The dyke profiles developed over the course of the centuries in response to the rise in sea level. The new dykes were built according to the previously registered highest water level plus a small tolerance height. In contrast to the strategy adopted nowadays, no account was taken of expected future conditions. Dyke construction and dyke maintenance were tasks undertaken by farmers. With an increasing awareness of the importance of dykes for the well-being of the local community, larger groups gradually took on responsibility for dyke construction and maintenance. Due to the limited technical resources then available, an enormous amount of physical effort was required to build the dykes andprotection struc- tures. Due to the fact that these structures were often destroyed by storm surges in a matter of hours, many people lost their lives or were forced to resettle.
To achieve a comprehensive solution of coastalprotection problems on the Lower We- ser, the provincial government of Lower Saxony andthe Senate of the Free and Hanseatic City of Bremen decided on the erection of three tidal barrages in the river mouths of Hunte, Lesum and Ochtum, tributaries to the Weser. At that time, this solution seemed to be the most economical way to guarantee storm surge protection within a short time span. Because of their influence on the tidal water levels downstream these three barrages could only start to operate conjointly and after the completion of all other flood protection installations alongthe Lower Weser. This condition was finally met in 1979, even though the construction of the Lesum Barrier had been completed in 1974.
For the Meldorf Bay the figure shows that in the time span from 1977 to 1996 some smaller tidal channels silted up. This can be understood as a response to the reclamation of the inner Meldorf Bay, which took place in the 1970s. This artificial reduction of the tidal prism also resulted in adaptations of the Sommerkoog Steertloch tidal drainage system. To- gether with intensified meandering and lateral channel migration in an easterly direction, a decrease of the subtidal volume can be observed. This trend to stronger meandering is most pronounced in the main channel opposite the harbour entrance of Büsum (Fig. 14) where relatively strong accretion can be observed alongthe southern flank and erosion alongthe channel slope in front of the Büsum waterfront. A more detailed analysis of the progressive channel displacement suggests that the breakwaters of Büsum port and other coastal defence structures counteract erosion alongthe channel’s stoss-side. Whereas the shrinkage of the subtidal volume in the inner bay caused by siltation is directly related to the reduced water masses passing through the channels, migration and meandering seem to be controlled by other factors, considering that an increasing meandering tendency was already detectable prior to the diking (W IELAND , 1984).
The Schlei estuary is an inlet extending about 40 kilometers from the mouth at Schleimünde to the town Schleswig. Its geomorphological creation was in the Weichsel ice age, caused by the extending glaciers. In the mid ages the Schlei was an important waterway connection to theNorthSea with only a land bridge of about 16 kilometers width dividing it from the Treene, a small river flowing into the Eider. Vi- king town Haitabu near Schleswig still documents its historic importance (W IKIPEDIA 2014). The water- way is nowadays still used by water tourism as well as small fishery and touristic vessels. The hinterland is characterized by intensive agriculture. The diffusive freshwater input to the Schlei by small creeks im- ports also a significant nutrient load into the water.
In 1995 the Governing Council of the United Nations Environment Programme (UNEP) negotiated the Stockholm Convention in order to reduce the release of persistent organic pollutants (POPs) to the environment. POPs are hardly degradable in the environment and accumulate alongthe food chain causing possible health hazards to humans and wildlife. Today POPs are globally distributed. Enhanced concentrations have been detected even in remote regions like the Arctic, where they have never been used.  During the first period, twelve organic compounds (“dirty dozen”) have been subject to the convention, namely aldrin, chlordane, 1,1,1-trichloro-2,2-di(4- chlorophenyl)ethane (DDT), dieldrin, endrin, heptachlor, hexachlorobenzene (HCB), polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). In May 2009 nine additional POPs were incorporated in the convention, i.e., α-hexachlorocyclohexane, β-hexachlorocyclohexane, lindane, chlordecone, hexabromo- biphenyl, hexabromodiphenyl ether and heptabromodiphenyl ether, pentachlorobenzene, perfluoroctane sulfonic acid and perfluorooctane sulfonyl fluoride, tetrabromodiphenyl ether and pentabromodiphenyl ether. Endosulfan was classified as 22nd POP in April 2011. Moreover, a further category named persistent bioaccumulative and toxic (PBT) chemicals is defined by UNEP, including the POPs as an integral part. The PBT group additionally contains among others trace metals and organo-metal compounds as well as further organic compounds, e.g., perfluorooctanoic acid and polycyclic musks, which may be prospective POP candidates. In order to verify the effectiveness of the Stockholm Convention, comprehensive monitoring data of all environmental compartments are required. Especially, the atmosphere is expected to be an efficient indicator of decreasing POP releases, because atmospheric concentrations change rapidly according to variations in primary sources. [10-13] Europe, USA, Canada andthe Russian Federation additionally ratified the POP protocol of the Convention on Long-Range Transboundary Air Pollution originally negotiated in Geneva 1979. It was entered into force in 2003 and comprises a more extensive spectrum of organic compounds than the “dirty dozen” of the Stockholm convention, e.g., additionally including hexachlorocyclohexanes (HCHs) and polycyclic aromatic hydrocarbons (PAHs). In this context the European Monitoring and Evaluation Programme (EMEP) runs an air monitoring network throughout Europe. Currently the network encloses more than 100 sampling sites, whereof 20 sampling sites distributed in 14 countries are measuring POPs in the atmosphere. Sampling sites on sea are not established. [4, 6, 14]
The research on sea salt emissions and their dependence on wind, waves, temperature, and salinity is a broad field of research that dates back to the 1960s and 70s [Blanchard, 1964; Junge, 1972; Duce and Hoffman, 1976]. In the 1980s, Edward C. Monahan performed detailed studies on the wind dependence of sea salt emissions [Monahan and Muircheartaigh, 1980; Monahan et al., 1982, 1986] forming a basis for nowadays’ sea salt emission parameterization. In recent years, more sophisticated sea salt emission parameterizations were derived – amongst others a parameterization by Ovadnevaite et al.  based on wave model data. However, there are still large uncertainties in the size distribution of sea salt emissions (size distribution = “How much particles of which size are emitted?”). This size distribution is very important for estimating both the atmospheric life time of sea salt particles andthe particle surface area. Particularly in thecoastal regions, the estimation of sea salt emissions is afflicted with large uncertainties because the wave breaking is more complex to predict alongthe coastline due to flat bathymetry and different types of land-water boundaries such as beaches and cliffs. But it would be important to reduce these uncertainties in order to better estimate deposition patterns of sea salt particles and substances attached to them, such as nitrate and ammonium, as well
This paper examines the impact of marine ecosystem quality on inbound coastal tourism in theBaltic, NorthSea, and Mediterranean countries. Given extensive empirical …ndings in ecological science, we use marine protected areas (MPAs) andthe fraction of species that are …shed in each country’s exclusive economic zone that are overexploited or collapsed as a proxy for marine ecosystem quality. We use an autoregressive distributed lag model in a destination-origin panel set up. The empirical …ndings of this paper suggest that MPAs have a negative direct e¤ect on tourism. However, this e¤ect is reversed when the interaction terms with economic variables are included. Also, by using the fraction of species that are overexploited as an indicator of the deterioration of marine ecosystem quality, we …nd a considerable negative impact of this index on inbound coastal tourism. The short-term (current) impact of this index on tourism constitutes less than half of the long-term impact. Results provide valuable information for policy makers, suggesting that measures enhancing marine ecosystem quality should be considered in addition to conventional tourism policies focused on price.
sector, i.e. from the Northeast to Southeast at about 30 % of the time or directly from the South at about 10 to 15 % of the time. The varying shape and changing orientation of the coastlines are the reason that general wind conditions are modified on a regional level. In the Szczecin Lagoon (Stettiner Haff), for example, the south-westerly winds give mainly way to southerly winds and, though less frequently, to westerly winds. The main wind direction varies throughout the year. In April, the wind very often blows from the northern to eastern direction (Fig. 13). Moderate winds from the western wind sector are more frequent in the summer in July (Fig. 14). North-westerly wind directions predominate at theNorthSea coast, while thecoastsalongtheBalticSea mainly receive westerly and south-westerly winds, which often blow gently. October is dominated by winds from southern directions (Fig. 15), with the winter being characterised by southerly/westerly winds at elevated wind speeds (Fig. 16).
In recent times Scyphomedusae attract more attention by unusual “blooms”, non- indigenous species invading new ecosystems (reviewed in Mills 2001) or plagues of giant medusae in Japan (Kawahara et al. 2006). Medusae generally show high inter-annual fluctuations in their abundance (Schneider and Behrends 1994), but native and non- indigenous species have increased in local or regional ecosystems in the last years (reviewed in Mills 2001). Their abundance was increasing in the Bering Sea, Benguela Current and Yangtze Estuary (Brodeur et al. 1999, 2002; Brierley et al. 2001; Purcell 2005; Xiang et al. 2005), but also decreases in medusae populations were reported (Mills 2001; Dawson et al. 2001). Changes are probably caused by pollution or overfishing (Brodeur et al. 1999; Arai 2001; Purcell and Arai 2001). Massive removals of fish from ecosystems open up food sources for gelatinous predators and allow the population to expand (Mills 2001). Also an increase in man-made structures such as floating piers in coastal areas may lead to mass occurrence of medusae (Miyake et al. 2002), as they often provide an adequate hard substrate for polyp settlement. In addition, there is evidence that changes in medusae abundance are indicators of climate induced regional regime shifts (Brodeur et al. 1999; Lynam et al. 2004, 2005a). These climate effected changes in the oceans may be man-made, but also natural climate cycles may affect jellyfish populations. Because of their short generation times, populations of scyphozoan medusae appear to respond to climate forcing without a time lag (Lynam et al. 2005a). To identify the influence of climate variations, records of jellyfish abundance were related to indices of climate oscillations such as El Niño Southern Oscillation or North Atlantic Oscillation (NAO) (reviewed in Purcell 2005). Overlaid on natural climate variation is the potential effect of global warming, which indicates an average warming (0.31°C) in the upper 300m of the world ocean since the mid-1950s (Levitus et al. 2000). The abundance of many jellyfish species may increase in warm conditions (reviewed in Purcell 2005), whereas cold conditions were associated with high medusae abundance in theNorthSea (Lynam et al. 2005a).
To determine the mercury concentration in andthe deposition from the atmosphere we used the chemistry transport model (CTM) CMAQ (Community Model for Air Quality). The CMAQ modelling system was developed by the U.S. EPA and is currently one of the most used CTMs worldwide (Byun & Ching, 1999; Byun & Schere, 2006). Here, we used CMAQ version 5.0.1 with the carbon bond chemistry mechanism version 5 including updated toluene chemistry and improved chlorine reactions: cb05tump (Tanaka et al., 2003; Sarwar et al., 2007), andthe multi pollutant aerosol module aero6 (Yarwood et al., 2005; Whitten et. al., 2010). The mercury chemistry in CMAQ is based on the implementation of Bullock and Brehme (2002) but was updated based on observations and model inter-comparisons in the course of the EU FP7 project GMOS (Global Mercury Observation System) (Bieser et al., 2014) (Eq. 1-1 to 1-5). CMAQ includes three mercury species in the atmosphere: Gaseous Elemental Mercury (GEM), Gaseous Oxidized Mercury (GOM), and Particle Bound Mercury (PBM). To determine the exchange of mercury between the atmosphere and other environmental compartments we utilized a bi-directional flux implementation by Bash (2010). For the default CMAQ runs the dry deposition velocity of mercury is set to zero above water bodies andthe net deposition is calculated using a fixed concentration for mercury in the surface ocean (Bash, 2010). In a second step we re-run CMAQ for the years 2000 and 2005 using the air-sea exchange calculated by the ocean-ecosystem-chemistry model instead for theNorth- andBalticSea, considering the following reactions:
The results on the perception of the SQ conditions at the most often visited BalticSea sites seem to reflect that the overall water quality alongtheBalticSea coast as perceived by the visitors is relatively good even though there are pronounced differences among the countries. Of course this raises the question of whether such perceptions reflect actual envi- ronmental conditions, i.e., physical or bio-geochemical conditions as measured by natural- scientific methods. However, there is evidence that the correlation between perceived and physically measured conditions is significant and positive, even though respondents tend to perceive environmental conditions to be better than objective ones especially when objec- tive water quality assessments state poor conditions (Artell et al. 2013 ). Moreover, percep- tions matter for individual decision-making and are thus central for evaluating impacts of environmental changes (Adamowicz et al. 1997 ). Taken together, the observations on the perceptions of environmental quality at the most often visited BalticSea sites support the usage of the CB method applied in this paper because this method is able to capture the effects of environmental changes that go beyond observed levels. This would have been a limitation of using the TC method for valuing recreational benefits in a case where per- ceived environmental conditions are relatively uniformly distributed and do not include rather poor water qualities.
The overarching goal of this dissertation is to explore the saline and brackish grassland vegetation of theBalticSea coast in order to provide insights into its ecology, phytosociology and conservation potential. Within the three studies that make up this dissertation, I aimed to (i) convert Fennoscandian species-plot data to make them compatible with other data and thereby significantly contributing to the completeness of the data available for broad-scale vegetation analyses of BalticSeacoastal grasslands, (ii) classify and characterise saline and brackish grasslands from the entire BalticSea coast to generate for the first time an overview on their diverse plant communities and ecology from a transnational perspective, (iii) regard the classified plant communities from a North-west European perspective to evaluate their similarities and contrasts with tidal salt grasslands outside the studies’ scope, (iv) discuss their nature conservation aspects on European scale to investigate their conservation potential, (v) investigate the relation between Elytrigia repens and characteristic species of BalticSeacoastal grasslands to get insights into shifts in species composition and other structural and soil abiotic changes and (vi) elaborate a plot-based monitoring concept for BalticSeacoastal grasslands to provide a long-term monitoring system and thus, contribute to the conservation of this vulnerable grasslands.
The concentration time series in Fig. 5 shows that the dates of peaks are consistent across all three stations. The correla- tion coefficient is greater than 0.75 in winter and greater than 0.70 in summer. However, the magnitudes of the peak values do differ in most situations. The model overestimates these values. During winter, overestimations of peak concentra- tions occur at all stations, which is indicated by the box plots (Fig. 5) andthe bias values (Table 2). Coastaland inland sta- tion cannot be distinguished via the MNB during winter, but the RAE is higher at coastal stations than at inland ones. The correlation coefficient is nearly 0.6 or above at all stations except at Ulborg, Keldsnor, and Virolahti II. During summer, sea salt is moderately overestimated at coastal stations (West- erland and Zingst) and underestimated inland (Waldhof), as indicated by the plots and bias values. The MNBs of the other stations, except those of Tange and Keldsnor, support this finding. The measured base line concentrations, i.e., when no peaks are present, are well matched by the model. Win- ter sodium concentrations are approximately twice as high as summer concentrations (see scale in Fig. 5). The RAE andthe MNB values are lower at most stations during summer than during winter, whereas R does not show any tendency between the two seasons.
With 2000-3000 µmol m -2 d -1 , the sedimentation of organic carbon (Fig. 25) was in the same range during peak periods of the three different growth phases. An exception occurred in the beginning of August, where over a period of just 5 days a tenfold (23000 µmol m -2 d -1 ) flux was recorded which was associated with a mixture of diatoms and dinoflagellates. This singular peak comprised all measured elements (C, N, P, Si) and bulk mass but showed no anomalies in qualitative terms (C/N, C/P, C/Si, δ13C-signature) except for the δ15N- values (Fig. 30), which were extremely high (11,85 ‰ ). As this value is much higher than the ~ 8‰ which can be found in nitrate-rich deep or winter water and later in spring bloom material, it is very probable that at that time a lateral intrusion of water with land-derived dissolved nitrogen from livestock farming occured. In July 2017, the rainfall in theNorth-East of Germany was extremely high (223% of the long-term mean in the Rostock region) and it is therefore very likely that runoff from manure loaded rivers draining into the Arkona Sea (e.g. river Peene), from the Danish Sound or from diffuse coastal sources increased the nutrient levels correspondingly at the end of July.
This paper deals with hydrodynamic forcing alongthe open sea boundaries of process- based models for simulating flow and waves in the central Dithmarschen Bight, a tidally-domina- ted area on the German NorthSea coast. The effectiveness of various approaches for determining water levels and waves as open sea boundary input to coastal area models was verified. Compa- risons of measured and computed water levels and waves at several locations for a wide range of conditions typical of the study area were carried out in order to verify the performance of the approaches adopted. The results obtained were found to be in good agreement with observations and confirmed the suitability of the different approaches for describing the hydrodynamics in the study area. In the case of the flow model better agreement was obtained using the approach based on water levels measured directly alongthe open sea boundaries. The mean absolute error in amplitudes and phases at high and low water levels was found to be less than 3 % of the mean tidal range and about 5 % of the tidal period, respectively. Corrections to the results obtained from thenorth-west European Continental Shelf Model based on measured water levels proved to be quite effective for improving the water levels prescribed alongthe open sea boundaries of larger models. The open sea boundary conditions for the wave model, which represent incoming swell energy, were defined by directly imposing (parametric) values deduced from measurements at a location alongthe open boundary and by the application of a model nesting sequence. A comparison between the results of the latter approach and direct measurements showed good agreement. On the basis of the quality standards adopted, the results obtained by applying mo- del nesting were rated as ‘good’ for significant wave heights and ‘reasonable to fair’ for peak periods.
Water level recordings and measurements of currents and waves are the basis for these parameters. The first water level measurements at the tide gauge on Helgoland were carried out and recorded in September 1880. After changing its location several times, the gauge has been at its current position (Fig. 1) since Nov. 1, 1961. Time series of water levels include gaps, particularly for HW, between 1911 and 1952 and during war times. Since 1952, water levels have been continuously recorded, analyzed and published in the Hydrological Year Book (Deutsches Gewässerkundliches Jahrbuch) for theNorthandBalticSea coast (R OHDE , 1990). While the annual means for the time series 1996 – 2005 show a HW = NN + 1.16 m, LW = NN – 1.23 m and a tidal range of 2.39 m the highest recorded storm surge at the gauge Helgoland was at NN + 3.87 m on Feb. 16, 1962. Other major storms occurred in Jan. 1976, Feb. 1990 and Nov. 1982.
Schleswig-Holstein. For theNorthSea coast, the reader is referred to chapter 1.2.1. In contrast to the relatively plane NorthSea coast, theBalticSea coastline of Schleswig- Holstein was formed during the last ice age by glaciers. They left a strongly undulating relief with moraine hills and glacier valleys. In the course of the Holocene sea level rise, the valleys were inundated and a coastal landscape developed, characterised by elongated bays (Förden) and headlands. In all, the coastline measures 637 km, 162 km of which belong to the semi- enclosed Schlei-Förde and another 87 km to the island of Fehmarn (Fig. 1). About 148 km of the coastline are occupied by soft cliffs. As a result of the Holocene sea level rise andthe hydrologic forcing, the long-term morphologic development is characterised by a general retreat of the headlands. For example, the headland “Brodtener Ufer” to theNorth of Lübeck retreated by about 6 km in 6,000 years. The material that was eroded from the headlands was partly transported into the bays (longshore drift). Here, it accumulated in spits which in some cases almost completely cut off the bay from theBalticSea (e.g., Schlei-Förde). Over the time period of 1872/76 to 1951/68, almost 182 km of the coastline receded, whereas 128 km moved forward. Maximum retreat rates are registered at Heiligenhafen cliff with up to 2.5 m/a, whereas the ‘Graswarder’ spit situated some kilometres to the East is growing by 2 to 3 m/a (Fig. 2).
Alongthe northern coastline of the islands, mostly natural dune chains with a width of about 200 to 400 m are to be found. Nowadays, they are defined by decree to be protective dunes. In the central as well as in the southern parts of the islands, marshlands dominate, and almost no protective dunes exist. Here, main dikes have to protect the islands. Dunes and main dikes form a ring of flood protection elements for inhabitated and economically utilized areas (Fig. 7). During storms surges, the islands also reduce the energy of waves approaching the mainland coast. Therefore, they contribute to the safety of the mainland coast and have to be preserved. The eastern shorelines of many of the islands are part of the National Park „Niedersachsen Wadden Sea”. They are not protected by coastal defence structures with the objectives of nature conservation and letting natural processes prevail.
The height, form and duration of storm surges depend on which of the above-mentioned factors are involved and how they are superimposed. In the most unfavourable case, i.e. when all factors coincide with their respective maximum possible increases in water level, it must be assumed that storm surge peak values of about 4.0 m above the normal average water level may result alongthe German BalticSea coast. Although such values have not as yet been measured, historical records handed down over the past 1000 years as well as the geological findings of the University of Greifswald derived from core samples of coastaland seabed deposits as well as shingle deposits on Rügen indicate that such extreme storm surges are indeed possible, as is also evident in the included table. The upper part of this short list con- tains the highest storm surges on theBalticSea coast of Mecklenburg-Vorpommern over the past 1000 years (1044 up to and including 1872) while the lower part of the list contains the highest storm surges accurately measured along our coast since 1872.
The younger history of theBalticSea was dominated by decreasing temperatures over the past 2.4 million years and at least three glacial periods, when ice was advancing from Scandinavia towards NW-Europe. The depression already used by theBaltic Main Stream was carved out further by these ice advances, of which the latest formed the specific geomor- phological shape of the basins, bays, fjords andcoastal areas as we see it today (Fig. 6). Mar- ginal contours of the ice cover are formed by end-moraines, indicating how far these advan- ces and sub-advances, representing an oscillating ice front, were reaching. The distance bet- ween these different contours of the latest ice advance increase from West to East (Fig. 7). Between them melt-water sediments composed of silt, sand and gravel have been deposited. As such, the amount of sand and gravel below the veneer of the modern, post-littorina marine sediments increases from west to east, namely from Schleswig-Holstein via Mecklenburg- Vorpommern to Poland.