Bachelor's degree programme: Environmental Sciences, 42 pages (first reviewer)

This thesis analyses the distribution of Schoenus nigricans on Spiekeroog, as well as the ecological parameters to which the occurrences are subject. In order to provide introductory information about Spiekeroog and the study area, the origin and phytosociological structure of East Frisian islands is presented. To determine the intensity/density of Schoenus nigricans colonisation, point mapping was carried out in the study area and the surrounding areas. In addition, the entire flora in the study area was recorded by vegetation mapping using standard phytosociological methods. Biotope types were assigned, which divided the study area into the vegetation types grey dune, the upper salt marsh of the brackish transition and the salt marsh dunes within it. Within six defined transects, various abiotic parameters were determined by means of soil and pore water analyses. The soil was analysed for grain size, organic matter, moisture, pH value and electrical conductivity. The pore water was analysed for pH value and electrical conductivity. Furthermore, elevation data was recorded for each transect.

In the context of previous investigations, it can be deduced that the beginnings of a very early pioneer stage of Junco baltici - Schoenetum nigricantis are recognisable. However, some ecological parameters point to a community that is closer to the Centaurio-Saginetum. Long-term monitoring could be useful in order to continue to understand the development of this area. In order to promote the Junco baltici - Schoenetum nigricantis community and with it a moist, groundwater-dependent dune valley, careful management of the freshwater lentil is required.

Bachelor's programme in Environmental Sciences, 39 pages (first reviewer)

The biomass provided by diatoms and the diatoms (genus level) which were related to that were studied by analyzing the chlorophyll a contents and the diatom composition in different habitats. The sampling points represented five different habitats characterised by different environmental conditions at two study areas. Samples were taken over periods of five months (at Schillig) and two months (in the Jade Bay). The chlorophyll a content showed a seasonal variability during the sampling period (at Schillig) with highest values in June (sand) and May (mixed sediment). The comparison of the chlorophyll a contents in different habitats (in sediment samples of the Jade Bay) showed highest values in seagrass beds and muddy sediment. There were also differences in the diatom composition in different habitats and areas. Seasonal variability in diatom composition was marked by variability in abundance of diatoms. The total diatom composition was made of mobile diatoms which migrate upwards in the mudflat sediment and immobile diatoms which did not migrate upwards. Mobile diatoms can be distinguished from immobile diatoms in a laboratory experiment. Mobile diatoms which were most frequent in the samples were Navicula, Amphora and Tryblionella (on a genus level). The most frequent immobile genus was Achnanthes. An important factor for the distribution of diatoms is the grain-size distribution. The relationships between the distribution of diatoms and macrofauna organisms (depending on their feeding types) are discussed to characterise the role of diatoms in the Wadden Sea food web.

Bachelor's degree programme: Environmental Sciences, 64 pages (first reviewer)

Barckhausen (1969), who extensively explored the island in the 1960s, made an important contribution to the breakdown of Langeoog's geological development. Barckhausen's aim was to delineate the old core of Langeoog and search it for datable layers. In the course of this, he described four geological horizons that allow conclusions to be drawn about the development and formation of Langeoog. These geological horizons are the so-called Hydrobienbank, the Kleibank, and the lower and upper Moorerdebank.

According to the current state of research, more recent investigations and absolute age dating are already available for the lower and upper bog soil bank and the hydrobial bank, which means that the entire development of Langeoog can be reassessed (Bungenstock et al, 2015). Only for the so-called Kleibank are there still no recent geoscientific findings. The aim of this work was therefore to locate the exact position and distribution of the Kleibank in the eastern part of Langeoog's summer polder based on the preliminary work of Barckhausen (1969) (pile-driving core soundings), to obtain sample material (coring device) and to analyse this geologically and palaeoecologically (grain size, diatom and macro-residue analysis).

On the basis of these investigations, the distribution of the clover bank could be specified, its facies described and, as a result, assigned to a period of island development. The species composition of the diatoms, the grain size distribution and the macroremains clearly indicate that the clover bank represents a transition zone between salt marsh and mudflats. The diatoms have indicated this transition zone in the greatest detail, as they react much more sensitively to facies changes or indicate them. Stratigraphically, the Kleibank thus lies between the mudflat facies and the island moor, which corresponds to the genetic sequence from marine-dominated sediments to semi-terrestrial layers, which are characteristic of the island structure. Based on the stratigraphic sequence and the more recent age dating (Bungenstock et al, 2015) of the remaining Leithorizons (Hydrobienbank 1400-1100 B.P. and Moorerdebank 700 B.P.), it can be assumed that the Kleibank was formed around 1100 - 700 B.P.

Bachelor's degree programme in Environmental Sciences: 42 pages (first reviewer)

The topic "Investigation of spatial and temporal distribution of diatom communities in the Jade Bay using short cores" was chosen because diatoms are important indicators of current and past environmental conditions and are therefore highly relevant to research. The Jade Bay as part of the German Wadden Sea represents a constantly changing habitat and is therefore an interesting area to study. The aim of this thesis is to examine short cores (puncture boxes) obtained from the Jade Bay in view of the diatom assemblages and to draw conclusions about the palaeoenvironment from the results. It should ultimately be able to answer the following questions: Are there changes in the spatial distribution of diatom assemblages between the studied sites? Are there already changes in the temporal distribution of diatom communities at shallow depths (up to 30 cm)? The following scientific methods were chosen to analyse the short cores: Microscopy and determination of diatoms, loss on ignition (loss on ignition) and grain size analysis.

Two-subject Bachelor of Biology/Art and Media: 62 pages (first supervisor)

In recent years, an increased spread of the Crassulaceae Crassula helmsii (KIRK) COCKAYNE, originally from New Zealand and Australia, has been observed on the East Frisian island of Norderney. The establishment of this invasive neophyte can result in considerable changes to the indigenous vegetation structures due to its high competitive ability and the formation of extensive monodominant populations, and thus have negative ecosystem effects. In order to be able to predict the potential spread of C. helmsii within the study areas, vegetation surveys were carried out at 22 sampling points and basic abiotic soil factors were recorded.

Based on the data collected in the course of this work, no conclusive assessment of the dispersal tendencies of C. helmsii into the neighbouring plant communities within the study areas can be made. However, the broad ecological amplitude of Crassulaceae derived from the data suggests a high invasive potential. A threat to the biodiversity of the indigenous flora cannot be ruled out. In order to assess the potential threat posed by C. helmsii to the Lower Saxony Wadden Sea National Park ecosystem in the future, comprehensive monitoring of vegetation populations is therefore urgently required. In addition, there is a great need for research into possible nature conservation measures to prevent the further spread of this invasive neophyte.

Master's programme in Environmental Sciences: 76 pages (first author)

The near-surface tidal flat deposits of the Arngastsand tidal flat ridge in the Jade Bay, a bay tidal flat on the German North Sea coast, were analysed with regard to their depositional energies. Seven sediment cores were taken and the sediment profiles were analysed sedimentologically, diatomologically and geochemically.

The suspension load of at least one high-energy event was deposited in the sediment profiles. This event horizon extends over the entire transect of approx. 1 km in length. Prior to this event deposition, fine-grained sediment was deposited in the study area, in which large, weakly silicified species belonged to the diatom communities. Such a deposit indicates calm sedimentation conditions. After the high-energy event, the sedimentation conditions remained at a higher energetic level. Coarser sediment was deposited, which provided a habitat for small, heavily silicified diatom species.

The deposits show anthropogenic pollution of heavy metals (Pb, Zn). These accumulations show that the sediment layers were deposited after 1900.

The entire sedimentation regime on the Arngastsand tidal flat ridge has been subject to a change in deposition energies in recent decades. A very calm depositional environment was followed by an environment that was subject to a higher energy level.

Bachelor's degree programme in Environmental Sciences: 46 pages (first reviewer)

Due to the steadily increasing import of synthetic substances since the beginning of the 20th century, litter in the North Sea has become a growing problem. Ecological consequences such as the strangulation of marine animals, financial losses in the shipping industry and the loss of tourism due to polluted beaches are the most frequent consequences. In order to identify possible distribution patterns of litter in the German Bight, this thesis analysed litter collection data from the environmental associations Mellumrat e.V., Jordsand e.V. and the Wadden Sea Protection Station, the coast of Lower Saxony, Hamburg and Schleswig-Holstein and examined regional differences in the plastic litter category. In addition, particle simulations were carried out using the mathematical calculation programme MATLAB, which was used to calculate possible entry paths for beach litter.

It became clear that litter abundance in the German Bight varies greatly from region to region and can be linked to ship density. This is also shown by the particle simulations, which revealed that the input paths of beach litter in North Friesland differ from the input paths in East Friesland. These regional differences could also be approximately identified on the basis of the plastic composition of the mapping routes. In order to improve the legal basis for the protection of the marine environment, these observations should be continued in future studies.

Bachelor's programme in Environmental Sciences: 42 pages (first reviewer)

In recent decades, the marram grass(Elymus athericus), a native grass species, has spread massively in the salt marshes along the North Sea coast. As a result of this development, the diversity of species in the salt marshes is declining. The Langeooger Sommerpolder, a formerly diked and now renaturalised area within the salt marshes on the East Frisian island of Langeoog, has also seen a significant increase in the area covered by the marram grass (Agropyretum litoralis) in recent years. Although Agropyretum litoralis is a community of the upper salt marsh, the stands on Langeoog are distributed over the entire width of the salt marsh. It appears that Elymus athericus has penetrated far into the area of the lower salt marsh. To characterise the couch grass sites, seven study plots in transitional areas between Agropyretum litoralis and other plant communities were investigated with regard to terrain height and soil parameters. The areas were closely surveyed and digital terrain models were created on the basis of the measurements. A comparison of terrain height and vegetation revealed a clear difference in height between Agropyretum litoralis and Halimionetum portulacoides, a community of the lower salt marsh. The measurements revealed slight differences in height between Agropyretum litoralis and the Festuca rubra community as well as Artemisietum maritimae, two communities of the upper salt marsh. However, differences between the communities in terms of soil parameters could not be identified on the basis of the measurements taken. The analysis of the elevation data confirms the assumption that Elymus athericus spreads in the summer polder at higher locations, i.e. in the area of the upper salt marsh. The fact that these areas are scattered over almost the entire width of the salt marsh is probably due to the original coastline. This is indicated by the analysis of a historical map.