Wadden Sea Area Research Articles

Harbour porpoise (Phocoena phocoena) in the Wadden Sea World Heritage Site and requirements for trilateral monitoring

The harbour porpoise (Phocoena phocoena) is considered part of the ‘Outstanding Universal Value’ characterising the Wadden Sea World Heritage Site (WS WHS). The Trilateral Wadden Sea Plan aims to preserve the conservation status of the Trilateral Wadden Sea Cooperation Area, encompassing the WS WHS. The plan has specified two conservation targets for the harbour porpoise: (1) viable stocks and a natural reproduction capacity and (2) conservation of habitat quality for its conservation. To assess the current occurrence of the harbour porpoise in the Wadden Sea area, we collated and analysed data from regional and national research projects using telemetry, aerial surveys, strandings and passive acoustic monitoring, obtained over the years 1990–2020. The results illustrate that porpoises occur in both offshore and intertidal waters, showing seasonal movements and changes in local occurrence over time. Some porpoises displayed limited home ranges throughout the year, suggesting a possible residency for some of the animals using the Wadden Sea area. We also showed that methods, frequency and spatial coverage of monitoring activities vary among the countries Denmark, Germany and the Netherlands. We discuss the suitability of the different methods both regarding the challenges of monitoring in the complex Wadden Sea habitat as well as their ability to target the conservation aims of the WHS. We give several recommendations to assess the status of the species to meet the identified conservation aims.

Evaluation of seagrass as a nature-based solution for coastal protection in the German Wadden Sea

Global climate change increases the overall risks for coastal flooding and erosion. Meanwhile, nature-based solutions (NbS) are increasingly becoming a focus of coastal protection measures to improve the climate adaptability. In this study, the present and potential future role of seagrass in coastal risk reduction strategies were explored for the highly energetic Wadden Sea area of the German Bight. The methodology in this study combined seagrass coverage data (Zostera marina and Zostera noltei) obtained by field surveys and what-if scenario simulations using the SCHISM unstructured grid model framework, coupling hydrodynamics, waves, sediments, and a seagrass module. The results suggest that the introduction of seagrass meadows locally can reduce both current velocities and significant wave heights in the order of up to 30% in the deeper areas and above 90% in the shallow areas. Reduction in bottom shear stress of a similar relative magnitude significantly reduced sediment mobilisation on the order of 2 g/L in the 95th quantile of bottom layer sediment concentrations. Effectively altering hydromorphodynamic conditions favouring sediment accumulation, seagrass expansion could help tidal flats height growths to keep up with SLR, thus further maintaining the bathymetry-induced tidal dampening and lowering flooding and erosion risks as well the amount of energy at dike infrastructure. The accumulated effect of seagrass under calm weather conditions is considered more important than the increased attenuation in absolute values it provides during extreme conditions. The overall conclusion is that seagrass expansion could be a useful addition to engineered coastal protection measures.

Braving the extremes: foraminifera document changes in climate-induced and anthropogenic stress in Wadden Sea salt marshes

Tidal wetlands are highly dynamic ecosystems that are susceptible to changes in sea level and flooding from storm surges. Among them, salt marshes play a key role in coastal protection as they contribute to wave attenuation through their regulating ecosystem services, thereby promoting sediment deposition and shoreline stabilization. However, the resilience of salt marshes, particularly those that have been modified and cultivated for centuries, is questionable in the face of accelerated sea-level rise (SLR) and increasing run-up heights of storm surges. In this context, this study aims to investigate the historical foraminiferal records of two sedimentary salt marsh archives from the Wadden Sea area (Dithmarschen and North Frisia, Germany) that have been modified to varying degrees by human management activities over the last century. The foraminiferal records document how physico-chemical traits of salt marshes of the central Wadden Sea have responded to storm tide inundation over the last century, providing information about salt marsh stability and vulnerability. Abnormally grown tests of the salt marsh indicator speciesEntzia macrescensincreased in number between 1950 CE and the late 1980s, indicating the concurrent increase of environmental stress caused by the effects of times of increased salt marsh flooding. These trends can be linked to observations of amplified North Sea storm surges, corroborating that salt marsh ecosystems respond to changing climate conditions. Differences in the number of abnormal foraminifera between the studied salt marshes suggest a particularly high vulnerability of intensively human-modified coastal wetland ecosystems to amplified storm climate conditions.

Mass mortality among colony-breeding seabirds in the German Wadden Sea in 2022 due to distinct genotypes of HPAIV H5N1 clade 2.3.4.4b.

Mass mortality was observed among colony-breeding seabirds in the German Wadden Sea area of the North Sea during the summer months of 2022. Several species' colonies were affected, most notably sandwich terns (Thalasseus sandvicensis), common terns (Sterna hirundo) and Germany's only northern gannet (Morus bassanus) colony on the island of Heligoland. Mortality in some tern colonies reached 40%, while other colonies were almost spared. In all cases, infections with the high-pathogenicity avian influenza virus (HPAIV) subtype H5N1 of clade 2.3.4.4b were identified to have caused the epidemic. Phylogenetic analysis of whole-genome sequences revealed that the outbreaks were dominated by two genotypes, Ger-10-21 N1.2 and Ger-10-21 N1.5, previously identified in Germany. Spatiotemporal analyses of phylogenetic data suggested that these viruses could have entered the continental North Sea coastal region via the British Isles. A close linkage of viruses from tern colonies in the German Wadden Sea was evident with further connections to breeding colonies in Belgium and the Netherlands, and further spread to Denmark and Poland. Several of the affected species are endangered, such that negative effects of epizootic HPAIV infections on populations are feared, with uncertain long-term consequences.

A monitoring and data analysis method for microplastics in marine sediments

In Europe, policy frameworks demand the monitoring of microplastics in marine sediments. Here we provide a monitoring and data analysis method for microplastic particles designed to be used in the context of Marine Strategy Framework Directive (MSFD) and OSPAR policy frameworks. Microplastics were analysed in marine sediments at four different locations in Dutch coastal and transitional waters using replicate sampling to investigate micro-spatial variation. Particle size distribution followed a power law with slope 3.76. Thirteen polymers were identified, with their composition varying between sediments near densely populated West coast areas versus the more rural Wadden Sea area. We quantify differences in the micro-spatial variation of microplastic concentrations between locations using the relative standard error of the mean (RSEM). This metric provides an opportunity to optimize the sensitivity of trend detection in microplastic monitoring networks by selecting locations with relatively low micro-spatial variation. We provide a method to optimize the number of replicate samples for a given location using its relationship with the RSEM. Two replicate samples appear to be cost-effective for relatively homogenous locations, whereas more heterogenous locations require four replicates.

Numbers of Horned Lark (Eremophila alpestris) are increasing at high alpine and arctic breeding sites in Norway

Cover photo: Female Horned Lark Eremophila alpestris. Photo: Terje Lislevand. Strong declines in number of breeding Horned Larks Eremophila alpestris were reported from several Fennoscandian breeding grounds in the 1960s and 1970s. Counts from the species’ high alpine breeding grounds at Hardangervidda, southern Norway in the early 1980s and the first couple of decades in the 2000s, and from its arctic breeding grounds in the Varanger region, northern Norway in the period 1996-2021, show a reversal of the trend. The increase in numbers is suggested to have resulted primarily from recovery of nonbreeding habitat after cessation of extensive building of embankments to prevent flooding in the German Wadden Sea area, which is the main wintering area of Fennoscandian Horned Larks.

Changes in tidal asymmetry in the German Wadden Sea

The recent morphological development of the German Wadden Sea (North Sea, Europe) has been characterized by expanding intertidal flats and deepening, narrowing tidal channels at declining subtidal volume. This study analyzes the effect of these changes on tidal asymmetry, based on numerical modeling with high-resolution bathymetry data, and discusses possible adaptations of the import and export behavior in intertidal systems. As common descriptors of tidal asymmetry may show a high spatial variability in bathymetrically complex intertidal systems, we develop a novel subregion averaging approach for a more robust trend estimation. Our data reveal a statistically significant decrease in flood and flood current duration in the period from 1996 to 2016 resulting in declining flood dominance or enhanced ebb dominance in most tidal basins of the German Wadden Sea. Mean and peak current asymmetry also indicate significant decreases in mean flood current magnitude. We relate decreasing flood dominance mostly to local bathymetric volume changes rather than tidal amplitude. However, it appears likely that the sum of local effects facilitates the adaptation of regional tidal dynamics which affects especially the northern German Bight. This regional shift is explained by the deceleration of rising tides due to increased friction on laterally expanded intertidal flats and decreased subtidal channel volume. The decrease in flood or increase in ebb dominance, respectively, indicates that the recent trend of sediment accretion in Wadden Sea areas may cease soon.

Lost in the North Sea-Geophysical and geoarchaeological prospection of the Rungholt medieval dyke system (North Frisia, Germany).

We performed geophysical and geoarchaeological investigations in the Wadden Sea off North Frisia (Schleswig-Holstein, Germany) to map the remains and to determine the state of preservation of the medieval settlement of Rungholt, especially its southern dyke segment, called the Niedam dyke. Based on archaeological finds and historical maps, Rungholt is assumed to be located in the wadden sea area around the island Hallig Südfall. During medieval and early modern times, extreme storm events caused major land losses, turning cultivated marshland into tidal flats. Especially the 1st Grote Mandrenke (or St. Marcellus' flood), an extreme storm surge event in 1362 AD, is addressed as the major event that flooded and destroyed most of the Rungholt cultural landscape. Cultural traces like remains of dykes, drainage ditches, tidal gates, dwelling mounds or even plough marks were randomly surveyed and mapped in the tidal flats by several authors at the beginning of the 20th century. Due to the tidal flat dynamics with frequently shifting tidal creeks and sand bars, the distribution of cultural remains visible at the surface is rapidly changing, making it hard to create a comprehensive map of the cultural landscape by surveying. Today, the Niedam dyke area is fully covered by tidal flat sediments, depriving any remains from further archaeological investigation. Since little is known about the precise location or state of preservation of these remains, our investigation aimed at the rediscovery of the medieval dyke system and associated structure with modern and accurate geophysical, geodetical and geoarchaeological methods. Magnetic gradiometry revealed a large part of the medieval dyke, confirming two tidal gates and several terps connected inland with the dyke, providing a detailed example of a Frisian medieval dyke system. Based on our results, the so far inaccurate and incomplete maps of this part of Rungholt can now be specified and completed. Beyond that, seismic reflection profiles give a first depth resolving insight in the remains of the dyke system, revealing a severe threat to the medieval remains by erosion. The site is exemplary for the entire North Frisian coast, that was influenced by multiple flood events in the middle ages to modern times.

The Overlooked Hybrid: Geographic Distribution and Niche Differentiation Between Spartina Cytotypes (Poaceae) in Wadden Sea Salt Marshes

Whole genome duplications (WGDs) lead to polyploid specimens and are regarded as major drivers for speciation and diversification in plants. One prevalent problem when studying WGDs is that effects of polyploidization in ancient polyploids cannot be disentangled from the consequences of selective evolutionary forces. Cytotypic differences in distribution, phenotypic appearance and in response to surface elevation (determined by HOF-modeling) were identified in a relatively young taxa-group of a hexaploid F1-hybrid (Spartina× townsendii H. Groves & J. Groves, Poaceae) and its dodecaploid descendent (Spartina anglica C.E. Hubbard, Poaceae) using vegetation assessments (1029 plots; 1 × 1 m2) from the European Wadden Sea mainland salt marshes, including elevational and mean high tidal (MHT) data. While the F1-hybrid was mainly present in the eastern part of the Wadden Sea, its dodecaploid descendent occurred in the entire Wadden Sea area. The Spartina cytotypes differed in phenotypes (median of Spartina cover: hexaploid = 25% vs. dodecaploid = 12%) and in elevational niche-optimum (hexaploid = − 49.5 cm MHT vs. dodecaploid = 8.0 cm MHT). High ploidy levels correlated with establishment success in Spartina along geographic gradients but did not seem to increase the capacity to cope with abiotic severity downwards the elevational gradient in salt marshes.

Raise the dikes and re-use the past? Climate adaptation planning as heritage practice

Across Europe, coasts are drastically being changed to adapt to relative sea level rise, which will influence coastal landscapes and heritage in many ways. In this paper, we introduce a methodological starting point for analysing the ways in which landscape architects and spatial planners engage with coastal landscapes and coastal heritage in the context of current climate adaptation projects. We test these methodologies by applying them to the Marconi dike strengthening project in Delfzijl, the Netherlands. This city’s dike fortification is an interesting case, as it offers many opportunities for re-designing heritage. The city borders the Wadden Sea area, a tidal mudflat area protected as a UNESCO World Heritage Site for its natural and geological heritage values. The area also consists of a rich cultural landscape, which is overlooked in the public image and in local policy. We conclude that landscape architects and planners should strengthen not only the dike, but also the interpretation of the past that dominates policy and political debates in the area. We also find that the existing heritage production model of Ashworth and Tunbridge can provide some useful structure for understanding and contextualizing spatial planning for climate change as a way of doing heritage.

Small-Scale and Long-Term Variability in Population Dynamics of the Cockle Cerastoderma edule in a Southern North Sea Tidal Flat System

The cockle Cerastoderma edule is one of the most common macrofauna species in the Wadden Sea areas of the North Sea. Cockle population dynamics are influenced by various abiotic and biotic factors such as temperature, food availability, and inter- and intraspecific competition. Cockles play an important role in the food web of the Wadden Sea, for instance, large shellfish-eating birds, such as oystercatchers and common eiders, use the cockle C. edule and the blue mussel Mytilus edulis as a main diet component. However, the populations of shellfish-eating bird species have been declining dramatically across the Wadden Sea since the beginning of the 21st century. While there are detailed monitoring programs in blue mussels due to commercial interests, little information is known about the stocks and long-term dynamics of cockles in the German Wadden Sea. To fill this gap, in 2005 a local conservation society (“Der Mellumrat e.V.”) initiated a study to sample cockles at one transect per year south of the island of Mellum, which was extended by 5 more transects in 2011. In addition to the spatial analysis, we analyzed the long-term variability in cockle population dynamics. Min/max autocorrelation factor analysis (MAFA) revealed a decline in cockle abundance, while no clear length trends were found. Canonical and spearman correlation analyses exposed significant correlations between cockle abundance and length and chlorophyll a, mussel bank area as well as oystercatcher and common eider populations. This study clearly shows that there is an urgent need for comprehensive time series of cockle data to analyze and explain ecological long-term changes in cockle population dynamics in relation to environmental changes and to point out how parts of the Wadden Sea food web, such as shellfish-eating birds are affected by these changes.

A Diachronic Triangular Perspective on Landscapes: a Conceptual Tool for Research and Management Applied to Wadden Sea Salt Marshes

Strong disciplinary academic fragmentation and sectoral division in policies lead to problems regarding the management of landscapes. As a result, there is a focus on the preservation and development of either cultural or natural landscapes. We argue that framing landscapes as “natural” or “cultural” will not help sustainable management. The goal of this paper is to show that even what is referred to as nature, virtually always features an intricate combination of physical geography, biology, and cultural history. It provides an analytical framework that visualizes the three forces at play in physical landscapes. Therefore, we introduce a diachronic triangular approach to study and manage landscapes from a holistic point of view, allowing an exchange of different perspectives. To test this approach, we have applied our model to a diachronic case study on Wadden Sea salt marshes. That area has been influenced by physical-geographical, biological, and cultural landscape forces, which are still visible in the landscape to a large extent. By placing different landscape zones in the triangular concept for different time periods, we can identify and visualize these driving forces through time for this specific landscape. These all play their specific roles in the appearance of the landscape over time in a close mutual interconnection. More importantly, we show that the diverse and complex interplay between these forces makes the current-day landscape what it is. We therefore conclude that the diachronic triangular approach provides a conceptual tool to define and operationalize landscape management in the Wadden Sea area. We welcome similar approaches in other landscapes to assess the usefulness of the diachronic triangular landscape approach.

Livestock grazing reduces sediment deposition and accretion rates on a highly anthropogenically altered marsh island in the Wadden Sea

Coastal salt marshes and their provided ecosystem services are threatened by rising sea levels all over the world. In the Northern Wadden Sea region, a sea-level rise of 4 mm y−1 was recorded for recent years. Identifying and understanding factors that affect sediment deposition and determine vertical accretion of salt marshes is crucial for the management of these ecosystems. Even though major processes contributing to sedimentation and accretion have already been identified, the influence of reduced canopy heights due to livestock grazing is still debated. On a highly anthropogenically altered marsh island in the Wadden Sea, sediment deposition, accretion and suspended sediment concentration was analyzed on grazed and adjacent ungrazed plots both at the marsh edge and at the marsh interior. Due to a low seawall (a so-called ‘summer dike’), flooding frequency on the island is reduced and flooding mainly takes place during storm surges. After five flooding events within a year, mean sediment deposition and accretion were found to be up to seven times higher on ungrazed plots compared to grazed plots, but only at the marsh edges. This result was not explained by the overmarsh suspended sediment concentration (SSC), which was found to be twice as high on grazed plots compared to ungrazed plots. It is concluded that grazing has a negative effect on sediment deposition and accretion on Wadden Sea marsh islands and areas with similar conditions (e.g. presence of a summer dike) by reducing the sediment trapping capacity of those marshes. Overall, vertical marsh accretion ranged from 0.11 ± 0.09 mm y−1 on a grazed plot at the marsh edge to 1.12 ± 0.71 mm y−1 on an ungrazed plot at the marsh edge. By increasing the discrepancy between accretion and sea-level rise, livestock grazing can lead to higher inundation levels and in turn to increased hydrodynamic forces acting on these anthropogenically altered marshes.

A new ΔR value for the southern North Sea and its application in coastal research

AbstractAccelerator mass spectrometry (AMS) radiocarbon (14C) dating ofCerastoderma edule(Linnaeus 1767) andMytilus edulis(Linnaeus 1758) shells sampled in AD 1889 near the island of Wangerooge gave a new local correction factor ΔR of −85 ± 1714C years for the Wadden Sea area. The value is considerably higher than the available scattered data from the North Sea, which were obtained from pre-bomb growth rings of livingArctica islandica(Linnaeus 1767). This can be explained by the incorporation of14C-depleted terrestrial carbon into the shell material which compensates the intensified exchange of CO2between atmosphere and shallow coastal water, e.g. by tidal currents. Additionally, two examples of application of the new ΔRvalue in coastal research give deeper insights into the dynamics of bivalve shell preservation in the Wadden Sea and the need for further research to clarify the Holocene reintroduction ofMya arenaria(Linnaeus 1758) into European waters.

Regulating Subsidence and its uncertainty in the Dutch Wadden Sea

Abstract. At the start of gas production its effects on land subsidence are not certain. There are uncertainties in mechanisms, models and parameters. Examples are non-linear deformation of reservoir rock, fault transmissibility, behaviour of overlaying salt and aquifer activity. Looking back at historical cases in the Netherlands, a factor two or three difference between initial prediction and final outcome is quite common. As the Dutch regulator, SSM is tasked with assuring proper management by operators of the risks associated with land subsidence from natural gas production in The Netherlands. Large initial uncertainties can only be tolerated if operators can demonstrate that timely actions can still be taken when predefined subsidence limits are at risk of being exceeded now or in the future. The applied regulatory approach is illustrated by the case history of gas production induced subsidence in the Dutch Wadden Sea area. This environmentally highly sensitive UNESCO World Heritage Site is a natural gas province. Extensive legal, technical and organisational frameworks are in place to prevent damage to its natural values. Initial uncertainties in the predicted subsidence (rate) were later exacerbated by the detection of strong non-linear effects in the observed subsidence behaviour, leading to new concerns. It was realised that – depending on the underlying physical cause(s) – there will be a different impact on future subsidence. To assure proper management of the additional uncertainty by the operator, several improvements in the regulatory approach have been implemented. Possible underlying mechanisms had to be studied in depth and improved data analysis techniques were requested to narrow down uncertainties as time progresses. The approach involves intensified field monitoring, scenario's covering the full range of uncertainties and a particle filter approach to handle uncertainties in predictions and measurements. Spatial-temporal double differences, production data and the full covariance matrix are used to confront scenario predictions against measurements and to assess their relative probability. The regulator is actively involved in assuring this integrated control loop of predictions, monitoring, updating, mitigation measures and the closing of knowledge gaps. The regulator involvement is supported in the Mining law and by appropriate conditions in the production plan assent. With the approach it can be confidently assured that subsidence (rate) will remain within the allowed range.

Coastal heritage in touristic regional identity narratives: a comparison between the Norwegian region Sørlandet and the Dutch Wadden Sea area

ABSTRACTHeritage plays a central role in narratives of coastal regions that promote them as places of leisure. This paper compares this role of heritage in Sørlandet (Norway) and the Dutch Wadden Sea area. Both regions have rich and related cultural histories, but at the same time exhibit striking differences in the role of cultural heritage and other aspects of heritage in regional identity narratives that are aimed at attracting tourists. We conclude that while the narratives of Sørlandet affirm a romantic, picturesque image of pre-industrial, societies, those in the Dutch Wadden Sea area frame this region as a pristine and timeless wilderness, in which human history has no place.

Holocene relative mean sea‐level changes in the Wadden Sea area, northern Netherlands

ABSTRACTAlthough the Netherlands has a long tradition of sea‐level research, no Holocene relative sea‐level curve is available for the north of the country. Previous studies hypothesized that the relative sea‐level reconstruction for the western Netherlands is also valid for the northern part of the country. However, glacial isostatic adjustment (GIA) models predict a lower and steeper relative sea‐level curve because of greater postglacial isostatic subsidence. Long‐term data of relative sea‐level change are important to inform GIA models and understand postglacial vertical land motion related to the rebound of Fennoscandia and neotectonic activity. We compiled and evaluated a set of basal peat radiocarbon dates to reconstruct the Holocene relative mean sea‐level rise in the Dutch Wadden Sea area. For the early Holocene, this reconstruction is lower than the western Netherlands curve. After 6400 cal a BP, the curve for the Wadden Sea is statistically indistinguishable from that for the western Netherlands, a result that conflicts with GIA model results. It remains to be investigated whether the problem lies with the GIA model predictions or with the quality of the available data. Additional basal peat radiocarbon dates from suitable sites should be collected to further resolve this problem.

Subsidence in the Dutch Wadden Sea

AbstractGround surface dynamics is one of the processes influencing the future of the Wadden Sea area. Vertical land movement, both subsidence and heave, is a direct contributor to changes in the relative sea level. It is defined as the change of height of the Earth's surface with respect to a vertical datum. In the Netherlands, the Normaal Amsterdams Peil (NAP) is the official height datum, but its realisation via reference benchmarks is not time-dependent. Consequently, NAP benchmarks are not optimal for monitoring physical processes such as land subsidence. However, surface subsidence can be regarded as a differential signal: the vertical motion of one location relative to the vertical motion of another location. In this case, the actual geodetic height datum is superfluous.In the present paper, we highlight the processes that cause subsidence, with specific focus on the Wadden Sea area. The focus will be toward anthropogenic causes of subsidence, and how to understand them; how to measure and monitor and use these measurements for better characterisation and forecasting; with some details on the activities in the Wadden Sea that are relevant in this respect. This naturally leads to the identification of knowledge gaps and to the formulation of notions for future research.

Shifting land use in German coastal mainland destinations: historical development of tourism in Norden-Norddeich

Purpose The purpose of this paper is to present the way in which the mainland of the German Wadden Sea area transitioned from traditional sectors into an almost entirely tourism destination, and which factors contributed to and/or necessitated such a development. Design/methodology/approach The overall approach in this paper has adopted a focus on an extensive case study of the German mainland of the Wadden Sea area. Scientific articles have been used to, first, structuring the theoretical framework and then to gain a general understanding on what a transition exactly entails. As a result, the theoretical framework has been written in an examination of existing literature on transitions and functioned as the theoretical support and foundation for the case study analysis. The analysis has been shaped by means of a number of scientific articles, branch reports, books and websites that, in most instances, specifically focused on the chosen case. Since the area of study is located in Germany, specific literature on this area was mostly limited to the German language, a language of which the author has a basic, yet not thorough, understanding. However, the overall scope of the developments in the case in regard to the transition from agricultural and fishing communities to communities in which tourism plays a substantial role has been understandable. Findings One of the most important sectors that economically benefit the Wadden Sea region, especially on the Dutch and German Wadden islands, is tourism. While tourism development on the Dutch mainland is minimal, the sector considerably developed in the past few decades on the German mainland, generally as a result of declining yields through multifarious unfavorable developments in traditional sectors such as agriculture and fishing, amongst others. Throughout previous centuries, Norden-Norddeich possessed some small-scale tourism facilities; however, negative developments in those traditional sectors required the municipality to prevent an impasse situation, resulting in altering business models and upscaling tourism facilities. Initiatives in different layers (micro, meso and macro) were initiated and gradually intensified in order to develop Norden-Norddeich as a counter destination for the expensive German islands. Following the phases of transition, Norden-Norddeich gradually developed and can now be regarded as a stable and dynamic holiday destination as well as a system that nowadays almost completely adheres to tourism. It took Norden-Norddeich ten years to transition toward tourism. Presently, Norden-Norddeich is the most visited mainland destination at the German Wadden Sea coast. In contrast, small-scale activities are set up in the mainland part of the Wadden Sea area in the Netherlands, but miss out on effective collaboration between different stakeholders that are involved in both planning and management (such as policy makers) and executive roles (such as the people who organize activities and/or facilities). Furthermore, the area is managed in such a way that does not contribute yet to upscaling economic development, mostly as a result of regulatory issues that hinder such developments. However, increasing efforts by several stakeholders are being taken that should ultimately lead to a sustainable socio-economic development of the Dutch mainland part of the Wadden Sea area. Originality/value Analyzing the stages of transition on the German mainland of the Wadden area might function as an example for stakeholders in villages or cities located on the mainland of the Dutch Wadden to become aware of how processes of tourism transitions occur, what factors are needed to start off such a transition and what effects a transition might have on the revitalization of a certain area. Moreover, the case of Norden-Norddeich could stand out as an example for Dutch stakeholders in the Wadden region to perceive in what way a locked-in situation could be prevented or solved by shifting from one system to another by taking on a wide range of initiatives that might be led and stimulated by different actors.

Moving beyond the hard boundary

PurposeThe purpose of this paper is to assess the consequences of a nature-culture divide in spatial policy on cultural heritage in the Dutch Wadden Sea area, which is protected by UNESCO for its ecological assets.Design/methodology/approachThis paper investigates this by discussing the international and national policy frameworks and regional examples of the consequences of the divide.FindingsThe effects of the nature-culture divide appear to be negative for the landscape. Approaching the Wadden Sea Region as an agricultural-maritime landscape could help overcome the fixation on nature vs culture and the hardness of the sea dikes as spatial boundaries between the two domains. A reconsideration of the trilateral Wadden Sea region as a mixed World Heritage Site could lead to a more integrated perspective.Originality/valueThese findings inform policy development and the management of landscape and heritage in the region. This case forms an example for other European coastal regions that struggle with conflicting natural and cultural-historical interests.