German Baltic Research Articles

On the Long-term Changes of Extreme Wave Heights at the German Baltic Sea Coast

ABSTRACT Xu, Z.S.; Dreier, N.; Chen, Y.P., Frohle, P. and Xie, D.M., 2016. On the long-term changes of extreme wave heights at the German Baltic Sea Coast. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 962–966. Coconut Creek (Florida), ISSN 0749-0208. The assessment of extreme wave heights is of great importance for the design of coastal protection strucutres. This paper aims to present long-term changes of extreme wave heights at several selected locations at the German Baltic Sea Coast. Annual maximum significant wave heights were selected from the hourly wave data obtained from a hybrid approach (wind-wave-correlations combined with numerical simulations on the basis of the SWAN model) for a total period of 140 years, spanning from 1961 to 2100. The future projections of wind data were dreived from the regional COSMO-Climate Local Model for t...

ASSESSMENT OF CHANGES OF EXTREME WAVE CONDITIONS AT THE GERMAN BALTIC SEA COAST ON THE BASIS OF FUTURE CLIMATE CHANGE SCENARIOS

Information on possible changes in extreme wave heights is needed to determine the future effectiveness and safety of coastal and flood protection structures. In this study, an assessment of possible changes in the extreme wave heights at selected locations along the German Baltic Sea coast has been carried out on the basis of numerical simulations of waves in the western Baltic Sea and regional climate model data for the past and the future (1961-2100). The future climate change signal of significant wave heights with a return period of 200 years mainly depends on: (i) the location, (ii) the climate change scenario run, (iii) the time period of the comparison, and (iv) the approach adopted to calculate the wave climate. The results show increases of up to +0.5 m and decreases of up to -0.5 m of the extreme wave heights. The increases might have considerable effect on the constructional design of coastal and flood protection structures-such as breakwaters, sea dykes, and vertical walls-because the extreme wave heights are used as input parameters for the design of the structures.

Glyphosate and AMPA in the estuaries of the Baltic Sea method optimization and field study

Water samples from ten German Baltic estuaries were collected in 2012 in order to study the presence of the herbicide glyphosate, its primary metabolite AMPA and their potential transport to the marine environment. For the analyses an LC–MS/MS based analytical method after derivatization with FMOC-Cl was optimized and validated for marine water samples. All investigated estuarine stations were contaminated with AMPA and nine of them also with glyphosate. Concentration ranges observed were 28 to 1690ng/L and 45 to 4156ng/L for glyphosate and AMPA, respectively with strong spatial and temporal fluctuations. Both contaminants were found at inbound sampling sites in the stream Muehlenfliess and concentrations decreased along the salinity gradient to the estuaries of the Baltic Sea. The data obtained in this study clearly depict the transport of glyphosate and AMPA to the Baltic Sea. Hence, detailed fate and risk assessment for both contaminants in marine environments are required.

Microplastic concentrations in beach sediments along the German Baltic coast

The contamination with microplastic particles and fibres was evaluated on beaches along the German Baltic coast. Sediments were sampled near the Warnow and Oder/Peene estuaries, on Rügen island and along the Rostock coast to derive possible entry pathways. Seasonal variations were monitored along the Rostock coast from March to July 2014. After density separation in saline solution, floating particles were found to be dominated by sand grains. Water surface tension is shown to be sufficient to explain floatation of grains with sizes less than 1.5mm. Selecting intensely coloured particles and fibres, we find lower limits of the microplastic concentrations of 0–7particles/kg and 2–11fibres/kg dry sediment. The largest microplastic contaminations are measured at the Peene outlet into the Baltic Sea and in the North Sea Jade Bay. City discharges, industrial production sites, fishing activity and tourism are the most likely sources for the highest microplastic concentrations.

Phosphorus storage and mobilization in coastal Phragmites wetlands: Influence of local-scale hydrodynamics

Coastal Phragmites wetlands are at the interface between terrestrial and aquatic ecosystems and are important for nutrient retention and regulation. They can act both as nutrient sinks and sources for phosphorus, depending on environmental conditions, sediment properties as well as antecedent nutrient loadings and sorption capacities of the sediments. The Darss-Zingst Bodden Chain is a shallow lagoon system at the German Baltic coast with a long eutrophication history which is lined almost at its entire length by Phragmites wetlands. In order to elucidate under which conditions these wetlands act as sources or sinks for phosphorus, in-situ data of chemo-physical characteristics of water and sediment samples were combined with hydrodynamic measurements and laboratory experiments. A basin zone within the wetland serves as accumulation sink for fine-grained particles rich in phosphorus, iron, manganese and organic matter. The Phragmites stems reduce the water flow and allow the accumulation of organic matter and minerals. Without turbulent mixing and downward flow the bottom water and the sediment surface lack replenishment of oxygen. The relationship between oxygen saturation in the water and soluble reactive phosphorus (SRP) concentrations showed a threshold-type behavior. Under oxygen deficiency soluble reactive phosphorus concentrations in the water were significantly higher than under aerated conditions (oxygen saturation <10%: mean SRP = 0.22 mg/L vs. oxygen saturation >10%: mean SRP = 0.02 mg/L). During stagnant periods with low water level, low-turbulence and thus low-oxygen conditions phosphorus from the sediments is released. But the sediments are capable of becoming sinks again once oxygen is resupplied. When vertical downward flows are dominant in the water and turbulent kinetic energy rises, oxygen saturation increases. A thin oxic sediment surface layer rich in iron and manganese is able to readsorb phosphorus quickly as kinetic sorption experiments show, but due to its redox sensitivity the immobilization is – at least in part – only temporary. This study demonstrated that sediments in coastal Phragmites wetlands can switch their function from sink to source of soluble reactive phosphorus on a very short time-scale, depending on local-scale hydrodynamic conditions and the state of the oxic–anoxic sediment interface.

Biotope map of the German Baltic Sea

Full-coverage maps on the distribution of marine biotopes are a necessary basis for Nature Conservation and Marine Spatial Planning. Yet biotope maps do not exist in many regions. We are generating the first full-coverage biotope map for the German Baltic Sea according to the HELCOM Underwater biotope and habitat classification system (HUB). Species distribution modelling is applied to create full-coverage spatial information of biological features. The results of biomass modelling of twelve target taxa and presence/absence modelling of three target taxa enabled the identification of biological levels up to HUB level 6. Environmental data on bathymetry, light penetration depth and substrate are used to identify habitat levels. HUB biotope levels were combined with HUB habitat levels to create a biotope map. Altogether, 68 HUB biotopes are identified in the German Baltic Sea. The new biotope map combining substrate characteristics and biological communities will facilitate marine management in the area.

Luminescence dating of Weichselian interstadial sediments from the German Baltic Sea coast

A cliff outcrop called Kluckow, in the Baltic Sea area, with a (glacio-) fluvial to (glacio-) lacustrine succession, provides a unique opportunity to resolve uncertainties in the timing and extent of several poorly constrained Weichselian ice advances. Based on a detailed lithofacies analysis, we selected four sampling horizons for luminescence dating to determine a depositional chronology. We measured both coarse-grain quartz and potassium-rich feldspar for age determination using optically stimulated luminescence (OSL) and post-IR infrared stimulated luminescence (pIRIR). Furthermore we addressed potential problems such as incomplete bleaching and quartz saturation effects. The resulting luminescence-chronology, supported by one radiocarbon age, illustrates a depositional time interval of the investigated sequence between ∼62 and ∼22 ka. Within this sequence a mussel-bearing fluvial sand indicate interstadial climate conditions at approximately 46 ka. The upper part of the section is composed of a 4 m thick glaciolacustrine silty clay and an overlying glaciofluvial sand; the latter yielded an OSL age of ∼22 ka. Shortly after these sequences formed, the subsequent ice advance (indicated by the overlying till sheet) reached the study area. Based on our new chronology and lithofacies analysis, we conclude that the Scandinavian Ice Sheet did not reach the study area between ∼62 and ∼22 ka.

Climate-change lore and its implications for climate science: Post-science deliberations?

Using of the results of survey questionnaires distributed to climate scientists who focus on the German Baltic coast, regional political decision makers on the German Baltic coast and weather observations from the same region, this paper assesses the existence of developing climate-change lore and the implications for the role of climate science in the science–policy interface. The Oxford Dictionary (1993) provides one definition of lore as ‘A doctrine, a precept; a creed, a religion.’ This is the definition adopted for this paper. The paper concludes that the discrepancies among weather observations, scientific assessments and decision makers’ perceptions suggest that climate-change lore exists, or is coming into existence. The paper then discusses the implications for the science–policy interface and suggests that given current trajectories, science could come to play a secondary role to climate-change lore in regional political decision making concerning climate change. To the truth-to-power model of the science–policy interface and the tenets of post-normal science, three additional possibly evolving science–policy configurations (as pertaining to the climate change issue) are offered.

Implementation of European marine policy: New water quality targets for German Baltic waters

A full re-calculation of Water Framework Directive reference and target concentrations for German coastal waters and the western Baltic Sea is presented, which includes a harmonization with HELCOM Baltic Sea Action Plan (BSAP) targets. Further, maximum allowable nutrient inputs (MAI) and target concentrations in rivers for the German Baltic catchments are suggested. For this purpose a spatially coupled, large scale and integrative modeling approach is used, which links the river basin flux model MONERIS to ERGOM-MOM, a three-dimensional ecosystem model of the Baltic Sea. The years around 1880 are considered as reference conditions reflecting a high ecological status and are reconstructed and simulated with the model system. Alternative approaches are briefly described, as well. For every WFD water body and the open sea, target concentrations for nitrogen and phosphorus compounds as well as chlorophyll a are provided by adding 50% to the reference concentrations. In general, the targets are less strict for coastal waters and slightly stricter for the sea (e.g. 1.2mg/m³ chl.a summer average for the Bay of Mecklenburg), compared to current values. By taking into account the specifics of every water body, this approach overcomes the inconsistencies of earlier approaches. Our targets are well in agreement with the BSAP targets, but provide spatially refined and extended results. The full data are presented in Appendix A1 and A2.To reach the targets, German nitrogen inputs have to be reduced by 34%. Likely average maximum allowable concentrations in German Baltic rivers are between 2.6 and 3.1mgN/l. However, the concrete value depends on the scenario and uncertainties with respect to atmospheric deposition. To our results, MAI according to the BSAP may be sufficient for the open sea, but are not sufficient to reach a good WFD status in German coastal waters.

Using indicators based on primary fisheries' data for assessing the development of the German Baltic small-scale fishery and reviewing its adaptation potential to changes in resource abundance and management during 2000–09

Despite recent progress in the study of the German Baltic Small-Scale Fishery (SSF), there is still a lack of relevant data and quantitative assessments of the SSF sector's key characteristics (e.g. fleet, catch). Moreover, little insight exists on the impacts of past environmental and management changes on the German Baltic SSF. Using a spatial database developed specifically for the German Baltic SSF sector, we assess the sector's key structural and operational characteristics (vessel numbers, gears, landings and target species) to review its development during the period between 2000–09. We link exhibited trends with changes that took place in the wider Baltic Sea region in fisheries' resource abundance and management, in order to provide insights in the sector's adaptation potential to past changes. Results suggest that the SSF was affected by changes in the abundance and allocation of fishing opportunities (TACs) of major target species (herring and cod) and technical measures for fishing gear. There is also evidence to suggest that the SSF was affected by measures directed to the activity of the Large-Scale Fishery (LSF). We argue that such an approach can provide new insights on the impacts of future management changes or incidents of environmental variability on the SSF sector and is crucial in order to effectively integrate SSFs within policy.

Lithosphere and upper-mantle structure of the southern Baltic Sea estimated from modelling relative sea-level data with glacial isostatic adjustment

Abstract. During the last glacial maximum, a large ice sheet covered Scandinavia, which depressed the earth's surface by several 100 m. In northern central Europe, mass redistribution in the upper mantle led to the development of a peripheral bulge. It has been subsiding since the begin of deglaciation due to the viscoelastic behaviour of the mantle. We analyse relative sea-level (RSL) data of southern Sweden, Denmark, Germany, Poland and Lithuania to determine the lithospheric thickness and radial mantle viscosity structure for distinct regional RSL subsets. We load a 1-D Maxwell-viscoelastic earth model with a global ice-load history model of the last glaciation. We test two commonly used ice histories, RSES from the Australian National University and ICE-5G from the University of Toronto. Our results indicate that the lithospheric thickness varies, depending on the ice model used, between 60 and 160 km. The lowest values are found in the Oslo Graben area and the western German Baltic Sea coast. In between, thickness increases by at least 30 km tracing the Ringkøbing-Fyn High. In Poland and Lithuania, lithospheric thickness reaches up to 160 km. However, the latter values are not well constrained as the confidence regions are large. Upper-mantle viscosity is found to bracket [2–7] × 1020 Pa s when using ICE-5G. Employing RSES much higher values of 2 × 1021 Pa s are obtained for the southern Baltic Sea. Further investigations should evaluate whether this ice-model version and/or the RSL data need revision. We confirm that the lower-mantle viscosity in Fennoscandia can only be poorly resolved. The lithospheric structure inferred from RSES partly supports structural features of regional and global lithosphere models based on thermal or seismological data. While there is agreement in eastern Europe and southwest Sweden, the structure in an area from south of Norway to northern Germany shows large discrepancies for two of the tested lithosphere models. The lithospheric thickness as determined with ICE-5G does not agree with the lithosphere models. Hence, more investigations have to be undertaken to sufficiently determine structures such as the Ringkøbing-Fyn High as seen with seismics with the help of glacial isostatic adjustment modelling.

Reference conditions for rivers of the German Baltic Sea catchment: reconstructing nutrient regimes using the model MONERIS

We introduce an approach for establishing reference conditions (RC) for rivers of the German Baltic Sea catchment, based on predictive modelling. An extensive data set of statistics from the year 1880 was coupled with literature data, providing a comprehensive basis for the calculation of regional historical nutrient emissions into rivers, river nutrient concentrations, and nutrient loading into the sea. Four different scenarios were calculated: scenario 1 assumed RC following previously established criteria for lakes (Poikane et al. in Environ Manag 45(6):1286–1298, 2010), scenario 4 applied the nutrient emission conditions of 1880 (considering non-intensive land usage, the presence of tile drainage systems, sewer systems, and the human population from 1880), and scenarios 2 and 3 considered intermediate conditions. Our results showed that nutrient emissions from scenario 1 accounted for approximately one-tenth of the currently observed total nitrogen (TN) and total phosphorus (TP) emissions. The nutrient emissions calculated for 1880 (scenario 4) were found to be 47 % (TN) and 55 % (TP) higher than those calculated considering reference lake conditions (scenario 1). Our results suggest that RC nutrient concentrations in rivers in the German Baltic Sea catchment were clearly below 0.05 mg/l for TP and 1 mg/l for TN. This range is in accordance with historical and calculated pristine nutrient concentrations from other rivers in similar catchments.

Opportunities of Airborne Laser Bathymetry for the Monitoring of the Sea Bed on the Baltic Sea Coast

Abstract. Traditional ship-based bathymetric surveys based on echo sounding are expensive and time consuming. This paper presents a project with the aim of identifying the opportunities of airborne laser bathymetry for the monitoring of the sea bed at the German Baltic Sea coast. Such devices operate with laser signal in the green part of the visible spectrum which is capable to penetrate the water. The depth is determined from the two-way runtime between the water surface and reflections from the ground underneath. Several flight campaigns in representative test areas will be carried out in order to analyze the reachable depths, the accuracies of the acquired points, and the detection of obstacles depending on different water conditions (e.g. turbidity). We discuss some preliminary results of a pilot project and the first campaign of a study area close to the island of Poel, Germany.

Natural variability in hard-bottom communities and possible drivers assessed by a time-series study in the SW Baltic Sea: know the noise to detect the change

Abstract. In order to detect shifts in community structure and function associated with global change, the natural background fluctuation in these traits must be known. In a 6 yr study we characterized the composition of young benthic communities at 7 sites along the 300 km coast of the Kiel and Lübeck bights in the German Baltic Sea and we quantified their interannual variability of taxonomic and functional composition. Along the salinity gradient from NW to SE, the relative abundance of primary producers decreased while that of heterotrophs increased. Along the same gradient, annual productivity tended to increase. Taxonomic and functional richness were higher in Kiel Bight as compared to Lübeck Bight. With increasing species richness functional group richness showed saturation indicating an increasing functional redundancy in species rich communities. While taxonomic fluctuations between years were substantial, functionality of the communities seem preserved in most cases. Environmental conditions potentially driving these fluctuations are winter temperatures and current regimes. We tentatively define a confidence range of natural variability in taxonomic and functional composition a departure from which might help identifying an ongoing regime shift driven by global change. In addition, we propose to use RELATE, a statistical procedure in the PRIMER (Plymouth Routines in Multivariate Ecological Research) package to distinguish directional shifts in time ("signal") from natural temporal fluctuations ("noise").

Genotypic Diversity and Virulence Characteristics of Clinical and Environmental Vibrio vulnificus Isolates from the Baltic Sea Region

The genetic diversity of Vibrio vulnificus isolates from clinical and environmental sources originating from the Baltic Sea region was evaluated by multilocus sequence typing (MLST), and possible relationships between MLST clusters, potential genotypic and phenotypic traits associated with pathogenicity, and source of isolation were investigated. The studied traits included genotyping of polymorphic loci (16S rRNA, vcg, and pilF), presence/absence of potential virulence genes, including nanA, nab, and genes of pathogenicity regions, metabolic features, hemolytic activity, resistance to human serum, and cytotoxicity to human intestinal cells. MLST generated 35 (27 new) sequence types and divided the 53 isolates (including four reference strains) into two main clusters, with cluster I containing biotype 1 and 2 isolates of mainly environmental origin and cluster II containing biotype 1 isolates of mainly clinical origin. Cluster II isolates were further subdivided into two branches. Branch IIB included isolates from recent cases of wound infections that were acquired at the German Baltic Sea coastline between 2010 and 2011 and isolates from seawater samples of the same regions isolated between 1994 and 2010. Comparing the MLST data with the results of genotyping and phenotyping showed that strains of MLST cluster II possess a number of additional pathogenicity-associated traits compared to cluster I strains. Rapid microbiological methods such as matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry combined with typing of selected virulence-associated traits (e.g., serum resistance, mannitol fermentation, nanA, and pathogenicity region XII) could be used for risk assessment purposes regarding V. vulnificus strains isolated from the Baltic Sea region.

Nienhagen Reef: Abiotic Boundary Conditions at a Large Brackish Water Artificial Reef in the Baltic Sea

Schygulla, C. and Peine, F., 2013. Nienhagen Reef: abiotic boundary conditions at a large brackish water artificial reef in the Baltic Sea. This paper briefly describes the abiotic boundary conditions at the artificial reef area in Nienhagen on the coast of the German Baltic Sea. This reef, the largest man-made reef in the Baltic Sea (about 4 ha), was built in autumn 2003 by the state research institute for agriculture and fisheries (LFA) in 12 m water depth. The artificial reef area in the Mecklenburg Bight was mainly constructed to enhance fish populations, especially for the commercially important Baltic cod population. Reef monitoring of abiotic factors (temperature, salinity, O2, pH) started in 2003 and is still in progress, complemented by sediment sampling. The reef rises from the seafloor, up to 3 m at the central structures and between 1 and 2 m in the outer regions. The reef units were chosen for their long life and high stability and for the creation of cavity systems and hideaways for juvenile organisms. The used concrete material was composed in a special way to reach neutral pH values, with regard to the surrounding waterbody, on the surfaces of the structures. The reef units were placed on a strong marl layer with a thin sediment layer of sand and gravel. The grain size distribution and sediment composition within the reef area has changed compared with the surrounding areas since the installation of the reef units.

The application of a Biopollution Index in German Baltic estuarine and lagoon waters

This paper assesses the status of three German Baltic estuarine and lagoon waters with respect to invasive species (macrozoobenthos) and their impact. A Biological Pollution Index was applied and evaluated. Overall 130 macrozoobenthic species were identified, 17 of which were aquatic alien species. The Szczecin Lagoon had the highest number of invasive species (13). Most species were of Pontocaspian origin; inland waterways are likely to play a significant role in their migration. According to the Biological Pollution Index Level (BPL) this lagoon was ‘moderately influenced’ by invasive species. Warnow Estuary had 11 invasive species; their origin noted generally from North-America, suggesting shipping traffic as the major distribution vector; invasive species had the same BPL as in the Szczecin Lagoon. In the Dars-Zingst-Bodden-Chain only 6 invasive species were observed, having the highest relative abundance (9–71%). Furthermore, this area had the highest BPL of all three areas, i.e. a strong negative impact. The BPL required a lot of data (including historical) and some ratings were subjective and comparisons with other areas assessed were difficult and often impossible. Due to these limitations, it is suggested that the BPL should only be used with restrictions as a universal assessment tool for invasive species in the estuarine and lagoon waters of the Baltic Sea.

Growth of European eel Anguilla anguilla along the southern Baltic coast of Germany and implication for the eel management

To detect growth differences of European eel Anguilla anguilla along the southern German Baltic coast 728 yellow eels, with total lengths ranging from 256 to 944 mm and ages ranging from 3 to 15 years were collected from six coastal areas from 2005 to 2009. The estimation of the growth performance was based on the otolith increments. The mean growth rate of the female yellow eels varied from 56 to 62 mm year–1. No significant differences in the mean growth rate were detected between eels from inner and open coastal areas. The overall mean annual increment of eels was estimated at 59 mm year−1. Specific growth rates (SGR) of female yellow eels decreased with increasing age from 0.68 % day−1 in the first year to 0.05 % day−1 in the tenth year. Results indicate that no separation is needed in the development of population models or management initiatives based on the growth performance of eel in inner and open coastal waters of the southern German Baltic coast.

Changes of 21stCentury's average and extreme wave conditions at the German Baltic Sea Coast due to global climate change

Dreier, N., Schlamkow, C., Fröhle, P. and Salecker, D., 2013. Changes of 21st Century's average and extreme wave conditions at the German Baltic Sea Coast due to global climate change.On the basis of hourly simulated wind data from a regional circulation model (Cosmo-CLM) long-term time series (1960–2100) of wave parameters were compiled for two of the SRES scenarios A1B, B1 at three locations along the German Baltic Sea Coast. The time series of wave parameters were calculated with the help of statistical correlations between observed wind and wave data, which were derived for the three locations in the study area. Furthermore, we applied a wave model for the Western Baltic Sea to correct some of the calculated wave information. The key findings of this study are that: (i) significant changes of average wind conditions can directly be linked to significant changes of the average wave conditions, (ii) a spatial pattern for the changes of average wave conditions can be found, (iii) no general trend can be found for the changes of extreme wave conditions. Comparisons of wind conditions, as simulated by the regional circulation model, for the past and the future are showing two main changes: (a) increases of average wind velocities to the end of the 21st century up to 4% and (b) more wind events from westerly and less events from easterly directions. The changes of the average wind velocities are resulting in increases of the average significant wave heights at westerly wind exposed locations up to 7% and small decreases of the average significant wave heights at easterly wind exposed locations. The future changes of the wave directions, with more wave events from W-NW and fewer events from N-NE, can be connected to the future changes of wind directions. Analyses of extreme wave heights with a return period of 200 years are showing both increasing and decreasing changes of up/down to /−14%. At one location of the study area (Warnemünde) a slight increasing trend for the change of extreme wave heights to the end of the 21st century exists.

FUTURE EXTREME WAVES AT THE GERMAN BALTIC SEA COAST DERIVED FROM REGIONAL CLIMATE MODEL RUNS

Information about possible changes of extreme wave heights are essential for the future safe design of coastal and flood protection structures likes dykes, flood protection dunes, revetments etc. In this study, scenarios of regional climate change up to 2100 are used for the evaluation of changes of wave conditions. Analyses on calculated significant wave heights derived from extreme value statistics are showing a different signal of change for the selected locations along the German Baltic Sea Coast. The results are showing that extreme wave heights with a return level of 200 years can increase up to +14%. But also a decrease of down to -14% were found compared to actual conditions, depending on the location and climate change scenario applied. At the location of Warnemunde a slight increasing trend for the change of extreme wave heights could be found for 3 of 4 scenario runs with a maximum increase of +7%.