Mytilus galloprovincialis-type foot-protein-1 alleles occur at low frequency among mussels in the Dutch Wadden Sea

The presence of M. galloprovincialis-type genes among the population of mussels in the Dutch Wadden Sea, historically described as M. edulis, was assessed. We applied the molecular technique in which a fragment of the gene coding for an adhesive protein of the byssus of mussels is amplified by PCR and assayed for length using electrophoresis. Among 321 individual mussels collected in August–October 2001 at 14 sites (5 intertidal, 9 subtidal) widely dispersed over the Dutch Wadden Sea, 6 specimens (collected at 5 sites) were found that showed a heterozygote genotype with both the M. edulis- and the M. galloprovincialis-type alleles being amplified; all others were identified as homozygotes for the M. edulis-type allele. Differentiation in frequencies of heterozygotes among sites was not detected. The ofact that the M. galloprovincialis-type allele was present at low frequency (0.0093) may be attributed to one of three possible, and not mutually exclusive, causes: incomplete diagnosticity of this marker, an historically stable introgression zone in the Wadden Sea, or a recent invasion.

Radio-telemetry observations of the first 650 km of the migration of Bar-tailed Godwits Limosa lapponica from the Wadden Sea to the Russian Arctic

In 1999 and 2000, 45 Bar-tailed Godwits Limosa lapponica were supplied with radio-transmitters during spring staging on the island Texel in the western Wadden Sea. With the use of Automatic Radio Tracking Stations (ARTS) on Texel and in south Sweden, and hand-held receivers on Texel, it was possible to follow the later part of the stopover period on Texel for 34 birds (76%) and the passage over south Sweden for 26 birds (58%). Thus, the method of automatic tracking of overflying migrating shorebirds works successfully where the migration corridor is narrow and predictable, as in the case with late spring shorebird migration from the Wadden Sea towards arctic Russia. The timing of departure from Texel and passage over south Sweden of radio-marked birds, with median dates of 30 May and 2 June respectively, were in agreement with published data on the spring migration of Siberian-breeding Bar-tailed Godwits L. l. taymyrensis. The individual variation in migration dates was larger than expected, with birds passing south Sweden between 25 May and 10 June, indicating that the time-window for departure might be broader than previously thought. There was no clear difference between males and females in timing of migration. The time difference between departure from Texel and passage over south Sweden (average 3.3 days) indicates that most Bar-tailed Godwits do not embark on the long flight towards Siberia directly from the western Wadden Sea, but are more likely to stop in the more easterly portion of the Wadden Sea before the final take-off. This pattern is similar to what has been found in other shorebirds and geese (e.g. Red Knots Calidris canutus and Dark-bellied Brent Geese Branta bernicla) migrating along the same route.

High risk exotic species with respect to shellfish transports from the Oosterschelde to the Wadden Sea

This study presents the results of a literature review on 11 exotic marine species that are present in the Oosterschelde and could potentially be introduced into the Wadden Sea with shellfish transfers. Ten of the species result from a previous risk study, where they were identified as the species posing the highest risk. The Japanese oyster drill, that was recently observed in the Oosterschelde was also included in this study. The species discussed in the present study are: colonial tunicates Didemnum sp and Botrylloides violaceus the American oyster drill (Urosalpinx cinerea) and the Japanese oysterdrill (Ocinebrellus inornatus), the copepods Myticola orientalis and M. ostreae, the colonial bryozoan Smittoidea prolifica, Marteilia refringens and the macroalgae Gracilaria vermiculophylla, Polysiphonia senticulosa and Undaria pinnatifida. Four of these species (Gracilaria vermiculophylla, Undaria pinnatifida, Didemnum vexillum and Botrylloides violaceus) have recently been observed in the Wadden Sea. Some of these species are known pest species and could have an impact on the Wadden Sea ecosystem and/or the shellfish culture. The information that is collected in this study can be used to get a more realistic estimation of the risks compared to the risk assessment study of 2008 which was based on a worst-case approach. Moreover, the results can be used in the development of mitigating measures to reduce the risks of introducing these exotic species with the shellfish transfer from the Oosterschelde to the Wadden Sea

The impact of intertidal areas on the carbonate system of the southern North Sea

The coastal ocean is strongly affected by ocean acidification because of its shallow water depths, low volume, and the closeness to terrestrial dynamics. Earlier observations of dissolved inorganic carbon (DIC) and total alkalinity (TA) in the southern part of the North Sea, a northwest European shelf sea, revealed lower acidification effects than expected. It has been assumed that anaerobic degradation and subsequent TA release in the adjacent back-barrier tidal areas (Wadden Sea) in summertime is responsible for this phenomenon. In this study the exchange rates of TA and DIC between the Wadden Sea tidal basins and the North Sea and the consequences for the carbonate system in the German Bight are estimated using a 3D ecosystem model. The aim of this study is to differentiate the various sources contributing to observed high summer TA in the southern North Sea. Measured TA and DIC in the Wadden Sea are considered as model boundary conditions. This procedure acknowledges the dynamic behaviour of the Wadden Sea as an area of effective production and decomposition of organic material. According to the modelling results, 39 Gmol TA yr−1 were exported from the Wadden Sea into the North Sea, which is less than a previous estimate but within a comparable range. The interannual variabilities in TA and DIC, mainly driven by hydrodynamic conditions, were examined for the years 2001–2009. Dynamics in the carbonate system are found to be related to specific weather conditions. The results suggest that the Wadden Sea is an important driver for the carbonate system in the southern North Sea. On average 41 % of TA inventory changes in the German Bight were caused by riverine input, 37 % by net transport from adjacent North Sea sectors, 16 % by Wadden Sea export, and 6 % were caused by internal net production of TA. The dominant role of river input for the TA inventory disappears when focusing on TA concentration changes due to the corresponding freshwater fluxes diluting the marine TA concentrations. The ratio of exported TA versus DIC reflects the dominant underlying biogeochemical processes in the Wadden Sea. Whereas aerobic degradation of organic matter played a key role in the North Frisian Wadden Sea during all seasons of the year, anaerobic degradation of organic matter dominated in the East Frisian Wadden Sea. Despite the scarcity of high-resolution field data, it is shown that anaerobic degradation in the Wadden Sea is one of the main contributors of elevated summer TA values in the southern North Sea

Academic Engagement with Wadden Sea Stakeholders: A Review of Past Foci and Possible Futures

The Wadden Sea became a UNESCO World Heritage Site in 2009 owing to its geographical and ecological importance. Given its status and its global recognition, academic understanding of, and engagement with, a diverse set of stakeholders is crucial to the sustainability of the Wadden Sea and the wildlife that inhabit its transnational boundaries. As such, this paper reviews with whom, how, and to what extent the academy has engaged with Wadden Sea stakeholders. This study finds that stakeholder groups (whom, with vested interests in the sea, might be expected to be present) are missing from academic publications focused on stakeholders in the Wadden Sea. Moreover, existing studies tend to focus on singular, categorized stakeholder ‘groups’, and lack transboundary integration, as well as reference to UN Sustainability Goal 14 – a key target for environmental protection. In sum, the review provides (1) an analysis of academic work that engages Wadden Sea stakeholders to assist future researchers undertaking work in this global ecologically significant area, and (2) a discussion of where future academic work might be developed

Age and environment affect constitutive immune function in Red Knots (Calidris canutus)

We studied subspecies, age and environmental effects on constitutive immune function (natural antibody and complement titres, haptoglobin activity and leukocyte concentrations) in Red Knots (Calidris canutus). We compared C. c. islandica and C. c. canutus in the Wadden Sea and found no difference in immune function between subspecies. However, C. c. canutus on their wintering grounds in Banc d’Arguin had higher natural antibody and lower complement levels than C. c. canutus or C. c. islandica in the Wadden Sea. This suggests that immune function is determined more by the surrounding environment than by subspecies. We also compared age classes in the Wadden Sea and found that first year birds had significantly lower natural antibody levels than adults, but that second year birds no longer differed from adults. Finally, we examined the interaction of age and environment in Banc d’Arguin. We found that first year birds (but not adults) in a low quality habitat had higher leukocyte concentrations than first year birds or adults in a high quality habitat. Differences in available resources and defence needs between environments, and differences among individuals differentially distributed between sites, are likely important contributors to the variation in immune function we report. Future studies, which examine these factors on wild birds, will be important for our understanding of how animals function in their natural environment.

Sustainable tourism development and the world heritage status of the Wadden Sea: The case of Terschelling

National governments and regions make great efforts to obtain international recognition for their natural heritage, for instance through UNESCO’s World Heritage Sites list. Since June 2009, the Dutch Wadden Sea has been on the World Heritage List. Our study investigates to what extent the World Heritage status of the Wadden Sea matters to tourists visiting the Wadden island of Terschelling, in the off season. Results showed that for most respondents (93.5%) the World Heritage Status was not a reason to visit Terschelling, while almost a quarter (23.7%) did not know about the World Heritage Status. However, the Wadden Sea was regarded as one of the most attractive elements of the area, together with the North Sea beach, dunes and forests of the Wadden island of Terschelling. For 58% of the respondents, the Wadden Sea was the reason to visit. To conclude, the Wadden Sea is highly appreciated, but for domestic tourists, the designation as World Heritage Site is not a reason for visiting. First-time or international tourists, who are more likely to be attracted by the World Heritage status, were not found during the off season. More efforts could be made to promote the Wadden Sea area as an attractive natural area among these groups of tourists, in order to gain more support for nature protection and preservation of this unique natural heritage region.Keywords: tourist motivations, valuation, natural landscapes, coastal tourism, long-term nature protectio

Evaluation of the Wadden Sea Particularly sensitive Sea Area. On behalf of the Common Wadden Sea Secretariat.

The purpose of this document is to present the high level outcomes for the evaluation of the effectiveness of the Wadden Sea PSSA, seven years after its designation by the IMO. Key changes with regard to IMO and EU shipping policy are identified and described, followed by a review of ‘expert’ opinion focused on the issues relating to PSSAs. The development of an evaluative framework and the resulting findings are introduced and discussed in context. Using existing data against this evaluative framework we conclude that six key elements require action in order to fully describe the efficacy of the designation, and our recommendations to address these concerns are presented.<br/

Seals in motion. How movements drive population development of harbour seals and grey seals in the North Sea

The harbour seal Phoca vitulina and the grey seal Halichoerus grypus have been inhabitants of the Wadden Sea since millennia. Prehistoric findings indicate the presence of both species around 5000 BC. This changed dramatically in the mid Middle-Ages as around 1500 AC, the grey seal disappeared from the Wadden Sea as a consequence of persecution. With growing hunting pressure, especially in the 20th century and concurrent habitat destruction and pollution, the harbour seals reached all time low numbers in the 1970’s. Banning the hunt in countries around the southern North Sea, limiting pollution and protection from disturbance allowed the harbour seals to slowly recover and the grey seals to return to the Wadden Sea. In this thesis the population trends and inherent dynamics of the recovery for both species is described. Also the movements of individual animals are studied to explain possible mechanisms

Projected Responses of Tidal Dynamics in the North Sea to Sea-Level Rise and Morphological Changes in the Wadden Sea

This study explores the projected responses of tidal dynamics in the North Sea induced by the interplay between plausible projections of sea-level rise (SLR) and morphological changes in the Wadden Sea. This is done in order to gain insight into the casual relationships between physical drivers and hydro-morphodynamic processes. To achieve this goal, a hydronumerical model of the northwest European shelf seas (NWES) was set-up and validated. By implementing a plausible set of projections for global SLR (SLRRCP8.5 of 0.8 m and SLRhigh−end of 2.0 m) by the end of this century and beyond, the model was run to assess the responses of the regional tidal dynamics. In addition, for each considered SLR, various projections for cumulative rates of vertical accretion were applied to the intertidal flats in the Wadden Sea (ranging from 0 to 100% of projected SLR). Independent of the rate of vertical accretion, the spatial pattern of M2 amplitude changes remains relatively stable throughout most of the model domain for a SLR of 0.8 m. However, the model shows a substantial sensitivity toward the different rates of vertical accretion along the coasts of the Wadden Sea, but also in remote regions like the Skagerrak. If no vertical accretion is assumed in the intertidal flats of the Wadden Sea, the German Bight and the Danish west coast are subject to decreases in M2 amplitudes. In contrast, those regions experience increases in M2 amplitudes if the local intertidal flats are able to keep up with the projected SLR of 0.8 m. Between the different scenarios, the North Frisian Wadden Sea shows the largest differences in M2 amplitudes, locally varying by up to 14 cm. For a SLR of 2.0 m, the M2 amplitude changes are even more amplified. Again, the differences between the various rates of vertical accretion are largest in the North Frisian Wadden Sea (&gt; 20 cm). The local distortion of the tidal wave is also significantly different between the scenarios. In the case of no vertical accretion, tidal asymmetry in the German estuaries increases, leading to a potentially enhanced sediment import. The presented results have strong implications for local coastal protection strategies and navigation in adjacent estuaries. © Copyright © 2021 Jordan, Visscher and Schlurmann