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

This work was able to provide initial findings on the distribution of litter on the different types of banks of the Elbe and identify problem areas that require further research.

Comparable results could be achieved with the help of the OSPAR protocol. However, the data collection on the transect showed that litter carried in by the Elbe was predominantly deposited in the mudflats. The position of the scouring margin was strongly dependent on the height of the flood and the wind. This must be taken into account in future research. In addition, it was possible to gain insights into various influencing factors due to the chosen period of data collection.

The quantity and composition of the litter could be clearly recorded and showed that these were different on the three types of banks. This difference between the bank types is also reflected in the sources of the litter. The stone shore type in particular stands out from the other two in all three aspects: sources, quantity and composition. This and the identification of the most common items per site provide a good basis for the creation of specific management strategies to reduce the input and also for the removal of existing litter. The fact that most of the waste was packaging waste shows that it is overdue to develop alternative and sustainable packaging options. Initial steps are being taken, but are far from sufficient to tackle this problem.

The insight into the variations in the quantity and composition of waste in different weather and tidal conditions, in seasonal dependence and in dependence on geographical location showed that these factors all have a significant influence. The influence of Hamburg as a major city and seaport could not be conclusively clarified and should be examined in further studies in order to develop action strategies for metropolitan regions and waste management strategies in tourist-rich areas.

At almost all locations, the waste was deposited by local people and not washed up by the Elbe. Only the rubbish in Brokdorf Süd Watt could be reliably identified as rubbish from the Elbe. Many objects from shipping were found here, as well as objects from distant foreign countries, which were presumably brought in by foreign container ships. accumulation sites such as Brokdorf therefore serve as good study areas for qualitatively analysing the actual waste load and composition of the Elbe. The phenomenon of slimy decay of plastic films in the mudflats should be investigated further.

It was confirmed that humans are the main input factor and that the holiday season and thus tourism serve as reinforcing factors. The resulting adjustments to waste management have not yet been sufficient and must continue to be optimised. The realisation that the composition of waste hardly changes seasonally, but only the quantity decreases towards the low season, helps to better address these seasonal fluctuations. The existing waste management system should be adapted more specifically to these factors and target groups. In addition, further data should be collected to clarify whether the increase in waste volumes in the southern direction is caused by population density or by a lack of responsibility and environmental awareness in larger cities. Field work and, above all, communication with local residents were important sources of knowledge. For this reason, social interaction should not be forgotten in further studies in addition to possible simulations of conditions.

An investigation of the influence of the further deepening of the Elbe on the distribution of waste is recommended. Presumably, stronger currents and higher tides will lead to more litter entering the Elbe and influence the accumulation behaviour on the different types of banks and the distribution of the litter already present. It is desirable to use sensor drifters to trace the path of the litter in more detail in order to identify sinks within the tidal current and to gain more knowledge about the influence of the long transit time. This could also provide new insights into the extent to which tide-dominating rivers serve as sources or sinks.

In conclusion, it can be said that the data collection on the Elbe was able to provide an insight into many different factors and highlighted a variety of problems. With these findings, further fields of research could be identified and ideas for better waste management could be provided.

As a major river in Central Europe with many large-scale industries on its banks, the Elbe has been subject to heavy pollution for many years. Thanks in part to the work of IKSE, the Elbe is now in a good condition. What has already been possible in the past should continue to be the goal. As part of the work to maintain the condition of the Elbe, attention should be paid in future not only to water quality, but also to pollution from waste. The Elbe should be managed with care as a tributary of the North Sea and therefore also a tributary to the Wadden Sea World Heritage Site, as well as the basis of life for a huge catchment area.

Bachelor's degree programme in Environmental Sciences, 49 pages (first and second reviewer)

Litter poses a significant threat to the conservation of ecosystems and biodiversity in the oceans. The majority of marine litter is discharged from land. In this research project, one aspect of the land-based sources of litter will be analysed: The aim was to show the spatial and temporal variability of litter at public benches and rubbish bins in two German coastal destinations - Wilhelmshaven and Dangast - and to provide suggestions for reducing the amount of litter. Based on this, the amount and composition of litter, the average length of stay and the influence of existing litter bins on the amount of litter were determined.

The results showed that public benches and rubbish bins are litter hotspots during the high season with a significant accumulation of litter. In total, over 9,000 pieces of rubbish were collected during the nine-week study, with 18 rubbish collection days, of which 6,000 were found on benches. Seventy-five per cent of the total litter was cigarette butts, with the remaining 25% consisting of plastic packaging and other plastic products, tissues, pieces of paper and metal bottle tops. In addition, the presence of litter bins was found to influence the amount of litter on the benches, but other factors such as the design of the bins and the frequency of use of the benches were also found to be relevant. Despite the short dwell time of 1.5 weeks per litter item, the course of the dwell time experiment showed a steadily increasing amount of litter on the selected benches.

This study makes it clear that the presence and retention of pieces of litter at the investigated sites represents a significant problem for the local environment, as the pieces of litter can enter the protected areas of the Wadden Sea and thus the North Sea. The aim should therefore be to prevent the generation of litter and the discharge of litter into the environment, for which it is essential to raise awareness of this problem.

Bachelor's degree programme in Environmental Sciences, 55 pages (first author)

The analyses showed that there is an influence and thus an occurrence of disturbance and ruderal species in all path categories along the paths. However, the intensity and number of disturbance and ruderal species is highly dependent on the category of path.

The greatest disturbance is found along forest roads, whereas paths sometimes have almost no disturbance effect at all. The type and frequency of use is particularly important. On most forest paths and forest roads, the use of the paths includes accessibility by car. In many places, this requires road stabilisation by compacting the soil with gravel. This leads to altered site conditions and thus gives species that are particularly foreign to the site a good chance to colonise. In particular, the necessary width of the forest roads also leads to increased light intensity directly along the path.

As the aim of a national park is the development of potentially natural vegetation, which leads to a natural dynamic in most areas, traditional forestry is no longer necessary. As a result, a well-developed network of paths, with almost seventy per cent of them passable, is no longer necessary for today's use. In addition to protecting nature, it is also important to provide hikers with a special experience of nature. This is particularly guaranteed with narrow paths and vegetation along the way that is as unalienated as possible.

In conclusion, it can be said that converting the paths to the path category is a sensible measure, as it has the least impact on the surrounding vegetation. This is confirmed by the successful downgrading of paths carried out to date.

Master's degree programme Marine Environmental Sciences, 79 pages (first reviewer)

As part of this thesis, the amphibian populations on the North Sea island of Amrum were mapped in spring 2018 between March and June. The focus was on the natterjack toad and moor frog species, which are categorised as "endangered" and "declining" in the Red List of endangered amphibians and reptiles in Schleswig-Holstein (as of 2003) and whose populations are also declining on Amrum. The aim of the work was an island-wide survey of the amphibians as well as an assessment of the population situation and development trends. Furthermore, insights were to be gained into the spawning site preferences of the individual species and the available spawning sites for each species, using a previously conducted water mapping as a basis. Finally, the causes of the population trends and possible conservation measures were discussed.

Four amphibian species were recorded: The moor frog (Rana arvalis), the natterjack toad (Epidalea calamita), the common toad (Bufo bufo) and the pond newt (Lissotriton vulgaris). No evidence of the controversial grass frog (Rana temporaria) was found. The common newt is the most widespread amphibian species on the island and was recorded in 63 different bodies of water, with dune pools accounting for a high proportion (87 %). Its preference for vegetation-rich waters with generous shallow water areas and little shade favours a large selection of spawning waters on the island that are available to this species.

The common toad was recorded in 21 different bodies of water, including dune pools and ponds. The distribution was limited to the southern part of the island with a focus on the Wittdün dunes and the Wittdüner Vogelkoje. The northernmost point where an individual was found was in the village of Nebel. During the last mapping in 2003 (ROßDEUTSCHER 2004), however, the distribution area of the presumably introduced common toad was limited to the area around the Wittdüner Vogelkoje with only five adults. The species has spread rapidly and is expected to spread further in the coming years, favouring ponds and other comparatively deep bodies of water. In addition to the Norddorfer Vogelkoje, dune tumps could also represent possible spawning habitats.

The population situation and the availability of spawning waters for both the newt and the common toad do not appear to be at risk.

The situation for the moor frog and natterjack toad on Amrum is worse. Although the number of moor frog spawning waters (20) is similar to that of the common toad, whose population is estimated to be very good, 50 waters were identified as spawning grounds for the moor frog 15 years previously. In addition to the number of spawning waters, the number of spawning bales recorded also fell by 72 % to 513 spawning bales. The once large moor frog populations in the marsh areas of the island have disappeared and those in the Wittdün dunes have also been greatly thinned out. Only in the Norddorfer Vogelkoje area have small increases been recorded.

Three beach lakes near Nebel should be mentioned as new spawning waters for the moor frog and the natterjack toad. These waters are particularly important for the pioneer species natterjack toad, which is dependent on open, low-vegetation primary habitats. With 46 callers, around 70 % of all 66 male natterjack toads heard were recorded in the beach lakes. The population in the Wittdün dunes is very small with 20 callers, spread over three dune ponds, and as with the moor frog, no more individuals could be sighted or heard in the marshes.

In addition to predation by various predators, the causes of the population declines are primarily due to the disappearance or deterioration of suitable spawning habitats. The marshes hardly offer any suitable spawning waters for either species. The supply of spawning waters in the dunes is also declining: waters in the initial stage of succession have now largely disappeared and a lack of dynamism in the dunes is leading to their ageing, so that dune pools and terrestrial habitats are increasingly becoming overgrown with bushes. This not only has a negative impact on the natterjack toad, which is tied to open primary habitats, but also on the moor frog, which favoured the comparatively more open dune ponds with existing open water zones during its spawning season on Amrum. As succession progresses, these waters are gradually becoming overgrown, which means that important spawning habitats for both species are being lost. As a result, the moor frog and natterjack toad are much more limited in their selection of spawning waters on Amrum than the pond newt and the common toad. The latter could benefit from succession and displace the less competitive natterjack toad in particular.

The population situation and development of the moor frog and natterjack toad population on Amrum is worrying, and without appropriate conservation measures there is a high risk of extinction in the medium term. In order to counteract the population decline of both species, measures should be taken to improve the spawning waters and land habitats around the water bodies. Possible management measures include cutting back higher vegetation structures in and around water bodies, flattening the banks of ditches, grazing in marsh and dune areas and rewetting marshes. Following the realisation of conservation measures, long-term success monitoring should take place in order to adjust maintenance and conservation measures if necessary.

Master's programme in Landscape Ecology, 54 pages (first reviewer)

The development of the sandflats off Schillig is analysed on the basis of the diatom communities occurring there. This is based on diatomological and sedimentological analyses of a drill core from the sandflats off Schillig. In order to investigate the relationship between the composition of diatom communities and environmental variables, current samples from various mudflat and salt marsh sites will also be analysed. Statistical analyses will be used to transfer the data from the surface samples to fossil samples from the drill core. The methodology developed will be tested on this and another drill core. It turns out that the methodology works, but the data set of surface samples used has some weaknesses. Therefore, possibilities of the methodology for the reconstruction of environmental conditions and possible adaptations and extensions of the data set of the surface samples are discussed.

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

A height model was used to monitor the success of the renaturalisation measure of the Langeoog summer polder from 2004. This was done by comparing an elevation model created from laser scan data with the mapped vegetation zonation from 2017.

The following results were obtained.
The upper and lower salt marshes as well as the pioneer zone and the mudflats and water areas cover more area than the elevation model suggests, but come close to expectations. The higher salt marsh only occurs in very small proportions in the area in 2017, but should cover around a third of the area according to the elevation model. An equalisation can be achieved on the one hand through succession and on the other through targeted measures.

The renaturalisation of the summer polder into a near-natural salt marsh can be considered successful. It should be considered whether the salt marsh can be modified to a more species-rich area through grazing, or whether the natural state should be favoured. In many respects, such as increased species diversity, further optimised grazing would make sense for the management of Langeoog's summer polder.

Subject Bachelor's programme in Biology, 22 pages (first reviewer)

The plant Crassula helmsii (T. Kirck) Cockyane, which originates from Australia and New Zealand, has been spreading in many regions of Europe for several decades. In these areas, the species sometimes forms large populations in and near water. Where C. helmsii occurs, this neophyte can become the dominant plant species in this area due to its strong growth and vegetative reproduction. Due to its sometimes carpet-like spread, C. helmsii is able to displace other plant species over large areas.

Research results have shown that the populations of C. hel msii can be effectively contained through the use of herbicides, biological agents, darkening with foil or flooding of diked areas with seawater. In this context, the salt tolerance of C helmsii is to be determined here, with the aim of minimising the damage to native species when flooding with salt water, despite the high mortality of C. helmsii. For this purpose, an experiment was carried out in which individuals of C. helmsii were exposed to different saltwater concentrations over several weeks. The evaluation of the data yielded contradictory results, which meant that the determination of the salt tolerance of C. helmsii could not be conclusively clarified.

Bachelor's programme in Environmental Sciences, 40 pages (first reviewer)

Since the end of the Weichselian Ice Age, the area of today's north-west German coastal landscape has changed continuously. The sea level has gradually risen with the melting of the glaciers and has constantly shifted the coastline. The sediment load transported by the water was deposited in the respective coastal area. In many places there were marshlands that were covered by marine sediment. However, there were also phases in which the coastline shifted seaward. In some areas, bogs formed again, which were then covered by marine sediment in subsequent transgression phases. This alternation of transgression and regression can be reconstructed using geological boreholes. In addition, the pollen contained in the deposited peat can provide information on the prevailing landscape, the colonisation of the area and the age of the peat and thus also on the period of the transgression and regression phases.

A borehole profile from Hilgenriedersiel was analysed for this bachelor thesis. The drilling was carried out as part of the WASA project (Wadden Sea Archive). The depositional conditions were reconstructed on the basis of the drilling profile, whereby other profiles in the surrounding area were also included. A chronological classification of the peat layers was carried out using the results of the pollen analysis, which also allowed conclusions to be drawn about the prevailing landscape and anthropogenic interventions. The results should help to reconstruct the Holocene landscape development in the study area.

The Pleistocene subsoil began at 6.70 metres during the drilling in Hilgenriedersiel. The basalt peat deposited above this had a thickness of 33 cm and is around 5000 to 6000 years old. At the time of peat deposition, the predominant type of forest in the area was probably a mixed oak forest with hazel bushes. Alders, pines and birches may have colonised the fringes of the moor. The sea level was at most a few metres below today's level, so that the moor was occasionally flooded. Evidence in the pollen diagram of salt marsh species suggests that the coastline was not too far from the moor. The area was probably only colonised on a larger scale from the late Atlantic onwards, as indicated by a change in the pollen content above the centre of the peat body.

The peat came under the influence of salt water as the coastline shifted, resulting in the deposition of lagoonal material. The flooding only occurred on a small scale, presumably the area was located in a depression, so that lagoonal deposits only occurred in the immediate vicinity in an area of around 3.5 km², beyond which the peat continued to grow. Subsequently, the coastline shifted seaward again, resulting in renewed peat formation in the area under investigation.

The peat was formed during the Subboreal period. The climate here was drier than in the Atlantic, which was also evident in the peat, which was more decomposed than the lower peat layer. The sea level continued to fall, with salt marsh vegetation presumably still growing near the study area at first. In the course of the regression, the coastline shifted further northwards and the vegetation in the study area changed to alder swamp forest with ferns. The predominant type of forest here was probably an oak-hazel forest. The pollen diagram shows no evidence of agriculture during this period. In a new transgression phase, the peat was again overlaid by marine sediments. The erosion contact shown in the profile between the peat and the marine sediment indicates that an event such as a heavy storm surge occurred, which eroded part of the deposits. Subsequently, the area was permanently in the marine sediment area and was part of a salt marsh at the time of drilling.

Bachelor's degree programme in Environmental Sciences, 21 pages (first reviewer)

This study has shown that the waste along the Ems originates mainly from regional sources such as tourism, neighbouring settlements and industry. On the one hand, it is important to identify these sources in order to develop prevention strategies; on the other hand, people need to be made aware of the problem through environmental education. In order to sensitise people to this problem, it would certainly be possible to carry out clean-ups with the public. However, attention should be paid to safety when walking along the banks. These bank clean-ups are most useful after extreme weather events, as this is when the most rubbish is washed up on the banks. The method used in the study has shown that the monitoring of litter on rivers can be carried out well using the OSPAR protocol. However, it is important to define precise specifications for the riverbank sections in order to ensure the uniformity and comparability of the data with other rivers.

In order to make a more concrete assessment of the river input pathway into the North Sea, further monitoring and data collection from the water column and the bottom of the rivers must be documented and analysed. A comparison of the occurrence of waste on the east and west banks of the Ems was not included in this study. This could provide further information on inputs and accumulation points of litter in the Ems. The number of sites should be increased in further studies, as it was not possible to include more than nine sites in the scope of this study. In addition, the differences in the residence time of individual litter particles on different types of banks would be of interest for further investigation. The drifting of litter particles along the river systems is already being investigated in the project "Macroplastics in the southern North Sea" and will hopefully provide clarifying results (Schöneich-Argent et al. 2016).

Litter monitoring, as is already used on beaches, should also be carried out regularly on rivers in accordance with uniform standards. Surveys along the rivers Ems, Weser and Elbe should also be taken into account in order to be able to estimate the input of marine litter into the North Sea via these input pathways.

Abstract
In the following study, abundance and composition of anthropogenic macrolitter were investigated along the riverbanks of the North Sea tributary Ems. The OSPAR-guidline, a guideline for monitoring marine litter on beaches, was tested as a possible method to collect and categorize data on riverine litter. The majority of litter collected along the Ems consisted of plastic (54 %). The observed litter composition of this river can be attributed to human influence along its course. The abundance of litter generally is connected to the riverbank structure. The highest amounts of litter were often found in places with sheet piling or vegetation. The amount of litter in places with sheet piling or vegetation were statistically significantly higher than in places with stones. The results confirm that riverine transport has an important impact on litter abundances in the North Sea. To effectively monitor riverine waste, it is important to create a standardised method to collect data along riverbanks. A practical approach would be the OSPAR-guidline.

Bachelor's degree programme in Environmental Sciences, 28 pages (first reviewer)

This thesis suggests that private individuals are the main source of
waste in the study area. Education and waste prevention strategies
should therefore focus on the individual and less on higher-level
instances. There seems to be a particular need for education with regard to cigarette butts.
Although cigarette butts do not have a large volume, they can be found in large numbers
. Some cigarette butts consist of harmful substances that
can damage the environment, especially when dissolved in bodies of water (Zhao et al. 2010;
Micevska et al. 2006; Register 2000). The categorisation of cigarette butts in the
paper category trivialises their impact on the environment and implies a negligible
burden. Concrete solutions could be smoking bans on
riverbanks, as already enforced on some beaches (Ariza & Leatherman
2011), or biodegradable cigarette filters.

The work shows that litter on the banks of the Weser is a potential source of marine litter
. In order to be able to make fundamental statements, the influence of this source must
be investigated in further studies and, above all, linked to the other parts of the
project. These include surface monitoring,
and the investigation of waste in the water column. For further
work, e.g. on the Elbe, it is advisable to determine the exact frequency of human use of the shore sections
.

The OSPAR protocol developed for coastal beaches is generally transferable to riverbanks with
different characteristics. The use of standardised protocols
should be extended to other studies in order to improve comparability
and pooling of results.

Abstract
Composition and abundance of litter were investigated at three different types of riversides
("river-"beach, stone site and harbour) of the river Weser between Bremerhaven
and Elsfleth in northern Germany. Three locations per type of riverside were visited from
July to September twice per week in 2017 (20 sampling days). The investigation was
based on the Guideline for Monitoring Marine Litter on the Beaches in the OSPAR Maritime
(hereafter OSPAR), which was originally designed for litter monitoring on beaches.
The applicability of the OSPAR method for riversides was the main methodic question
of this study. Furthermore, other issues addressed by this study were (i) the general
examination of riversides of the Weser as a possible source for marine litter and (ii) to
determine differences regarding the litter between types of riverside and between locations
of the same type.
Plastics, Polystyrene and Paper strongly dominated the litter composition at all types of
riversides. Most of the objects found were private, not industrial, litter. The most frequently
found litter on beaches and stone sites were cigarette butts. Between the different
types of riversides, there were significant differences between both beach and stone
site compared to harbour, whereas no difference between beach and stone site was observed
(in consideration of litter quantity). Furthermore, comparing the locations of a single
riverside type the analysis also revealed differences. Although the human impact at every
location was not precisely quantified, it is a reasonable assumption to explain many of
the differences between locations with the respective human impact. Particularly cigarette
butts being the most abundant litter highlight the importance of private litter deposition
as a possible source of litter. Thus, the role of a single person should not be neglected.
To summarise the feasibility of the OSPAR method for riversides: apart from a
few changes (e.g. clear definition of riverside types), the OSPAR method is applicable to
monitor litter at riversides.