Master's programme Marine Environmental Sciences, 46 pages (first reviewer)

The blue mussel(Mytilus edulis Linnaeus, 1758) is one of the most common species of macrozoobenthos in the North Sea and plays a central role in the food web. However, its population is exposed to numerous anthropogenic threats. These include the effects of climate change, the spread of neozoa such as the Pacific oyster(Magallana gigas, Thunberg, 1793) and fishing. Changes in sediment dynamics caused by dredging and dumping of dredged material, for example, can also pose a risk.

As part of the "SediEms" project, which dealt with the modelling and in-situ measurements of sediment dynamics in the Ems estuary, a study on the nutritional status of M. edulis was carried out in summer 2023 in cooperation with the Lower Saxony Wadden Sea National Park Authority. The aim of this study was to gain insights into the nutritional status of the mussels and possible correlations with sediment dynamics. The mussel beds Randzel 2 (RG) and Nordland (JUI1), which are located at different sites in the Ems estuary, were sampled. Individuals of six different size classes were selectively sampled at six sampling sites each. The ash-free dry mass (AFTM), the cooked mass and the shell length were recorded and the a-value calculated. In this study, the a-value serves as an index of condition and indicates the nutritional status.

The results show that the a-value of M. edulis does not differ significantly between the mussel beds. In addition, the a-values from 2016 to 2023 did not differ statistically from each other. As the north-east of Schleswig-Holstein does not have any influential estuaries and the sediment concentration in the seawater is therefore presumably lower than in the Wadden Sea of Lower Saxony, the data collected from Schleswig-Holstein and the values of other mussel beds in Lower Saxony were used for comparison. However, no significant difference was found. Only the meat content showed a significant difference between the Randzel 2 and Nordland products.

Bachelor's degree programme in Environmental Sciences, 26 pages (first and second reviewer)

The management of the invasive aquatic plant Crassula helmsii poses a significant challenge, as few methods prove effective both in the short and long term. Currently, aside from burial, there are no established mechanisms for the proper disposal of removed plant material. This gap is addressed in the present study. Drying and composting processes are investigated as potential strategies for eliminating the regenerative ability of Crassula helmsii. The results demonstrate that both drying and composting are effective methods for eradicating the plant. In drying experiments, a temperature of at least 40 °C for 48 hours results in almost complete water loss, effectively preventing the regeneration of C. helmsii. Similarly, composting in a thermophilic environment over six weeks achieves comparable results. However, since plant fragments near the cooler edges of the compost heap may survive, a combination of both methods - initial drying followed by composting - is recommended as the most reliable approach for complete degradation of the plant and its sustainable control. The goal of this study is to establish this method as a well-founded recommendation for the practical disposal of Crassula helmsii.

Bachelor's programme in Environmental Sciences, 43 pages (first reviewer)

English version see below.

Species-rich wet grasslands have lost considerable area in recent decades. In the Lower Saxony Wadden Sea National Park, such areas can be preserved through extensive management and are of great importance for meadow-breeding bird species. On the funnel area on Wangerooge, species-rich wet meadows have been lost due to succession as a result of abandonment. A section of the site was cleared of grass by spring 2017 and has been mulched once every summer since then.

Investigations in 2024 showed that large areas of nutrient-rich wet meadows (of the Calthion association) have developed on the de-cussed area. There are also dominant stands of Phragmites australis and Juncus effusus. The development of stable plant communities will probably take even longer. The P. australis stands provide good breeding habitats for some species. The structures remaining after the clearing are used as breeding sites by greylag geese(Anser anser). The current maintenance prevents renewed shrub encroachment, but could be supplemented by further measures.

English version

Species-rich wet grasslands have lost considerable area in recent decades. In the Wadden Sea National Park, such areas can be preserved through extensive
management and are of great importance for meadow-breeding bird species. On the
"Trichtergelände" on the island of Wangerooge, species-rich wet grasslands have been lost due to shrub encroachment as a result of abandonment. A section was cleared of bushes by spring 2017 and has been mulched once every summer since then.

Investigations in 2024 show that large areas of nutrient-rich wet meadows (of the Calthion association) have developed on the cleared area. There are also dominant stands of Phragmites australis and Juncus effusus. The development towards stable plant communities will probably take even longer. The P. australis stands provide good breeding habitats for some species, and the structures left behind by the clearing are used as breeding sites by greylag geese(Anser anser). The current maintenance prevents renewed succession but could be supplemented by further measures.

Bachelor's programme in Environmental Sciences, 36 pages (first reviewer)

English version see below.

Meadow bird populations in Europe have been declining for several decades. In addition to changes in land use, poor breeding success, mainly due to nest predation and
chick predation, is considered a major driver of declining populations. Island food webs in particular are very sensitive to predation or competition from introduced mammals. There are several reports from the East Frisian Islands of breeding losses of ground-nesting birds due to the invasive mammals cat(Felis catus) and hedgehog(Erinaceus europaeus). The aim of the study is to better understand the composition of chick and clutch predators of lapwing(Vanellus vanellus) and black-tailed godwit(Limosa limosa) on Wangerooge. To this end, artificial ground nests were created and monitored with wildlife cameras. In addition, observations were made of the defensive behaviour of the breeding adults and the predation success of nest predators at different times of day.

The results show that no predation by mammals was detected, even though the presence of the two predatory mammal species was recorded several times in the area. The eggs of the artificial nests were almost exclusively predated bycorvids (Corvidae). Corvids(Corvus corone) were the most common predators observed. There were no clear differences in the defensive behaviour of the two breeding bird species. Artificial nest experiments have a reputation for poor external validity. Here too, many deviations from the real breeding conditions cast doubt on the transferability to the actual predation conditions. Furthermore, the results of the predation observations are subject to a systematic error that probably overestimates the diurnal predators, as the nocturnal observations could not be meaningfully carried out due to technical limitations. This work emphasises the need for further research on predation in the valuable habitat that the islands and the Wadden Sea represent.

English version

Meadow bird populations in Europe have been declining for several decades. In addition to changes in land use, poor breeding success, primarily due to nest and chick predation, is considered a major driver of declining populations. Island food webs are particularly sensitive to predation or competition from introduced mammals. There are some reports from the East Frisian Islands of breeding losses of ground-nesting birds due to the invasive mammals cat (Felis catus) and hedgehog (Erinaceus europaeus). The aim of this study is to better understand the composition of chick and clutch predators of lapwing (Vanellus vanellus) and black-tailed godwit (Limosa limosa) on Wangerooge. For this, artificial ground nests were created and monitored with wildlife cameras. In addition, observations of the defensive behaviour of the breeding adults and the predation success of the nest predators at different times of day were made.

The results show that no predation by mammals was detected, even though the presence of the two predatory mammal species in the area was recorded several times. The eggs of the artificial nests were almost exclusively predated by corvids (Corvidae). Carrion crows were the most common predators observed. There were no clear differences in the defensive behaviour
of the two breeding bird species. Artificial nest experiments face criticism for lacking external validity. Various deviations from natural breeding conditions question the applicability to real-world predation conditions. Furthermore, the results of the predation observations are subject to a bias that likely overestimates the diurnal predators, as the nocturnal observations could not be carried out meaningfully due to technical limitations. This work highlights the need for further research on predation in the valuable habitat that the islands and the Wadden Sea represent.

Master's programme Marine Environmental Sciences, 71 pages (first and second reviewer)

The master thesis analyses an alternative method to the currently used field-based seagrass detection in the Wadden Sea of Lower Saxony. The use of unmanned aerial vehicles (UAV) with high-resolution cameras offers the possibility of analysing seagrass areas over large areas with the help of machine learning. Corresponding vegetation analyses have already been used for macrophytes and mussels, for example, and could also be promising for seagrass beds. The focus is on analysing and optimising the detection of the seagrass species Zostera noltii(Z. noltii) using high-resolution red-green-blue (RGB) images in a limited area of ten adjacent tiles, each 10 m x 12 m in size. The aim is to find optimal parameters for segmentation, machine learning algorithms (MLA), image resolution and training data using ArcGIS Pro to achieve the highest possible accuracy in recognising 'seagrass' and 'no seagrass'.

In this work, the different algorithms Support Vector Machine (SVM), Random Trees (RT), Nearest Neighbours (K) (KNN) and Maximum Likelihood (ML) were analysed. The results show that the optimal image segmentation values for SVM, RT and ML are 20 pixels for the spectral and spatial details and 20 pixels for the segmentation size setting. It also shows that the SVM method with the default setting of 500 samples (SVM 500) achieves the highest overall accuracy in seagrass detection with approx. 85 %. The same tile was used as the training and validation tile. Subsequently, several independent tiles were used as controls for a more realistic assessment of model performance. The results demonstrate that by increasing the number of training tiles to six, the overall accuracy of the SVM 500 method increases to 88.9 %. In addition, it became clear that a coarser pixel resolution (15 mm) not only leads to a slight improvement in the results (90.38 %), but also enables a significantly more efficient processing time.

The study confirms the effectiveness of seagrass detection, especially using the SVM method. The detection accuracy is 95.20 % for 'no seagrass' and 85.56 % for 'seagrass', which indicates a reliable application for monitoring in the Wadden Sea.

Bachelor's programme in Environmental Sciences, 50 pages (first reviewer)

The study investigates the macrolitter pollution at different riverbank types of the Weser, a German North Sea tributary. The riverbanks were categorized stony, beach and harbor types to monitor the quantity and composition of debris along the shoreline. The Joint List of Marine Litter Categories for Marine Macrolitter Monitoring (J-List) was utilized to classify the found items according to the material and purpose of usage. According to that, data was collected weekly in April and June 2024 to examine seasonal differences in litter accumulation. The analysis reveals that plastic waste, especially cigarette butts, dominates the litter found across all shoreline types. Furthermore, correlations between variations in the distribution and the specific characteristics of each location were eminent. The stony area had the highest litter concentrations in total, while the harbour area exhibits the highest pollution by cigarette butts due to increased human activity, while the beach areas show less variations but continuous similar patterns of waste accumulation. These findings highlight the necessity of long-term monitoring efforts to facilitate the implementation of targeted waste management strategies and policies. Furthermore, the research emphasises the importance of environmental awareness in the public to promote sustainable practices in coastal areas and reduce litter pollution effectively.

Bachelor's degree programme in Environmental Sciences, 31 pages (first and second reviewer)

Anthropogenic climate change presents forest managers with the challenging task of making the forest more resilient as a natural and economic asset. Many conifer monocultures are currently being converted into mixed beech forests (Knoke et al., 2008). However, the choice of beech as a tree species in climate change is viewed critically, as this review shows. Regression models such as that of Leuschner et al. (2023), which combine various climate scenarios with data from dendrochronological analyses, show a significant decline in the potential range of beech. However, such models do not take into account factors such as adaptation potential. For example, the results of the provenance experiments investigated here point to the great genetic and epigenetic diversity of beech, which is associated with a high phenotypic plasticity and could ensure acclimatisation, at least in the short term.

The results summarised in this paper on the adaptability of beech to increased drought events and rising temperatures illustrate the importance of cross-method studies in the context of climate change. Further research projects are needed in order to be able to make more precise statements about the future of the tree species and more targeted forestry measures. Both young plants and adult trees should be analysed over longer periods of time and as many environmental factors as possible should be included, such as soil properties, competitive pressure and water availability. Such multifactorial studies would better illustrate the complexity of adaptive abilities and enable more targeted interpretations for forestry. In addition, further studies at the genetic level are necessary in order to be able to make more precise statements about the genetic material of the individuals.

However, as the changes caused by anthropogenic climate change are relatively rapid and the life cycles of forests are comparatively slow, it seems necessary to take action now. One such measure could be the assisted migration of more drought-tolerant individuals of the same species from other origins. Even if the choice of suitable individuals does not appear to be clear, such plantations could lead to an increase in epigenetic and genetic variance and thus act as a buffer for the beech population as a whole. However, it is not possible to say with the available data whether such a measure is sufficient to keep beech forests climate-resistant and thus usable for forestry in the long term. Precisely because climate change is such a complex problem, forest managers should therefore pursue a variety of solution strategies in order to preserve the forest ecosystem.

Bachelor's programme in Environmental Sciences, 62 pages (first reviewer)

Silicate is a crucial nutrient for diatom growth, but it is often overlooked compared to nitrogen and phosphorus. However, globally, a decrease in silicate concentrations has been observed, which may impact diatom blooms. Eutrophication and changes in river water management, primarily due to damming, have significantly altered silicate inputs.

Lagoons, such as the Oder Lagoon, are sensitive ecosystems where changes in nutrient dynamics can alter the system significantly. The silicate concentrations in the Oder Lagoon are primarily influenced by the Oder River, one of the last major rivers in Europe with minimal damming. This study examines silicate concentrations in the Oder Lagoon from 1980 to 2021. Findings reveal that springtime silicte limitation has shifted earlier over the years, while autumn silicate concentations have increased over the years.

Bachelor's programme in Environmental Sciences, 45 pages (first reviewer)

English version see below.

Seagrass meadows are productive habitats that play a key role for biodiversity, coastal protection and as carbon sinks. They are also used as an indicator of water quality. A global decline in seagrass populations has been documented for decades, which also affects the populations of Zostera noltii (dwarf seagrass) in the Lower Saxon Wadden Sea National Park and requires regular monitoring.

In order to document the changes in seagrass stocks in the Wadden Sea in a comprehensive and time-efficient manner, an automated seagrass detection system is being tested using high-resolution multispectral images. The data is recorded using a drone and analysed using object-based and monitored classification with the ArcGIS Pro geoinformation system, version 3.1.0 from esri. In order to achieve the highest overall accuracy (OA) in seagrass detection, the RGB and colour IR band combinations, segmentation and the classifiers Support Vector Machine (SVM), Random Trees (RT), k-Nearest Neighbor (kNN)
and Maximum Likelihood (ML) are tested with different hyperparameters and by varying the data sets.

The results show that the spatial resolution is more important than the spectral resolution and that the band combinations had little influence on the OA. All four classifiers led to high OAs, with SVM and RT with the default settings providing the most reliable results with high OAs of > 90%. In contrast, ML and kNN were more sensitive to changes in data and training sets, leading to classification errors and scatter in the results.

This work demonstrates the potential of automated, GIS-based seagrass detection for Z. noltii standsin the Wadden Sea of Lower Saxony and provides a basis for further studies. In the long term, this method could document the effectiveness of conservation measures and changes in seagrass populations more regularly and comprehensively.

English version

Seagrass meadows are highly productive ecosystems that fulfil a key role in coastal ecosystems and are used as indicators of water quality. In recent decades, a global decline in seagrass populations has been observed, impacting Zostera noltii (dwarf seagrass) in the Lower Saxony Wadden Sea and highlighting the need for regular monitoring.

To address this, a machine learning approach is being tested using high-resolution multispectral imagery obtained from an unmanned aerial system. The data are analysed using supervised object-based classification with ArcGIS Pro, version 3.1.0 from Esri. The study has investigated the influence of different band combinations, segmentation as well as the classifiers Support Vector Machine (SVM), Random Trees (RT), k-Nearest-Neighbor (kNN) and Maximum Likelihood (ML) tested with different hyperparameters.

The results show that the spatial resolution is more important than the spectral resolution and that the band combinations had hardly any influence on the Overall Accuracy (OA). All four classifiers resulted in high OAs, while SVM and RT led to the highest OAs of >90% using the default settings. In contrast, ML and kNN were more sensitive to changes in data and training samples, leading to classification errors and scatter of the results.

This study demonstrates the potential for machine learning methods like supervised and object-based classifications for seagrass monitoring. It provides a basis for further studies to support the monitoring of Z. noltii in the Wadden Sea. On a long term basis, this method can be used to document the changes in seagrass populations and provide data for the effectiveness of conservation measures.

Master's programme in Landscape Ecology, 72 pages (first reviewer)

The expansion of onshore wind energy is a central component of the German energy transition, but is often accompanied by conflicts of land use in the area of nature conservation. This master's thesis analyses the land use conflict between the energy transition and nature conservation using the example of the Weser-Ems region in Lower Saxony and develops solutions to take into account all interests involved. The focus is on the questions of which approaches can best reconcile the interests of the stakeholders in the conflict between the expansion of onshore wind energy and nature conservation and how these can contribute to minimising or overcoming the conflict. The study is based on a document analysis and guided interviews with experts. It shows that repowering is seen as an effective measure to minimise interventions in nature and reduce the amount of land required. A revision of the legal guidelines is considered to be urgently required in order to improve practical feasibility. In addition, technical means should be developed that can not only relieve the burden on authorities and counteract the shortage of skilled labour. Accelerated monitoring approaches and further developed protective measures are also of great importance. The importance of increased and early communication between the various interest groups is also emphasised in order to minimise the potential for conflict. As nature and climate protection, the economy and society are significantly affected by the land use conflict, a sustainable solution is crucial. Effective strategies, developed from interviews with experts and relevant literature, are to offer solutions in the context of this work that accelerate the expansion of wind energy and at the same time take nature conservation concerns into account.

Bachelor's programme in Environmental Sciences, 53 pages (first and second reviewer)

English version below.

Ruppia maritima L, known as sea lettuce, belongs to the Ruppiaceae family and is typical of brackish and saltwater habitats worldwide. This plant is highly tolerant of extreme environmental conditions and plays an important ecological role as submerged aquatic vegetation. In Germany, its distribution is limited to a few locations on the North Sea and Baltic coasts. The Lower Saxony Wadden Sea National Park therefore bears a special responsibility for its protection and has recognised it as a species of responsibility. The study analyses the distribution and endangerment of R. maritima on the East Frisian island of Wangerooge as well as the environmental factors that influence the growth and spread of the plant. Currently, R. maritima occurs in large populations in four bomb funnel waters in the outer Groden of the island. The studies show that the micro-waters on Wangerooge provide a valuable environment for R. maritima, but that the number of marine saltmarsh sites is limited by regular flooding of the salt marsh and the associated increased salinity in the micro-waters of > 25 PSU. The loss of sites over the last 25 years is mainly due to the change in salinity. Sites inside the dykes are now too low in salinity, while sites outside the dykes are too saline. Future challenges for the survival of the species on Wangerooge could arise from climate change, which could increase the salinity and temperature in the micro-waters due to rising sea levels and temperatures. This could lead to the premature death of the sea salt marshes during the vegetation period. Monitoring of salinity and temperature is therefore necessary to investigate the influence of these environmental factors on R. maritima and to ensure the long-term conservation of the populations.

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Ruppia maritima L, known as wigeongrass, belongs to the family of the Rupptaceae and is typical for brackish and saltwater habitats worldwide. This plant is highly tolerant of extreme environmental conditions and plays an important ecological role in submerged aquatic vegetation {SAVJ. In Germany, its distribution is limited to a few locations, particularly on the North Sea and Baltic coasts. Therefore the Lower Saxon Wadden Sea National Park bears a special responsibility for its protection and has designated it as a species of responsibility. This study examines the distribution and endangerment of R. maritima on the East Frisian island of Wangerooge and the environmental factors influencing its populations. The study shows that the small water bodies on Wangerooge provide 3 valuable environment for R. maritima. Ruppia maritima currently occurs in large populations in bomb craters that were formed during World War II and now form small bodies of water in the backside salt marsh of the island. Their abundance is limited by the availability of water bodies with the salinity range suitable for R. maritima and is further restricted by salt marsh inundation. The loss of sites over the last 25 years is mainly due to changes in salinity. Future challenges for the survival of the species could be posed by climate change, which could increase the salinity and temperature in the small water bodies due to rising sea levels and temperatures. This could lead to the premature death of the wigeongrass during the growing season. Monitoring of salinity and temperature is therefore necessary to investigate the influence of these environmental factors on R. maritima and to ensure the long-term conservation of the populations.

Bachelor's programme in Environmental Sciences, 45 pages (first and second reviewer)

This bachelor thesis investigates the sedimentological development and heavy metal contamination of clover pits in the salt marshes of the western Jade Bay. The aim of the study is to find out to what extent clover pits can serve as indicators of heavy metal pollution. Clay pits, created by the extraction of clay for dyke construction, are dynamic and diverse habitats. Clay, a mixture of clay, silt and sand, is ideal for dyke construction due to its density. After extraction, the ebb and flow of the tide and sedimentation cause the pits created by clay extraction to revert to near-natural salt marshes.

Five clover pits in various stages of age and development were analysed, as well as a reference area in a salt marsh that had not been filled. The study areas consistently show a high dominance of clay and silt fractions, characteristic of quiet depositional environments. The loss on ignition, an indicator of organic materials in the sediment, is at a similar level in all areas and increases with altitude, which indicates an accumulation of organic matter. The heavy metal concentrations of arsenic, cobalt, chromium, copper and nickel show no significant differences between the different plots and remain within a constant value range, which indicates a natural origin of these elements. In contrast, lead and zinc show increased concentrations in the upper sediment layers, which indicate industrial influences since the beginning of industrialisation. The comparison of the measured heavy metal concentrations with the OSPAR environmental standards shows that the values of lead and zinc are much higher in most cases, indicating potential environmental pollution.

The results of this study suggest that clover ponds can serve as indicators of heavy metal input. The increased concentrations of lead and zinc in the upper sediment layers could serve as markers for industrial activities. The decrease in concentrations with increasing depth indicates pre-industrial, uncontaminated sediment. These findings help to improve our understanding of environmental pollution and sedimentological development in the Jade Bay. Future studies with larger sample numbers and higher-resolution methods could further deepen the knowledge gained here and more precisely record the relationships between clover chutes and environmental changes.

Bachelor's degree programme in Environmental Sciences, 24 pages (first and second reviewer)

Crassula helmsii is a semi-aquatic, invasive neophyte that forms dense stands in wet biotopes and leads to species-poor vegetation. After Crassuia helmsii was found in a body of water on Wangerooge in 2018, the species showed strong tendencies to spread, so the body of water was filled in to protect other habitats on Wangerooge. This study aims to analyse the threat posed by Crassuia helmsii to the small waterbodies on the island. The questions are which small bodies of water offer the neophyte an opportunity to colonise and which endangered species are displaced by colonisation.

To this end, 41 small bodies of water were analysed in terms of vegetation, hydrochemistry and sedimentology. The site conditions of the small bodies of water on Wangerooge were compared with Crassula helmsii populations on Norderney. The probability of occurrence of Crassuia helmsii was calculated using a habitat model.

The results show that all small bodies of water on Wangerooge are suitable habitats for Crassula helmsii and that several endangered species are present. In addition, Crassula helmsii was found in a body of water in which it is likely to spread further. Due to the presence and suitability of all water-bearing sites for Crassula helmsii, the neophyte poses a major threat to the vegetation present and the endangered species. The investigations support approaches for preventive action and possible control of the neophyte on Wangerooge.

Bachelor's programme in Environmental Sciences, 44 pages (first and second reviewer)

English version see below.

The Wadden Sea with its tidal flats and associated islands is a dynamic habitat. As a national park and UNESCO World Heritage Site, the Wadden Sea is a strictly protected area. In order to preserve this area, efforts are being made to leave nature to its own devices. However, despite this high level of protection, the habitats on and around the islands are still characterised by tourism and the lives of the islanders.

The subject of this work is the vegetation communities of the dunes on Mellum, a young uninhabited island near the East Frisian Islands in the Wadden Sea National Park, which were recorded phytosociologically according to Braun-Blanquet. From this, conclusions can be drawn about the dune succession on Mellum when these are compared with the vegetation communities of the dunes from earlier years. The areas of the island where accumulation and erosion processes are taking place can be determined. The southern dune shows clear erosion processes, while accumulation processes are taking place on the southern and northern parts of the western dune.

In addition, the locations and site size of the neophytes Rosa rugosa and Senecio inaequidens were recorded. This data is compared with that of previous years. When analysing the spread of the two neophytes Rosa rugosa and Senecio inaequidens , it becomes clear that they are continuing to spread, although the spread of Senecio inaequidens is much faster and the number of individuals has doubled in the last four years.

Climate change will also have an increasing impact on the dune vegetation on Mellum in the future, with rising sea levels and rising temperatures being the most important factors. While rising sea levels could lead to increased habitat loss, rising temperatures could lead to a geographical shift in the habitats of some plant species. This offers the potential for the immigration and spread of neophytes.

All of these changes need to be monitored in the future in order to be able to react to possible consequences and thus maintain the ecosystem function of Mellum.

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The Wadden Sea with its tidal flats and the associated Islands is a dynamic habitat. As a national park and UNESCO World Heritage Site the Wadden Sea is a strictly protected area. To preserve this area, it is attempted to leave nature to itself. However, despite this high level of protection, the habitats on and around the islands are still stamped by tourism and the live of the islanders.

The subject of this work are vegetation communities of the dunes on Mellum, a young uninhabited island located close by the East Frisian Islands in the Wadden Sea National Park, which were recorded phytosociologically according to Braun-Blanquet. From this, conclusions can be drawn about the dune succession on Mellum if these are compared with the vegetation communities of the dunes from previous years. The areas of the island where accumulation and erosion processes take place can be evaluated. The southern dune shows clear erosion, while accumulation processes are taking place on the southern and northern parts of the western dune.

In addition, the locations and site size of the neophytes Rosa rugosa and Senecio inaequidens were recorded. This data is compared with that of previous years. When looking at the distribution of the two neophytes Rosa rugosa and Senecio inaequidens it becomes apparent that they are continuing to spread, with the spread of Senecio inaequidens occurring much faster and the number of individuals having doubled in the past four years.

Climate change will also have an increasingly large impact on dune vegetation on Mellum in the future, with the most important factors being sea level rise and the increase of temperature. While sea level rise could lead to increasing habitat loss, the temperature increase could lead to a geographical shift in the habitats of some plant species. This provides the potential for the immigration and the spreading of neophytes.

All these changes must be monitored further in the future in order to be able to react on possible consequences and thus to preserve the ecosystem function of Mellum.

Master's programme Marine Environmental Sciences, 68 pages (first reviewer)

Occurring approximately 34 million years ago (Ma) the earth transitioned from a largely ice-free greenhouse climate to an icehouse climate, involving the first major glaciation of Antarctica. The Eocene/Oligocene Transition (EOT) is also marked by global changes in ocean circulation and variations in productivity. As primary producers, diatoms play an integral role in the marine food web and global biological carbon pump. They are also sensitive to their environment. Size is widely considered to be a "master trait" in unicellular organisms such as diatoms. Changes in size can occur as a response to a series of abiotic and biotic factors. With drastic shifts in temperature, productivity and ocean circulation, the EOT offers a time frame to better understand diatom size dynamics under a changing environment.

This thesis measures the area of over 10,000 diatom specimens from the genera Azpeitia and Coscinodiscus across the equatorial Atlantic to the Southern Ocean (DSDP Site 366, DSDP Site 511, ODP Site 699, ODP Site 1090 and ODP Site 689) over the time period of ~38 - 30 Ma, in order to examine diatom size developments over this transitional period. Diatom size generally increased over the boundary between the Eocene and Oligocene epoch across the five sites. Diatom size was compared to published data on Sea Surface Temperature (SST) and export productivity, when available. The relationship between SST and diatom size presented a mixed result. This thesis found a compelling possible link between diatom size and export productivity based on visual correlation.

Master's programme Landscape Ecology, 112 pages (first reviewer)

Due to the ongoing war conditions from 2011 until today, the migration of a large number of people and the deterioration of the economic and environmental structure, a state of instability has occurred in Syria, leading to an over-utilisation of natural resources such as soil and water. This has led to a proliferation of areas exposed to erosion and drought, especially in the semi-arid and arid climates of north-eastern Syria, particularly in the Al-Hasakah region.

In this paper, after describing the geographical, ecological, climatic and political conditions, three cultivation projects and a soil improvement programme are presented to address the deteriorating conditions in the country. The aim of the study is to increase agricultural production, improve the soil and make agricultural food available at all times of the year and at lower prices. This also includes the production of livestock feed and its availability. In addition, the use of chemicals and fertilisers is to be reduced and the depletion of groundwater counteracted.