2020 Conservation Outlook Assessment

IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

Wadden Sea

SITE INFORMATION Country: Denmark, Germany, Netherlands Inscribed in: 2009 Criteria: (viii) (ix) (x)

The Wadden Sea is the largest unbroken system of intertidal sand and mud flats in the world. The site covers the Dutch Wadden Sea Conservation Area, the German Wadden Sea National Parks of Lower Saxony and Schleswig-Holstein, and most of the Danish Wadden Sea maritime conservation area. It is a large, temperate, relatively flat coastal wetland environment, formed by the intricate interactions between physical and biological factors that have given rise to a multitude of transitional habitats with tidal channels, sandy shoals, sea-grass meadows, mussel beds, sandbars, mudflats, salt marshes, estuaries, beaches and dunes. The area is home to numerous plant and animal species, including marine mammals such as the harbour seal, grey seal and harbour porpoise. Wadden Sea is one of the last remaining large- scale, intertidal ecosystems where natural processes continue to function largely undisturbed. © UNESCO

SUMMARY

2020 Conservation Outlook Finalised on 02 Dec 2020

GOOD

The Wadden Sea is a unique area in densely populated Europe, with a legacy of ecological damage prior to inscription. It faces a large number of threats, some of which are on a global scale and driven by factors outside of the direct control of the management authority (i.e. climate change). At the same time, the World Heritage site is excellently managed and studied by well-organized, cooperative and highly competent management authorities operating under the tripartite framework for conserving the site, being supported in this role by an active and committed NGO community and the civil society in the region. Under this framework, conservation measures being undertaken are demonstrating positive results despite the significant challenges being faced, but could improve further through the finalization of the single integrated management plan. Therefore, while significant challenges remain to be managed and the site will require continued monitoring, the conservation outlook for this site in the short-term is Good. IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

FULL ASSESSMENT

Description of values

Values

World Heritage values

▶ Depositional coastline of unparalleled scale and diversity Criterion:(viii)

The Wadden Sea is a depositional coastline of unparalleled scale and diversity. It is distinctive in being almost entirely a tidal flat and barrier system with only minor river influences, and an outstanding example of the large-scale development of an intricate and complex temperate-climate sandy barrier coast under conditions of rising sea-level. Highly dynamic natural processes are uninterrupted across the vast majority of the World Heritage site, creating a variety of different barrier islands, channels, flats, gullies, saltmarshes and other coastal and sedimentary features (IUCN, 2009; 2014; World Heritage Committee, 2009; 2014).

▶ One of the last remaining natural large-scale intertidal Criterion:(ix) ecosystems with natural processes continuing to function largely undisturbed

Natural processes continue to function largely undisturbed in one of the last remaining natural large- scale intertidal ecosystems. Geological and geomorphologic features are closely entwined with biophysical processes and provide an invaluable record of the ongoing dynamic adaptation of coastal environments to global change. There is a multitude of transitional zones between land, sea and freshwater that are the basis for the species richness of the World Heritage site. The productivity of biomass in the Wadden Sea is one of the highest in the world, most significantly demonstrated in the numbers of fish, shellfish and birds supported by the site (IUCN, 2009; 2014; World Heritage Committee, 2009; 2014).

▶ Key site for migratory birds Criterion:(x)

The World Heritage site is a key site for migratory birds as a staging, moulting and wintering area, providing high level of food and a low level of disturbance for some 10-12 million birds passing through the site each year (with up to 6.1 million birds present at the same time). The site is the essential stopover that enables the functioning of the East Atlantic and the African-Eurasian migratory flyways. For 43 migratory bird species the Wadden Sea supports more than 1% of the entire flyway population, and for 29 species more than 10% of their flyway population. In addition, the site supports 30 breeding bird species (IUCN, 2009; 2014; World Heritage Committee, 2009; 2014).

▶ Exceptional species richness in a salt marsh Criterion:(x)

The World Heritage site protects critical habitat for about 2,700 marine species in the intertidal and subtidal zones and at least 5,000 semi-terrestrial and terrestrial species, mostly the flora and fauna of salt marshes and dunes on the islands. There are 2,300 species of flora and at least 4,200 species of fauna (IUCN, 2009; 2014; World Heritage Committee, 2009; 2014).

Other important biodiversity values

▶ Important refuge for marine mammals

Marine mammals include Harbour Seal, Grey Seal, and Harbour Porpoise. After centuries of hunting, protection measures have resulted in recovery of the seal populations. The Wadden Sea now sustains approximately 20% of the North-east Atlantic subspecies of Harbour Seal: a total of 26,788 were IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

counted in an annual survey in 2013 compared to about 4,000 thirty years earlier (IUCN, 2009; CWSS, 2013). The number of new-borns counted in 2020 was the highest registered since pup surveys began in 2000 and its percentage of the total August moult count was reported as the second highest ever recorded (Galatius et al., 2020).

Assessment information

Threats

Current Threats High Threat

The list of current threats is long, and include a number of high threats such as climate change effects, chemical contamination from industry and agriculture, invasive species, unsustainable fisheries, industrial and harbour development (including maritime traffic), increasing offshore wind farms and visitor pressure. It is important to note that the management responses to most of these threats have reduced the likelihood of damage to the values for which the site was inscribed on the World Heritage list. However, given some threats with potentially catastrophic consequences, even if the site continues being well- managed, and those which cannot necessarily be managed at the site level (i.e. climate change) the site is subject to high threat overall.

▶ War, Civil Unrest/ Military Exercises Low Threat (Military activity) Inside site, scattered(5-15%) Outside site There are a number of active military areas which pose threats to the values of the site. In Denmark, Rømø, Ho Bay, Skallingen and Oksbøl are used in landing exercises and live firing drills are carried out; in Germany, Meldorfer Bucht has been a ballistic testing site although is rarely used and thought to be of very low impact, and the Federal Ministry of Defence is also searching for alternative testing sites outside the Wadden Sea (Kloepper et al., 2017). The extent of military activities has decreased including the abandonment of exercise sites in the early 1990s (Burbridge, 2000) and military activity has been significantly reduced since, including cooperation between military forces and conservation organisations towards the protection of the site's values (Kloepper et al., 2017). As such a number of protocols have been implemented including flight restrictions which take into account of the breeding and moulting times for birds and seals (CWSS, 2012). Historical ammunition dumping at several sites which now lie within the boundaries of the World Heritage site is considered problematic (Böttcher et al., 2015; Kloepper et al., 2017).

▶ Industrial/ Military Effluents, Agricultural effluents High Threat (Chemical contamination from industry and agriculture) Inside site, throughout(>50%) Outside site Agricultural and industrial runoff into the World Heritage site, including large amounts of nutrients and toxic substances was serious in the past but greatly improved through regulation. However, BirdLife (2009) note that levels of pollutants were slowly increasing again following a sharp decrease throughout the 1990s, with a large number of substances are still exceeding safe norms, including organotin compounds, PCBs and hexachlorobenzene. Furthermore, newly developed xenobiotics, such as hormones disruptors, may have negative impacts (CWSS, 2012). The most recent monitoring data from 2015, which was determined though seabird eggshell chemical composition analysis, suggests that there is still cause for concern with no significant reduction in chemical contamination, including that common tern eggs exceeding the limit values of Hg, PCB, HCB and DDT under Ecological Quality Objectives (EcoQOs) defined by OSPAR for coastal bird eggs from the North Sea area (OSPAR, 2007; Dittmann et al., 2012) at all investigated areas (Kloepper et al., 2017).

▶ Flight Paths High Threat (Air traffic) Inside site, throughout(>50%) Outside site Since 2015, SERA (Standardised European Rules of the Air) is active, which means a minimum flight altitude in open landscapes of 500 ft (150 m). There are (at least in Germany) no special rules for the IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

World Heritage site (IUCN Consultation, 2020b). Unfortunately, on some of the inhabited islands there is quite a lot (and possibly increasing) of air traffic. Servicing the increasing number of off-shore wind farms has also recently increased air traffic over the World Heritage site concurrently. Therefore, locally the quietness of the area is considerably reduced and large flocks of birds are potentially being disturbed.

▶ Invasive Non-Native/ Alien Species High Threat (Invasive species) Inside site, throughout(>50%) Outside site The list of Wadden Sea alien species comprises 90 recorded alien marine species in the Wadden Sea (Gittenberger, 2016; Kloepper et al., 2017), without accounting for terrestrial and freshwater taxa occurring on the Wadden Sea islands, on which there are a number of vascular plants, mosses and animals of various taxa that are also considered invasive. Only a small proportion of the alien marine species are considered to have a strong impact on the composition of the existing biota in the Wadden Sea. A permanent trilateral coordination group on alien and invasive species was formed by the Wadden Sea Board in 2018, with the remit of finalising a trilateral management and action plan on alien species (MAPAS) and coordinating efforts towards a harmonized trilateral and ongoing specific monitoring program for alien species (CWSS, 2020a).

▶ Livestock Farming / Grazing Low Threat (Inappropriate livestock grazing) Inside site, localised(<5%) Outside site Inappropriate livestock grazing practices could be affecting salt marsh species composition and regeneration. However, the impact has been reduced considerably already during the last 30 years. Grazing of parts of mainland salt marshes is carried out as part of coastal defense measures, or, in some areas, to aim for an enhanced biodiversity and heterogeneity of salt marshes (CWSS, 2014). Recent studies have shown different grazing regimes within a spatial mosaic, with the inclusion of long-term abandonment to be effective in achieving these goals (van Klink et al., 2016). However, the degree to which results such as these are applied in grazing management and livestock rotation is unclear.

▶ Fishing / Harvesting Aquatic Resources High Threat (Fisheries) Inside site, widespread(15-50%) Outside site The site contains a number of important fisheries, the most prominent of which are blue mussel and brown shrimp, with the cockle fisheries having been significant in the past. A legacy of bottom-dredging fishery (the mechanical Dutch cockle fishery in particular) has destroyed biodiversity-rich communities including the disappearance of the intertidal mussel beds in some areas of the site (Ens et al., 2004). Studies on the impact of the cockle fishery in particular concluded that the area of mudflats containing sufficient shellfish for feeding knots decreased by fifty-five percent between 1996 and 2005. During the same period, knot numbers decreased by forty-two percent (Kraan et al., 2009) and was also attributed to the loss of 15,000 oystercatchers (Ens et al., 2004). The shrimp fishery, which has been increasing for many years, is also responsible for a large bycatch of young fish, young shrimp and other invertebrates. Also a number of fish species with slow growth (rays and sharks) and reef building animals such as Sabellaria have disappeared in the Wadden Sea, the shrimp fishery most probably being responsible (IUCN Consultation, 2017). Except for the Danish Wadden Sea there is very little management of this fishery. Management is also complicated by the human induced population growth of brown shrimp, thought to have been induced by overfishing of predator species such as cod and whiting (Kloepper et al., 2017). Fisheries have now been further regulated (IUCN, 2009) and the blue mussel and brown shrimp fisheries are now subject to increased efforts towards sustainability (Kloepper et al., 2017). These include a transition to alternative fishing methods and a new Management Plan for North Sea Brown Shrimp; and alternative seed mussel collection technology being developed (Kloepper et al., 2017) and Denmark has now banned shrimp and mussel fishery entirely. IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

▶ Shipping Lanes High Threat (Harbours, industrial facilities and maritime traffic) Inside site, scattered(5-15%) Outside site International and smaller ports and harbours directly adjacent to the World Heritage site and shipping lines close to and through the site open up a threat of maritime pollution. Access to the harbours and maintenance of navigation channels is subject to an integrated planning system including sediment management, both to maintain the shipping routes and to avoid environmental impacts to the marine and coastal ecosystems. However, it is clear that the deepening of the navigation channels also has an impact on the site, which should be kept as small as possible. Also there is a tendency to modify and/or enlarge harbours, with some impact on the site, which must be reduced as much as possible. On New Year's Day 2019, a cargo ship lost 342 containers and 3,000 tons of cargo overboard, resulting in huge quantities of litter washing up on beaches and into the sea within the site in the Netherlands (and to a lower extend also in Germany), leading a report to recommend measures including those for '(a specific category of) container ships, and if necessary alteration of the two shipping routes north of the Wadden Islands' (Corder, 2019). Designation as an IMO Particularly Sensitive Sea Area (PSSA) and implementation of a shipping Traffic Management System and emergency contingency plans are state of the art, but shipping will continue to be a significant risk for the foreseeable future (IUCN, 2009). Due to intensive wind farm development in the North Sea outside the Wadden Sea there is clearly an increase in the risk for shipping accidents which would then have an impact on the site. Industrial plants such as power or chemical plants are close to the site in some areas.

▶ Renewable Energy High Threat (Wind farms) Inside site, extent of threat not known Outside site No construction of new wind turbines is allowed within the World Heritage site, although a barrier of offshore wind-farms is present and being further developed outside of the site. In a few cases, the wind farms are even quite close. Submarine cables to the wind farms are also placed within the site although these are said to cause only temporary impact (IUCN, 2009). However, due to the dynamic nature of the area there is the risk that frequent repair will be required, causing additional impact. The impact is already being reduced by bundling cables in fewer routes and with higher capacities, although the need for more cables is increasing. There might be a limit for the number of cables being acceptable in the site. All in all, the region around the Wadden Sea can provide large amounts of renewable energy, but it is very important (and possible) to do this with careful planning, which should respect all the natural values and should keep the landscape integrity preserved (WWF, 2012).

▶ Tourism/ visitors/ recreation Low Threat (Visitor and tourism pressures) Inside site, widespread(15-50%) Outside site Approximately 20 million tourists stay overnight and 30-40 million day trippers visit the Wadden Sea region, mainly on the islands and the coastal areas on the mainland (IUCN, 2009), other tourism statistics provided in Europarc (2012). The major part of the tourism activity and infrastructure takes place outside the Wadden Sea. A tourism development strategy for the World Heritage destinations (the site itself and adjacent areas on the mainland and islands) has been developed. Tourism activities are comprehensively regulated including specific management frameworks in all three states; e.g. visitor information and guidance, zoning, closure of sensitive areas, and guided walks to experience the area (PROWAD, 2014; CWSS, 2014). However, increased visitor pressure has led to the development of a more static coastline and increased disturbance, and may be one of the causes for the detriment of breeding populations of species such as Little Tern, Kentish Plover and Sandwich Tern (BirdLife, 2009). To summarize, tourism in the Wadden Sea today has quite a big impact, but this has developed over many decades and was not caused by the inscription of the site on the World Heritage List. Overall (with some local exceptions e.g. showing indication of over-tourism) the impact is acceptable as of today, with very many areas not being affected by tourism. But there are risks and challenges for the protection of the area if the number of tourists would increase considerably (e.g. there is a trend IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

towards more inland tourism in the Wadden Sea countries).

▶ Temperature extremes, Storms/Flooding Very High Threat (Climate change) Inside site, throughout(>50%) Outside site Past and to some extent present interference with the natural dynamics of the Wadden Sea system means that it has lost much of its resilience and flexibility to adapt to the impacts of climate change, including rising sea level, temperature change and natural disasters including flooding of sandbanks and salt marshes, all of which is already occurring. Increasing storm tides, for example, wash away Sandwich Tern nests (BirdLife, 2009). It is positive that the Wadden Sea countries have agreed on a “Trilateral Climate Change Adaptation Strategy” (CWSS, 2014), that Schleswig-Holstein has decided on a "Wadden Sea Strategy 2100" (MELUR 2015), and that some local and regional initiatives are on the way to search for nature friendly and sustainable methods to prepare for sea level rise and to start pilot projects (WWF, 2014). An initiative on creating a "Climate Vulnerability Index" was supported by the Wadden Sea countries. Though there is a positive trend towards "nature based solutions" with the coastal defence sector, there also remain risks that large scale constructions against storm tides could in the future seriously impact the key values of the World Heritage site. Climate change, and in particular the associated sea level and temperature rise, is considered the biggest threat for the Wadden Sea in the long term, with the potential to have severe impact, potentially up to the destruction of the key values of the World Heritage site (Heron et al. 2020).

▶ Hunting and trapping Low Threat (Hunting) Inside site, localised(<5%) Outside site Hunting has been or will be phased out in almost the entire Dutch and German Conservation Areas (Burbridge, 2000), with some local exceptions. Hunting is still allowed in large parts of the Danish Conservation Area (Miljøstyrelsen, 2017). It is noted that hunting is especially damaging in Denmark, causing disturbance, particularly in high tide roosting areas (BirdLife, 2009). The current extent and effect of hunting pressure and disturbance is unknown.

▶ Oil/ Gas exploration/development Low Threat (Oil and gas exploitation) Inside site, localised(<5%) Outside site No new exploitation installations for oil and gas are permitted in the World Heritage site. One existing installation, the Mittelplate, was excised from the site, as well as a gas exploitation area in the Netherlands. An independent research and monitoring programme has been conducted at Mittelplate in the Schleswig-Holstein Wadden Sea to assess its ecological impact and no negative effects have been found in an extensive area surrounding the platform (IUCN, 2009). However, there is obviously large scale damage to the natural beauty and the wilderness appearance of the site. Subsidence as a result of gas extraction in the Dutch part of the Wadden Sea is causing impacts, with a maximum of 42cm subsidence reported in 2015 underneath Ameland island (van Thienen-Visser et al., 2015). However, gas production is adjusted or halted if there are signs that the subsidence capacity will be exceeded (Kloepper et al., 2017). Considering that due to sea level rise the Wadden Sea may face a sediment deficit in the longer term, the sediment which compensates now the subsidence will later be missing in the site.

▶ Agricultural effluents Low Threat (Eutrophication through nutrient inflow) Inside site, widespread(15-50%)

Nutrient enrichment from river inflow has impacted the Wadden Sea ecology including loss of seagrass, increased phytoplankton blooms, and increased green macroalgae blooms (van Beusekom et al., 2019). However, the situation has improved since the nutrient input peaked in the 1980s, with 2.5% decrease per annum since that period on average. Currently, although the trilateral goal of achieving an 'eutrophication non-problem area' status in the Wadden Sea has not been met yet (Kloepper et al., 2017) indicators of eutrophication (such as phytoplankton biomass (measured as chlorophyll a), as measured in van Beusekom et al., 2019, in the Wadden Sea has reached a comparatively low level and IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

is therefore currently a low threat.

▶ Water Pollution, Solid Waste Low Threat (Marine litter, including microplastic pollution) Inside site, throughout(>50%) Outside site Marine litter poses a threat to the biological values of the Wadden Sea through its effect on wildlife, mainly through entanglement, ingestion and smothering, particularly amongst seabirds and marine mammals (Kloepper et al., 2017). Recent studies have found litter in stomachs of large marine mammals such as harbour porpoises (Unger et al., 2017), as well as in seabirds such as fulmars (Kloepper et al., 2017), with 60 % of the fulmars found in the Dutch/German Wadden Sea region clearly exceeding quality standard thresholds for plastic pollution from the most recent available data gathered between 2010 and 2014 (OSPAR, 2009; Kloepper et al., 2017). Such ingestion has varying degrees of effects ranging from sub-lethal with no likely population effect (as in porpoises (Unger et al., 2017)) to more serious threats posed to fulmars (and likely other seabirds) due to direct mortality effects of plastic ingestion (Kloepper et al., 2017; Kühn et al., 2015). Microplastics have also been found to be present in sediment beaches, dunes and the seafloor along the entire Wadden Sea coast (Kloepper et al., 2017; Claessens et al., 2011; Fries et al., 2013; Dekiff et al., 2014).

Potential Threats Low Threat

New dikes and harbours, which could severely impact the World Heritage site, are currently unlikely to be approved. Potential threats also include new invasions of alien species and pathogens, and catastrophic oil spills, but risk assessment plans are in place.

▶ Dams/ Water Management or Use Very Low Threat (Construction of new dikes or dams to combat sea level rise) Inside site, extent of threat not known Outside site Further embankments are not allowed and areas of legal conservation have been extended and amended; the large majority of the Wadden Sea Area has been designated as Natura 2000 areas in the framework of the EU Habitat and Bird Directives and hence been subject to the stipulations of Art. 6 of the Habitat Directive (Burbridge, 2000). However, new dikes are still in the realm of possible for reasons of overriding public interest and if no alternatives can be found. However, all in all it seems very unlikely that ideas for such constructions would really be brought forward.

▶ Water Pollution Very Low Threat (Deposition of mud from port of Hamburg and the river Elbe at Inside site, scattered(5-15%) Wadden Sea) Outside site

It is in the public discussion to deposit mud from the port of Hamburg and the river Elbe at Wadden Sea sites close to the mouth of river Elbe. This sediment might be contaminated by toxics to an extent that deposition at a site from where it could spread over the Wadden Sea would not be acceptable. The risk that such a plan would really go forward can be considered very low (IUCN Consultation, 2020).

Overall assessment of threats High Threat

The list of current threats is long, but it is important to note that the management responses to most of these threats have reduced the likelihood of damage to the values for which the site was inscribed. However, as the site is faced with so many threats, both current and potential, and some which cannot be addressed at the site level, it is still assessed as facing a high level of threat even if this is mitigated to some extent by good management. Climate change, and in particular the accelerated sea level rise associated with this, will certainly have a great effect on the site’s natural values.

Protection and management IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

Assessing Protection and Management

▶ Management system Highly Effective

The collective management effort is somewhat complex (involving several different associations and/or organisations) but in many ways exemplary, creating true and functional cooperation between the three countries at different levels (CWSS, 2016). The cooperation is long-standing and predates the World Heritage nomination, the Trilateral Wadden Sea Cooperation (TWSC) was established in 1978. The actual management on the trilateral level is handled by the Common Wadden Sea Secretariat (CWSS), on the national/regional level by the respective authorities. The Wadden Sea Plan and the Integrated Coastal Zone Management (ICZM) Strategy, prepared to address recommendations from the European Parliament on coastal zone conservation and management, provide a framework for managing the area. There are specific management plans for the different protected areas within the World Heritage site (IUCN, 2009). Work towards a single integrated management plan (SIMP) has been started, a roadmap and actual development onset of the SIMP has been initiated with content development for the plan beginning in 2020, following a process of gaining an overview of the management of the Trilateral Wadden Sea Cooperation and identifying key issues for inclusion in the SIMP (Wadden Sea Board, 2019).

▶ Effectiveness of management system Mostly Effective

The management is effective and adaptive, and supported by large-scale monitoring data as presented in the periodic Quality Status Reports. There are serious challenges concerning fisheries monitoring and management, due to intersecting responsibilities, commercial fisheries management in the three countries and high political pressure. Currently there are separate plans and guidelines in effect in the three countries, usually in line with the trilateral agreements and the Wadden Sea Plan, but the management is working also towards a single integrated management plan. The current management is adequate to maintain the site’s Outstanding Universal Value (OUV) to the extent possible, but may also have some room for improvement.

▶ Boundaries Highly Effective

The site was extended in 2014 and now also includes areas in Denmark. Clear maps detailing site's boundaries are publicly available for the whole transboundary World Heritage site. The management have all necessary boundary data to adequately maintain the site’s OUV. A navigation system used for commercial and recreational boasts in the Wadden Sea has geo-referenced information on the boundaries of all existing protected areas and the restrictions associated to each of them (IUCN, 2009).

▶ Integration into regional and national planning systems Mostly Effective

The Wadden Sea Plan was officially adopted in 1997 and updated in 2010 and is a politically binding document and constitutes the common framework for the protection and sustainable management of the World Heritage site as an ecological entity. The implementation of the plan is done by the standing bodies of the Trilateral Wadden Sea Cooperation through the Ministerial Council and a Wadden Sea Board which oversees operational aspects of implementation and ensures effective coordination of the different tiers of management, and being advised in this role by a regional stakeholder forum and by Nature NGOs. The Common Wadden Sea Secretariat (CWSS) is tasked with the daily implementation of the Wadden Sea Plan, coordination of the activities in the framework of the plan and a regular review of its implementation (IUCN, 2009). The finalization of the Single Integrated Management Plan will greatly improve the integration of management across the regional and national planning systems in this transboundary serial site.

▶ Relationships with local people Mostly Effective

Local communities are strongly committed to nature conservation through environmental education, through nature based tourism activities, but also through love for their "Heimat". An exceptional level of public consultation was undertaken when preparing the nomination. Conservation efforts are also strongly supported by regional governments, by almost all municipalities and by local and regional IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

NGOs who provide significant volunteer and also public support to management activities (IUCN, 2009).

▶ Legal framework Mostly Effective

The site includes mostly protected areas legally established by federal or state decrees. A small part of them is under private ownership. Management of private lands is regulated by existing protective measures and entirely embedded in the trilateral protection and management scheme according to the Joint Declaration on the Protection of the Wadden Sea in conjunction with the Trilateral Wadden Sea Plan, which represents a planning and management framework for the whole area (IUCN, 2009). Other legally binding directives under European legislation are also very important by e.g. the Bird and the Habitat Directive, as well as the legal implementation of the trilateral decisions on the national and the regional level. Consideration for protected areas in fishery and the shipping legislation in particular could be improved (IUCN Consultation, 2020).

▶ Law enforcement Mostly Effective

There is in many cases effective law enforcement via local police, coastguards and naval police forces through an integrated system of patrolling and inspection (IUCN, 2009). Fishing vessel movement is partly collected using VMS data, however, it is unclear if this is done in real-time (facilitating fisheries enforcement) or collected later (CWSS, 2016) or at all. Overall the management is actively pursuing effective enforcement, however, there are still few official rangers/wardens and many warden activities are undertaken by volunteers or employees of NGOs. An observer system has been in place in Dutch and German fisheries within the site since 2009 to monitor fishing practices as well as gather data on bycatch (Kloepper et al., 2017), although this system is limited (IUCN Consultation, 2020a).

▶ Implementation of Committee decisions and Highly Effective recommendations

Recommendations in World Heritage Committee Decision 33COM 8B.4 to prepare an extension to include the Danish Wadden Sea, to undertake a tourism strategy, to improve monitoring of invasive species and to cooperate with other sites along the East Atlantic flyway have been mostly fulfilled. The Danish part of the Wadden Sea was inscribed (in 2014), the Tourism Strategy adopted (in February 2014) and the East Atlantic Flyway cooperation has made extensive progress through active effort by the management. Progress has been made on the alien species issue through the establishment of a permanent trilateral coordination group on invasive and alien species in 2018, with a mandate to finalise the management and action plan on alien species (MAPAS) and to coordinate efforts towards a harmonized trilateral and ongoing specific monitoring program for alien species (CWSS, 2020a). Recommendations in the Committee Decision 38COM 8B.13 (Request No. 5) to prepare an implementation plan to enhance the conservation and management in the Danish part has been undertaken. The Danish National Park was evaluated in 2016-2017 and a new plan was approved in 2019 (Nationalpark Vadehavet, 2019). Recommendations in the Committee Decision 38COM 8B.13 (Request No. 6) to implement a single integrated management plan (SIMP) and to strengthen the implementation of coordinated management have been undertaken. The current timeline resulted in a formal decision on the development of the SIMP in spring 2018 (Trilateral Governmental Conference), which provided the necessary institutional support and funding to start developing the SIMP in mid-2018 (Leeuwarden Declaration, 2018). The development of the SIMP is currently in progress. Recommendations in the Committee Decision 38COM 8B.13 (Request No. 7) to extend the monitoring of impacts of fisheries and to ensure protection from detrimental impacts have been started in the form of a trilateral Framework of Sustainable Fisheries (adopted in 2014) listing several important principles. There is also a basic fisheries monitoring in place (using VMS, logbooks and a black box approach). However, the actual implementation on the Committee Decision still lacks a clear timetable and /or a roadmap for implementation, as well as more clearly defined targets, methods and dependencies between detrimental effects, species, biotopes and fishing methods.

▶ Sustainable use Mostly Effective

North Sea fish have for a long time been subject to strong fishery pressure, and after large fish had IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

disappeared, fisheries in the Wadden Sea focused on shellfish and shrimp. This has affected the benthos in general: native oysters and Sabellaria reefs and some fish species have vanished, in some areas, subtidal mussels are mostly confined to culture lots, and intertidal beds are intermittently strongly decimated, while catches of shrimp have been sustained. Industrial cockle fishery has recently been banned completely. There seems to be a large potential for fish and shellfish recovery but management efforts are still in their infancy (Wolff et al., 2010). The management are taking important steps to improve and integrate fisheries management with conservation goals, including adopting specific trilateral policy principles (in 2014), however, the implementation (in combination with connected monitoring schemes) still has to take full effect (Jager, 2015; CWSS 2016; Kloepper et al., 2017). Monitoring data for the hunting effort and the effect of hunting disturbance on migrating, staging and wintering birds in the Danish part is not available, but hunting could negatively affect shorebirds (BirdLife, 2009; Madsen et al., 1995; Madsen, 1998).

▶ Sustainable finance Mostly Effective

The site was well supported in terms of human and financial resources at the time of inscription (IUCN, 2009), and remains so through the commitments made by the three States Parties in the Joint Declaration on the Protection of the Wadden Sea and corresponding Trilateral Wadden Sea Cooperation , and the national activities. However, there remains underfunding in terms of on ground management e.g. warden activities of the area, coordinating the educational activities (IWSS), or the capacity to develop pilot projects with the purpose of both restoring lost nature and preparing for the sea level rise.

▶ Staff capacity, training, and development Highly Effective

Existing staff working directly in the protected areas within the World Heritage site include over 200 permanent positions covering technical experts, scientist and rangers. These permanent staff positions are complemented by over 200 additional staff funded by NGOs and local governments. Staff are mostly highly qualified and subject of on-going training programmes to enhance their effectiveness (IUCN, 2009). However, the number of wardens could be increased.

▶ Education and interpretation programs Highly Effective

The site benefits from a highly effective education and interpretation programme which is now guided by the Wadden Sea Strategy on Education for Sustainable Development and World Heritage Interpretation, adopted in 2018, which will 'provide a trans-boundary framework for environmental education and interpretation in the entire Wadden Sea World Heritage Site. It stands for ONE Wadden Sea and builds up on the local, regional and national strategies, concepts and individual activities – without replacing these – and provides an umbrella to promote the Wadden Sea’s OUV in an international and interdisciplinary approach' (CWSS, 2020b). The “International Wadden Sea School” (IWSS) has been established to support this network on a permanent basis in cooperation with the WWF (CWSS, 2014).

▶ Tourism and visitation management Mostly Effective

A Sustainable Tourism Strategy has been developed to enhance the cooperation between tourism and nature conservation to protect and maintain the OUV of the site (PROWAD, 2012; CWSS, 2014). Over 50 good interpretation centres exist. There is also an action plan accompanying the tourism strategy. In terms of monitoring tourism, there is no comprehensive measurements of tourism activities in place for the entire Wadden Sea Region, despite available statistics for each country, mainly due to difficulties in harmonising national statistics under one unified system (Kloepper et al., 2017). The 2017 Quality Status report recommends 'that the three countries identify which monitoring means can be put in place in all three countries as part of the TMAP with a view to ensuring appropriate and compatible monitoring of tourism activities in the entire Wadden Sea Region' (Kloepper et al., 2017). There is also a lack of clarity whether there are already signs of over-tourism in certain spots and how to cooperatively handle/manage the issues associated with this issue (IUCN Consultation, 2020).

▶ Monitoring Highly Effective

There is a harmonized and coordinated Trilateral Monitoring and Assessment Programme which provide IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

regular reports on the progress in implementation the targets of the Wadden Sea Plan and a scientific assessment of the ecological status of the World Heritage site, with the last iteration of the report published in 2017 (CWSS, 2013; CWSS, 2016; Kloepper et al., 2017). The entire site is subject to active planning, management and monitoring, in national and international contexts, and in many cases with a good level of integration and harmonized approach between the three countries involved in the management of the Wadden Sea (IUCN, 2009).

▶ Research Highly Effective

One attribute of the OUV of the site is that “it is also one of the best-studied coastal areas on the planet, providing lessons of wider scientific importance for wetland and coastal management of international importance” (World Heritage Committee, 2009). Tremendous amount of research is ongoing on in the area, including research and modelling applied on climate change predictions in the Wadden Sea (IUCN, 2009), evidenced by recent publications such as Becherer et al., 2018; Benninghoff and Winter, 2019 and Vermeersen et al., 2018 etc., as well as the 2017 Wadden Sea Quality Status Report (Kloepper et al., 2017). The management has been quite effective in getting research done in key management areas.

Overall assessment of protection and management Highly Effective

Effective protection and management protocols are underpinned by excellent cooperation between the three States Parties such that there is institutional, financial and technical capacity to maintain the values and integrity of the site. The greatest management challenge is in maintaining the values of the site in the context of the globally-driven threat of climate change through effective on-site interventions to increase resilience and adapt to sea level rise and other climate change associated threats, which will undoubtedly impact the site's World Heritage values. Indeed, the Wadden Sea Plan is a good example in managing a number of serious threats to the site from beyond its borders, however, protection and management would further benefit from the finalisation and implementation of the Single Integrated Management Plan. Overall, protection and management are highly effective, though fisheries guidelines fully implemented and monitoring harmonized across the three countries in which the site is located would further enhance the site's conservation.

▶ Assessment of the effectiveness of protection and Highly Effective management in addressing threats outside the site

Given the scale of threats outside the site (fisheries, oil and gas extraction, shipping, wind farms) management tools to mitigate the threats posed to the site are state of the art.

▶ Best practice examples

The Wadden Sea Plan is a good example in managing a number of serious threats to the site from just beyond its borders.

State and trend of values

Assessing the current state and trend of values

World Heritage values

▶ Depositional coastline of unparalleled scale and diversity Good Trend:Stable

The natural processes continue mostly uninterrupted across the vast majority of the World Heritage site, and the Wadden Sea remains one of the most dynamic and valuable areas in the world. Considerable past interference (prior to inscription) (IUCN, 2009), through halting channel migration, fixation of IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

dunes, blocking overwash transport and developing and protecting tidal marshes (Kloepper et al., 2017) raises management challenges in how to maintain these processes through ongoing management interventions in the context of a changing climate (Kloepper et al., 2017). Since then, there were some small cases where natural processes were re-established, while at the same time the naturalness of the sediment processes close to the mouth of river Elbe has been reduced due to further deepening of this estuary. More effort is required to understand the relative importance of the major sediment transport processes in order to respond to sea level rise and other climate change associated threats in the future (Kloepper et al., 2017).

▶ One of the last remaining natural large-scale intertidal Low Concern ecosystems with natural processes continuing to function Trend:Stable largely undisturbed

These processes continue to function well within the intertidal ecosystems despite considerable interference in the past (prior to inscription) (IUCN, 2009). Natural dynamics occur mainly on the uninhabited parts of the site, such as the the barrier islands without coastal protection and uninhabited islets. However, to keep the Wadden Sea healthy despite sea level rise, nature restoration projects will be necessary, especially in inhabited areas. Initial projects such as the opening of summer dikes achieved success in restoring some of the natural dynamic processes (CWSS, 2010). Further projects such as the dune activation projects in the Netherlands have also been shown to increase dynamics (Kloepper et al., 2017), which will enhance ecosystem functionality. Some concerns have, however, been raised in the ongoing function of estuarine system, particularly the rivers Elbe, Weser and Ems, which experience high levels of industrial activity which has led to impacts on morphology, hydrography (including tidal amplitude), and loss of freshwater and brackish marshes (Kloepper et al., 2017), albeit some of which occurred before inscription with the subsequent implementation of Habitat and Water Framework Directives now improving the situation (Kloepper et al., 2017).

▶ Key site for migratory birds Low Concern Trend:Stable

The Wadden Sea remains of low concern overall as a key site for migratory birds along the East Atlantic Flyway. Monitoring of all the bird species in the World Heritage site is thorough and well established, with monitoring and population development calculations in the entire Wadden Sea having taken place for almost 30 years (e.g. Ens et al., 2009; Laursen et al., 2010; Hôtker et al., 2010; van Roomen et al., 2012; Koffijberg, 2015; Blew et al., 2016; Thorup et al., 2016; Kloepper et al., 2017). Analysis of trends of 34 species of migratory bird from the most recent available data collected between 2004/05 to 2013/14 show that overall six species are increasing, 14 species are stable and eleven species are decreasing; for three species no statistically significant trends could be estimated (Kloepper et al., 2017), and therefore can be assessed as stable overall. While there could be cause for concern for some migratory bird species, bird population dynamics and their conservation status depends largely on the conditions at all sites within their distribution range in the East Atlantic Flyway, and further data is required to identify the causes and understand if they could be changed by changes in management to the Wadden Sea World Heritage site (Kloepper et al., 2017). Factors inside the World Heritage site potentially impacting breeding, migrating and wintering birds negatively include indirect effects of fisheries activity (available food resources) and direct effects of human disturbance (incl. hunting) and predation (especially during the breeding season) (IUCN Consultation, 2017). As with the other values, climate change represents the greatest threat through disappearing foraging and breeding habitat by sea-level rise, alterations in the food web and emerging phenological mismatches, both inside the site and along the Flyway (Reneerkens, 2020). In the framework of the Wadden Sea Flyway Initiative, the 2nd total count of the East Atlantic Flyway was carried out in January 2017 in 33 countries - 11 in Europe and 22 in Africa. Most waterbird populations show a favourable trend, either increasing or stable. Moderate declines account for 23% of all populations. For short-term trends over the past 10 years, the situation is more uncertain, as short- term fluctuations confound a reliable and significant trend estimate. However, species showing positive long-term trends have also tended to increase over the past 10 years, and many species with a long- term decreasing trend further went down in recent years. Species in decline share several similar characteristics: they use intertidal flats for feeding, depend on benthic food and breed in the Arctic. IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

Waders breeding in the Siberian Arctic show the least favourable trends, whilst they are also highly susceptible to issues like climate change, interplaying with their tight migration strategies (Koffijberg and van Roomen, 2019; van Roomen et al., 2018).

▶ Exceptional species richness in a salt marsh Low Concern Trend:Stable

There is no indication of significant change in species richness since inscription in 2009, when baseline data (e.g. Marencic, 2009; Wolf et al., 2010) was collected. Seagrass populations have seemingly reached their optimum extent in the last five years following a steady increase in bed area since the mid-1990s (Kloepper et al., 2017), and new meadows have even appeared south of the Rottums and near Griend in the Netherlands (Kloepper et al., 2017), although recovery has yet to be recorded in central and south western areas (Kloepper et al., 2017). Subtidal habitats are reported to have shown an overall increase in quality and quantity since 2010 according to mapping of the subtidal zone of the Wadden Sea (Kloepper et al., 2017). However, still important subtidal habitats such as Sabellaria reefs, mussel banks and seagrass banks continue to be missing almost completely, just as fishes such as rays, small sharks and seahorses are missing. There is a lack of comprehensive data on beach and dune systems, but there are indications that this ecosystem is under pressure, albeit under no more threat than at the time of inscription in 2009 (Kloepper et al., 2017). Some salt marshes, particularly on the mainland coast, are in a rather bad shape, in particular due to heavy coastal engineering impacts such as strong drainage systems. Restoration projects as part of the daily management of the competent authorities are required for those sites and could certainly increase species richness there and return to a more 'natural' state (Kloepper et al., 2017).

Summary of the Values

▶ Assessment of the current state and trend of World Low Concern Heritage values Trend: Data Deficient

Excellent monitoring indicates that the natural values in the Wadden Sea World Heritage site are for the most part being conserved and are of low concern overall. A number of fluctuations in numbers of migratory and breeding waterbirds over the last decades have been recorded, with some important declines as well as increases, the number of declines being higher than the number of increases. More studies to determine the reasons for any declines and to understand appropriate management responses are under way. Marine mammal populations are also intensively studied and indicate positive trends.

▶ Assessment of the current state and trend of other Good important biodiversity values Trend: Data Deficient

Marine mammal populations are also intensively studied and indicate positive/ stable trends. The population of the harbour seal has shown a rapid recovery from previously low levels and now sustains approximately 20% of the North-east Atlantic subspecies of harbour seals. In 2020, the number of new-borns was the highest and its percentage of the total August moult count was reported as the second highest ever recorded (Galatius et al., 2020). While seal populations go through periodic fluctuations due to virus epidemics (e.g. in 1988 and 2002), this indicates a remarkable recovery. The grey seal has returned to the Wadden Sea and is now also showing good numbers again with the most recent pup survey showing a 2% growth overall from last year at 1726 (Brasseur et al., 2020). The overall trend for seals is positive (CWSS, 2010; Trilateral Seal Management Plan 2012-2016; 2018-2022). IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

Additional information

Benefits

Understanding Benefits

▶ Direct employment

Provision of revenue and jobs through tourism and park management

▶ Outdoor recreation and tourism

Beneficiaries include local and regional businesses that rely on tourism, and the tourists themselves. The World Heritage site is visited by over 10 million visitors annually (30-40 million day-trippers). Mudflat-walking, mostly guided, has become popular among tourists. Factors negatively affecting provision of this benefit : - Overexploitation : Impact level - High, Trend - Continuing

▶ Wilderness and iconic features

While it is difficult to consider the site as true “wilderness” (seeing that man-made structures can be perceived from much of the area), at the same time large areas of muddy sandflats with no perceptible human influence still exist. In a European context this is very rare and is of great value in a regional context.

▶ Importance for research

The site has been inscribed as “one of the best-studied coastal areas on the planet, providing lessons of wider scientific importance for wetland and coastal management of international importance”.

▶ Fishing areas and conservation of fish stocks

Area is an essential reserve for fish spawning and continues to be used for fisheries (mussels, shrimps). However, present fisheries should be better monitored and the effect on the site’s values minimized, by less bycatch, less intensity and leaving large areas unfished, while at the same time maintaining a regional and sustainable coastal fishery fully in line with the protection requirements. Factors negatively affecting provision of this benefit : - Climate change : Impact level - Low, Trend - Increasing - Pollution : Impact level - Low, Trend - Continuing - Overexploitation : Impact level - High, Trend - Continuing - Invasive species : Impact level - Low, Trend - Continuing

▶ Carbon sequestration, Flood prevention

Large areas of undeveloped coastal land with continuing sedimentation processes provide environmental services in flood reduction (including lessons learned) and probably contribute to climate change mitigation.

Summary of benefits

This large area of undeveloped or little developed coastal and marine habitats provides a wide array of benefits to the large numbers of people who live within or just outside of the World Heritage site or which come as visitors. In addition to nature conservation and wilderness values, the site provides a wide range of ecosystem services, furnishes a wealth of scientific knowledge, experiences with nature restoration and climate adaptation measures, and provides jobs, particularly through tourism but also from fisheries, park management, research and education. IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

Projects

Compilation of active conservation projects

№ Organization Brief description of Active Projects Website

1 Common Wadden Wadden Sea flyway initiative https://www.waddensea- Sea Secretariat worldheritage.org/breeding-and- migratory-birds

2 Common Wadden Prowad Link - Protect and Prosper https://www.waddensea- Sea Secretariat worldheritage.org/linking-sustainable- growth-and-nature-conservation

3 Numerous research Numerous research and conservation projects are and conservation undertaken in the site by the three State Parties, projects too numerous to list here. IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

REFERENCES

№ References

1 Becherer, J., Hofstede, J., Gräwe, U., Purkiani, K., Schulz, E., & Burchard, H. (2018). The Wadden Sea in transition-consequences of sea level rise. Ocean Dynamics, 68(1), pp.131-151.

2 Benninghoff, M., & Winter, C. (2019). Recent morphologic evolution of the German Wadden Sea. Scientific Reports, 9(1), 9293.

3 BirdLIfe (2009). The Wadden Sea: A vision for the conservation of a Natural Heritage. http://www.birdlife.org/europe/pdfs/Waddenvision.pdf

4 Blew, J., Günther, K., Hälterlein, B., Kleefstra, R., Laursen, K. and Scheiffarth, G. (2016). Trends of Migratory and Wintering Waterbirds in the Wadden Sea 1987/1988 - 2013/2014. Wadden Sea Ecosystem No. 37. Common Wadden Sea Secretariat, Joint Monitoring Group of Migratory Birds in the Wadden Sea, Wilhelmshaven, Germany. http://www.waddensea-secretariat.org/sites/default/files/do…

5 Brasseur S., Carius F., Diederichs B., Galatius A., Jeß A., Körber P., Schop J., Siebert U., Teilmann J., Bie Thøstesen C. & Klöpper S. (2020). EG-Seals grey seal surveys in the Wadden Sea and Helgoland in 2019-2020. Common Wadden Sea Secretariat, Wilhelmshaven, Germany.

6 Burbridge, P.R. (2000). The Nomination of the Wadden Sea Conservation Area as a World Heritage Site: A Feasibility Study For the Trilateral Wadden Sea Cooperation/ Common Wadden Sea Secretariat. 29 pp.

7 CWSS (2010). Wadden Sea Plan 2010. Eleventh Trilateral Governmental Conference on the Protection of the Wadden Sea. Common Wadden Sea Secretariat, Wilhelmshaven, Germany.

8 CWSS (2012). The Wadden Sea, Germany and Netherlands (N1314) - Extension Denmark and Germany. Nomination file for Danish extension to the WHC.

9 CWSS (2013). Aerial surveys of Harbour Seals in the Wadden Sea in 2013. Available at: https://www.waddensea-worldheritage.org/resources/2013-grey…

10 CWSS (2014). Ministerial Council Declaration. 12th Trilateral Governmental Conference on the Protection of the Wadden Sea, Trilateral Wadden Sea Governmental Council Meeting, Tønder, 5 February 2014. Available at: https://www.waddensea-worldheritage.org/resources/2014-tønd…

11 CWSS (2016). Report on the State of Conservation of the World Heritage property “The Wadden Sea (N1314)”. Wilhelmshaven, Germany.

12 CWSS (2020a). Alien Species. [online] Available at: https://www.waddensea-worldheritage.org/alien- species (Accessed 17 September 2020).

13 CWSS (2020b). Shaping a Sustainable Tomorrow - Wadden Sea Strategy on Education for Sustainable Development and World Heritage Interpretation. [online] Available at: https://www.waddensea- worldheritage.org/resources/education… (Accessed 18 September 2020).

14 CWSS (2018). 2018- 2022 Conservation Management Plan Wadden Sea Seal Population. [online] Available at: https://www.waddensea-worldheritage.org/resources/seal-mana… Accessed 18 September 2020).

15 Claessens, M., De Meester, S., Van Landuyt, L., De Clerck, K., Janssen, C.R. (2011). Occurrence and distribution of microplastics in marine sediments along the Belgian coast. Marine Pollution Bulletin. 62: 2199-2204. IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

№ References

16 Corder, M. (2020). Report highlights risks for container ships in Wadden Sea. Associated Press. [online] Available at: https://www.businessinsider.com/report-highlights-risks-for… (Accessed 18 September 2020).

17 Dekiff, JH., Remy, D., Klasmeier, J., Fries, E. (2014). Occurrence and spatial distribution of microplastics in sediments from Norderney. Environmental Pollution, 186, pp.248-256.

18 Dittmann T., Becker P.H., Bakker J., Bignert A., Nyberg E., Pereira M.G., Pijanowska U., Shore R., Stienen E., Toft G.O. & Marencic H. (2012). Large-scale spatial pollution patterns around the North Sea indicated by costal bird eggs within an EcoQO programme. Environ. Sci. Pollut. Res. 19: 4060- 4072.

19 Ens, B. J., Smaal, A. C., & De Vlas, J. (2004). The effects of shellfish fishery on the ecosystems of the Dutch Wadden Sea and Oosterschelde: final report on the second phase of the scientific evaluation of the Dutch shellfish fishery policy (EVA II) (No. 1011). Alterra.

20 Ens, B.J., Blew, J., van Roomen, M.W.J., & van Turnhout, C A.M. (2009). Exploring contrasting trends of migratory waterbirds in the Wadden Sea. Wadden Sea Ecosystem no. 27. Common Wadden Sea Secretariat.

21 Europarc Consulting (2012). Facts and Figures of the Wadden Sea Region. Part I of the Baseline Study for the Strategy for Sustainable Tourism in the Wadden Sea. Prowad Protect and Prosper: Sustainable Tourism in the Wadden Sea, co-financed by Interreg IVE North Sea Region Programme and EU European Regional Development Fund.

22 Fries, E., Dekiff, J.H., Willmeyer, J., Nuelle, M.-T., Ebert, M., Remy, D. (2013). Identification of polymer types and additives in marine microplastic particles using pyrolysis-GC/MS and scanning electron microscopy. Environmental Science: Processes and Impacts, 15, pp.1949-1956.

23 Galatius, A., Brackmann, J., Brasseur, S., Diederichs, B., Jeß, A., Klöpper, S., Körber, P., Schop, J., Siebert, U., Teilmann, J., Thøstesen, B. and Schmidt, B. (2020) Trilateral surveys of Harbour Seals in the Wadden Sea and Helgoland in 2020. Common Wadden Sea Secretariat, Wilhelmshaven, Germany.

24 Gittenberger, A. (2016). Alien species of the Wadden Sea database. Issued by Office of risk assessment and research, the Netherlands Food and Consumer Product Safety Authority.

25 Heron S.F., Day J.C., Zijlstra R., Engels B., Weber A., Marencic H and Busch J.A. (2020). Workshop report: Climate Risk Assessment for Wadden Sea World Heritage property. Application of the Climate Vulnerability Index – Outstanding Universal Value (OUV) Vulnerability. 68 pages. Common Wadden Sea Secretariat, Wilhelmshaven, Germany.

26 Hötker, H., Schrader, S., Schwemmer, P., Oberdiek, N., and Blew, J. (2010). Status, threats and conservation of birds in the German Wadden Sea. Technical Report NABU (available online at: http://www.unep-aewa.org/news/news_elements/2010/NABU_Statu…).

27 ICES (2003). Ecological Quality Objectives. ICES 2003ACE Report

28 ICES (2004). Ecological Quality Objectives. ICES Advice 2004, ACFM/ACE Report

29 IUCN (2009). World Heritage Nomination – IUCN Technical Evaluation, The Wadden Sea (Germany/The Netherlands). In: IUCN World Heritage Evaluations 2009, IUCN Evaluations of nominations of natural and mixed properties to the World Heritage List. WHC/09/33.COM/INF.8B2. [online] Gland, Switzerland: IUCN, pp.16-28. Available at: ; [Accessed November 2020]. IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

№ References

30 IUCN (2014). World Heritage Extension Nomination – IUCN Technical Evaluation, Wadden Sea (Denmark, Germany, The Netherlands). In: IUCN World Heritage Evaluations 2014, IUCN Evaluations of nominations of natural and mixed properties to the World Heritage List. WHC/14/38.COM/INF.8B2. [online] Gland, Switzerland: IUCN, pp.43-51. Available at: https://whc.unesco.org/en/list/1314/documents/ [Accessed 24 September 2020].

31 Jager, Zwanette (2015). Conservation Management of Fish Populations in the Wadden Sea. Hamburg, 8-9 January 2015 - Workshop Report. Common Wadden Sea Secretariat. 26 pp. http://www.waddensea-secretariat.org/sites/default/files/do…

32 Kloepper, S., Baptist, M. J., Bostelmann, A., Busch, J.A., Buschbaum, C., Gutow, L., Janssen, G., Jensen, K., Jørgensen, H.P., de Jong, F., Lüerßen, G., Schwarzer, K., Strempel, R. & Thieltges, D. (2017). Wadden Sea Quality Status Report 2017. [online] Common Wadden Sea Secretariat. Available at: https://qsr.waddensea-worldheritage.org/ (Accessed 17 September 2020).

33 Koffijberg, K. and van Roomen, M. (2019). Wadden Sea Flyway Initiative - Linking the Wadden Sea World Heritage Site with tropical wetlands and the Arctic Tundra. Available at: https://www.waddensea-worldheritage.org/sites/default/files…

34 Koffijberg, K., Laursen, K., Hälterlein, B., Reichert, G., Frikke, J. and Soldaat, L. (2015). Trends of Breeding Birds in the Wadden Sea 1991 - 2013. Wadden Sea Ecosystem No. 35. Common Wadden Sea Secretariat, Joint Monitoring Group of Breeding Birds in the Wadden Sea, Wilhelmshaven, Germany. http://www.waddensea-secretariat.org/sites/default/files/do…

35 Kraan, C., Van Gils, J. A., Spaans, B., Dekinga, A., Bijleveld, A. I., Van Roomen, M., ... & Piersma, T. (2009). Landscape‐scale experiment demonstrates that Wadden Sea intertidal flats are used to capacity by molluscivore migrant shorebirds. Journal of Animal Ecology, 78(6), 1259-1268.

36 Laursen, K., Blew, J., Eskildsen, K., Günther, K., Hälterlein, B., Kleefstra, R., Lüerssen, G., Potel, P., and Schrader, S. (2010). Migratory Waterbirds in the Wadden Sea 1987- 2008. Wadden Sea Ecosystem No.30. Common Wadden Sea Secretariat, Joint Monitoring Group of Migratory Birds in the Wadden Sea, Wilhelmshaven, Germany (available online at: http://www.waddensea- secretariat.org/sites/default/files/do…).

37 Leeuwarden Declaration. (2018). Ministerial Council Meeting: Leeuwarden Declaration. [online] 13th Trilateral Governmental Conference on the Protection of the Wadden Sea Leeuwarden, 18 May 2018. Available at: https://www.waddensea-worldheritage.org/sites/default/files… (Accessed 18 September 2020).

38 MELUR (Ministerium für Energiewende, Landwirtschaft, Umwelt und ländliche Räume des Landes Schleswig-Holstein). 2015. Strategie für das Wattenmeer 2100. Online: http://www.schleswig- holstein.de/DE/Fachinhalte/N/nationalp….

39 Madsen, J. (1998). Experimental Refuges for Migratory Waterfowl in Danish Wetlands: II. Tests of Hunting Disturbance Effects. Journal of Applied Ecology, 35, 398-417.

40 Madsen, J. and Fox, A.D. (1995). Impacts of Hunting Disturbance on Waterbirds - a Review. Wildlife Biology, vol 1, no. 4, pp. 193-206.

41 Marencic, H. (2009). The Wadden Sea - Introduction. Thematic Report No. 1. In: Marencic, H. & Vlas, J. de (Eds), 2009. Quality Status Report 2009. Wadden Sea Ecosystem No. 25. Common Wadden Sea Secretariat, Trilateral Monitoring and Assessment Group, Wilhelmshaven, Germany.

42 Miljøstyrelsen (2017). Fiskeriterritoriet og reservater. Vadehavet. [online, map]. Available at: mst.dk/media/129515/vadehavet-kortbilag-1.pdf

43 Nationalpark Vadehavet (2019). Plan for Nationalpark Vadehavet 2019 – 2014. Available at: https://nationalparkvadehavet.dk/media/246375/npv-plan-2019… IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

№ References

44 Nolte, S. (2013). Grazing as a nature-management tool on mainland salt marshes - Results of the Noord-Friesland grazing experiment. Univ Groningen. (paper given on Wadden Sea Day 29 August, 2013).

45 Nomination (2008). The Wadden Sea German/The Netherlands). Volume 1 (164 pp.) Volume 2 (24 annexes).

46 OSPAR (2007). Background document on the EcoQO on mercury and organohalogens in seabird eggs. OSPAR Commission, Assessment and Monitoring series, No. 331.

47 OSPAR (2009). EcoQO Handbook - Handbook for the application of Ecological Quality Objectives in the North Sea. Second Edition - 2009. OSPAR Biodiversity Series Publication 307/2009. OSPAR Commission London, 65 pp.

48 PROWAD (2014). Sustainable Tourism in the Wadden Sea World Heritage Destination. PROWAD – Protect and Prosper: Sustainable Tourism in the Wadden Sea’, co-financed by the Interreg IVB North Sea Region Programme (www.prowad.org).

49 Reneerskens, J. (2020). Climate change effects on Wadden Sea birds along the East-Atlantic flyway. [online] Leeuwarden:Wadden Academy. Available at: https://www.waddenacademie.nl/organisatie/publicatie-lijst/… (Accessed 18 September 2020).

50 Rösner, H-U. (2010). The Guiding Principle for the Wadden Sea: Advantages of a dynamic approach in a changing world. Wadden Sea Ecosystem 26: 23-28.

51 Thienen-Visser, V., Breunese, J. N., & Muntendam-Bos, A. G. (2015). Subsidence due to gas production in the Wadden Sea: How to ensure no harm will be done to nature. In 49th US Rock Mechanics/Geomechanics Symposium. American Rock Mechanics Association.

52 Thorup, O. and Koffijberg, K. (2016). Breeding success in the Wadden Sea 2009-2012 A review. Ecosystem No. 36. Common Wadden Sea Secretariat, Wilhelmshaven, Germany. http://www.waddensea-secretariat.org/sites/default/files/do…

53 Unger, B., Herr, H., Benke, H., Böhmert, M., Burkhardt-Holm, P., Dähne, M., Hillmann, M., Wolff- Schmidt, K., Wohlsein, P., Siebert, U. (2017). Marine debris in harbour porpoises and seals from German waters. Marine Environmental Research, 130, pp.77-84.

54 Vermeersen, B. L., Slangen, A. B., Gerkema, T., Baart, F., Cohen, K. M., Dangendorf, S., ... & Jevrejeva, S. (2018). Sea-level change in the Dutch Wadden Sea. Netherlands Journal of Geosciences, 97(3), pp.79-127

55 WWF (2012). Energy Production and Nature Conservation in the Wadden Sea Region and the Wadden Sea: Future Perspectives. Presentation at Wadden Sea Day, 30 August 2012. Available at: http://www.wwf.de/fileadmin/fm-wwf/Publikationen-PDF/120830…

56 WWF (2013). A Bright Outlook - Feasibility Study on Climate-friendly Tourism in the Wadden Sea Region. WWF Germany, Husum. Available at: http://www.wwf.de/fileadmin/fm-wwf/Publikationen- PDF/Feasib…

57 WWF (2014). Klimaschutz und -anpassung im Wattenmeer [online]. WWF Deutschland, updated 22 February 2016. Available at: http://www.wwf.de/watt/klima

58 Wadden Sea Board. (2019). Agenda Item: 5.1 World Heritage; Development of the Single Integrated Management Plan. [online] Common Wadden Sea Secretariat. Available at: https://www.waddensea- worldheritage.org/system/files/wsb-29… (Accessed 17 September 2020).

59 Wanner, A. (2013). Grazing effects on vegetation, breeding birds, silica and sediments in salt marshes: Results of the BASSIA-project. Univ. Hamburg. (paper given on Wadden Sea Day 29 August, 2013). IUCN World Heritage Outlook: https://worldheritageoutlook.iucn.org/ Wadden Sea - 2020 Conservation Outlook Assessment

№ References

60 Wolff, W.J., Bakker, J.P., Laursen, K. and Reise, K. (2010). The Wadden Sea Quality Status Report—Synthesis Report 2010. Wadden Sea Ecosystem No. 29. Common Wadden Sea Secretariat, Wilhelmshaven, Germany. Pp. 25-74.

61 World Heritage Committee (2009). Decision: 33 COM 8B.4 The Wadden Sea Statement of Outstanding Universal Value (Germany, Netherlands). In: Decisions Adopted by the World Heritage Committee at its 33rd Session (Seville, 2014). [online] Paris, France: UNESCO World Heritage Centre, pp.183-186. Available at: ; [Accessed November 2020].

62 World Heritage Committee. (2014). Decision: 38 COM 8B.13. Wadden Sea (Denmark, Germany, The Netherlands). In: Report of decisions of the 38th session of the World Heritage Committee. [online] Paris, France: UNESCO World Heritage Centre. Available at: https://whc.unesco.org/en/decisions/6098 [Accessed 24 September 2020].

63 van Beusekom, J., Carstensen, J., Dolch, T., Grage, A., Hofmeister, R., Kerimoglu, O., ... & Rönn, L. (2019). Wadden Sea Eutrophication: long-term trends and regional differences. Frontiers in Marine Science, 6, 370.

64 van Roomen, M., Laursen, K., van Turnhout, C., van Winden, E., Blewc, J., Eskildsen, K., Günther, K., Hälterlein, B., Kleefstra, R., Potel, P., Schrader, S., Luerssen, G., and Ens, B. J. (2012). Signals from the Wadden sea: Population declines dominate among waterbirds depending on intertidal mudflats. Ocean & Coastal Management 68: 79-88.

65 van Roomen, M., Nagy, S., Citegetse, G. and Schekkerman, H. (2018) (eds). East Atlantic Flyway Assessment 2017: the status of coastal waterbird populations and their sites. Wadden Sea Flyway Initiative p/a CWSS, Wilhelmshaven, Germany, Wetlands International, Wageningen, The Netherlands, BirdLife International, Cambridge, United Kingdom. Available at: https://www.waddenseaworldheritage.org/sites/default/files/…