Description: The statoliths of cephalopods are calcified bio mineral structures found in the gravity receptor system in the head of cuttlefish and squid. They grow throughout the lifetime of the animal and deposit microscopically visible daily increments similar to the annual rings in tree stems. Statolith growth and composition are linked to environmental factors. Thus, the statolith reveals the biological history of each individual cephalopod. If a relationship can be established between the composition of a growth layer of the statolith and the ambient water properties, then the statolith chemistry becomes a predictor of the surrounding water chemistry and/or temperature. Provided that statolith material is not altered or resorbed after deposition, the statolith becomes a permanent archive of environmental conditions and may provide information on habitat use, timing of exposure to a pollutant, and timing of migrations. Several micro analytical state-of-the-art techniques have been applied in this thesis to investigate the spatially resolved chemical composition of cephalopod statoliths. Recent applications of these methods include mainly geological samples, which do not contain organic compounds. Therefore a considerable part of this project focussed on adjusting and optimising the respective methods to the analyses of biogenic aragonite intergrown with organic compounds. In this thesis, the influence of different environmental factors on the chemical composition of cephalopod statoliths was investigated. On the basis of laboratory experiments under controlled conditions, it is now possible to qualify the influences of salinity, temperature and diet on the concentrations of several elements in the statoliths. Analytical results indicate that the incorporation of a number of elements is influenced by environmental factors. Barium and iodine appear to be the most suitable indicators for temperature. The incorporation of strontium into cephalopod statoliths, however seems to be influenced to a greater extent by diet than by the surrounding water. This is contradictory to results from corals and fish otoliths, where strontium is a well-established indicator for both temperature and salinity. The suitability of statolith micro-chemistry for field-studies has been proven as well. Statolith trace element compositional zoning reflects very well the life history and ontogenetic habitat-shifts of the boreoatlantic armhook squid Gonatus fabricii. Further, this thesis gives valuable insights into the microstructure of statoliths and the elemental nano-scale distribution in daily increments. For the first time, the application of NanoSIMS NS50 provided distribution patterns of calcium, strontium and sodium in cephalopod statoliths with a spatial resolution of 400nm. The results of this study provide an essential basis for future investigations in the field, probably leading into further understanding of yet unknown migration patterns and spawning grounds of various cephalopod species. Applying these future approaches could establish a consolidated biological knowledge on cephalopod species and stocks, and therefore may contribute to an effective and sustainable management of this both ecologically and economically valuable resource.

Description: After the closure of the Central American Seaway around 3.6 Ma, the benthic carbonate ecosystems developed differently in the Caribbean and on the Pacific side of the Isthmus of Panama. In this thesis, fossil and recent carbonate systems were studied and a comparison was made between fossil and present-day carbonate ecosystems from the same paleolatitude. This opens up the possibility to document the evolution of these sedimentation systems through time.

Description: This Doctorial Thesis investigates the fundamental problem of flow and deposition processes of unsteady, inertial flows of granular media and elucidates its implications for the behaviour of pyroclastic flows formed in explosive volcanic eruptions. A three-fold approach is followed including laboratory experiments, their theoretical analysis, and field work on the pristine pyroclastic flow deposits of the 1975 eruption of Mt. Ngauruhoe (New Zealand). The experiments are based upon the physical problem of the sudden collapse of vertical columns of granular media onto a base and their subsequent spreading behaviour. Through investigations of the pyroclastic flow deposits of the 1975 eruption of Mt. Ngauruhoe, first complete data sets of the internal structure and grain-size distribution and the morphology of the upper free surface of small-volume pyroclastic flow deposits as a function of travel distance, underlying slope and topographic confinement are presented. This detailed data set is interpreted using the experimental findings on the propagation of an internal interface, and a qualitative time- and space-dependent model on transport, segregation and deposition is developed for pyroclastic flows.

Description: Die Arbeit beschäftigt sich mit der Reaktion von Nahrungsquantität und -�qualität sowie Umweltfaktoren wie Temperatur und Salzgehalt auf die Reproduktion, das Überleben und die Verbreitung von calanoiden Copepoden. Diese Experimente wurden mit Organismen aus der Nord- und Ostsee sowie unter Labor- also auch unter Freilandbedingungen durchgeführt. Hierbei waren die calanoiden Copepoden Acartia clausii, A. tonsa, A. longiremis und Temora longicornis in Kombination mit Rhodomonas sp.(Chrypthophycea), Thalassiosira weissflogii (Bacillariophycea), dem heterotrophen Dinoflagellaten Oxyrrhis marina, sowie einem oligotrichen Ciliaten Strombidium conicum untersucht worden. Rhodomonas sp. verändert seine Nahrungsqualität unter Stickstoffmangel. Copepoden wie Acartia clausii und A. tonsa reagieren darauf mit einer Erhöhung der Eiproduktion. Wenn heterotrophen Protisten wie O. marina (Dinoflagellat) bzw. S. conicum (Ciliat) im Vergleich zu nur Rhodomonas sp. gefüttert wurden, dann war die Eiproduktion signifikant höher. Aber zwischen den beiden Versuchsansätzen mit den heterotrophen Protisten gab es keinen Unterschied. Durch Versuche mit Freilandtieren an verschiedenen Orten in der Ostsee lässt sich schlussfolgern, dass der Salzgehalt, die Temperatur und die Nahrungskonzentration einen großen Einfluss auf die Populationsdynamik dieser Art haben. Die Messung der Reproduktion von Freilandtieren auch in der Nordsee haben gezeigt, dass die Temperatur nicht der einzige Kontrollfaktor bei der Reproduktion von marinen Copepoden ist. Stattdessen lässt sich schlussfolgern, dass die Quantität der Nahrung und die Qualität der Nahrung ein dominierender Faktor im saisonalen Verlauf bei der Reproduktion von Temora longicornis eine Rolle spielen kann.

Description: Aim of this study was the investigation of the vertical dis-tribution of N2O and the factors influencing this distribu-tion. Dissolved and atmospheric N2O was measured in the North Atlantic Ocean and the Baltic Sea. These data, in com-bination with physical and chemical parameters, were used to determine sources and sinks of N2O. Possible production pathways were investigated using the relationship between N2O and relevant production parameters, and their relation to physical processes in the oceans. The hypothesis whether N2O concentrations increased by oceanic iron fertilization via enhanced substrate supply for microbial respiration, was tested during the European Iron Fertilization Experi-ment (EIFEX) in the subpolar South Atlantic. The vertical structure of bacterial communities in the subtropical North Atlantic was investigated, with the intention to find corre-lations between the community structure of bacteria and the distribution of N2O. In summary, this study presents a de-tailed picture of the distribution of N2O in the North At-lantic Ocean and the Baltic Sea and adds 80 profiles of the Atlantic and 26 profiles of the Baltic Sea to the database.

Description: In this thesis a potential conceptual design of a recirculation system not only with water processing but also with an enhanced nutrient recycling is presented. The underlying principle of the recirculation system was based on that of an artificial ecosystem and combined several trophic levels (fish, macroalgae, microalgae, worms) (MARE = Marine Artificial Recirculated Ecosystem). The main goal of this thesis was the development of a continuous photobioreactor system for cultivation of Nannochloropsis spec. based on dissolved nutrients of the recirculation system. Furthermore, the efficacy of ozone and foam fractionation was investigated regarding removal of bacteria and particles from effluents of a marine recirculation system.

Description: Dispersal and disturbance are major factors regulating the number of coexisting species. However, the relationship between species diversity and ecosystem processes has mainly been analysed for communities closed to dispersal, i.e. without looking at the mechanisms of coexistence. I experimentally investigated how initial local diversity, dispersal and disturbance rates affect local diversity and biomass production in metacommunities with marine benthic microalgae and in natural rock pool assemblages. Final local species richness and local biomass production were strongly influenced by dispersal frequency and by disturbance but not by initial local diversity (chapters 1 and 2). Both final local richness and final local biomass showed a hump-shaped pattern with increasing dispersal frequency and also with increasing suucessional time, with a maximum at intermediate dispersal frequencies and successional time. Consequently, final local biomass increased linearly with increasing final richness. In the rockpools system, diversity effects occurred in the absence of dispersal and depended on two effective grazers in the community (chapter 3). I conclude that the general relationship between richness and ecosystem functioning remains valid in open systems, but the maintenance of ecosystem processes significantly depends on the mechanism of species coexistence.