West German foreign policy towards the Arab states, 1967-1979: history of a disappointment

Over the past ten years, a large amount of research on Germany in the Middle East has been undertaken, with many studies focusing on the period of the World Wars or, later, German-Israeli relations. Less well studied, however, are relations between West Germany and the Arab states after 1945. The thesis addresses this gap by providing original research, based primarily on archival material, on West German foreign policy towards the Arab states during the Cold War. It shows how, during the 1970s, West Germany attempted to engage in a specific ‘Arab policy’, which ran along five dimensions: the dynamics of the Cold War, the Arab-Israeli conflict, the Palestinian question, oil politics, and common European foreign policy making. The findings shed new light on the role of the Arab states for German politics more generally, while also providing a number of new insights based on thus far unused archival material. The thesis shows how the Cold War was a key framework structuring the relevance of the Arab states for the Bonn government, linking with each other the geopolitics of Central Europe and the Middle East. Overall, the thesis adds to research on German foreign policy history, on the role of external powers in the Middle East as well as on diplomatic studies more generally.PhD funding generously provided by German Academic Exchange Service (DAAD) and German National Scholarship Foundation (Studienstiftung

Movement patterns and shelter choice of spiny-cheek crayfish (Orconectes limosus) in a large lake’s littoral zone

he study of individual movement patterns and habitat choice is a fundamental step to assess an invasive species’ range extension and to inform possible management options. The spiny-cheek crayfish is an invasive species currently spreading in Europe and also in Lake Constance. This is of concern because the greater Lake Constance area still holds refugial populations of native crayfish that might be endangered by the invader. In invasive crayfish, individual movement patterns and the availability of suitable shelters can predict an invasive population’s spread. In a radio telemetry and mark-recapture study and in semi-natural outdoor experiments, we investigated movement patterns and shelter choice of spiny-cheek crayfish. In the field, radio-tagged and marked crayfish moved distances up to 1200 m within 4 and 13 days, respectively and mostly prevailed within the littoral zone at less than 3 m depth. Tracked crayfish resided close to artificial structures such as boat harbours in the study area. In the outdoor experiments spiny-cheek crayfish used litter as daytime shelter but also chose natural stones and macrophytes. We provide the first large- lake telemetry data on crayfish movement and our results suggest that spiny-cheek crayfish will expand its range within the lake moving along the shoreline. Artificial structures such as boat harbours and litter might facilitate this spread by providing suitable shelters. Our results can help to inform the implementation of countermeasures against the spread of invasive crayfish populations

Integrating Economic and Ecological Benchmarking for a Sustainable Development of Hydropower

Hydropower reservoirs play an increasingly important role for the global electricity supply. Reservoirs are anthropogenically-dominated ecosystems because hydropower operations induce artificial water level fluctuations (WLF) that exceed natural fluctuations in frequency and amplitude. These WLF have detrimental ecological effects, which can be quantified as losses to ecosystem primary production due to lake bottoms that fall dry. To allow for a sustainable development of hydropower, these “ecological costs” of WLF need to be weighed against the “economic benefits” of hydropower that can balance and store intermittent renewable energy. We designed an economic hydropower operation model to derive WLF in large and small reservoirs for three different future energy market scenarios and quantified the according losses in ecosystem primary production in semi-natural outdoor experiments. Our results show that variations in market conditions affect WLF differently in small and large hydropower reservoirs and that increasing price volatility magnified WLF and reduced primary production. Our model allows an assessment of the trade-off between the objectives of preserving environmental resources and economic development, which lies at the core of emerging sustainability issues

Flow field-induced drag forces and swimming behavior of three benthic fish species

Modern ethohydraulics is the study of the behavioral responses of swimming fish to flow fields. However, the exact drag forces experienced by fish remain poorly studied; this information is required to obtain a better understanding of the behavioral responses of fish and their current resistance strategies. We measured near-ground frontal drag forces on preserved individuals of three benthic fish species, round goby ( Neogobius melanstomus ), gudgeon ( Gobio gobio ) and bullhead ( Cottus gobio ), in a flow channel. The forces were compared to acoustic Doppler velocity (ADV) measurements and fish tracking data based on video observations of live fish in the flow channel. Overall, we observed drag coefficients (C D ) of ∼10 −3 at Reynolds numbers ∼10 5 . The frontal drag forces acting on preserved fish with non-spread fins ranged from -1.96 mN*g -1 (force per fish wet weight, velocity 0.55 m*s -1 ) to 11.01 mN*g -1 (velocity 0.85 m*s -1 ). Spreading the fins strongly increased the drag forces for bullhead and round goby. In contrast, the drag forces were similar for gudgeon with spread fins and all fish with non-spread fins. Video tracking revealed no clear relationship between the position of the fish in the flow field and the forces experienced by the preserved fish at these positions. Collectively, these results suggest that i) the differences in frontal drag forces between species are small in homogenous flow, ii) individuals chose their position in the flow field based on factors other than the drag forces experienced, and iii) whether fins are spread or non-spread is an essential quality that modulates species-specific differences. The methodology and results of this study will enable integration of flow measurements, fish behavior and force measurements and inform ethohydraulics research. More advanced force measurements will lead to a detailed understanding of the current resistance strategies of benthic fish and improve the design of fish passes

Transport, Magnetic and Vibrational Properties of Chemically Exfoliated Few Layer Graphene

We study the vibrational, magnetic and transport properties of Few Layer Graphene (FLG) using Raman and electron spin resonance spectroscopy and microwave conductivity measurements. FLG samples were produced using wet chemical exfoliation with different post-processing, namely ultrasound treatment, shear mixing, and magnetic stirring. Raman spectroscopy shows a low intensity D mode which attests a high sample quality. The G mode is present at $1580$ cm$^{-1}$ as expected for graphene. The 2D mode consists of 2 components with varying intensities among the different samples. This is assigned to the presence of single and few layer graphene in the samples. ESR spectroscopy shows a main line in all types of materials with a width of about $1$ mT and and a $g$-factor in the range of $2.005-2.010$. Paramagnetic defect centers with a uniaxial $g$-factor anisotropy are identified, which shows that these are related to the local sp$^2$ bonds of the material. All kinds of investigated FLGs have a temperature dependent resistance which is compatible with a small gap semiconductor. The difference in resistance is related to the different grain size of the samples

Comparative swimming performance and behaviour of three benthic fish species: The invasive round goby (Neogobius melanostomus), the native bullhead (Cottus gobio), and the native gudgeon (Gobio gobio)

Efforts to restore river ecosystem connectivity focus predominantly on diadromous, economically important fish species, and less attention is given to nonmigratory, small‐bodied, benthic fish species. Data on benthic fish swimming performance and behaviour in comparison with ecologically similar native species are especially relevant for the study of one of the most successful invaders in the last decades: the Ponto‐Caspian gobiid species Neogobius melanostomus. To evaluate future measures against its further upstream dispersal, we conducted comparative swimming performance and behaviour experiments with round goby and two native species: the European bullhead (Cottus gobio) and the gudgeon (Gobio gobio). Experiments in a swim tunnel revealed a high variation in the swimming performance and behaviour within and among the three species. Gudgeon performed best in both U$_{crit}$ and U$_{sprint}$ experiments and displayed a rather continuous, subcarangiform swimming mode, whereas bullhead and round goby displayed a burst‐and‐hold swimming mode. Experiments in a vertical slot pass model, which contained a hydraulic barrier as a challenge to upstream movement, confirmed the high swimming performance of gudgeon. Gudgeon dispersed upstream even across the hydraulic barrier at the highest flow velocities. Round goby showed a higher capability to disperse upstream than bullhead, but failed to pass the hydraulic barrier. Our results on comparative swimming performance and behaviour can inform predictive distribution modelling and range expansion models, and also inform the design of selective barriers to prevent the round goby from dispersing farther upstream

Flow, force, behaviour: assessment of a prototype hydraulic barrier for invasive fish

Migration barriers being selective for invasive species could protect pristine upstream areas. We designed and tested a prototype protective barrier in a vertical slot fish pass. Based on the individuals’ swimming responses to the barrier flow field, we assumed this barrier would block the ascension of the invasive round goby, but allow comparable native species (gudgeon and bullhead) to ascend. The barrier was tested in three steps: flow description, quantification of forces experienced by preserved fish in the flow field, and tracking the swimming trajectories of ca. 43 live fish per trial and species. The flow and the forces were homogenous over the barrier, though gudgeon experienced significantly smaller forces than round goby or bullhead. The swimming trajectories were distinct enough to predict the fish species with a random forest machine learning approach (92.16% accuracy for gudgeon and 85.24% for round goby). The trajectories revealed round goby and gudgeon exhibited increased, but varied, swimming speeds and straighter paths at higher water discharge. These results suggest that passage of round goby was prevented at 130 L/s water discharge, whereas gudgeon and bullhead could pass the barrier. Our findings open a new avenue of research on hydraulic constructions for species conservation

Impact of hydraulic forces on the passage of round goby (Neogobius melanostomus), gudgeon (Gobio gobio) and bullhead (Cottus gobio) in a vertical slot fish pass

Every fish migrating upstream through vertical slot fish passes must swim through slots, where the resistance force of flowing water could affect the passage success. We measured the hydraulic force acting on the body of preserved benthic fish in a vertical slot at different water discharge rates (80 and 130 L/s) to compare the hydraulic burden individual fish species (round goby Neogobius melanostomus Pallas, 1814, gudgeon Gobio gobio L. and bullhead Cottus gobio L.) must overcome. The forces measured in three spatial axes were then compared to acoustic Doppler velocity measurements and the passage probability of 39–45 live fish per species. Passage probability reduction of 28.26% for round goby and 39.29% for bullhead was observed at the higher water discharge. Gudgeon showed increased numbers of passages and approaches when larger hydraulic forces were experienced at 130 L/s compared to the lower water discharge. Gudgeon experienced significantly lower hydraulic forces (mean 0.27 N ± 0.12 standard deviation) compared to round goby (mean 0.32 N ± 0.12 SD) and bullhead (0.35 N ± 0.14 SD). Potentially, the increased hydraulic forces at the higher water discharge contributed to the reduction in passages in round goby and bullhead. That gudgeon behaved differently from the other species illustrates how fish species deal differently with flowing water and the hydraulic forces experienced. Our approach provides a species-oriented assessment of the flow field in ecologically relevant fish passes. These findings represent an important step towards the development of purposeful fish pass designs, which is essential for ecosystem-oriented river connectivity

Flow field-induced drag forces and swimming behavior of three benthic fish species

Modern ethohydraulics is the study of the behavioral responses of swimming fish to flow fields. However, the exact drag forces experienced by fish remain poorly studied; this information is required to obtain a better understanding of the behavioral responses of fish and their current resistance strategies. We measured near-ground frontal drag forces on preserved individuals of three benthic fish species, round goby ( Neogobius melanstomus ), gudgeon ( Gobio gobio ) and bullhead ( Cottus gobio ), in a flow channel. The forces were compared to acoustic Doppler velocity (ADV) measurements and fish tracking data based on video observations of live fish in the flow channel. Overall, we observed drag coefficients (C D ) of ∼10 −3 at Reynolds numbers ∼10 5 . The frontal drag forces acting on preserved fish with non-spread fins ranged from -1.96 mN*g -1 (force per fish wet weight, velocity 0.55 m*s -1 ) to 11.01 mN*g -1 (velocity 0.85 m*s -1 ). Spreading the fins strongly increased the drag forces for bullhead and round goby. In contrast, the drag forces were similar for gudgeon with spread fins and all fish with non-spread fins. Video tracking revealed no clear relationship between the position of the fish in the flow field and the forces experienced by the preserved fish at these positions. Collectively, these results suggest that i) the differences in frontal drag forces between species are small in homogenous flow, ii) individuals chose their position in the flow field based on factors other than the drag forces experienced, and iii) whether fins are spread or non-spread is an essential quality that modulates species-specific differences. The methodology and results of this study will enable integration of flow measurements, fish behavior and force measurements and inform ethohydraulics research. More advanced force measurements will lead to a detailed understanding of the current resistance strategies of benthic fish and improve the design of fish passes