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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.
Quellen sind hochdiverse Lebensräume mit einer stark spezialisierten Fauna, wobei noch Lücken im Verständnis der besiedlungsrelevanten Faktoren für die aquatische Makrofauna bestehen, so dass die Arbeit einen klärenden Beitrag hinsichtlich anthropogener Veränderungen und ihrer Auswirkungen auf die Besied-lung leisten will. Basierend auf Daten von 334 Quellen aller Grundwasserlandschaften von Rheinland-Pfalz wurden die Quellen morphologisch und faunistisch bewertet. Außerdem wurden die Quellen des Landes morphologisch typisiert, Referenzquellen analysiert und ein Ansatz für die morphologische und faunistische Leitbildentwicklung gegeben. Außerdem wird ein selbst entwickeltes, kompaktes Kartier- und Bewertungsverfahren zur Quellstruktur vorgestellt, wo bislang noch ein Defizit bestand. Das Verfahren erfasst in einem Erfassungsbogen alle ökologisch bedeutsamen Strukturparameter und bewertet in einem 5-stufigen System. Quellen sind hochdiverse Lebensräume mit kleinen Populationen in isolierter Lage. Bei der Untersuchung der 310 Quellen wurden insgesamt 292 Arten bzw. höhere Taxa des Makrozoobenthos nachgewiesen. Es wurden 89 quellassoziierte Taxa gezählt, hiervon waren 24 krenobiont und 65 krenophil. Der Anteil der quellassoziierten Fauna an der Gesamtfauna lag bei über 30%. Es fanden sich 19 Erstnachweise für Rheinland-Pfalz, 9 besondere Nachweise (seltene Arten) und 19 Rote-Liste-Arten. Erstnachweise fanden sich in wenig bearbeiteten Dipterengruppen, vor allem den Psychodidae (13), Limoniidae (5) und ferner den Simu-liidae (1). Bei den Köcherfliegen wurden etliche seltene Arten gefunden, welche bisher in Rheinland-Pfalz kaum gefunden wurden. Häufigere krenobionte Taxa waren Crunoecia irrorata, Bythinella dunkeri, Niphar-gus sp., Pisidium personatum, Salamandra salamandra, Thaumalea sp., Agabus guttatus, Crenobia alpina, Oxycera sp. und Beraea maura. Die durchschnittliche Taxazahl pro Quelle betrug 11, die maximale 62 Taxa. Schüttung und Morphologie der Quellen waren von Naturraum und Grundwasserlandschaft abhängig, so schütteten etwa Buntsandsteinquellen ergiebiger und konstanter als Tonschieferquellen. Quellen spiegeln die Hydrologie ihrer Einzugsgebiete wider, so dass in verschiedenen hydrogeologischen Einheiten die chemischen Parameter differierten. In einzelnen Quellen schwankte die Hydrochemie jahreszeitlich aber nur gering. Der pH-Wert etwa war im Quellwasser versauerungsgefährdeter Gebiete niedrig (Hunsrück, Pfälzer-wald), der Nitratgehalt anthropogen bedingt hoch in intensiv landwirtschaftlich genutzten Räumen. Die morphologische Quelltypologie, welche sich in erster Linie auf gängige Quelltypen stützte, ergab in elf hydrogeologischen Quelltypenräumen vier Basisquelltypen und fünf geochemische Sondertypen. Die Wan-derquelle wurde neu hinzu genommen. Die landesweite Verteilung der Quelltypen ergab bei ungefassten Quellen 57 % Sicker-, 32 % Sturz-, 9 % Tümpel- und über 2 % Wanderquellen. Wanderquellen dürften aber noch öfter vorkommen. Relief und Substrateigenschaften waren entscheidende Faktoren für die Typologie, so dass etwa Sturzquellen vor allem im Buntsandstein häufig waren, während Sickerquellen im Tonschiefer des rheinischen Schiefergebirges dominierten. Es wurden 85 Strukturreferenzquellen als typische, naturnahe Beispiele für einzelne Quelltypenräume genannt. Etwa zwei Drittel aller Quellen waren strukturell beein-trächtigt bis stark geschädigt, 59 % gefasst. Fassungen, Verrohrungen und Betonverbau waren ökologisch besonders bedeutsam. In Regionen mit intensiver Landwirtschaft lagen generell die stärksten Schädigungen vor. Im Forst waren Quellen durch Nadelholzmonokulturen und in den Hochlagen pufferarmer Mittelgebirge durch Versauerung geschädigt. Hinsichtlich der Besiedlung ergaben sich Unterschiede zwischen den Naturräumen, beeinflusst durch die Faktoren Geologie, Hydrochemie, Schüttungsverhältnisse, Landnutzung im Einzugsgebiet sowie die Struk-turvielfalt an der Quelle. Strukturell unveränderte und unversauerte Quellen besaßen im Schnitt höhere Ta-xazahlen. Einzelne Faktoren mit Einfluss auf die Besiedlung wurden in ihrer Auswirkung getestet. In Quel-len ist die Versauerung grundsätzlich besiedlungsbeschränkend und überlagert strukturelle Faktoren. Bei niedrigen pH-Werten kommt es zu verminderten Taxazahlen, allerdings sind viele Quellorganismen offen-sichtlich an eine leichte Versauerung angepasst, da in sauren Quellen der Anteil der Quellfauna höher war. Außerdem ergab die Untersuchung, dass neue und intakte Fassungen weniger Taxa und Quelltaxa aufwiesen, während bei alten und verfallenen Fassungen oft eine hohe Quelltaxazahl vorlag, so dass diese als sekundär ökologisch wertvoll zu bezeichnen sind. Die Umfeldnutzung und die Größe des Quellbereichs sind ebenfalls wichtig, so dass Quellen in Laub- und Mischwald sowie in extensivem Grünland am besten besiedelt waren. Die stärksten statistischen Zusammenhänge mit der faunistischen Besiedlung ergaben sich bei den Bewer-tungsergebnissen des Strukturverfahrens, was zeigt, dass das Verfahren realistisch bewertet. Multivariate statistische Methoden dienten der Ermittlung von Besiedlungsfaktoren und der Leitbildentwick-lung. Es ergab sich eine unterschiedliche Besiedlung bei verschiedener Hydrogeologie und Hydrochemie sowie bei verschiedenen Quelltypen. Allerdings waren die Ergebnisse nicht eindeutig, so dass die Trennung der Quelltypen nur teilweise gelang und die Quelltypen von den Grundwasserlandschaften überlagert waren. Die Faunenunterschiede verschiedener Regionen waren größer als die einer Region, so dass morphologische Quelltypen faunistisch nur innerhalb einer hydrogeologischen Einheit von Bedeutung sind. Es wurden regionale faunistische Leitarten für vier Grundwasserlandschaften genannt, wobei sich auf wenige hochstete Quellarten beschränkt wurde. Die Arbeit zeigt, dass faunistisch orientierte Leitbilder nur unter Schwierigkeiten anzugeben sind und vollständige Typuszönosen für größere Gebiete grundsätzlich in Frage zu stellen sind. Sehr häufige grundsätzliche Leitarten für Quellen silikatischer Mittelgebirge in Rheinland-Pfalz sind Crunoecia irrorata und Bythinella dunkeri.
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.
Fate and effects of insecticides in vegetated agricultural drainage ditches and constructed wetlands
(2006)
Studies have shown that runoff and spray-drift are important sources of nonpoint-source pesticide pollution of surface waters. Owing to this, public concern over the presence of pesticides in surface and ground water has resulted in intensive scientific efforts to find economical, yet environmentally sound solutions to the problem. The primary objective of this research was to assess the effectiveness of vegetated aquatic systems in providing buffering between natural aquatic ecosystems and agricultural landscape following insecticide associated runoff and spray-drift events. The first set of studies were implemented using vegetated agricultural ditches, one in Mississippi, USA, using pyrethroids (bifenthrin, lambda-cyhalothrin) under simulated runoff conditions and the other in the Western Cape, South Africa using the organophosphate insecticide, azinphos-methyl (AZP), under natural runoff and spray-drift conditions. The second set of studies were implemented using constructed wetlands, one in the Western Cape using AZP under natural spray-drift conditions and the other in Mississippi, USA using the organophosphate MeP under simulated runoff conditions. Results from the Mississippi-ditch study indicated that ditch lengths of less than 300 m would be sufficient to mitigate bifenthrin and lambda-cyhalothrin. In addition, data from mass balance calculations determined that the ditch plants were the major sink (generally > 90%) and/or sorption site for the rapid dissipation of the above pyrethroids from the water column. Similarly, results from the ditch study in South Africa showed that a 180 m vegetated system was effective in mitigating AZP after natural spray drift and low flow runoff events. Analytical results from the first wetland study show that the vegetated wetland was more effective than the non-vegetated wetland in reducing loadings of MeP. Mass balance calculations indicated approximately 90% of MeP mass was associated with the plant compartment. Ninety-six hours after the contamination, a significant negative acute effect of contamination on abundances was found in 8 out of the 15 macroinvertebrate species in both wetland systems. Even with these toxic effects, the overall reaction of macroinvertebrates clearly demonstrated that the impact of MeP in the vegetated wetland was considerably lower than in the non-vegetated wetland. Results from the constructed wetland study in South Africa revealed that concentrations of AZP at the inlet of the 134 m wetland system were reduced by 90% at the outlet. Overall, results from all of the studies in this thesis indicate that the presence of the plant compartment was essential for the effective mitigation of insecticide contamination introduced after both simulated and natural runoff or spray-drift events. Finally, both the vegetated agricultural drainage ditch and vegetated constructed wetland systems studied would be effective in mitigating pesticide loadings introduced from either runoff or spray-drift, in turn lowering or eliminating potential pesticide associated toxic effects in receiving aquatic ecosystems. Data produced in this research provide important information to reduce insecticide risk in exposure assessment scenarios. It should be noted that incorporating these types of best management practices (BMPs) will decrease the risk of acute toxicity, but chronic exposure may still be an apparent overall risk.
The estimation of the potential risk of pesticide entries into streams - and therefore the potential risk for the ecosystems - is an important requirement for the planning of risk mitigation strategies. Especially on the landscape level the required event triggered sampling methods are conjuncted with considerable efforts with regard to input data, time and personnel. To circumvent these problems simulation models form a reasonable alternative. The aims of this work were (A) the development of a simulation tool for the estimation of pesticide entries into surface waters on the landscape level, and (B) the application of the simulator for an exposure- and risk-assessment as well as the assessment of negative effects of pesticides on aquatic communities. Section 1 - Exposure-, Risk- and Effects In sections 1.1 and 1.2 the simulation model was applied to a multitude of small and medium sized streams in an agricultural impacted study area around the city of Braunschweig, Germany. Section 1.3 gives an overview of the simulators field of application and the general system structure. Section 1.1 - Scenario based simulation of runoff-related pesticide entries into small streams on a landscape level (English publication, p. 27): In this paper we present a simulation tool for the simulation of pesticide entry from arable land into adjacent streams. We used the ratio of exposure to toxicity (REXTOX) model proposed by the OECD which was extended to calculate pesticide concentrations in adjacent streams. We simulated the pesticide entry on the landscape level at 737 sites in small streams situated in the central lowland of Germany. The most significant model parameters were the width of the no-application-zone and the degree of plant-interception. The simulation was carried out using eight different environmental scenarios, covering variation of the width of the no-application-zone, climate and seasonal scenarios. The highest in-stream concentrations were predicted at a scenario using no (0 m) buffer zone in conjunction with increased precipitation. According to the predicted concentrations, the risk for the aquatic communities was estimated based on standard toxicity tests and the application of a safety factor. Section 1.2 - Linking land use variables and invertebrate taxon richness in small and medium-sized agricultural streams on a landscape level (English publication, p. 50): In this study the average numbers of invertebrate species across an arable landscape in central Germany (surveys from 15 years in 90 streams at 202 sites) were assessed for their correlation with environmental factors such as stream width, land use (arable land, forest, pasture, settlement), soil type and agricultural derived stressors. The stress originating from arable land was estimated by the factor "risk of runoff", which was derived from a runoff-model (rainfall induced surface runoff). Multivariate analysis explained 39.9% of the variance in species number, revealing stream width as the most important factor (25.3%) followed by risk of runoff (9.7%). Section 1.3 - Informationssystem zur ökotoxikologischen Bewertung der Gewässergüte in Bezug auf Pflanzenschutzmitteleinträge aus der Landwirtschaft - Systemaufbau und Anwendungsmöglichkeiten (German publication, p. 61): Section 1.3 contains a short overview of the simulation tool, the field of application and some examples of use, covering the effects of the width of the buffer zone as well as the creation of risk maps on the landscape level. Section 2 - The simulation tool An important aspect for the employment of a simulation model in the context of risk assessment is the applicability in practice: the accessibility of the needed input data, the conversion of the mathematical model into a software application that can be run on any current personnel computer and also an appropriate end-user documentation of the system. Section 1.4 - Informationssystem zur ökotoxikologischen Bewertung der Gewässergüte in Bezug auf Pflanzenschutzmitteleinträge aus der Landwirtschaft - Simulationsmodell und Systemaufbau (German report, p. 67): In this section a general overview of the simulation model as well as the schematic system structure given. Section 1.5 - Benutzerhandbuch (German report, p. 71): The user manual contains details concerning the installation of the system, generation of the required input data and the general use of the system. Moreover it presents some application examples (what-if analyses). Section 1.6 - Technical documentation (German report, p. 104): The technical documentation describes internal structures and processes of the simulation system. Section 1.6 provides information regarding the required structure of input/output tables.
Die Arbeit stellt die Frage nach den Effekten einer tertiären Präventionsmaßnahme in Bezug auf Schmerzbewältigung und Schmerzveränderung bei chronischen Lumbalgiepatienten. Im Rahmen der Überprüfung werden ausdifferenzierte psychophysische Interventionsmaßnahmen aus den Bereichen der Physiotherapie/Krankengymnastik und Psychologie eingesetzt. Die Gruppenunterteilung erfolgt in eine behandelte Versuchsgruppe und eine unbehandelte Warte-Kontrollgruppe mit jeweils 100 Probanden (N=200). Die Ergebnisse der tertiären Präventionsmaßnahme zeigen statistisch und klinisch relevante sowie positive Veränderungen in den Bereichen der Schmerzbewältigung und Schmerzveränderung.
Gibt es unterschiedliche Qualitäten für das Wohnumfeld von Bewohnern ländlicher Siedlungen in der südlichen Pfalz? Wie könnte man diese Unterschiede quantifizierbar machen? Dies sind die beiden zentralen Fragen dieser Arbeit. Die Raummerkmale sollen zunächst objektiv erfasst werden. In einem weiteren Schritt werden die subjektiven Einschätzungen der Bevölkerung ermittelt und schließlich mit der objektiven Aufnahme verglichen. Zu diesem Zweck wur¬den 12 Ortschaften im Bereich der südlichen Pfalz ausgewählt. Jeweils vier Siedlungen verteilen sich auf den Pfälzerwald (Wilgartswiesen, Bundenthal, Ludwigswinkel, Silz), auf die Weinstraße (Siebeldingen, Göcklingen, Oberotterbach, Pleisweiler-Oberhofen) und auf die Rheinebene (Kapsweyer, Winden, Hayna, Büchelberg). Ein klar umgrenzter geographischer Raum wurde um jede Siedlung im Hinblick auf natürliche Gunst-/Ungunstfaktoren (aus den Bereichen Geologie, Boden, Geomorphologie, Klima, Hydrologie und Vegetation) und kulturhistorische Gunst-/Ungunstfaktoren (aus den Bereichen Siedlung, Flur, Mensch) mit ausgewählten aussagekräftigen Parametern untersucht. Diese wurden zu Merkmalskomplexen zusammengeführt und die dabei gewonnenen Erkenntnisse mit einem Bewertungsraster verknüpft und den einzelnen Orten zugeordnet. Die menschlichen Einschätzungen der gegebenen und auch der gemachten Umwelt sollen in die Überlegungen mit einfließen, und deshalb sind Befragungen der Einwohner durchgeführt worden. So erhielt man Erkenntnisse sowohl über die objektiven Lebensraumbedingungen als auch über die subjektiven Lebensraumbewertungen des Untersuchungsraumes. Eine zentrale Rolle spielt hier also der Raum mit seinen Verflechtungen, Interaktionen und Systembeziehungen für das menschliche Leben darin. Zur Ermittlung der objektiven Merkmale der Siedlungen wurden die folgenden Parameter erfasst: Ortseingänge, Naturnähe, Vielfalt, Eigenart, Ästhetik, Klima, Raum, Lärm/Luft, Erdbeben und Ertrag. Orte mit hohem Waldanteil (v. a. Pfälzerwaldorte) wiesen bessere Bewertungen in den Kategorien Naturnähe, Vielfalt, Ästhetik und Klima auf. Orte mit höheren Reb- und Ackerfluranteilen schnitten bei der Eigenart und dem Ertrag besser ab. Deshalb wurden die Orte im Pfälzerwald insgesamt und durchschnittlich am besten bewertet, gefolgt von den Siedlungen der Rheinebene und der Weinstraße. Diese Ergebnisse wurden anschließend mit den Ergebnissen der Befragungen in den einzelnen Orten, welche selbst sehr unterschiedlich ausfielen, verglichen. Dabei musste festgestellt werden, dass die Bewertung der lebensräumlichen Gegebenheiten durch die Befragten in der Regel besser ausfiel als deren objektive Einstufung. Am zufriedensten sind und am besten bewertet haben die Bewohner der Pfälzerwaldorte, gefolgt von denen der Rheinebene und der Weinstraße. Diese somit feststellbare positive Korrelation lässt vermuten, dass zukünftiges Planen im Meinungsbild der Bevölkerung, die schließlich besonders davon betroffen ist, auch akzeptiert werden kann. Öffentlichkeitsarbeit und die Aufklärung der Bevölkerung in lebensraumrelevanten Angelegenheiten sollten dabei nicht vernachlässigt werden.
Recent EU-frameworks enforce the implementation of risk mitigation measures for nonpoint-source pesticide pollution in surface waters. Vegetated surface flow treatments systems (VTS) can be a way to mitigate risk of adverse effects in the aquatic ecosystems following unavoidable pollution after rainfall-related runoff events. Studies in experimental wetland cells and vegetated ditch mesocosms with common fungicides, herbicides and insecticides were performed to assess efficiency of VTS. Comprehensive monitoring of fungicide exposure after rainfall-related runoff events and reduction of pesticide concentrations within partially optimised VTS was performed from 2006-2009 at five vegetated detention ponds and two vegetated ditches in the wine growing region of the Southern Palatinate (SW-Germany).
Influence of plant density, size related parameters and pesticide properties in the performance of the experimental devices, and the monitored systems were the focus of the analysis. A spatial tool for prediction of pesticide pollution of surface waters after rainfall-related runoff events was programmed in a geographic information system (GIS). A sophisticated and high resolution database on European scale was built for simulation. With the results of the experiments, the monitoring campaign and further results of the EU-Life Project ArtWET mitigation measures were implemented in a georeferenced spatial decision support system. The database for the GIS tools was built with open data. The REXTOX (ratio of exposure to toxicity) Risk Indicator, which was proposed by the OECD (Organisation for Economic Co-operation and Development), was extended, and used for modeling the risk of rainfall-related runoff exposure to pesticides, for all agricultural waterbodies on European scale. Results show good performance of VTS. The vegetated ditches and wetland cells of the experimental systems showed a very high reduction of more than 90% of pesticide concentrations and potential adverse effects. Vegetated ditches and wetland cells performed significantly better than devices without vegetation. Plant density and sorptivity of the pesticide were the variables with the highest explanatory power regarding the response variable reduction of concentrations. In the experimental vegetated ditches 65% of the reduction of peak concentrations was explained with plant density and KOC. The monitoring campaign showed that concentrations of the fungicides and potential adverse effects of the mixtures were reduced significantly within vegetated ditches (Median 56%) and detention ponds (Median 38%) systems. Regression analysis with data from the monitoring campaign identified plant density and size related properties as explanatory variables for mitigation efficiency (DP: R²=0.57, p<0.001; VD:
R²=0.19, p<0.001). Results of risk model runs are the input for the second tool, simulating three risk mitigation measures. VTS as risk mitigation measures are implemented using the results for plant density and size related performance of the experimental and monitoring studies, supported by additional data from the ArtWET project. Based on the risk tool, simulations can be performed for single crops, selected regions, different pesticide compounds and rainfall events. Costs for implementation of the mitigation measures are estimated. Experiments and monitoring, with focus on the whole range of pesticides, provide novel information on VTS for pesticide pollution. The monitoring campaign also shows that fungicide pollution may affect surface waters. Tools developed for this study are easy to use and are not only a good base for further spatial analysis but are also useful as decision support of the non-scientific community. On a large scale, the tools on the one hand can help to compute external costs of pesticide use with simulation of mitigation costs on three levels, on the other hand feasible measures mitigating or remediating the effects of nonpoint-source pollution can be identified for implementation. Further study of risk of adverse effects caused by fungicide pollution and long-time performance of optimised VTS is needed.
Studies have shown that wastewater treatment plant (WWTP) effluents are the major pathways of organic and inorganic chemicals of anthropogenic use (=micropollutants) into aquatic environments. There, micropollutants can be transferred to ground water bodies - and may finally end up in drinking water - or cause various effects in aquatic organisms like multiple resistances of bacteria. Hence, the upgrading of WWTPs with the aim to reduce the load of those micropollutants is currently under discussion.
Therefore, the primary objective of this thesis was to assess ecotoxicological effects of wastewater ozonation, a tertiary treatment method, using specifically developed toxicity tests with Gammarus fossarum (Koch) at various levels of ecological complexity. Several studies were designed in the laboratory and under semi-field conditions to cope with this primary objective. Prior to the investigations with ozone treated wastewater, the ecotoxicity of secondary treated (=non-ozone treated) wastewater from WWTP Wüeri, Switzerland, for the test species was assessed by a four-week experiment. This experiment displayed statistically significant impairments in feeding, assimilation and physiological endpoints related to population development and reproduction. The first experiment investigating ecotoxicological implications of ozone application in wastewater from the same WWTP displayed a preference of G. fossarum for leaf discs conditioned in ozone treated wastewater when offered together with leaf discs conditioned in non-ozone treated wastewater. This effect seems to be mainly driven by an alteration in the leaf associated microbial community. Another series of laboratory experiments conducted also with wastewater from WWTP Wüeri treated with ozone at the lab- or full-scale, revealed significantly increased feeding rates of G. fossarum exposed to ozone treated wastewater compared to non-ozone treated wastewater. These laboratory experiments also indicated that any alteration in the organic matrix potentially caused by ozone treatment is not related to the effects in feeding as this endpoint showed only negligible deviation in secondary treated wastewater, which contained hardly any (micro)pollutants (i.e. pharmaceuticals), from the same wastewater additionally treated with ozone. Moreover, it was shown that shifts in the dissolved organic carbon (DOC) profile do not affect the feeding rate of gammarids. In situ bioassays conducted in the receiving stream of the WWTP Wüeri confirmed the results of the laboratory experiments by displaying significantly reduced feeding rates of G. fossarum exposed below the WWTP effluent if non-ozone treated wastewater was released. However, at the time the ozonation was operating, no adverse effects in feeding rates were observed below the effluent compared to the unaffected upstream sites. Also population studies in on-site flow-through stream microcosms displayed an increased feeding and a statistically significantly higher population size after ten weeks when exposed to ozone treated wastewater compared to non-ozone treated wastewater.
In conclusion, the present thesis documents that ozonation might be a suitable tool to reduce both the load of micropollutants as well as the ecotoxicity of wastewaters. Thus, this technology may help to meet the requirements of the Water Framework Directive also under predicted climate change scenarios, which may lead to elevated proportions of wastewater in the receiving stream during summer discharge. However, as ozone application may also produce by-products with a higher toxicity than their parent compounds, the implementation of this technique should be assessed further both via chemical analysis and ecotoxicological bioassays.
Wild boars belong to the most wide spread ungulates in the world. They are characterized by a well performed adaption to their environment mainly due to their omnivorous dietary. The wild boar population in Germany increased during the past three decades. Nowadays their high density leads to problems in agricultural areas due to damage of crops and plays a significant role as disease vector as the classical swine fever. For an effective population management population size information is of crucial importance. Different traditional methods exist to estimate population sizes as direct sightnings, faecal drop counts or hunting harvest which provide only relative estimates and population trends. Absolute population sizes could be yielded by a Capture-Mark-Recapture (CMR) approach. However, capturing of wild boars is difficult to realize and costly in terms of personnel and field effort.
Furthermore the capture probabilities are heterogeneous due to the variable behaviour of individuals influenced by age, sex, and experience of the animals. Non-invasive genetic methods are a promising complement to the traditional methods for population size estimation particularly for wild boar. These methods reduce stress and capture bias and increase the number of re-captures. Faeces proved to be a suitable DNA source for wild boar genotyping, due to almost equal capture probability. However working with faeces implicates difficulties such as low DNA rnquality and quantity, genotyping errors as dropout and false alleles.
The main aim of the present study was to develop a reliable, cost-efficient, reproducible and practicable method for wild boar genotyping. This method should provide a reliable dataset of genotypes obtained from the collected faeces samples. Individual identification forms the basis for an improved mark-recapture approach. As there is no sound method for absolute population counts in free living wild boar, reference values for the validation of this new approach are missing. Therefore, different routines to reduce and to assess genotyping errors were compared within this thesis. For maximum amplification rate, the storage, the extraction methods and the PCR-procedure were optimised. A step by step procedure was evaluated in order to determine the minimum required microsatellite (MS) number for reliable individual identification including a test with family groups (female and embryo tissue) to distinguish even between close relatives. A multiple-tubes approach, post-amplification checking and different correction procedures were applied to reduce genotyping errors. In order to quantify real genotyping error rates (GER) of datasets derived from sampling in the Palatinate Forest in western Germany, different methods for GER determination were compared with each other, obtaining GERs between 0% and 57.5%. As a consequence, more strict criteria for the multi-tube approach and increased repetition number of homozygous samples were used. An additional method validation was the implementation of a blind test to achieve the reliability of the genotyping and error checking procedure. Finally a strict and practicable proposal for the lab procedure was developed, by beginning with faecal sample collection and ending with a reliable dataset with genotypes of each sample.
The results of the presented method were derived from two sampling periods in a 4000 ha area in the Palatinate Forest in Rhineland-Palatinate in December 2006 and 2007. Both provided high confidence intervals (CI) applying inaccurate estimates (eg. for 2006 population size amounted to 215 with CI 95% of 156-314 and for 2007 population size amounted to 415 with CI 95% of 318-561) due to low sampling sizes (for 2006 n = 141 and for 2007 n = 326), successfully analysed samples (for 2006 n = 89 and for 2007 n = 156) and recapture numbers (for 2006 n = 12 and for 2007 n = 24). Furthermore, the population estimates even for the lowest values were considerably higher than previously assumed by hunting statistics, which implicates an ineffective hunting regime in the study area. For the future prospect, to obtain more precise population size estimations the increase of sampling sizes is inevitable, because absolute and reliable estimates are highly desirable for wildlife management and the control of diseases transmission. Nevertheless, the method for individual genotyping of wild boars evaluated in this thesis could be successfully established resulting in reliable datasets for population estimation modelling with sufficiently low GER.
Population genetic structure in European Hyalodaphnia species: Monopolization versus gene flow
(2012)
Cyclic parthenogens displays an alternation of asexual and sexual reproduction which has consequences for the genetic structure of these organisms. The clonal diversity of cyclic parthenogenetic zooplankton populations is influenced by the size of the dormant egg bank, i.e., the amount of sexually produced dormant eggs that assembled in the sediment, as these dormant eggs contribute new genetic variants to the populations. Further, the clonal diversity is impacted by clonal erosion over time, which reduces the number of different clones through stochastic and selective processes. Although freshwater invertebrates are good dispersers through their dormant stages, the influence of gene flow is assumed to be negligible, as the local population successfully monopolizes the available resources. As these populations reach carrying capacity fast due to the asexual reproduction, the first colonizing individuals are able to successfully establish in the habitat, resulting in a priority effect which hinders the invasion of new genotypes. Due to clonal selection and sexual reproduction a population will locally adapt over time and will establish a dormant egg bank which facilitates the fast re-colonization after a hostile period. This thesis evaluates the processes altering the population genetic structure of cyclic parthenogenetic zooplankton with a special focus on the concepts of monopolization as well as the counteracting effects of gene flow, using large-lake Daphnia species. Thirty-two variable microsatellite DNA markers were developed and a subset of twelve markers was evaluated regarding their suitability for species assignment and hybrid class detection. With this marker set and an additional mitochondrial DNA marker forty-four natural European populations of the species D. cucullata, D. galeata and D. longispina were studied. In D. galeata, most populations were characterized by low clonal diversities which suggest high influence from clonal erosion over the growing season and a low contribution from the dormant egg bank. Further, recent expansions as well as gene flow were detected, probably caused by the anthropogenic alteration of freshwater habitats, in particular eutrophication of many European lakes. D. longispina and D. cucullata revealed a different genetic structure compared to D. galeata, with high genetic differentiation among populations. This indicates low levels of effective gene flow which is in line with the predictions of monopolization. Further, high clonal diversities were found in populations of the two taxa, suggesting a high contribution from the dormant egg bank while clonal erosion was often not detectable. In D. longispina, mitochondrial data revealed an ancient expansion which was probably initiated by the formation of glacial lakes after the last ice age.
In addition, in D. longispina not only clonal diversity but also genetic diversity was high, indicating that during the build-up of the studied populations the influence from gene flow was probably high. To better understand the processes that act on early populations the population build-up in regard to the temporal advantage of clones during invasion succession was experimentally studied and revealed that priority effects shape population structure of Daphnia species. However, in certain cases the highly superior clones resulted in the extinction of inferior clones independent of the temporal advantage the single clones had.
This clearly shows that not only the time of succession is important but also the competitive strength. rnIn conclusion, the results obtained show that the population genetic structure in cyclic parthenogenetic zooplankton species is impacted by various processes. In addition to earlier studies, which mainly focus on local adaptation, clonal erosion and the size of the dormant egg bank to understand population genetic structure, this thesis could show that gene flow may be effective as well. During population build-up the advantage of early arriving individuals does not necessarily predict the outcome of population assembly, as additional genotypes may contribute to the population. Finally, the genetic structure of established populations may be severely impacted by effective gene flow, if severe environmental changes alter the habitat of the locally adapted population.
To assess the effect of organic compounds on the aquatic environment, organisms are typically exposed to toxicant solutions and the adverse effects observed are linked to the concentration in the surrounding media. As compounds generally need to be taken up into the organism and distributed to the respective target sites for the induction of effects, the internal exposure is postulated to best represent the observed effects.
The aim of this work is to contribute to an improved effect assessment of organic compounds by describing experimental and modelling methods to obtain information on the internal exposure of contaminants in organisms.
Chapter 2 details a protocol for the determination of bioconcentration parameter for uptake (k1) and elimination (k2) of organic compounds in zebrafish (Danio rerio) eggs. This enables the simulation of the internal exposure in zebrafish eggs from an ambient exposure concentration over time. The accumulated contaminant amount in zebrafish eggs was also determined, using a biomimetic extraction method. Different bioconc-entration estimation models for the determination of internal steady-state concentrat-ion of pharmaceutical compounds in fish to an environmental exposure are presented in Chapter 3. Bioconcentration factors were estimated from the compounds octanol: water partition coefficient (KOW) to determine the internal exposure to an ambient concentration.
To assess the integral bioavailable fraction from the water and sediment phase of environmental contaminants for rooted aquatic plants, the internal exposure in river-living Myriophyllum aquaticum plants were determined over time, presented in Chapter 4. The plants were collected at different time points, with the accumulated organic contaminants determined using a liquid extraction method.
In Chapter 5 a protocol was established to enable the non-invasive observation of effects in M. aquaticum plants exposed to contaminated sediments over time. Since the toxicant effects are a result of all uptake and distribution processes to the target site and the toxico-dynamic process leading to an observed effect during static exposure, information on the internal exposure could thus be gained from the temporal effect expression.rn
New media are continually gaining importance in society. This process also has an increasing influence on developments in the field of education. Due to the use of computers as an integral part of schooling, new possibilities with regard to the organisation of learning processes arise. In this context, it is of great significance that appropriate computer applications for the respective learning group be prepared, so that justifiable use of computers in lessons can take place. Furthermore, efficient integration of computers requires changes in spatial organisation, in teaching methodology and in the role of the teacher. Such reflection and re-orientation are the essential basis for meaningful usage of new media in teaching and learning processes. An initial aim of this thesis is an empirical analysis of the situation regarding the usage of computers in geometry lessons in primary schools, based on a regional survey. The evaluation gives information as to how intensively the computer is used in the learning process and shows us which factors determine the use of computers in geometry lessons.
The results are an empirical foundation for the development of a computer-based learning environment called "Geolizi" (the second aim of my study). Within this learning environment, the pupils should work independently on the topics "mirror-imaged figures" and "the construction of rectangles and squares", with the help of the computer. During this process, hands-on media, traditional drawing instruments and interactive worksheets are available to the pupils. The computer (with its appropriate applications) takes over different functions in this learning process. Testing of this learning environment ("Geolizi") took place in several primary school classes, within the scope of formative and summative evaluation. With the help of questionnaires filled in by the pupils, the usability of the individual elements was tested. Based on a pre-post-investigation design, an attempt has been made to discover possible changes in the attitude of teachers regarding the usage of computers in the teaching of elementary geometry.
The results of this test phase, together with the evaluation of the questionnaires, lead to the founded presumption that usage of the multimedia-based learning environment " Geolizi " could result in greater use of computers in geometry lessons. All in all, the developed learning environment demonstrates an interesting possibility of how to use computers in the teaching of geometry at primary schools, thus making an important contribution to an independent, individualised learning process.
Agricultural pesticides, especially insecticides, are an integral part of modern farming. However, these may often leave their target ecosystems and cause adverse effects in non- target, especially freshwater ecosystems, leading to their deterioration. In this thesis, the focus will be on Insect Growth Regulators (IGRs) that can in many ways cause disruption of the endocrine system of invertebrates. Freshwater invertebrates play important ecological, economic and medical roles, and disruption of their endocrine systems may be crucial, considering the important role hormones play in the developmental and reproductive processes in organisms. Although Endocrine Disruption Chemicals (EDCs) can affect moulting, behaviour, morphology, sexual maturity, time to first brood, egg development time, brood size (fecundity), and sex determination in invertebrates, there is currently no agreement upon how to characterize and assess endocrine disruption (ED). Current traditional ecotoxicity tests for Ecological Risk Assessment (ERA) show limitations on generating data at the population level that may be relevant for the assessment of EDCs, which effects may be sublethal, latent and persist for several generations of species (transgenerational).
It is therefore the primary objective of this thesis to use a test method to investigate adverse effects of EDCs on endpoints concerning development and reproduction in freshwater invertebrates. The full life-cycle test over two generations that includes all sensitive life stages of C. riparius (a sexual reproductive organism) allows an assessment of its reproduction and should be suitable for the investigation of long-term toxicity of EDCs in freshwater invertebrates. C. riparius is appropriate for this purpose because of its short life cycle that enables the assessment of functional endpoints of the organism over several generations. Moreover, the chironomid life cycle consists of a complete metamorphosis controlled by a well-known endocrine mechanism and the endocrine system of insects has been most investigated in great detail among invertebrates. Hence, the full life-cycle test with C. riparius provides an approach to assess functional endpoints (e.g. reproduction, sex ratio) that are population-relevant as a useful amendment to the ERA of EDCs. In the laboratory, C. riparius was exposed to environmentally-relevant concentrations of the selected IGRs in either spiked water or spiked sediment scenario over two subsequent generations.
The results reported in this thesis revealed significant effects of the IGRs on the development and the reproduction of C. riparius with the second (F1) generation showing greater sensitivity. These findings indicated for the first time the suitability of multigenerational testing for various groups of EDCs and strongly suggested considering the full life-cycle of C. riparius as an appropriate test method for a better assessment of EDCs in the freshwater environment. In conclusion, this thesis helps to detect additional information that can be extrapolated at population level and, thus, might contribute to better protection of freshwater ecosystems against the risks of Endocrine Disrupting Chemicals (EDCs.) It may furthermore contribute to changes in the ERA process that are necessary for a real implementation of the new European chemical legislation, REACH (Registration, Evaluation Authorization and Restriction of Chemicals). Finally, significant interactions between temperature, chemical exposure and generation were reported for the first time and, may help predict impacts that may occur in the future, in the field, under predicted climate change scenarios.
The conservation of groundwater ecosystems requires an assessment and evaluation scheme that shows the state of the ecosystem. Consequently, faunal and microbial criteria are required for groundwater monitoring, in addition to physico-chemical analyses. To proof the adequacy of the application of groundwater organisms for the biological assessment of groundwater quality, an extensive sampling collection of various groundwater systems was accomplished between 2002 and 2009 in Germany. Key aspects were the examination of the indicator potential of groundwater communities towards surface-groundwater interactions and anthropogenic impacts, as well as the analysis of stygofaunal distribution patterns, as a base and reference for a faunal assessment scheme of groundwater systems. The sampling design considered local, regional, and biogeographic conditions. To test the indicator potential of groundwater organisms on a local and regional scale, groundwater systems in Nordrhein-Westfalen (NRW) and Baden-Württemberg (BW) were examined. The faunal and microbial data from unconsolidated aquifers (Erftgebiet, NRW) show the sensitivity of groundwater organisms against land use effects, e.g. extensive agriculture. Data analyses revealed positive correlations of organic material (estimated amount of detritus, TOC) and nitrate with faunal abundance, species richness, diversity and the proportions of stygoxene species. Moreover, the bacterial abundance and diversity in the groundwater of the Erftgebiet was high compared to oligotrophic groundwater systems, indicating an effect of surface influence due to agricultural land use. The groundwater colonization in the Alb-Donau-Kreis (BW) was analyzed for regional effects (landscape, type of aquifer, hydrogeology) and local effects (comparing single wells). The results show that the fauna reflects the strength of the hydrological exchange on different spatial scales. Furthermore, the fauna reflects the interaction of regional and local conditions. Accordingly, the diversity and abundance of groundwater organisms was influenced by the high connectivity of the karst and unconsolidated alluvial aquifers, the type of land use, covering layers of soil, the age of groundwater, and the sampling depths. In general, faunal and microbial data of the Alb-Donau-Kreis are characteristic for oligotrophic, oligoalimonic groundwaters. The large scale analyses of stygofaunal distribution patterns revealed significant biogeographical differences of the communities. These community patterns of the groundwater fauna do not coincide with existing classification schemes defined for surface landscapes or freshwater systems. The largest differences between faunal surface and subsurface distribution patterns were found between the groundwater of northern and southern Germany and the foothills of the central mountain ranges - all of them regions shaped by the last ice ages.
In accordance with the faunal data assessed in groundwater, four different stygoregions were defined that are populated by distinct faunal assemblages. These are 1) the "Northern lowlands", 2) the "Central mountain ranges", 3) the "South-western mountain ranges", and 4) the "Southern mountain ranges and northern alps". The study corroborates that stygofaunal and microbial communities are an adequate tool for the qualitative assessment and monitoring of groundwater ecosystems. The best indicators to detect anthropogenic impacts on groundwater ecosystems are the faunal diversity, abundance, the proportions of stygobitic (obligate groundwater species) and stygoxene species (species not obligate for groundwater), and the bacterial abundance. The development of an ecologically based groundwater assessment and management, is crucial for the conservation of our groundwater ecosystems and thus, healthy drinking water. The defintion of "stygoregions" is an important base for the development of an assessment and reference scheme for groundwater ecosystems. The assessment of the ecological state of groundwater systems must be conducted on local scale, because the strength of the local hydrological influence determines the amount of food and oxygen as well as stygoxene animals within the aquifer, and thus shapes the local groundwater communities. Nevertheless, information of the biogeographic and regional conditions is needed as a reference for the type of species and abundances that potentially can occur in certain groundwater systems.
Worldwide one third to one half of the freshwater crayfish species are threatened with population decline or extinction. Besides habitat deterioration, pollution, and other man-made environmental changes, invasive species and pathogens are major threats to the survival of European crayfish species. Freshwater crayfish are the largest freshwater invertebrates and strongly influence the structure of food webs. The disappearance of crayfish from a water body may change the food web and could have dramatic consequences for an ecosystem.rnOne goal in modern species conservation strategies is the conservation of genetic diversity, since genetic diversity is an advantage for the long-term survival of a species. The main aim of my thesis was to reveal the genetic structure and to identify genetic hotspots of the endangered noble crayfish (Astacus astacus) throughout Europe (part 1 of my thesis). Since the most significant threat to biodiversity of European crayfish species is the crayfish plague pathogen Aphanomyces astaci I studied new aspects in the distribution of A. astaci (part two of my thesis). The results serve as a basis for future conservation programs for freshwater crayfish. In the first part of my thesis I conducted a phylogeographic analysis of noble crayfish using mitochondrial DNA and nuclear microsatellite data. With these methods I aimed to identify its genetic hotspots and to reconstruct the recolonization history of central Europe by this species. I detected high genetic diversities in southestern Europe indicating that noble crayfish outlasted the cold climate phases during the Pleistocene in this region (Appendix 1). Because of the high genetic diversity found there, southeastern Europe is of particular importance for the conservation of noble crayfish. The mitochondrial DNA analysis points to a bifurcated colonization process from the eastern Black Sea basin to a) the North Sea and to b) the Baltic Sea basin (Appendix 2). A second independent refugium that was localized on the Western Balkans did not contribute to the colonization of central Europe. Furthermore, I found that the natural genetic structure is dissolved, probably due to the high human impact on the distribution of noble crayfish (e.g. artificial translocation). In the second part of this thesis using real-time PCR I identified calico crayfish (Orconectes immunis) as the fourth North American crayfish species to be carrier of the agent of the crayfish plague (Appendix 3). Furthermore I detected the crayfish plague pathogen in American spiny-cheek crayfish (Orconectes limosus) and native narrow-clawed crayfish (Astacus leptodactylus) in the lower Danube in Romania (Appendix 4). The distribution of infected spiny-cheek crayfish poses a threat to the native biodiversity in southeastern Europe and shows the high invasion potential of this crayfish species. Moreover, I found that even the native narrow-clawed crayfish in the Danube Delta, about 970 km downstream of the current invasion front of American crayfish, is a carrier of A. astaci (Appendix 5). This finding is of high importance, as the native species do not seem to suffer from the infection. In Appendix 6 I elucidate demonstrate that the absence of the crayfish plague agent is the most likely explanation for the coexistence of populations of European and American crayfish in central Europe. In my thesis I show that the common assumption that all North American crayfish are carrier of A. astaci and that all native crayfish species die when infected with A. astaci does not hold true. The studies presented in my thesis reveal new aspects that are crucial for native crayfish conservation: 1) The genetic diversity of noble crayfish is highest in southeastern Europe where noble crayfish outlasted the last glacial maximum in at least two different refugia. 2) Not all American crayfish populations are carrier of A. astaci and 3) not all Europen crayish populations die shortly after being infected with the crayfish plague pathogen.rnTo conserve native crayfish species and their (genetic) diversity in the long term, further introductions of American crayfish into European waters must be avoided. However, the introduction will only decrease if the commercial trade with non-indigenous crayfish species is prohibited.
This habilitation thesis deals with the effects of toxicants on freshwater ecosystems and considers different toxicant classes (pesticides, organic toxicants, salinity) and biotic endpoints (taxonomic community structure, trait community structure, ecosystem functions).
The thesis comprises 12 peer-reviewed international publications on these topics. All of the related studies rely on mesocosm or field investigations, or the analysis of field biomonitoring or chemical monitoring data. Publications I and II are devoted to passive sampling of a neonicotinoid insecticide and polycyclic aromatic hydrocarbons (PAHs), respectively. They show that biofouling and a diffusion-limiting membrane can reduce the sampling rate of the pulsed insecticide exposure and that receiving phases of different thicknesses can be used to assess the kinetic regime during field deployment of passive samplers. Publications III to VI mainly focus on trait-based approaches to reveal toxicant effects on invertebrates in streams. An overview on the framework and several applications of a trait-based approach to detect effects of pesticides (SPEARpesticides index) are given in publication III. Publication IV describes the development of a trait database for South-East Australian stream invertebrates and its successful application in the adaptation of SPEARpesticides as well as the development of a salinity index. Moreover, a conceptual model for the future development of trait-based biomonitoring indices is proposed. Publication V reports a mesocom study on the effects of a neonicotinoid insecticide on field-realistic invertebrate communities. The insecticide had long-term effects on the invertebrate communities, which were only detected when grouping the taxa according to their life-history traits. A comprehensive field study employing different pesticide sampling methods including passive sampling and biomonitoring of the invertebrate and microbial communities is presented in publication VI. The study did not find pesticide-induced changes in the microbial communities, but detected adverse effects of current-use pesticides on the invertebrate communities using the trait-based SPEARpesticides index. This index is also applied in a meta-analysis on thresholds for the effects of pesticides on invertebrate communities in publication VII. It is shown that there is a similar dose-response relationship between SPEARpesticides and pesticide toxicity over different biogeographical regions and continents. In addition, the thresholds for effects of pesticides are lower than derived from most mesocosm studies and than considered in regulatory pesticide risk assessment. The publications VIII to X use statistical data analysis approaches to examine effects of toxicants in freshwater ecosystems. Using governmental monitoring data on 331 organic toxicants monitored monthly in 4 rivers over 11 years, publication VIII finds that organic toxicants frequently occurred in concentrations envisaging acute toxic effects on invertebrates and algae even in large rivers. Insecticides and herbicides were the chemical groups mainly contributing to the ecotoxicological risk. Publication IX introduces a novel statistical method based on a similarity index to estimate thresholds for the effects of toxicants or other stressors on ecological communities. The application of the method for deriving thresholds for salinity, heavy metals and pesticides in streams is presented in three case studies. Publication X tackles the question of interactive effects between different toxicants using data from a field study on stream invertebrates in 24 sites of South-East Australia. Both salinity and pesticides exhibited statistically significant effects on the invertebrate communities, but no interaction between the stressors was found. Moreover, salinity acted on a higher taxonomical level than pesticides suggesting evolutionary adaptation of stream invertebrates compared to pesticide stress. Publications XI and XII concentrate on the effects of toxicants on biodiversity, ecosystem functions and ecosystem services, with publication XI summarising different studies related to the ecological risk assessment for these endpoints. A field study on the effects of pesticides and salinity on the ecosystem functions of allochthonous organic matter decomposition, gross primary production and ecosystem respiration is presented in publication XII. Both pesticides and salinity reduced the breakdown of allochthonous organic matter, whereas no effects on the other ecosystem functions were detected. A chapter following these publications synoptically discusses all studies of this habilitation thesis and draws general conclusions. It is stressed that in order to advance the understanding of effects of toxicants on freshwater ecosystems more ecological realism is needed in ecotoxicological approaches and that the spatiotemporal extent of toxicant effects needs more scrutiny.
Studies on the toxicity of chemical mixtures find that components at levels below no-observed-effect concentrations (NOECs) may cause toxicity resulting from the combined effects of mixed chemicals. However, chemical risk assessment frequently focuses on individual chemical substances, although most living organisms are substantially exposed to chemical mixtures rather than single substances. The concepts of additive toxicity, concentration addition (CA), and independent action (IA) models are often applied to predict the mixture toxicity of similarly and dissimilarly acting chemicals, respectively. However, living organisms and the environment may be exposed to both types of chemicals at the same time and location. In addition, experimental acquisition of toxicity data for every conceivable mixture is unfeasible since the number of chemical combinations is extremely large. Therefore, an integrated model to predict mixture toxicity on the basis of single mixture components having various modes of toxic action (MoAs) needs to be developed. The objectives of the present study were to analyze the challenges in predicting mixture toxicity in the environment, and to develop integrated models that overcome the limitations of the existing prediction models for estimating the toxicity of non-interactive mixtures through computational models. For these goals, four sub-topics were generated in this study. Firstly, applicable domains and limitations of existing integrated models were analyzed and grouped into three kinds of categories in this study. There are current approaches used to assess mixture toxicity; however, there is a need for a new research concept to overcome challenges associated with such approaches, which recent studies have addressed. These approaches are discussed with particular emphasis on those studies involved in computational approaches to predict the toxicity of chemical mixtures based on the toxicological data of individual chemicals. Secondly, through a case study and a computational simulation, it was found that the Key Critical Component (KCC) and Composite Reciprocal (CR) methods (as described in the European Union (EU) draft technical guidance notes for calculating the Predicted No Effect Concentration (PNEC) and Derived No Effect Level (DNEL) of mixtures) could derive significantly different results. As the third and fourth sub-topics of this study, the following two integrated addition models were developed and successfully applied to overcome the inherent limitations of the CA and IA models, which could be theoretically used for either similarly or dissimilarly acting chemicals: i) a Partial Least Squares-Based Integrated Addition Model (PLS-IAM), and, ii) a Quantitative Structure-Activity Relationship-Based Two-Stage Prediction (QSAR-TSP) model. In this study, it was shown that the PLS-IAM might be useful to estimate mixture toxicity when the toxicity data of similar mixtures having the same compositions were available. In the case of the QSAR-TSP model, it showed the potential to overcome the critical limitation of the conventional TSP model, which requires knowledge of the MoAs for all chemicals. Therefore, this study presented good potential for the advanced integrated models (e.g., PLS-IAM and QSAR-TSP), while considering various non-interactive constituents that have different MoAs in order to increase the reliance of conventional models and simplify the procedure for risk assessment of mixtures.
Assessment of bat activity in agricultural environments and the evaluation of the risk of pesticides
(2013)
Although agriculture dominates with around 50% area much of Europe- landscape, there is virtually no information on how bats use this farmed environment for foraging. Consequently, little is known about effective conservation measures to compensate potential negative effects of agrarian management practice on the food availability for bats in this habitat. Moreover, there are currently no specific regulatory requirements to include bats in European Union risk assessments for the registration of pesticides since no information about pesticide exposure on this mammal group is available. To evaluate the potential pesticide exposure of bats via ingestion of contaminated insects, information about bat presence and activity in agricultural habitats is required. In order to examine bat activity on a landscape scale it was necessary to establish a suitable survey method. Contrary to capture methods, telemetry, and direct observations, acoustic surveys of bat activity are a logistically feasible and cost-effective way of obtaining bat activity data. However, concerns regarding the methodological designs of many acoustic surveys are expressed in the scientific literature. The reasons are the failing of addressing temporal and spatial variation in bat activity patterns and the limitations of the suitability of the used acoustic detector systems. By comparing different methods and detector systems it was found that the set up of several stationary calibrated detector systems which automatically trigger the ultrasonic recording has the highest potential to produce reliable, unbiased and comparable data sets on the relative activity of bats.
By using the proposed survey method, bat diversity and activity was recorded in different crops and semi-natural habitats in southern Rhineland-Palatinate. Simultaneously, the availability of aerial prey insects was studied by using light and sticky traps. In more than 500 sampling nights about 110,000 call sequences were acoustically recorded and almost 120,000 nocturnal insects were sampled. A total of 14 bat species were recorded, among them the locally rare and critically endangered northern bat (Eptesicus nilssonii) and the barbastelle (Barbastella barbastellum), all of them also occurring over agricultural fields. The agricultural landscape of southern Palatinate is dominated by vineyards, a habitat that was shown to be of low quality for most bat species because of the demonstrated low availability of small aerial insects. By surveying bat activity and food availably in a pair-wise design on several rain water retention ponds and neighbouring vineyards it was demonstrated that aquatic insect emergence in artificial wetlands can provide an important resource subsidy for bats. The creation of artificial wetlands would be a possibility to create important foraging habitats for bats and mitigate negative effects of management practice in the agricultural landscape.
In several other agricultural crops, however, high abundances of suitable prey insects and high bat activity levels, comparable or even higher than in the nearby forests and meadows known to be used as foraging habitats were demonstrated. Especially high bat activity levels were recorded over several fruit orchards and vegetable fields where insects were also present. Both crops are known for high pesticide inputs, and, therefore, a pesticide exposure through ingestion of contaminated insects can not be excluded. To follow the current risk assessment approach for birds and mammals pesticide residues were measured on bat-specific food items in an apple orchard following insecticide applications and bat activity was recorded in parallel. The highest residue values were measured on foliage-dwelling arthropods which may results in a reproductive risk for all bat species that, even to a small extent, include this prey group in their diet. The presence of bats in agricultural landscapes that form a majority of the land area in Europe but also on a global scale leads to exposure of bats by contaminated food and depletion of their food resources by pesticide use. So far conservation efforts for bats focussed on securing hibernation sites and the creation of artificial roost sites since especially the latter were thought to be limiting population growth. However the potential pesticide effects might be also crucial for the population persistence in agricultural landscapes of bats and need to be addressed adequately, especially in risk assessment procedures for the regulation of pesticides.
Chemical plant protection is an essential element in integrated pest management and hence, in current crop production. The use of Plant Protection Products (PPPs) potentially involves ecological risk. This risk has to be characterised, assessed and managed.
For the coming years, an increasing need for agricultural products is expected. At the same time, preserving our natural resources and biodiversity per se is of equally fundamental importance. The relationship of our economic success and cultural progress to protecting the environment has been made plain in the Ecosystem Service concept. These distinct 'services' provide the foundation for defining ecological protection goals (Specific Protection Goals, SPGs) which can serve in the development of methods for ecological risk characterisation, assessment and management.
Ecological risk management (RM) of PPPs is a comprehensive process that includes different aspects and levels. RM is an implicit part of tiered risk assessment (RA) schemes and scenarios, yet RM also explicitly occurs as risk mitigation measures. At higher decision levels, RM takes further risks, besides ecological risk, into account (e.g., economic). Therefore, ecological risk characterisation can include RM (mitigation measures) and can be part of higher level RM decision-making in a broader Ecosystem Service context.
The aim of this thesis is to contribute to improved quantification of ecological risk as a basis for RA and RM. The initial general objective had been entitled as "… to estimate the spatial and temporal extent of exposure and effects…" and was found to be closely related to forthcoming SPGs with their defined 'Risk Dimension'.
An initial exploration of the regulatory framework of ecological RA and RM of PPPs and their use, carried out in the present thesis, emphasised the value of risk characterisation at landscape-scale. The landscape-scale provides the necessary and sufficient context, including abiotic and biotic processes, their interaction at different scales, as well as human activities. In particular, spatially (and temporally) explicit landscape-scale risk characterisation and RA can provide a direct basis for PPP-specific or generic RM. From the general need for tiered landscape-scale context in risk characterisation, specific requirements relevant to a landscape-scale model were developed in the present thesis, guided by the key objective of improved ecological risk quantification. In principle, for an adverse effect (Impact) to happen requires a sensitive species and life stage to co-occur with a significant exposure extent in space and time. Therefore, the quantification of the Probability of an Impact occurring is the basic requirement of the model. In a landscape-scale context, this means assessing the spatiotemporal distribution of species sensitivity and their potential exposure to the chemical.
The core functionality of the model should reflect the main problem structures in ecological risk characterisation, RA and RM, with particular relationship to SPGs, while being adaptable to specific RA problems. This resulted in the development of a modelling framework (Xplicit-Framework), realised in the present thesis. The Xplicit-Framework provides the core functionality for spatiotemporally explicit and probabilistic risk characterisation, together with interfaces to external models and services which are linked to the framework using specific adaptors (Associated-Models, e.g., exposure, eFate and effect models, or geodata services). From the Xplicit-Framework, and using Associated-Models, specific models are derived, adapted to RA problems (Xplicit-Models).
Xplicit-Models are capable of propagating variability (and uncertainty) of real-world agricultural and environmental conditions to exposure and effects using Monte Carlo methods and, hence, to introduce landscape-scale context to risk characterisation. Scale-dependencies play a key role in landscape-scale processes and were taken into account, e.g., in defining and sampling Probability Density Functions (PDFs). Likewise, evaluation of model outcome for risk characterisation is done at ecologically meaningful scales.
Xplicit-Models can be designed to explicitly address risk dimensions of SPGs. Their definition depends on the RA problem and tier. Thus, the Xplicit approach allows for stepwise introduction of landscape-scale context (factors and processes), e.g., starting at the definitions of current standard RA (lower-tier) levels by centring on a specific PPP use, while introducing real-world landscape factors driving risk. With its generic and modular design, the Xplicit-Framework can also be employed by taking an ecological entity-centric perspective. As the predictive power of landscape-scale risk characterisation increases, it is possible that Xplicit-Models become part of an explicit Ecosystem Services-oriented RM (e.g., cost/benefit level).
Structure of soil organic matter (SOM) is a hot topic of discussion among scientific community for several decades. The mostly discussed models, among many, are polymer model and supramolecular model. While the former considers SOM as macromolecules consisting of amorphous and crystalline domains, the latter explains SOM as a physicochemical entity dominated by weak hydrophobic and H-bond interactions in the secondary level, which holds individual molecules of primary structure together. The weak forces in secondary level impart characteristic mobility of SOM. Very important consequence of this multidimensional formulation is that physicochemical structure plays a crucial role in most biogeochemical functions of SOM, apart from the chemical composition. Recently introduced concept of cation and water molecule mediated bridges between OM molecular segments (CaB and WaMB, respectively) evolved from physicochemical understanding of SOM structure. Even though several indirect evidences were produced for CaB and WaMB during last years, no clear-cut understanding of these processes has been achieved yet. Experimental difficulty due to overlapping effects of equally important CaB-governing parameters such a pH and competing cations raises huge challenge in investigating CaB-related influences. This thesis, therefore, aims to validate an experimental set-up for inducing CaB within OM structures and assessing it from various chemical and physicochemical aspects.
The method involved removal of omnipresent cations and adjustment of pH before cation addition. This helped to separate pH effects and cation effects. Based on results obtained on two different types of organic matter, it can be deduced that multivalent cations can cross-link SOM, given that functional group density of the SOM material is enough for the functional groups to be arranged in sufficient spatial proximity to each other. Physicochemical structural reorganisation during aging causes formation of more and/or stronger CaB and WaMB. As for inducing CaB directly after cation treatment, cationic size and valency were found determinant also for aging effect. A strongly cross-linked system in the beginning is less vulnerable to structural changes and undergoes aging with lower intensity, than an initially weakly cross-linked system. Responsible for the structural changes is, the inherent mobility of SOM within its physicochemical assemblage. Thus the information on structural requirement of CaB and its consequences on OM matrix rigidity will help to obtain insight into the physicochemical SOM structure. Additionally, organic matter quality (assessed by thermal analysis) and pore structure of SOM formed in a set of artificial soils showed that mineral materials are important for the chemical nature of SOM molecules, but not for the physical structure of organo-mineral associations, at least after several months of SOM development.
Furthermore, nanothermal analysis using atomic force microscopy (AFM-nTA) was implemented in soils for the first time to reveal nanoscale thermal properties and their spatial distribution in nano- and micrometer scales. This helped to identify physicochemical processes, such as disruption of WaMB, in low-organic soils, in which bulk methods fail due to their low sensitivity. Further, various types of materials constituting in soils were distinguished with high resolution by advanced application of the method, in combination with other AFM parameters. Attempts were done to identify various materials, with the usage of defined test materials. Above all, the method is potent to reveal microspatial heterogeneity on sample surfaces, which could help understanding process-relevant hotspots, for example.
This thesis thus contributes to the scientific understanding on physicochemical structural dynamics via cross-linking by cations and via nanoscale thermal properties. Direct investigation on CaB demonstrated here will potentially help making a big leap in knowledge about the interaction. The observed aging effects add well to the understanding of supramolecular consideration of SOM. By introducing nanothermal analysis to the field of soil science, it is made possible to face the problem of heterogeneity and spatial distribution of thermal characteristics. Another important achievement of AFM-nTA is that it can be used to detect physicochemical processes, which are of low intensity.
The polysaccharide hydration phenomenon is nowadays the subject of intense research. The interaction of native and modified polysaccharides and polysaccharides-based bioconjugates with water has an important influence on their functional behaviour. Notwithstanding that the hydration phenomenon has been studied for decades, there is still a lack of awareness about the influence of hydration water on the polysaccharide´s structure and consequences for industrial or medicinal applications. The hydration of polysaccharides is often described by the existence of water layers differing in their physical properties depending on the distance from the polysaccharide. Using the differential scanning calorimetry (DSC) such water layers were categorized according their properties upon cooling in hyaluronan (HYA, sodium salt of ß-1,4-linked units of ß-1,3-linked D-glucuronic acid and N-acetyl-D-glucosamine), a model polysaccharide in the present work. The amount of non-freezing water, i.e. water in close proximity of HYA chain which does not freeze et all, was determined around 0.74gH2O/gHYA for HYA with molecular weight from 100 to 740kDa and 0.84gH2O/gHYA for molecular weight of 1390kDa. The amount of freezing-bound water, the water pool which is affected by presence of HYA but freezes, was determined in the range from 0.74 to 2gH2O/gHYA. Above this value only non-freezing and bulk water are present since melting enthalpy measured above this concentration reached the same value as for pure water. Since this approach suffers from several experimental problems, a new approach, based on the evaporation enthalpy determination, was suggested. The analysis of the evaporation enthalpies revealed an additional process associated with apparent energy release taking part below the water content of 0.34gH2O/gHYA. Existence of this phenomenon was observed also for protonated form of HYA. The existence of energy compensating process was confirmed with the Kissinger-Akahira-Sunose method which allowed determination of actual water evaporation/desorption enthalpies in all stages of the evaporation process. In fact, the apparent evaporation enthalpy value increased until water content of 0.34gH2O/gHYA, and then dropped down to lower values which were, still higher than the value of the pure water evaporation enthalpy. By the use of time domain nuclear magnetic resonance (TD-NMR) technique it was revealed that this phenomenon is the plasticisation of HYA.
Further, it was revealed that the non-freezing water determined by the use of DSC consists of two water fractions, i.e. 15% of water structurally integrated, interacting directly with polar sites, and 85% of water structurally restricted, embedded in-between the HYA chains. The occurrence of plasticisation concentration close to equilibrium moisture content provided the possibility to influence the HYA physical structure during the drying. In this way three samples of native HYA, dried under various conditions were prepared and their physical properties were analyzed. The samples differed in kinetics of rehydration, plasticisation concentration, glass transitions, and morphology. The properties of water pool were studied in solutions of 10"25mg HYA/mL as well. The fast filed cycling (FFC) NMR relaxometry showed the existence of three water fractions which correlation times spanned from 10"6 to 10"10 seconds, progressively decreasing in dependency on its distance from HYA chain. The formation of a weak and transient intramolecular water bridge between HYA chains was observed. It was shown that, unlike the inorganic electrolytes, polyelectrolytes hydration is a dynamic process which reflects not only the technique used for the analysis, experimental conditions but also the conformation of the polysaccharide and its "thermal" and "hydration" history.
It was demonstrated that some native polysaccharide structures can be easily modified by manipulation of preparation conditions, giving fractions with specific physicochemical properties without necessity of any chemical modification.
Field margins are often the only remaining habitats of various wild plant species in agricultural landscapes. However, due to their proximity to agricultural fields, the vegetation of field margins can be affected by agrochemicals applied to the crop fields. The aim of this thesis was to investigate the individual and combined effects of herbicide, insecticide and fertilizer inputs on the plant community of a field margin. Therefore, a 3-year field experiment with a randomized block design including seven treatments (H: herbicide, I: insecticide, F: fertilizer, H+I, F+I, F+H and F+H+I) and one control was conducted on a low-production meadow. Each treatment was replicated 8 times in 8 m x 8 m plots with a distance of 2 m between each plot. The fertilizer rates (25 % of the field rate) and pesticide rates (30 % of the field rate) used for the plot applications were consistent with realistic average input rates (overspray + drift) in the first meter of a field margin directly adjacent to a wheat field.
The study revealed that fertilizer and herbicide misplacements in field margins are major factors that affect the natural plant communities of these habitats. In total, 20 of the 26 abundant species on the study site were significantly affected by the fertilizer and herbicide treatment. The fertilizer promoted plants with high nutrient uptake and decreased the frequencies of small species. The herbicide caused a nearly complete disappearance of three species directly after the first application, whereas sublethal effects (e.g., phytotoxic effects and reduced seed productions of up to 100 %) were observed for the other affected species. However, if field margins are exposed to repeated agrochemical applications over several years, then such sublethal effects (particularly reproduction effects) also reduce the population size of plant species significantly, as observed in this study.
Significant herbicide-fertilizer interaction effects were also detected and could not be extrapolated from individual effects. The fertilizer and herbicide effects became stronger over time, leading to shifts in plant community compositions after three years and to a 15 % lower species diversity than in the control. The insecticide significantly affected the frequencies of two plant species (1 positively and 1 negatively). The results of the experiment suggest that a continuous annual agrochemical application on the study site would cause further plant community shifts and would likely lead to the disappearance of certain affected plants. A clear trend of increasing grass dominance at the expense of flowering herbs was detected. This finding corresponds well with monitoring data from field margins near the study site.
Although herbicide risk assessment aims to protect non-target plants in off-field habitats from adverse effects, reproduction effects and combined effects are currently not considered. Furthermore, no regulations for fertilizer applications next to field margins exist and thus, fertilizer misplacements in field margins are likely to occur and to interact with herbicide effects.
Adaptations of the current risk assessment, a development of risk mitigation measures (e.g., in-field buffers) for the application of herbicides and fertilizers, and general management measures for field margins are needed to restore and conserve plant diversity in field margins in agricultural landscapes.
Mathematical Modelling of GIS Tailored GUI Design with the Application of Spatial Fuzzy Logic
(2014)
This PhD thesis is situated within the framework of the Research-Group Learning and Neurosciences (ReGLaN)-Health and Logistics project. The goal of this project is the optimisation of health service delivery in the rural areas of South Africa. Cooperation takes place between ReGLaN-Health and Logistics and the South African Council for Scientific and Industrial Research (CSIR) Meraka Institute, with Prof Dr Dr Marlien Herselman of Pretoria, South Africa, as the central contact person. This thesis deals with the mathematical modelling of Geographic Information System (GIS)-tailoredrnGraphical User Interface (GUI) design with the application of spatial fuzzy logic. This thesis considers the mathematical visualisation of risk and resource maps for epidemiological issues using GIS and adaptive GUI design for an Open Source (OS) application for digital devices. The intention ofrnthis thesis is to provide spatial decision support tailored to different user groups. In order for the GUI elements to be evaluated and initialised, empirical teaching-learning-research on dealing with geomedia and GUI elements was conducted.
Engineered nanoparticles (ENP) are widely used in different industrial fields and products. In the last years, the risk potential for the release of ENP in the environment has increased as never before. ENP are expected to pass the wastewater-river-topsoil-groundwater pathway. In the terrestrial and aquatic environment ENP can undergo aging and transformation processes which can influence fate, transport and toxicological effects to different living organisms.
The scope of this workshop is to gather researchers, scientists, experts and specialists from nanoparticle and colloid science, soil and environmental chemistry, ecotoxicology or neighbouring disciplines to discuss the latest results and findings in the field of aging, fate, transport and toxicological effects of nanoparticles in the environment.
The adoption of the EU Water Framework Directive (WFD) in 2000 marked the beginning of a new era of European water policy. However, more than a decade later, the majority of European rivers are still failing to meet one of the main objectives of the WFD: the good ecological status. Pesticides are a major stressor for stream ecosystems. This PhD thesis emphasises the need for WFD managers to consider all main agricultural pesticide sources and influencing landscape parameters when setting up River Basin Management Plans and Programmes of Measures. The findings and recommendations of this thesis can help to successfully tackle the risk of pesticide contamination to achieve the WFD objectives.
A total of 663 sites that were situated in the German Federal States of Saxony, Saxony-Anhalt, Thuringia and Hesse were studied (Chapter 3 and 4). In addition to an analysis of the macroinvertebrate data of the governmental WFD monitoring network, a detailed GIS analysis of the main agricultural pesticide sources (arable land and garden allotments as well as wastewater treatment plants (WWTPs)) and landscape elements (riparian buffer strips and forested upstream reaches) was conducted. Based on the results, a screening approach was developed that allows an initial rapid and cost-effective identification of those sites that are potentially affected by pesticide contamination. By using the trait-based bioindicator SPEARpesticides, the insecticidal long-term effects of the WWTP effluents on the structure of the macroinvertebrate community were identified up to at least 1.5 km downstream (in some cases even 3 km) of the WWTPs. The results of the German Saprobic Index revealed that the WWTPs can still be important sources of oxygen-depleting substances. Furthermore, the results indicate that forested upstream reaches and riparian buffer strips at least 5 m in width can be appropriate measures in mitigating the effects and exposure of pesticides.
There are concerns that the future expansion of energy crop cultivation will lead to an increased pesticide contamination of ecosystems in agricultural landscapes. Therefore, the potential of energy crops for pesticide contamination was examined based on an analysis of the development of energy crop cultivation in Germany and a literature search on perennial energy crops (Chapter 5). The results indicate that the future large-scale expansion of energy crop cultivation will not necessarily cause an increase or decrease in the amounts of pesticides that are released into the environment. The potential effects will depend on the future design of the agricultural systems. Instead of creating energy monocultures, annual energy crops should be integrated into the existing food production systems. Financial incentives and further education are needed to encourage the use of sustainable crop rotations, innovative cropping systems and perennial energy crops, which may contribute to crop diversity and generate lower pesticide demands than do intensive farming systems.
The transport of pesticides from agricultural land into surface waters via diffuse entry pathways such as runoff is a major threat to aquatic ecosystems and their communities. Although certain risk mitigation measures are currently stipulated during pesticide product authorisation, further approaches might be needed to manage hot spots of pesticide exposure. Such a management is, for example, required by the European Union- directive for the sustainable use pesticides (2009/128/EC).
The need for mitigation measures was investigated within the present thesis at stream sites draining an arable and a vineyard region in Germany by characterising pesticide exposure following edge-of-field runoff and (expected) effects on the aquatic macroinvertebrates. The results of these field studies showed, that streams in both regions were exposed to pesticide concentrations suggesting effects on the macroinvertebrate community. In the arable region the observed toxicity was mainly attributed to the insecticides lambda-cyhalothrin (in the water-phase samples) and alpha-cypermethrin (in the suspended particle samples), whereas in the vineyard region fungicides were most important. Furthermore stream water and suspended particles sampled in the vineyard region showed critical copper concentrations, which might cause ecotoxicological effects in the field. In addition to pesticide exposure, in the arable region also the effects on aquatic macroinvertebrates were assessed in the field. Generally, invertebrate fauna was dominated by pesticide-tolerant species, which suggested a high pesticide exposure at almost all sites. The elevated levels of suspended particle contamination in terms of maximum toxic units per sample (logTUMax > -2) reflect also this result. At two sites that received high aqueous-phase entries of the insecticide lambda-cyhalothrin (logTUMax > -0.6), the abundance and number of sensitive species (indicated by the SPEcies At Risk index) decreased during the pesticide application period. In contrast, at sites characterised by low water-phase toxicity (logTUMax < -3.5), no acute significant negative effects on macroinvertebrates were observed. In conclusion these data showed that in both regions the implementation of risk mitigation measures is needed to protect the aquatic communities.
To mitigate runoff-related pesticide entries, riparian buffer strips are often recommended. However, the mitigating influence with increasing buffer strip width could not be demonstrated for riparian buffers which were already present in the arable and vineyard region. This result was attributed in the vineyard region to the high number of paved field paths associated with artificial erosion rills, which concentrate and rapidly transport receiving edge-of-field runoff in stream direction. Consequently the pesticide reduction efficiency of buffer strips is considerably reduced. We assumed that a similar process occurred in the arable region, due to a high number of erosion rills, which complicate a laminar sheet flow of edge-of-field runoff through the riparian buffer strip. Additionally also the presence of ephemeral drainage ditches, which led surface runoff from the agricultural fields to the streams may have contributed to observed pesticide entries despite wide buffers.
Effective risk mitigation measures should address these identified most important input pathways in the study areas. As possible measures the implementation of grassed field paths and vegetated ditches or wetlands were suggested. In general also the improvement of currently present riparian buffer strips regarding their efficiency to reduce pesticide runoff entries should be taken into account. In conclusion the results of the field studies underline the importance that risk mitigation measures are identified specifically for the respective pollution situation in stream catchments. To facilitate this process, a user guide was developed within the present thesis for identifying appropriate mitigation measures at high-risk sites. Based on a survey of exposure relevant landscape parameter a set of risk mitigation measures is suggested that focus on the specific pollution situation. Currently the guide includes 12 landscape- and six application-related measures and presents an overview of these measures" efficiency to reduce pesticide entries via runoff and spray drift, their feasibility and expected acceptability to farmers. Based on this information the user can finally choose the mitigation measures for implementation. The present guide promotes the practical implementation of appropriate risk mitigation measures in pesticide-polluted streams, and thus the protection of aquatic stream communities against pesticide entries.
Larvae of Cx.pipiens coocurred with Cladocera, but the latter established delayed in time. Biotope structure influenced time of species occurrence with ponds at reed-covered wetlands favouring crustacean development, while ponds at grassland biotopes favoured colonization by mosquito larvae. The mechanisms driving the negative effect of crustaceans on mosquito larvae were investigated within an experiment under artificial conditions. Crustacean communities were found to reduce both oviposition and larval development of Cx.pipiens. Crustacean communities of high taxa diversity, including both predatory and competing crustaceans, were more effective compared with crustacean communities dominated by single taxa. Presence of crustacean communities characterised by high taxa diversity increased the sensitivity of Cx.pipiens larvae towards Bti and prolonged the time of recolonization. In a final step the combined approach, using Bti and crustaceans, was evaluated under field conditions. The joint application of Bti and crustaceans was found to reduce mosquito larval populations over the whole observation period, while single application of Bti caused only short-term reduction of mosquito larvae. Single application of crustaceans had no significant effect, because high abundances of prior established mosquito larvae impeded propagation of crustaceans. At combined treatment, mosquito larvae were reduced by Bti application and hence crustaceans were able to proliferate without disturbance by interspecific competition. In conclusion, natural competitors were found to have a strong negative impact on mosquito larval populations. However, a time span of about 2 weeks has to be bridged, before crustacean communities reached a level sufficient for mosquito control. Results of a combined approach, complementing the short-term effect of the biological insecticide Bti with the long-term effect of crustaceans, were promising. Using natural competitors within an integrated control strategy could be an important tool for an effective, environmentally friendly and sustainable mosquito management.
Biodiversity is not only threatened by habitat loss, climate change and pollution, but also by invasive species. The impact of introduced species is immense and causes substantial ecological and economical costs worldwide. With the start of domestications of the African wildcat (Felis lybica) in the Near East, the transport of house cats (Felis catus) around the world as a commensal and domesticate began. The general aim of my thesis was to investigate the impact of invasive feral cats on native species as well as underlying population genetic structures, diversity and phylogeography. This was studied in the context of the demographic history in Australia and Hawai'i. My studies confirmed that the main introductions of cats to Australia began in the 19th century via ships of European settlers, traders and workers. Similarly, I was able to confirm cat introductions to Hawai'i by European traders and explorers; which has to the present a devastating effect on Hawaiian endemic species. Likewise, cats are widespread across Australia, can be found on most islands and are recognized as one of the major threats to Australian native species. A selective feeding behaviour by invasive predators was found in one of my studies. This study additionally gives an indication for possible population recovery of small Western Australianrnvertebrate species after predator removal. Advancement and the combination of various management techniques allow, if adequately funded, a more efficient planning and implementation of eradication campaigns. Population genetic approaches are able to give insights into population genetic structure, diversity and kinship, thereby enabling management campaigns to be more cost effective and successful. No pattern of isolation by distance between populations of Hawai"i and Australia indicated that trade routes, such as the "Golden Round" of the maritime fur trade, facilitated a link between far off global cat populations. Multiple introductions to Australia and intermixing with domestic breed cats resulted in feral cat populations which showrnno signs of reduced genetic variability. My studies also revealed the advantages of bioproxies in combination with phylogeography, which enable the inference and reconstruction of introduction routes, history and origin of invasive species. Genetic signals of historically introduced genotypesrnare still discernible on islands with low number of introductions over time and thereby low intermixing with domestic fancy breeds. Feral cats' adaptability as an invader was reconfirmed and possible underlying genetic mechanisms enabling their success as a global invader ("global supercat") are discussed. Research into the feralisation process of cats will provide new information regarding the domestication of cats, the genetic basis of feralisation and allow additional insights into cats" adaptive potential.
Non-Consumptive Effects of Spiders and Ants: Does Fear Matter in Terrestrial Interaction Webs?
(2014)
Most animals suffer from predators. Besides killing prey, predators can affect prey physiology, morphology and behaviour. Spiders are among the most diverse and frequent predators in terrestrial ecosystems. Our behavioural arena experiments revealed that behavioural changes under spider predation risk are relatively scarce among arthropods. Wood crickets (Nemobius sylvestris), in particular, changed their behaviour in response to cues of various spider species. Thereby, more common and relatively larger spider species induced stronger antipredator behaviour in crickets.
Behavioural changes under predation risk are expected to enhance predator avoidance, but they come at a cost. Crickets previously confronted with cues of the nursery web spider (Pisaura mirabilis) were indeed more successful in avoiding predation. Surprisingly, crickets slightly increased food uptake and lost less weight under predation risk, indicating that crickets are able to compensate for short-term cost under predation risk. In a following plant choice experiment, crickets strongly avoided plants bearing spider cues, which in turn reduced the herbivory on the respective plants.
Similar to spiders, ants are ubiquitous predators and can have a strong impact on herbivores, but also on other predators. Juvenile spiders increased their propensity for long-distance dispersal if exposed to ant cues. Thus, spiders use this passive dispersal through the air (ballooning) to avoid ants and colonise new habitats.
In a field experiment, we compared arthropod colonisation between plants bearing cues of the nursery web spider and cue-free plants. We followed herbivory during the experimental period and sampled the arthropod community on the plants. In accordance with the plant choice experiment, herbivory was reduced on plants bearing spider cues. In addition, spider cues led to changes in the arthropod community: smaller spiders and black garden ants (Lasius niger) avoided plants bearing spider cues. In contrast, common red ants (Myrmica rubra) increased the recruitment of workers, possibly to protect their aphids.
Although behavioural changes were relatively rare on filter papers bearing spider cues, more natural experimental setups revealed strong and far-reaching effects of predation risk. We further suggest that risk effects influence the spatial distribution of herbivory, rather than reduce overall herbivory that is expected if predators kill herbivores. Consequently, the relative importance of predation and risk effects is crucial for the way predators affect lower trophic levels.
By the work presented in this thesis, the CH4 emissions of the River Saar were quantified in space and time continuously and all relevant processes leading to the observed pattern were identified. The direct comparison between reservoir zones and free-flowing intermediate reaches revealed, that the reservoir zones are CH4 emission hot spots and emitted over 90% of the total CH4. On average, the reservoir zones emitted over 80 times more CH4 per square meter than the intermediate reaches between dams (0.23 vs. 19.7 mol CH4 m-2 d-1). The high emission rates measured in the reservoir zones fall into the range of emissions observed in tropical reservoirs. The main reason for this is the accumulation of thick organic rich sediments and we showed that the net sedimentation rate is an excellent proxy for estimating ebullitive emissions. Within the hot spot zones, the ebullitive flux enhanced also the diffusive surface emissions as well as the degassing emissions at dams.
To resolve the high temporal variability, we developed an autonomous instrument for continuous measurements of the ebullition rate over long periods (> 4 weeks). With this instrument we could quantify the variability and identify the relevant trigger mechanisms. At the Saar, ship-lock induces surges and ship waves were responsible for over 85% of all large ebullition events. This dataset was also used to determine the error associated with short sampling periods and we found that with sampling periods of 24 hours as used in other studies, the ebullition rates were systematically underestimated by ~50%. Measuring the temporal variability enabled us to build up a conceptual framework for estimating the temporal pattern of ebullition in other aquatic systems. With respect to the contribution of freshwater systems to the global CH4 emissions, hot spot emission sites in impounded rivers have the potential to increase the current global estimate by up to 7%.
The increasing application of titanium dioxide nanoparticles (nTiO2) entails an increased risk regarding their release to surface water bodies, where they likely co-occur with other anthropogenic stressors, such as heavy metals. Their co-occurrence may lead to an adsorption of the metal ions onto the particles. These nanoparticles often sediment, due to their agglomeration, and thus pose a risk for pelagic or benthic species. The combined toxicity of nTiO2 and heavy metals is likely influenced by the properties of both stressors (since they may alter their interaction) and by environmental parameters (e.g., organic matter, pH, ionic strength) affecting their fate.
These issues were not yet systematically examined by the recent literature. Therefore, this thesis investigated the influence of nTiO2-products with differing crystalline phase composition on the toxicity of copper (as representative for heavy metals) in presence of different organic matters using the pelagic test organism Daphnia magna.
Moreover, the duration of the stressors` interaction (=aging) likely modulates the combined toxicity. Hence, the influence of nTiO2 on copper toxicity after aging as a function of environmental parameters (i.e., organic matter, pH, ionic strength) was additionally investigated.
Finally, the transferability of the major findings to benthic species was examined using Gammarus fossarum. The present thesis discovered a reduction of the copper toxicity facilitated by nTiO2 for all assessed scenarios, while its magnitude was determined by the surface area and structure of nTiO2, the quantity and quality of organic matter as well as the aging of both stressors. The general copper toxicity reduction by nTiO2 was also transferable to benthic species, despite their potentially increased exposure due to the sedimentation of nTiO2 with adsorbed copper. These observations suggest the application of nTiO2 as remediation agent, but potential side effects (e.g., chronic toxicity, reactive oxygen species formation) require further investigations. Moreover, questions regarding the transferability to other stressors (e.g., different heavy metals, organic chemicals) and the fate of stressors adsorbed to nTiO2 in aquatic ecosystems remain open.
The increasing, anthropogenic demand for chemicals has created large environmental problems with repercussions for the health of the environment, especially aquatic ecosystems. As a result, the awareness of the public and decision makers on the risks from chemical pollution has increased over the past half-century, prompting a large number of studies in the field of ecological toxicology (ecotoxicology). However, the majority of ecotoxicological studies are laboratory based, and the few studies extrapolating toxicological effects in the field are limited to local and regional levels. Chemical risk assessment on large spatial scales remains largely unexplored, and therefore, the potential large-scale effects of chemicals may be overlooked.
To answer ecotoxicological questions, multidisciplinary approaches that transcend classical chemical and toxicological concepts are required. For instance, the current models for toxicity predictions - which are mainly based on the prediction of toxicity for a single compound and species - can be expanded to simultaneously predict the toxicity for different species and compounds. This can be done by integrating chemical concepts such as the physicochemical properties of the compounds with evolutionary concepts such as the similarity of species. This thesis introduces new, multidisciplinary tools for chemical risk assessments, and presents for the first time a chemical risk assessment on the continental scale.
After a brief introduction of the main concepts and objectives of the studies, this thesis starts by presenting a new method for assessing the physiological sensitivity of macroinvertebrate species to heavy metals (Chapter 2). To compare the sensitivity of species to different heavy metals, toxicity data were standardized to account for the different laboratory conditions. These rankings were not significantly different for different heavy metals, allowing the aggregation of physiological sensitivity into a single ranking.
Furthermore, the toxicological data for macroinvertebrates were used as input data to develop and validate prediction models for heavy metal toxicity, which are currently lacking for a wide array of species (Chapter 3). Apart from the toxicity data, the phylogenetic information of species (evolutionary relationships among species) and the physicochemical parameters for heavy metals were used. The constructed models had a good explanatory power for the acute sensitivity of species to heavy metals with the majority of the explained variance attributed to phylogeny. Therefore, the integration of evolutionary concepts (relatedness and similarity of species) with the chemical parameters used in ecotoxicology improved prediction models for species lacking experimental toxicity data. The ultimate goal of the prediction models developed in this thesis is to provide accurate predictions of toxicity for a wide range of species and chemicals, which is a crucial prerequisite for conducting chemical risk assessment.
The latter was conducted for the first time on the continental scale (Chapter 4), by making use of a dataset of 4,000 sites distributed throughout 27 European countries and 91 respective river basins. Organic chemicals were likely to exert acute risks for one in seven sites analyzed, while chronic risk was prominent for almost half of the sites. The calculated risks are potentially underestimated by the limited number of chemicals that are routinely analyzed in monitoring programmes, and a series of other uncertainties related with the limit of quantification, the presence of mixtures, or the potential for sublethal effects not covered by direct toxicity.
Furthermore, chemical risk was related to agricultural and urban areas in the upstream catchments. The analysis of ecological data indicated chemical impacts on the ecological status of the river systems; however, it is difficult to discriminate the effects of chemical pollution from other stressors that river systems are exposed to. To test the hypothesis of multiple stressors, and investigate the relative importance of organic toxicants, a dataset for German streams is used in chapter 5. In that study, the risk from abiotic (habitat degradation, organic chemicals, and nutrients enrichment) and biotic stressors (invasive species) was investigated. The results indicated that more than one stressor influenced almost all sites. Stream size and ecoregions influenced the distribution of risks, e.g., the risks for habitat degradation, organic chemicals and invasive species increased with the stream size; whereas organic chemicals and nutrients were more likely to influence lowland streams. In order to successfully mitigate the effects of pollutants in river systems, co-occurrence of stressors has to be considered. Overall, to successfully apply integrated water management strategies, a framework involving multiple environmental stressors on large spatial scales is necessary. Furthermore, to properly address the current research needs in ecotoxicology, a multidisciplinary approach is necessary which integrates fields such as, toxicology, ecology, chemistry and evolutionary biology.
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
A fundamental understanding of attachment of engineered nanoparticles to environmentalrnsurfaces is essential for the prediction of nanoparticle fate and transport in the environment.
The present work investigates the attachment of non-coated silver nanoparticles and citraterncoated silver nanoparticles to different model surfaces and environmental surfaces in thernpresence and absence of humic acid. Batch sorption experiments were used for this investigation.
The objective of this thesis was to investigate how silver nanoparticles interactrnwith surfaces having different chemical functional groups. The effect of presence of HA, on the particle-surface interactions was also investigated. In the absence of humic acid, nanoparticle-surface interactions or attachment was influencedrnby the chemical nature of the interacting surfaces. On the other hand, in the presence ofrnhumic acid, nanoparticle-surface attachment was influenced by the specific surface area of the sorbent surfaces. The sorption of non-coated silver nanoparticles and citrate coatedrnnanoparticles to all the surfaces was nonlinear and best described by Langmuir isotherm, indicating monolayer sorption of nanoparticles on to the surfaces. This can be explained as due to the blocking effect generated by the particle-particle repulsion. In the presence of humic acid, sorption of nanoparticles to the surfaces was linear. When the humic acid was present in the interacting medium, both the nanoparticles and surfaces were getting coated with humic acid and this masks the chemical functionalities of the surfaces. This leads to the change in particle-surface interactions, in the presence of humic acid. For the silver nanoparticle sorption from an unstable suspension, the sorption isotherms did not follow any classical sorption models, suggesting interplay between aggregation and sorption. Citrate coated silver nanoparticles and humic acid coated silver nanoparticles showed arndepression in sorption compared to the sorption of non-coated silver nanoparticles. In therncase of citrate coated silver nanoparticles the decrease in sorption can be explained by thernmore negative zeta potential of citrate coated nanoparticles compared to non-coated ones. For humic acid coated nanoparticles the sorption depression can be due to the steric hindrance caused by the free humic acid molecules which may coat the sorbent surface or due to the competition for sorption sites between the nanoparticle and free humic acid molecules present in the suspension. Thus nanoparticle surface chemistry is an important factor that determines the attachment of nanoparticles towards surfaces and it makes the characterization of nanoparticle surface an essential step in the study of their fate in the environment.
Another aim of this study was to introduce the potential of chemical force microscopy for nanoparticle surface characterization. With the use of this technique, it was possible to distinguish between bare silver nanoparticles, citrate coated silver nanoparticles, and humic acid coated silver nanoparticles. This was possible by measuring the adhesion forces between the nanoparticles and five different AFM probes having different chemical functionalization.
The intention of this thesis was to characterise the effect of naturally occurring multivalent cations like Calcium and Aluminium on the structure of Soil Organic Matter (SOM) as well as on the sorption behaviour of SOM for heavy metals such as lead.
The first part of this thesis describes the results of experiments in which the Al and Ca cation content was changed for various samples originated from soils and peats of different regions in Germany. The second part focusses on SOM-metal cation precipitates to study rigidity in dependence of the cation content. In the third part the effects of various cation contents in SOM on the binding strength of Pb cations were characterised by using a cation exchange resin as desorption method.
It was found for soil and peat samples as well as precipitates that matrix rigidity was affected by both type and content of cation. The influence of Ca on rigidity was less pronounced than the influence of Al and of Pb used in the precipitation experiments. For each sample one cation content was identified where matrix rigidity was most pronounced. This specific cation content is below the cation saturation as expected by cation exchange capacity. These findings resulted in a model describing the relation between cation type, content and the degree of networking in SOM. For all treated soil and precipitate samples a step transition like glass transition was observed, determined by the step transition temperature T*. It is known from literature that this type of step transition is due to bridges between water molecules and organic functional groups in SOM. In contrast to the glass transition temperature this thermal event is slowly reversing after days or weeks depending on the re-conformation of the water molecules. Therefore, changes of T* with different cation compositions in the samples are explained by the formation of water-molecule-cation bridges between SOM-functional groups. No influence on desorption kinetics of lead for different cation compositions in soil samples was observed. Therefore it can be assumed that the observed changes of matrix rigidity are highly reversible by changing the water status, pH or putting agitation energy by shaking in there.
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.
Modern agriculture is a dominant land use in Europe, although it has been associated with negative effects on biodiversity in agricultural landscapes. One species-rich insect group in agro-ecosystems is the Lepidoptera (moths and butterflies); however, the populations of a number of Lepidoptera species are currently declining. The aims of this thesis were to assess the amount and structure of field margins in agricultural landscapes, study the effects of realistic field margin input rates of agrochemicals (fertilizer and pesticides) on Lepidoptera, and provide information on moth pollination services.
In general, field margins are common semi-natural habitat elements in agro-ecosystems; however, data on the structure, size, and width of field margins is limited. An assessment in two German agricultural landscapes (4,000 ha each) demonstrated that many of the evaluated field margins were less than 3 m wide (Rhineland‐Palatinate: 85% of margin length; Brandenburg: 45% margin length). In Germany, risk mitigation measures (such as buffer zones) to reduce pesticide inputs to terrestrial non-crop habitats do not have to be established by farmers next to narrow field margins. Thus, narrow field margins receive inputs of agrochemicals, especially via overspray and spray drift. These field margins were used as a development habitat for caterpillars, but the mean abundance of caterpillars was 35 – 60% lower compared with that in meadows. Caterpillars were sensitive to realistic field margin input rates of insecticide (pyrethroid, lambda-cyhalothrin) in a field experiment as well as in laboratory experiments. Moreover, 40% fewer Hadena bicruris eggs were observed on Silene latifolia plants treated with this insecticide compared with control plants, and the flowers of these insecticide-treated plants were less likely to be pollinated by moths. In addition, realistic field margin input rates of herbicides can also affect Lepidoptera. Ranunculus acris L. plants treated with sublethal rates of a sulfonylurea herbicide were used as host plants for Mamestra brassicae L. caterpillars, which resulted in significantly lower caterpillar weights, increased time to pupation, and increased overall development time compared with caterpillars feeding on control plants. These results might have been caused by lower nutritional value of the herbicide-treated plants or increased concentrations of secondary metabolites involved in plant defense. Fertilizer applications slightly increased the caterpillar abundance in the field experiment. However, fertilizers reduce plant diversity in the long term and thus, most likely, also reduce caterpillar diversity.
Moths such as Noctuidae and Sphingidae have been observed to act as pollinators for numerous plant species, including a number of Orchidaceae and Caryophyllaceae. Although in temperate agro-ecosystems moths are less likely to act as the main pollinators for crops, they can pollinate non-crop plants in semi-natural habitats. Currently, the role of moths as pollinators appears to be underestimated, and long-term research focusing on ecosystems is necessary to address temporal fluctuations in their abundance and community composition.
Lepidoptera represent a diverse organism group in agricultural landscapes and fulfill essential ecosystem services, such as pollination. To better protect moths and butterflies, agrochemical inputs to (narrow) field margins habitats should be reduced, for example, via risk mitigation measures and agro-environmental schemes.
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.
Engineered nanoparticles are emerging pollutants. Their increasing use in commercial products suggests a similar increase of their concentrations in the environment. Studying the fate of engineered colloids in the environment is highly challenging due to the complexity of their possible interactions with the main actors present in aquatic systems. Solution chemistry is one of the most central aspects. In particular, the interactions with dissolved organic matter (DOM) and with natural colloids are still weakly understood.
The aim of this work was to further develop the dedicated analytical methods required for investigating the fate of engineered colloids in environmental media as influenced by DOM. Reviewing the literature on DOM interactions with inorganic colloids revealed that a systematic characterization of both colloids and DOM, although essential, lacks in most studies and that further investigations on the fractionation of DOM on the surface of engineered colloids is needed. Another knowledge gap concerns the effects of DOM on the dynamic structure of colloid agglomerates. For this question, analytical techniques dedicated to the characterization of agglomerates in environmental media at low concentrations are required. Such techniques should remain accurate at low concentrations, be specific, widely matrix independent and free of artefact due to sample preparation. Unfortunately, none of the currently available techniques (microscopy, light scattering based methods, separation techniques etc.) fulfills these requirements.
However, a compromise was found with hydrodynamic chromatography coupled to inductively coupled plasma mass spectrometry (HDC-ICP-MS). This method has the potential to size inorganic particles in complex media in concentration ranges below ppb and is element specific; however, its limitations were not systematically explored. In this work, the potential of this method has been further explored. The simple size separation mechanism ensures a high flexibility of the elution parameters and universal calibration can be accurately applied to particles of different compositions and surface chemistries. The most important limitations of the method are its low size resolution and the effect of the particle shape on the retention factor. The implementation of HDC coupled to single particle ICP-MS (HDC-SP-ICP-MS) offers new possibilities for the recognition of particle shape and hence the differentiation between primary particles and homoagglomerates. Therefore, this coupling technique is highly attractive for monitoring the effects of DOM on the stability of colloids in complex media. The versatility of HDC ICP MS is demonstrated by its successful applications to diverse samples. In particular, it has been used to investigate the stability of citrate stabilized silver colloids in reconstituted natural water in the presence of different types of natural organic matter. These particles were stable for at least one hour independently of the type of DOM used and the pH, in accordance with a coauthored publication addressing the stability of silver colloids in the River Rhine. Direct monitoring of DOM adsorption on colloids was not possible using UV and fluorescence detectors. Preliminary attempts to investigate the adsorption mechanism of humic acids on silver colloids using fluorescence spectroscopy suggest that fluorescent molecules are not adsorbed on silver particles. Several solutions for overcoming the encountered difficulties in the analysis of DOM interactions are proposed and the numerous perspectives offered by further developments and applications of HDC-(SP)-ICP-MS in environmental sciences are discussed in detail.
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.