Description: Fouling communities are distributed worldwide, particularly in shallow and exposed marine systems. Due to their fast growth and their capacity to settle on artificial surfaces, these assemblages represent a suitable study system for ecologists and are therefore often used to investigate ecological models. Investigating broad scale ecological models has been of key interest since the time of the famous naturalist Charles Darwin. Two examples of well recognized macro-ecological patterns are i) the ‘latitudinal gradient of species richness’ and ii) the ‘relationship between local and regional diversity’. The first is the oldest paradigm about a large-scale ecological pattern and simply states that the tropical regions are richer in species than temperate and polar regions at higher latitudes. However, when exploring global diversity patterns, it is essential to comprehend not only the importance of differences in spatial scale for the observed patterns, but also how diversity at one scale may relate to diversity at a different scale. Indeed, several studies have shown that the number of species within small localities may increase either linearly or asymptotically with regional species richness (relationship between local and regional diversity). Exploring global diversity patterns still constitutes an important challenge for ecologists because it reflects the need to determine the current status of biodiversity. With the knowledge of today’s biodiversity, we can predict its future status and, as a consequence, be able to provide new answers to its probable response to phenomena such as climate change. In the present work, I investigate global diversity patterns in marine fouling communities, mainly by examining the previously mentioned macro-ecological patterns, i.e. the latitudinal gradient of species richness and the relationship between local and regional diversity. Previous studies investigating the local-regional diversity relationship have often assessed the number of species in a region by consulting available species lists. However, regional species pools based on such inventories may include species not susceptible to recruit into the community considered because they are restricted to different habitats and seasons. With the purpose of dealing with these difficulties, a few investigations have estimated regional richness based on local samples but confirmed a strong bias in relation to sampling effort. In order to optimize the quality of regional richness estimations, the current study develops a new statistical tool for estimating regional richness based on a limited number of replicates. Using three data-sets with a large number of replicates from different temperate shallow water habitats, I compare common richness estimators against the asymptote of the species accumulation curve, which was used as a reference for true regional richness. Subsequently and more importantly, the mis-estimation was quantified as a function of sampling effort. To complete this work, the relationship between local and regional diversity was expanded by integrating two categories of diversity (taxonomic and functional) and different successional stages at two different scales: European and global. At the European scale, the shape of the pattern was compared for different methods in assessing regional richness: species colonizing during a given period (transient regional richness) versus species colonizing during any phase of the experiment (total regional richness). At the global scale, I further examine whether the diversity of local communities is affected by parameters other than regional richness, such as number of functional groups or availability of resources. The results of this investigation support a clear influence of latitude on local species richness in marine fouling communities. In Chapter I, I show that tropical regions hold more marine fouling species when compared to areas at higher latitudes. In what concerns the regional richness assessment, I conclude that regional richness can be estimated based on a limited number of samples and that the quality of the estimation increases with sample effort. Moreover, the strength of the inevitable mis-estimation can be quantified (Chapter II). In addition, at the European scale (Chapter III), it was found that the shape of the relationship between local and regional diversity is sensitive to successional stage, the way regional richness is estimated and the dimension of diversity considered. The relevant regional richness, i.e. the regionally available colonizers, seems to vary in time and is larger when pooling all sampling events. As a consequence, the relationship between local and regional diversity is also influenced by the method in which regional richness is estimated. At a global scale (Chapter IV), the relationship between local and regional diversity in fouling assemblages is also affected by the succession process, if either taxonomic or functional diversity are considered. Local taxonomic diversity exhibits saturation at early stages of succession while saturation of local functional richness occurs later. In addition, functional groups were reported as the most influential predictor for local species richness.

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: The aim of this thesis was to examine metazoan parasite communities and viral infections of European eel, Anguilla anguilla, from fresh water, brackish and marine localities in northern Germany. The here collected data shall help to evaluate the suitability of the studied localities for potential restocking purposes regarding the presence of pathogens. In Chapter I a comparative examination of the metazoan parasite communities of the European eel was conducted including measures of parasite diversity characteristics. Special focus was given on the prevalence and intensity of infection with the invasive swim bladder nematode Anguillicoloides crassus and the gill monogenean Pseudodactylogyrus spp. In all, 29 parasite species/taxa were found in 170 eels from six different sample sites. Parasite communities of European eels clearly exhibit the habitat preferences of their hosts, salinity-dependent specificities, and a clustering into fresh-water, brackish, and marine groups. The highly pathogenic parasite species Anguillicoloides crassus and Pseudodactylogyrus spp. were found at all sampling sites in fresh water and brackish water, with high prevalence. Therefore, the common practice of catching glass eels in river estuaries for restocking solely in inland waters as management measure for stock recovery should be critically considered. To set a baseline for future trend analyses and biodiversity considerations an updated and comprehensive literature review on prevalence and distribution of parasites of the European eel in European waters was conducted (Chapter II). The resulting checklist provides evidence for 161 parasite species/taxa from 30 countries. Special consideration was given to the distribution of the swimbladder nematode Anguillicoloides crassus. A map and table of first reported records as well as a survey map indicating all published localities of A. crassus documented in the checklist are provided. In Chapter III the prevalence of virus infections in European eels from natural habitats with differing salinity regimes were evaluated. Out of the 140 examined eels, HVA was detected in two of the five investigated water bodies with an overall infection prevalence of 2%. Virus infection was only detected by direct PCR testing, whereas none of the three HVA PCR-positive eels showed any clinical sign of disease. However latent infections of HVA were found in the investigated water bodies and as proven for the first time, also in a marine habitat (Helgoland) of northern Germany. The only reliable method for the verification of viral genome in latent herpesvirus infections is by PCR examination. For the verification of even low virus copy numbers in asymptomatic carriers, a more sensitive detection method was developed (Chapter IV). This method was tested on eel samples from two freshwater localities in northern Germany, Lake Pönitz (n=16) and River Elbe (n=30). But even with this high sensitive nested-PCR, HVA positive eels were only detected in 2 eels from Lake Pönitz (Chapter IV). Hence, the rate of HVA infection seemed to be quite low among northern German eel stocks. But the source of infection is present in at least three of the seven studied localities (Chapter III & IV) and under favourable conditions for virus replication like high water temperature or stress a reactivation and further dispersal of HVA might be induced.

Description: The widespread decline of anadromous Atlantic salmon (Salmo salar L.) populations makes it imperative to research the underlying cause and to develop mitigation measures. One of the most vulnerable phases in the life-cycle of salmon is the fry stage in early spring. Survival rates of juveniles emerging from the gravel of riverbeds are related to the three-dimensional complexity of bottom morphology and hence the variety of microhabitats within the nursery area. However, anthropogenically increased sediment supply due to changes in agricultural land-use reduces complexity, especially the roughness of the streambed. This study used a series of controlled manipulative field experiments conducted in a purpose built raceway system, to provide quantitative data on the impact of sediment pollution on salmon production in freshwaters. The comparison of in-stream habitat with an increased sediment load and control (i.e. simulated natural) situations revealed that increased sedimentation drastically reduced the salmon fry carrying capacity of a stream. A modest increase in sand bed load (15%) in semi-natural streams reduced the fry density by 50% ten days after stocking with unfed fry. Emigration patterns of fry from sedimented habitat and control habitat were significantly different. Fry from both habitat types showed unusual active upstream migration which compensated for densities exceeding the carrying capacity. Riverine habitat was optimised on a reach scale to complement the raceway results and to provide a temporary mitigation measure. The in-stream habitat of a mill leat was manipulated to build the first Eco-Hatchery for salmon in the UK based, on results from the raceway and on an extensive literature review. The hatchery achieved high survival rates of salmon juveniles throughout their freshwater life stages. Furthermore, in-stream sediment traps were developed to offer effective protection for key fry nursery habitat from excess sand bed load. The data provided by the raceway system and the Eco-Hatchery inform riparian management plans. However, addressing sedimentation related issues in salmon rivers is a politically sensitive issue and will take time. Stocking with unfed fry is being used in the interim to temporarily enhance or restore populations. But stocking programmes based on conventional hatchery methodology as a response to declining stocks have frequently failed in both respects. A semi-natural incubator for salmon eggs, the Bamberger-box, was developed to address extremely low survival of newly stocked fry from conventional hatcheries. The new incubator mimics a natural salmon redd and aims in essence to produce wild fish in a hatchery environment. The results of five years field experiments using genetically different broodstock were encouraging. There was a significant increase in the average length and body mass of fry emerging from Bamberger-boxes and the mean eyed-egg-to-fry survival was 93% - greatly exceeding published data for egg-to-fry survival in the wild. Fry from Bamberger-boxes showed a significantly different and more natural rheotactic behaviour, and fewer fry had deformities when compared with fry incubated in conventional hatchery troughs. Seasonal and diurnal emergence patterns from Bamberger-boxes correlated with natural emergence patterns. A potentially crucial advantage of this new semi-natural incubation system was to ensure larvae survival during environmental extremes when all juveniles incubated in conventional hatchery troughs did not survive. Large-scale commercial incubators based on the same principles as the Bamberger-Box were developed and proved equally effective in producing ecologically viable fry. Low costs of production and operation render the new incubators an economically viable alternative to traditional incubation systems. Exploratory research on the influence of hyporheic invertebrates abundance on fry size at emergence was carried out as a next step in continuously improving semi-natural incubation technology.

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: This study explores life-history strategies of recent fishes based on a data set that is two orders of magnitude larger than those used in previous studies. Trophic level, size and productivity were taken as key traits and proxies for many other closely related traits. Size was strongly correlated with most life-history traits of fishes and also with morphological characters, behaviour, and preferred environmental conditions. Size was also a good predictor of placement on the r-K continuum. Productivity was derived from growth, age at maturity, maximum age, and fecundity data. It was positively correlated with metabolism and level of activity and was also an indicator for placement of species on the r-K continuum. It was strongly correlated with most life-history traits of fishes and also with morphological characters, behaviour, and preferred environmental conditions. It was negatively correlated with status of threat. The position of species in the food web was shown to restrict life-history options. The addition of trophic level as an orthogonal axis on the r-K continuum revealed unoccupied regions such as the combination of small size and high productivity with either herbivory or top-predatory, and the combination of very large size and very low productivity with herbivory. Discrete classes of size, trophic level and productivity were used to define 80 life history strategies. Only 50 of these strategies were used by recent species, with an exponential decline in species’ numbers from the most to the least used strategies. This decline is interpreted as an exponential increase in constraints associated with less-used strategies. Analysis of trade-off or constraint curves in life-history space revealed unoccupied areas as well as local maxima, i.e., areas occupied by more species than the surrounding space. Such a local optimum was occupied by very large top predators with very low productivity. Low-level predators of small to medium size and medium to high productivity were the three strategies used by altogether 60% of the species. Strategies used in extreme environments such as the deep and polar seas or high-altitude lakes were not ‘specialist strategies’ but rather among the 10 most-used strategies, suggesting that constraints imposed by extreme environments excluded strategies that had a high degree of inherent constraints. The number of strategies used by phylogenetic, environmental, morphological or behavioural groupings of fishes was highly predictable from the number of species in the respective groups. A preliminary chronology of life-history strategies showed that over 2/3 of recent strategies were invented only 200-150 million years ago during several radiations of the Actinopterygii, including small size, very large size (invented in parallel by Elasmobranchii), high productivity, and true herbivory. Phylogeny restricted the life-history options available to species with respect to size, place in the food web and productivity. There was evidence for a non-overlap of preferred life-history strategies between the two largest recent Classes, with Elasmobranchii tending towards large size and low to very low productivity, and Actinopterygii tending towards medium size with medium to high productivity. Nine selection theories were tested as to their ability to correctly predict adaptation of life-history traits in response to environmental conditions such as salinity, climate, zoogeographic realm, ocean basin, and habitat type. Predictions were 88 – 100% correct when cases where different theories predicted different adaptations were excluded. In conflicting cases, predictions by temperature theory usually prevailed over those by r-K and succession theories. Life-history strategies were examined with respect to their correlations with body shape, brain size, reproductive guild, migratory behaviour and status of threat. Productivity increased with body shape from eel-like to short and/or deep, with brain size from very small to normal and large, and with migratory behaviour from catadromous to amphidromous and non-migratory. Size decreased with migratory behaviour from catadromous to non-migratory, and with parental care from nonguarders to bearers (in Actinopterygii). Trophic level decreased with increase in brain size. Several life-history strategies were only used by migratory species. Non-threatened fishes had significantly higher productivity than threatened fishes. Life history-strategies that combined large size and low productivity contained proportionally more threatened species than other strategies. Independent estimates of abundance and distributional range of species were used as indicators of success of life-history strategies. Species showed preferences for strategies that were associated with high abundance or small to medium ranges. When abundance and range were combined into a single measure of success (Impact), most strategies were associated with impacts that were not significantly different from the overall mean. Only medium-sized low-level predators and omnivores with high productivity had significantly higher impact; these two strategies were used by 39% of the species.

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.