German Baltic Research Articles

Offshore pile load tests in Chalk to support the design of jacket foundations

Iberdrola developed the 350 MW Wikinger offshore windfarm (OWF) in the German Baltic Sea where ground conditions are mainly dominated by deposits of the Upper Quaternary series and post-glacial deposits overlying Cretaceous Upper Chalk (low-density, grade A1/A2) of Maastrichtian age and at some locations with Paleogene Limestone (high-density to very high density, grade A1/A2). Current pile design methods for open tubular steel piles in Chalk highlighted significant design uncertainties for open tubular piles that would lead to unnecessarily conservative pile dimensions of 70 m embedded length or longer for the 70 four-legged jacket wind turbine support structures and the six-legged offshore substation. For mainly axially loaded piles, German legislation requires the execution of dynamic pile load tests on production piles at a minimum of 10% of wind turbine generator locations immediately following pile installation. This practice offers no opportunity for pile design optimisation. If positive, the pile tests can confirm design assumptions, but risk costly delays in OWF commissioning if the dynamically ‘measured’ capacities fall below design requirements. After careful consideration of costs and benefits, and with the clear advantages of eliminating ambiguity of test results, it was decided that offshore tests at the Wikinger OWF offered the best return on investment regarding foundation design optimisation, assurance and certification. To address these concerns, in advance of final design, offshore dynamic and fully autonomous static pile load tests were commissioned. These were completed 10 weeks after pile driving on 50%-downscaled piles with penetrations of up to 31 m in water depths of around 40 m. This paper provides an overview of the test results and how they were applied in detailed design and validated during construction through dynamic pile tests. Lessons learned are shared and conclusions are drawn regarding on-site offshore pile test results and their transfer into the foundation design and planning process.

Avoidable Mortality in the German Baltic Sea Region Since Reunification: Convergence or Persistent Disparities?

The consequences of political reunification for health and mortality have the unique character of a 'natural experiment'. This is particularly true for the formerly divided German Baltic Sea region due to its cultural and geographic commonalities. This paper ascertains the changes and differences in premature mortality at ages 0-74 in urban and rural areas of the German states of Mecklenburg-Vorpommern (MV) and Schleswig-Holstein (SH) since reunification and the contribution made by 'avoidable' mortality. Using official cause-of-death data, the effectiveness of health care and health policies was measured based on the concept of avoidable mortality in terms of both amenable and preventable conditions. Methods of decomposition and standardisation were employed in order to erase the compositional effect from the mortality trend. As a result, mortality differences relate primarily to men and the rural areas of the German Baltic Sea region. Whereas the mortality levels in the urban areas of MV and SH have converged, the rural areas of MV still show higher levels of preventable and amenable mortality. The results show that the accessibility and quality of medical care in the thinly populated areas of MV and the effectiveness of inter-sectoral health policies through primary prevention, particularly with regard to men, have room for improvement.

Using Information on Settlement Patterns to Improve the Spatial Distribution of Population in Coastal Impact Assessments

Broad-scale impact and vulnerability assessments are essential for informing decisions on long-term adaptation planning at the national, regional, or global level. These assessments rely on population data for quantifying exposure to different types of hazards. Existing population datasets covering the entire globe at resolutions of 2.5 degrees to 30 arc-seconds are based on information available at administrative-unit level and implicitly assume uniform population densities within these units. This assumption can lead to errors in impact assessments and particularly in coastal areas that are densely populated. This study proposes and compares simple approaches to regionalize population within administrative units in the German Baltic Sea region using solely information on urban extent from the Global Urban Footprint (GUF). Our results show that approaches using GUF can reduce the error in predicting population totals of municipalities by factor 2 to 3. When assessing exposed population, we find that the assumption of uniform population densities leads to an overestimation of 120% to 140%. Using GUF to regionalise population within administrative units reduce these errors by up to 50%. Our results suggest that the proposed simple modeling approaches can result in significantly improved distribution of population within administrative units and substantially improve the results of exposure analyses.

Long term development of Bathing Water Quality at the German Baltic coast: spatial patterns, problems and model simulations

Bathing water quality plays a key role for public health, is highly important for recreational tourism and therefore monitored in the EU-Directive 2006/7/EC. To identify pollution hot spots, sources and impacts of the directive-change in 2006, including a change of indicator organisms, we evaluated monitoring data of the past 15 years, collected own data, determined survival rates of indicator organisms and applied hydrodynamic modelling in a micro-tidal-system.Due to higher survival rates under turbid conditions and restricted water exchange, shallow, eutrophic bays and lagoons are hot spots of microbial pollution. Rain events cause high microbial emission and distribution. Based on different decay rates, the ratio of E. coli to Enterococci can hint towards a pollution source. Including rain predictions, currents and winds, hydrodynamic models can then assess the daily risk of microbial pollution at each bathing site. They are an important tool to modify beach management and event-based monitoring.

Using standard additions to improve extraction and quantification of inositol hexakisphosphate in sediment samples by ion chromatography electrospray ionization mass spectrometry

Several key aspects for the analysis of inositol hexakisphosphate (InsP6) have been investigated in order to establish a suitable method for the study of sediment samples from different aquatic systems. Apparent matrix effects for the ion chromatography electrospray ionization tandem mass spectrometric detection (IC-ESI-MS/MS) method were accounted for with a standard addition approach, which also compensated for variation in extraction efficiency. Several parameters of the extraction method were optimized to improve the extraction efficiency for different sediment types. We observed an improvement in the extraction efficiency between 18% and 720%. Finally, the method was used to gain first insights into the relevance of InsP6 in two aquatic systems located at the German Baltic coastal area. InsP6 was detected in several sediment samples with concentrations between 2.3 and 15.2 µg InsP6-P/g dry weight (DW).

The conquest (and avoidance?) of the brackish environment by Ponto-Caspian amphipods: A case study of the German Baltic Sea

The conquest (and avoidance?) of the brackish environment by Ponto-Caspian amphipods: A case study of the German Baltic Sea

Diaspore bank analysis of Baltic coastal waters

The coastal waters are important transition zones for terrestrial nutrient and pollutant runoff and the open Sea. During the last decades, eutrophication has negatively influenced macrophyte communities of the coastal ecosystems, making restoration activities inevitable. This study analysed recent macrophyte vegetation and the reproductive potential through the sediment diaspore reservoir along the German Baltic Sea coastline. Salinity was identified to be the responsible factor for shifts in the macrophyte community with most commonly found species like Stuckenia pectinata or Myriophyllum spicatum. In contrast, the oospores of small charophytes (e.g. Tolypella nidifica) clearly dominated the sediment diaspore bank. The germination rates differed in the recent vegetation composition and the diaspore bank composition with Zannichellia palustris as the dominant species. However, several species not visually detected at the respective sites were represented in the diaspore bank and germinated at a low rate (e.g. Chara contraria and Lamprothamnium papulosum). The maximal germination frequency corresponded to the sediment layer in which diaspore density was the highest (5–15 cm). In conclusion, the germinable diaspores were observed at all sites. Considering the differences between the diaspore composition, recent vegetation and germination success, we have illustrated the potential of the diaspore banks for the restoration of the macrophyte communities after at least mid-term periods of disturbance.

Teredo navalis in the Baltic Sea: Larval Dynamics of an Invasive Wood-Boring Bivalve at the Edge of Its Distribution

Wooden groin systems on the southwestern Baltic Sea coast are a traditional and important coastal-protection facility, but have been regularly infested and destroyed by the wood-boring bivalve Teredo navalis since the early 1990s. The occurrence of T. navalis was presumed to be limited mainly by the prevailing low salinities. Recently, a possible range expansion of this invasive species to the more eastern parts of the Baltic Sea has been discussed. T. navalis larval settlement was therefore monitored at the distribution boundary of the species in the Baltic Sea over a period of four years. At seven stations along the prevailing salinity gradient on the Mecklenburg-western Pomeranian coast, larval traps were installed at regular time intervals, while at the same time water temperature and salinity were measured continuously every hour. Correlations between measured abiotic parameters and borehole abundance of T. navalis were tested. For the German Baltic Sea coast, no range expansion of T. navalis was confirmed. The salinity and temperatures at the groin systems varied among the study years, and significant correlations between T. navalis borehole abundance and salinity as well as temperature were found. Higher summer temperatures favor the T. navalis borehole abundance on the Mecklenburg-western Pomeranian coast, and may slightly shift the distribution border of this species toward lower salinities.

Regional decision-makers as potential users of Extreme Weather Event Attribution - Case studies from the German Baltic Sea coast and the Greater Paris area

Extreme Event Attribution has raised increasing attention in climate science in the last years. It means to judge the extent to which certain weather-related extreme events have changed due to human influences on climate with probabilistic statements. Extreme Event Attribution is often anticipated to spur more than just scientific ambition. It is able to provide answers to a commonly asked questions after extreme events, namely, ‘can we blame it on climate change’ and is assumed to support decision-making of various actors engaged in climate change mitigation and adaptation. More in-depth research is widely lacking about who these actors are; in which context they can make use of it; and what requirements they have, to be able to actually apply Extreme Event Attribution. We have therefore addressed these questions with two empirical case studies looking at regional decision-makers who deal with storm surge risks in the German Baltic Sea region and heat waves in the Greater Paris area. Stakeholder interviews and workshops reveal that fields of application and requirements are diverse, difficult to explicitly identify, and often clearly associated with stakeholders' specific mandate, the hazard background, and the regional socio-economic setting. Among the considered stakeholders in the Baltic Sea region, Extreme Event Attribution is perceived to be most useful to awareness-raising, in particular for climate change mitigation. They emphasised the importance of receiving understandable information - and that, rather later, but with smaller uncertainties than faster, but with higher uncertainties. In the Paris case, we typically talked to people engaged in adaptation with expertise in terms of climate science, but narrowly defined mandates which is typical for the Paris-centred political system with highly specialised public experts. The interviewees claimed that Extreme Event Attribution is most useful to political leverage and public discourses. If novel information like this is not sorted out a priori, it needs to be clearly linked to impacts, preferably as monetary values lost. These examples underline the significance of conducting case-specific stakeholder mappings and consultation. Overall, our studies can thereby provide methods and exemplary empirical evidence to support developing useful services from Extreme Event Attribution for targeted groups of users.

Developing criteria for a stakeholder-centred evaluation of climate services: the case of extreme event attribution for storm surges at the German Baltic Sea

Developing criteria for a stakeholder-centred evaluation of climate services: the case of extreme event attribution for storm surges at the German Baltic Sea

Stakeholder-based evaluation categories for regional climate services – a case study at the German Baltic Sea coast

Abstract. In this study, categories, dimensions, and criteria for evaluating regional climate services are derived by a participatory approach with potential service users at the German Baltic Sea coast. The development is carried out within nine face-to-face interviews conducted with decision makers, working in climate sensitive sectors at the German Baltic Sea coast. Three main groups of categories were localized which seem to matter most to the considered stakeholders and which seem to be crucial evaluation categories for regional climate services: (1) credibility, (2) relevance, and (3) appropriateness. For each of these evaluation categories several dimensions emerged, indicating certain perspectives of stakeholder demands. When summarizing these evaluation categories and their dimensions, 13 evaluation criteria for regional climate services can be derived (see Table 1). The results show that stakeholders do mainly address components other than those found in the literature (e.g. inputs, process, outputs, outcomes, and impacts). This might indicate that an evaluation, following solely literature-based (non-participative) components, is not sufficient to localize deficiencies or efficiencies within a regional climate service, since it might lead to results which are not relevant for potential users.

Occurrence of pharmaceuticals and UV-filters in riverine run-offs and waters of the German Baltic Sea

The occurrence of pharmaceuticals and personal care products (PPCPs) in the marine environment is of great concern. This study was done to determine the emergence of eight pharmaceuticals and eleven ultraviolet filters (UV-Filters) in 5 rivers/streams discharging into the Baltic Sea. Furthermore, a focus was put on the influence of wastewater treatment plant as indirect source and the occurrence of the PPCPs in close beach proximity. Two pharmaceuticals (sulfamethoxazole, salicylic acid) and two UV-filters (2-phenylbenzimidazole-5-sulfonic acid, octocrylene) were detected in all analyzed water samples, with concentration ranging from 0.6ng/L to 836.3ng/L. In all rivers the PPCP concentration decreases towards the Baltic Sea. Sulfamethoxazole was detected at comparable concentration along the coast, which leads to the assumption of stable concentration in beach proximity. Along the coast UV-filters appeared in varying concentrations, leading to the conclusion that the direct input into the marine environment plays a bigger role than the indirect input.

Eelgrass Leaf Surface Microbiomes Are Locally Variable and Highly Correlated with Epibiotic Eukaryotes

Eelgrass (Zostera marina) is a marine foundation species essential for coastal ecosystem services around the northern hemisphere. Like all macroscopic organisms, it possesses a microbiome (here defined as an associated prokaryotic community) which may play critical roles in modulating the interaction of eelgrass with its environment. For example, its leaf surface microbiome could inhibit or attract eukaryotic epibionts which may overgrow the eelgrass leading to reduced primary productivity and subsequent eelgrass meadow decline. We used amplicon sequencing of the 16S and 18S rRNA genes of prokaryotes and eukaryotes to assess the leaf surface microbiome (prokaryotes) as well as eukaryotic epibionts in- and outside lagoons on the German Baltic Sea coast. Prokaryote microbiomes varied substantially both between sites inside lagoons and between open coastal and lagoon sites. Water depth, leaf area and biofilm chlorophyll a concentration explained a large amount of variation in both prokaryotic and eukaryotic community composition. The prokaryotic microbiome and eukaryotic epibiont communities were highly correlated, and network analysis revealed disproportionate co-occurrence between a limited number of eukaryotic taxa and several bacterial taxa. This suggests that eelgrass leaf surfaces are home to a mosaic of microbiomes of several epibiotic eukaryotes, in addition to the microbiome of the eelgrass itself. Our findings thereby underline that eukaryotic diversity should be taken into account in order to explain prokaryotic microbiome assembly and dynamics in aquatic environments.

On the comparability of knowledge transfer activities – a case study at the German Baltic Sea Coast focusing regional climate services

Abstract. In this article the comparability of knowledge transfer activities is discussed by accounting for external impacts. It is shown that factors which are neither part of the knowledge transfer activity nor part of the participating institution may have significant impact on the potential usefulness of knowledge transfer activities. Differences in the potential usefulness are leading to different initial conditions of the knowledge transfer activities. This needs to be taken into account when comparing different knowledge transfer activities, e.g., in program evaluations. This study is focusing on regional climate services at the German Baltic Sea coast. It is based on two surveys and experiences with two identical web tools applied on two regions with different spatial coverage. The results show that comparability among science based knowledge transfer activities is strongly limited through several external impacts. The potential usefulness and thus the initial condition of a particular knowledge transfer activity strongly depends on (1) the perceived priority of the focused topic, (2) the used information channels, (3) the conformity between the research agenda of service providing institutions and information demands in the public, as well as (4) on the spatial coverage of a service. It is suggested to account for the described external impacts for evaluations of knowledge transfer activities. The results show that the comparability of knowledge transfer activities is limited and challenge the adequacy of quantitative measures in this context. Moreover, as shown in this case study, in particular regional climate services should be individually evaluated on a long term perspective, by potential user groups and/or by its real users. It is further suggested that evaluation criteria should be co-developed with these stakeholder groups.

Beach macro-litter monitoring on southern Baltic beaches: results, experiences and recommendations

Major objectives were to provide a comprehensive dataset on beach macro-litter for parts of the southern Baltic Sea and to analyse if the methodology is fully applicable and a suitable monitoring method in the Baltic. We carried out a regular macro litter beach monitoring (OSPAR methodology, 4 time a year) on 35 beaches along the German and Lithuanian Baltic coast over 2–5 years. Additional experiments addressed the subjectivity of the field surveys and spatio-temporal variability on different scales. We observed no seasonality of the data and a monthly compared to a 3-monthly sampling resulted in 3 times higher annual item numbers. Along the Lithuanian coast, the average number of items per survey varied between 138 and 340 and along the German Baltic coast between 7 and 404, with a median value of 47. All data showed a very high spatio-temporal variability. Using the Matrix Scoring Technique we assessed beach litter sources. With 50% tourism and recreation was the most important source. 3D–transport simulations helped to explain the minor role of shipping as a source and, compared to the North Sea, the low numbers of items on German Baltic beaches. Floating litter had a short duration time in the western Baltic Sea and offshore drift dominated. Further, the common regular beach cleanings reduced the potential for local litter accumulation and translocation. We suggest a monitoring system on 14 Baltic beaches in Germany and 2 in Lithuania and provide cost calculations. The analysis of macro-litter in cormorant nesting material and the search for beached dead animals did not show any result. We can conclude that the macro-litter beach monitoring method is less suitable for Baltic beaches and should only serve as a complementary method in combination with others.

Retrospective assessment of a managed coastal realignment and lagoon restoration measure: the Geltinger Birk, Germany

We document and analyse the implementation process of a large combined coastal protection realignment and nature protection rewetting scheme, covering about 1000 ha at the German Baltic coast. The assessment reviews local planning documents, includes a media analysis, a tourist survey, stakeholder interviews and we provide criteria for measuring success, derived from the Systems Approach Framework (SAF) concept. The full process in the Geltinger Birk took over 25 years and was finished in 2013. The early years were characterised by strong local opposition, a polarization of the local society, misinformation and negative media coverage. Land purchase, the establishment of a local information centre with an environmental manager, improved public participation, a more pro-active media strategy and the readiness to accept compromises finally enabled a successful implementation. Today, a comprehensive tourism information and guidance system exists and the area became a popular tourist place. 80% of all visitors point out the outstanding nature experience and 87% are positive about the combined coastal protection and restoration measure. Parallel, major stakeholders changed their attitude and today are positive about the situation. However, the long timespan between initiation of the process and implementation of the measure, calls for a systematic, guided management approach, like the SAF. Especially, because climate change, sea level rise and increasing pressures on the coasts require a much faster implementation of adaptation measures in future.

Managed Realignment (MR) along the Eastern German Baltic Sea: A Catalyst for Conflict or for a Coastal Zone Management Consensus

ABSTRACT de la Vega-Leinert, A.C.; Stoll-Kleemann, S., and Wegener, E., 2018. Managed realignment (MR) along the Eastern German Baltic Sea: A catalyst for conflict or for a coastal zone management consensus. Managed Realignment (MR), which involves the removal of coastal defences or their relocation further inland, is a desirable option for demographically and economically marginal rural areas, from scientific, political and managerial perspectives. In Europe, MR is reshaping coastal landscapes, and, though not directly endangering lives, is affecting people's sense of safety and control over their land and livelihoods. This can elicit conflict, but also foster consensus. In this study, participatory qualitative research methods were used to investigate stakeholders' perceptions and preferences with regard to coastal land management strategies on the eastern German Baltic coast in the state of Mecklenburg–Western Pomerania. MR reflects a change in the way in which coastal land is valued, with supporting a...

Baltic Sea extreme sea levels 1948-2011: Contributions from atmospheric forcing

Extreme sea levels in the Baltic Sea are usually analyzed from tide-gauge data covering more or less extended periods. More comprehensive spatial or systematic analyses are less frequently available. Data from a high-resolution tide-surge model driven by high-resolution reanalyzed atmospheric fields reconstructing Baltic Sea sea levels from 1948 to 2011 on an hourly basis are analyzed. Meteorologically induced sea levels are characterized by pronounced annual to decadal fluctuations and a typical seasonal distribution comparable to the variability in regional wind climate. No substantial long-term trends over the considered period could be detected. Wind set-up represents the most dominant factor, however, short term variations in the filling levels of the basin and seiches contributed substantially to some of the observed peak water levels in the past. For the tide-gauge Wismar at the German Baltic Sea coast, it is exemplarily demonstrated that storm surges during periods with and without high filling levels occurred at about equal shares. When high filling levels were present, lower wind speeds were generally needed to sustain comparable peak water levels. Seiches also contributed to some of the observed extremes usually with a preferred phase shift. For Wismar, in about one third of the cases contribution from seiches at peak water level was found to exceed 10 cm.

Late Saalian and Weichselian glaciations in the German Baltic Sea documented by Pleistocene successions at the southeastern margin of the Arkona Basin

Seismic profiles and numerous sediment cores of a planned offshore wind farm area northeast of Rügen Island provide a unique insight into the distribution and thickness of glacial deposits in the southern Baltic Sea. Fine gravel analysis enabled recognition of five tills that correspond to different ice advances. On the basis of a 3D structural model, the main Pleistocene events could be reconstructed and correlated with stratigraphical records in the circum‐Baltic area comprising Marine Isotope Stages (MIS) 6 to 2. The oldest till was deposited during the Late Saalian Warthe advance (qs2; c. 150–130 ka). It is only preserved in ENE–WSW trending subglacial channels incised into Upper Cretaceous soft chalk. Isolated rafts and remnants of two Middle Weichselian tills occur locally, whereas Eemian interglacial sediments are missing. The older till (qw*) has an unusual fine gravel composition and might have formed during ice advances known only from northern Denmark and northern Poland (c. 65–60 ka). The younger till represents the Warnow advance (qw0) in NE Germany that can be correlated with the Danish Ristinge advance (c. 55–50 ka). Furthermore, two tills deposited during the Late Weichselian Last Glacial Maximum (c. 24–16 ka) occur. One can be correlated with the Pomeranian advance (qw2), while the other has characteristics typical for the Mecklenburg advance (qw3). These advances eroded older Pleistocene deposits, thus probably also removing the till of the Brandenburg/Frankfurt advance (qw1) – in contrast to the onshore areas. The Pomeranian till is limited to the southeast, close to the shallow Adlergrund, but the Mecklenburg till covers the whole study area. This first detailed lithostratigraphical classification of till units from the Arkona Basin allows for the identification and correlation of Pleistocene successions in other parts of the southern Baltic Sea.

Reducing agricultural nitrogen inputs in the German Baltic Sea catchment - trends and policy options.

We depict recent agricultural nitrogen input and future loads to be expected in 2021 in the German Baltic Sea catchment to assess the feasibility of reaching water quality targets defined by the Marine Strategy Framework Directive (MSFD). We calculate recent and future nitrogen balances from agriculture by applying an interdisciplinary modelling system, also considering the effects of the Nitrate Directive. The nitrogen surpluses are transferred to a nutrient emission model to simulate nitrogen emissions, in-stream retention and resulting riverine loads to the sea until 2021. Finally, we analyse input reduction demands and agri-environmental measures necessary to attain water quality targets of the MSFD. The results are target-oriented mitigation options relevant for implementation, based on regional land use and nitrogen reduction demands. Furthermore, this paper discusses the effects of policies and measures implemented to reduce nitrogen loads.