2013
2013
Diatom occurrence in the Jade Bay. Quantitative and qualitative recording and biomass calculations in different facies of the intertidal.
(Bachelor thesis Celine Offermanns, September 2013)
Bachelor's programme in Environmental Sciences: 59 pp. (first reviewer)
This thesis deals with the biomass production of diatoms in different facies of the intertidal of the Jade Bay. The results show a difference in the diatom flora in the different habitat types. While the episammic genera dominate in abundance in the sandflats, their number of individuals decreases as the sediments become finer. The mudflats are also colonised by large epipelic diatoms. The sediment type plays an important role in the distribution of the diatom flora. The biomass calculation of the diatoms was carried out according to HILLEBRAND et al. (1994) and EDLER (1979). It was assumed that there were 300 diatoms per sample. The comparison between the abundance of a genus and its proportion of the total biomass showed that individual large diatoms provide more biomass than many small specimens. In line with this assumption, the mudflats were found to have the highest biomass production by diatoms compared to the mixed and sandflats. In order to be able to make a more precise statement about the productivity of the different habitat types, more extensive investigations should be carried out in further studies. A comparison of the annual biomass production of diatoms in the Jade Bay with the investigated areas near Sylt and the Elbe estuary was not carried out as part of this study. Furthermore, the study does not provide any information on seasonal variations. It only reflects a single ebb tide situation in each transect in June 2013.
Effects of a ship collision in the area of an offshore wind turbine on marine ecosystems
(Master thesis Vera Smid, August 2013)
Master's programme Landscape Ecology: 134 p. (First reviewer)
The results of the risk analysis have shown that the probability of a collision between a ship's hull and an offshore wind turbine in the KASKASI offshore wind farm is very low. The collision analysis made it clear that at a drift speed of approx. 2 m/s, no oil would escape from the double-hull tanker if the ship's hull were to rupture. However, as all risks should be taken into consideration before constructing an offshore wind farm, this study analysed oil leakage in a worst-case scenario and the associated consequences.
The modelling of oil spills in the four different seasons has shown that in all scenarios, the mudflats and salt marshes in the Schleswig-Holstein area, including the EU bird sanctuary "Eastern German Bight", would be most affected. On closer examination of the current, wind and wave movements, it became clear that the island of Heligoland would only be affected to a small extent by the effects of the collision with subsequent oil spill due to its special current conditions. The Sylt Outer Reef FFH area would also only be slightly affected due to the prevailing westerly winds. The Wadden Sea of Lower Saxony with the East Frisian Islands and the salt marshes would be much less affected by a collision at any time of year than the Schleswig-Holstein Wadden Sea. The reason for this is the prevailing winds and currents, which mainly blow from the west. However, a slight difference was found between the spring and summer months, as well as the autumn and winter months. In spring and summer, the percentage of oil in the Lower Saxony Wadden Sea and the salt marshes was slightly higher compared to the autumn and winter months. One reason for this may be the proportion of north-westerly winds in the spring and summer months, which blow at these times of year. Furthermore, the overall probability of any coastal section being affected was around 10 % higher in spring and summer than in autumn and winter, which is due to the high fluctuation of waves in the winter months. The wind and waves break up the cohesive oil and prevent it from drifting onto the coast in a closed oil slick. The amount that would drift onto the coastal areas can therefore be estimated to be much lower than it has been depicted. Although oil drift models offer the possibility of drift assumptions, they cannot fully take into account the existing environmental conditions and the resulting degradation processes.
After analysing the marine environment for the consequences of oil spills, it becomes clear that benthic communities, such as molluscs, would suffer the most severe impacts from long-term oil damage. Due to their sensitive reaction to oil, species that live on or near the sediment surface and feed as filter feeders would be particularly likely to die. However, the high reproduction rate of benthic communities has a positive effect on the reaction to oil. They would be able to recover from oil damage within a very short time.
The results of the effects on the avifauna show that their way of life would be most severely inhibited at the first moment of the oil spill. Breeding birds would be disturbed, especially during breeding in the salt marshes, and the food base would also be reduced due to the death of the benthic communities in the Wadden Sea. The low reproduction rate of the birds is also a negative factor in the reaction to oil. For the loon itself, the risk of being affected by oil is rather low, as the highest densities of individuals are north-west of KASKASI and the oil slick would most likely not reach this area due to the westerly winds. The avifauna would only be affected by oil if the oil spill were more advanced and no control measures were initiated. However, as this would not be the case due to the organisation of the oil spill response, it can be assumed that an oil spill would cause very little damage to the loons.
As the harbour porpoises raise their offspring in the area around Amrum in the spring and summer months, a collision at this time would have a negative effect on the reproduction rate. The calves would have little chance of escaping the oil slick.
However, due to the regular inspection flights, a collision between an offshore wind turbine and a double-hulled tanker with an oil spill could be identified very quickly. The organisation of the oil spill response and the measures to combat it are now so well developed that the oil damage could be contained within a very short time and the oil would hardly have the opportunity to drift into the Wadden Sea and the salt marshes. During the discussion, it was shown that certain control measures would have to be applied even if there was a risk of the oil reaching the coastal areas. The pollution control precautionary concept offers a sensible preparation for an oil spill. However, it must be recognised that the salt marshes with their special plant community and their large number of breeding and resting birds would suffer the greatest long-term damage from an oil spill. In the event of an oil spill, the focus is on rapid oil spill response, which can greatly limit the impact on flora and fauna.
The modelling of oil drift in all four scenarios showed that there were hardly any differences in the different seasons. For the marine environment and coastal areas, however, large differences between the summer and winter months can be recognised due to reproduction.
To summarise, the extent of the impact depends on the amount of pollutants emitted and the seasons. This work has made it clear that, depending on the oil damage, it is possible to limit the effects of an oil spill through preventive and curative measures. The findings on the effects of oil on marine organisms have so far only been studied to a limited extent. Accordingly, there is still a great need for research into the effects of oil on marine organisms.
Evaluation of existing management concepts to achieve the conservation value in the Lower Saxon Wadden Sea National Park using the example of the foreland between Lütetsburger Sommerpolder and Neßmersiel
(Bachelor thesis Jonas Löb, April 2013)
Bachelor's programme in Environmental Sciences: 65 pp. (First reviewer)
The data discussed in the thesis show a diverse picture of the various effects of the measures in the Lütetsburg summer polder, the influence of grazing in the Westernesmerheller, as well as the general development of breeding and visiting birds.
The measures carried out in the Lütetsburg summer polder in 2005 had a positive influence on the development of vegetation with regard to the establishment of salt marsh vegetation, but just two years after the measures, there was no difference in the frequency of guest birds. For breeding birds, the development of breeding suspects (BV) and breeding evidence (BN) even looks negative. It was not possible to find a clear reason for this.
In general, the measures of the foreshore management plan do not appear to be effective for breeding birds either. It is not possible to say exactly why this is the case. This may have nothing directly to do with the measures themselves, but may be related to other diverse factors such as climatic conditions, natural flooding frequency, varying predation pressure, vegetation development, etc.
It can also be concluded that breeding birds are not affected by varying degrees of extensive grazing. However, this only applies to areas that are already extensively grazed. It is therefore questionable at what grazing intensity the effects on the vegetation caused by the cattle influence the breeding birds in their choice of nesting site. This should be investigated further. It should also be examined more closely how possible grazing with sheep or horses or earlier or later mowing affects the vegetation and the associated development or breeding birds. A return to extensive grazing of the summer polder areas is not recommended from an ornithological point of view.
The general development of breeding and visiting birds shows a relatively uniform picture for breeding birds. A positive trend can be observed here until around the turn of the millennium, after which the number of breeding suspects and breeding records fell again significantly. Here, too, it was not possible to identify the exact causes of this development, as the influencing factors are too extensive and too diverse. The development of black-tailed godwit and redshank is striking here, as they have clearly developed negatively. The guest birds, on the other hand, show a very varied picture. There are species such as the white-fronted goose, which have developed positively during the period under review, but also species such as the golden plover, which are subject to strong fluctuations.
In all areas where measures have been implemented, vegetation development is moving away from grassland vegetation towards salt marsh vegetation. This is particularly noticeable in the foreshore areas and in the Lütetsburg summer polder. It appears that the measures described in the foreshore management plan and implemented in the Lütetsburg summer polder in autumn 2005 have had a positive effect in terms of developing a more natural environment.
Methods to develop vegetation cover on dikes in brackish water areas of SW-Bangladesh.
(Bachelor thesis Juliane Schöll, April 2013)
Bachelor's Programme Geoecology, Karlsruhe Institute of Technology: 63 p. (Second reviewer)
Erosive forces are considered as one of the most severe natural hazards people in Bangladesh are forced to struggle with and since the sea level is rising, the increasing number of cyclones and other climate impacts affect agri- and aquaculture areas. Therefore, an increased demand to combat these erosions arises. Due to a financial lack of the government, only little experience of appropriate dike building techniques, and missing awareness of a proper dike management, several national and international projects have been carried out realising requirements of a sustainable management. Within the ippp projects of the GIZ "Coastal Protection in the Sundarbans-sustainable development and biodiversity conservation in coastal protection forests", with participation of the WAB Trading International, a concept should be developed, to ensure build up of vegetation cover on dikes in areas of southwest Bangladesh. Implementation takes place through an involvement of shrimp farmers participating in the Organic Shrimp Project (OSP) of the WAB. Within this thesis, a list of suitable plants has been established considering some soil parameters with special focus on the soil electrical conductivity as the most limiting factor for cultivation. This list provides information of species, which might be suitable for climatic conditions of the country and for soils high in soluble salts. Soil samples have been collected from 30 dikes around different shrimp ponds for determination of soil parameters.