hazardous to non-target ecosystems. Still, the reestablishment of flood irrigation in formerly irrigated meadows, or even the establishment of new irrigation systems needs ecological and economic evaluation dependent on regional circumstances and specific species communities, at which this study could serve as a reference point.
Die deutsche Holzhausbranche wächst seit Jahren, allerdings beschäftigen sich die Unternehmen nicht strategisch mit dem Thema Marketing. Diese Dissertation bildet durch qualitative und quantitative Bewohnerbefragungen die Basis für die Entwicklung eines strategischen Marketingansatzes im Holzhausbereich.
Grundwasser ist eine lebenswichtige Ressource und gleichzeitig ein thermisch stabiler Lebensraum mit einer außergewöhnlichen Fauna. Aufgrund der Klimageschichte der letzten ca. 1,8 Millionen Jahre in Mitteleuropa war die Ausgangshypothese, dass die meisten Grundwasserarten an Temperaturen unterhalb von 14 °C angepasst sind und sich Temperaturerhöhungen daher negativ auf die Grundwasserfauna auswirken.
Um die Folgen einer Klimaerwärmung in situ beurteilen zu können, wurden anthropogen erwärmte Grundwässer als Modelle herangezogen. In ersten Teil dieser Arbeit wurden die Crustaceagemeinschaften natürlich temperierter und anthropogen erwärmter Standorte untersucht. Dazu wurden insgesamt 70 Grundwassermessstellen im Oberrheingraben über ein Jahr (2011 bis 2012) sechsmal beprobt. Ergänzend zu diesem synökologischen Ansatz wurde in einem zweiten Teil die Temperaturpräferenz ausgewählter Arten überprüft. Für diese autökologische Betrachtung wurde ein deutschlandweiter Datensatz herangezogen.
Die ausgewählten Untersuchungsgebiete haben sich als geeignete Modelle für die prognostizierten Temperaturerhöhungen herausgestellt. Die Temperatur erwies sich als einer der wichtigsten Parameter für die Crustaceagemeinschaften. Erwärmungen beeinflussen die Zusammensetzung der Gemeinschaften und die Diversität. Dabei zeigte sich, dass es artspezifisch unterschiedliche Temperaturpräferenzen gibt. Einige vermutlich weniger streng stygobionte Arten scheinen höhere Temperaturen zu tolerieren. Der Großteil der stygobionten Grundwasserarten bevorzugt allerdings Temperaturen unterhalb von 14 °C, wobei wenige Arten als „extrem kalt¬steno-therm“ einzustufen sind. Diese Arten wurden an Standorten nachgewiesen, die aufgrund der hydrologischen Verhältnisse relativ kühl sind und der Fauna auch zukünftig als kalte Refugien Schutz bieten könnten. Einer dieser Standorte ist aufgrund seiner Artenvielalt als „Hot Spot“ einzustufen. Die Ergebnisse legen nahe, dass vor allem kaltstenotherme Arten durch eine Klimaerwärmung und anthropogene Wärmeeinträge gefährdet sind.
Die Untersuchung zeigt, dass Grundwasserlebensräume vor Temperaturerhöhungen zu bewahren sind. Lokale anthropogene Wärmeeinträge sollten keine dauerhafte und großflächige Grundwassererwärmung über 14 °C zur Folge haben. Thermische Ein-träge sollten überwacht und bewertet werden. Es wird empfohlen, die bestehenden rechtlichen Rahmenbedingungen den ökologischen Erfordernissen anzupassen.