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The European Union's Habitats Directive has the obligation to restore natural habitats in order to increase biodiversity within Europe. The European flat oyster Ostrea edulis is a favorable habitat builder for ecological restoration for which large amounts of spat are needed. Yet, the supply of spat is a key limiting factor because rearing protocols for O. edulis have not been optimized. This study reports on successful hatchery production of O. edulis reared at different temperature regimes with the aim to determine the most suitable thermal condition for early-life growth and survival. Larvae were reared at 25 and 29 °C until they were competent for settlement. Then, the larval batch at either temperature was split into two. One half of the batch remained at the original temperature while the other half was exposed to another temperature (25 or 29 °C) until 14 days post settlement. Larval size was similar among temperature treatments until 10 days post release, after which larvae reared at 29 °C were slightly (3%) larger compared to those reared at 25 °C (p < 0.05). The percentage of larvae which developed competence for settlement was not different (p > 0.05) between 25 °C (37 ± 4%) and 29 °C (33 ± 4%). Two weeks post settlement, size of the spat reared at 29 °C with a larval thermal history of 25 °C was 23% larger (p < 0.05) compared to O. edulis constantly reared at either 29 or 25 °C. Spat survival, which varied between 29 ± 6% and 56 ± 15% among treatments, was not related to rearing temperatures during the larval and early benthic phase (p > 0.05). Spat reached a size at which they are suitable for release into restoration sites within two weeks, resulting in a hatchery period of as little as three weeks. Our results contribute to the optimization of O. edulis hatchery protocols to improve yields for a growing demand of spat used in ecological restoration.

Tidal flats are among the ecologically richest areas of the world where sediment composition (e.g. median grain size and silt content) and the macrozoobenthic presence play an important role in the health of the ecosystem. Regular monitoring of environmental and ecological variables is essential for sustainable management of the area. While monitoring based on field sampling is very time-consuming, the predictive performance of these variables using satellite images is low due to the spectral homogeneity over these regions. We tested a novel approach that uses features from a variational autoencoder (VAE) model to enhance the predictive performance of remote sensing images for environmental and ecological variables of tidal flats. The model was trained using the Sentinel-2 spectral bands to reproduce the input images, and during this process, the VAE model represents important information on the tidal flats within its layer structure. The information in the layers of the trained model was extracted to form features with identical spatial coverage to the spectral bands. The features and the spectral bands together form the input to random forest models to predict field observations of the sediment characteristics such as median grain size and silt content, as well as the macrozoobenthic biomass and species richness. The maximum prediction accuracy of feature-based maps was close to 62% for the sediment characteristics and 37% for benthic fauna indices. The encoded features improved the prediction accuracy of the random forest regressor model by 15% points on average in comparison to using just the spectral bands. Our method enhances the predictive performance of remote sensing, in particular the spatiotemporal dynamics in median grain size and silt content of the sediment thereby contributing to better-informed management of coastal ecosystems.

Het uitgangspunt van dit project is dat meer kennis over de oorzaken en gevolgen van de ontwikkelingen in de halfgeknotte strandschelp en zwarte zee-eend een nauwkeuriger bandbreedte oplevert voor een duurzame schelpdiervisserij en daarmee meer bedrijfszekerheid. Belangrijke vragen zijn ten eerste of een verdere analyse van de beschikbare meetgegevens meer inzicht geeft in de oorzaak van de eerdere achteruitgang van de halfgeknotte strandschelp, ten tweede hoe de zwarte zee-eend het best te beschermen is en ten derde wat dat betekent voor de mogelijkheden voor schelpdiervisserij. Het project ‘Ruimte voor vogels en vissers’ (2018-2023) beoogde een handelingsperspectief te schetsen voor een duurzame visserij op halfgeknotte strandschelpen in de Nederlandse kustwateren.

Phaeocystis is a globally widespread marine phytoplankton genus, best known for its colony-forming species that can form large blooms and odorous foam during bloom decline. In the North Sea, Phaeocystis globosa typically becomes abundant towards the end of the spring bloom, when nutrients are depleted and the share of mixotrophic protists increases. Although mixotrophy is widespread across the eukaryotic tree of life and is also found amongst haptophytes, a mixotrophic nutrition has not yet beendemonstrated in Phaeocystis. Here, we sampled two consecutive Phaeocystis globosa spring blooms in the coastal North Sea. In both years, bacterial cells were observed inside 0.6 – 2% of P. globosa cells using double CARD-FISH hybridizations in combination with laser scanning confocal microscopy. Incubation experiments manipulating light and nutrient availability showed a trend towards higher occurrence of intracellular bacteria under P-deplete conditions. Based on counts of bacteria inside P. globosa cells in combination with theoretical values of prey digestion times, maximum ingestion rates of up to 0.08 bacteria cell−1 h−1 were estimated. In addition, a gene-based predictive model was applied to the transcriptome assemblies of seven Phaeocystis strains and 24 other haptophytes to assess their trophic mode. This model predicted a phago-mixotrophic feeding strategy in several (but not all) strains of P. globosa, P. antarctica and other haptophytes that were previously assumed to be autotrophic. The observation of bacterial cells inside P. globosa and the gene-based model predictions strongly suggest that the phago-mixotrophic feeding strategy is widespread among members of the Phaeocystis genus and other haptophytes, and might contribute to their remarkable success to form nuisance blooms under nutrient-limiting conditions.

In depositional intertidal coastal systems, primary production is dominated by benthic microalgae (microphytobenthos) inhabiting the mudflats. This benthic productivity is supporting secondary production and supplying important services to humans including food provisioning. Increased frequencies of extreme events in weather (such as heatwaves, storm surges and cloudbursts) are expected to strongly impact the spatiotemporal dynamics of the microphytobenthos and subsequently their contribution to coastal food webs. Within north-western Europe, the years 2018 and 2019 were characterized by record-breaking summer temperatures and accompanying droughts. Field-calibrated satellite data (Sentinel 2) were used to quantify the seasonal dynamics of microphytobenthos biomass and production at an unprecedented spatial and temporal resolution during these years. We demonstrate that the Normalized Difference Vegetation Index (NDVI) should be used with caution in depositional coastal intertidal systems, because it may reflect import of remains of allochthonous pelagic productivity rather than local benthic biomass. We show that the reduction in summer biomass of the benthic microalgae cannot be explained by grazing but was most probably due to the high temperatures. The fivefold increase in salinity from January to September 2018, resulting from reduced river run-off during this exceptionally dry year, cannot have been without consequences for the vitality of the microphytobenthos community and its resistance to wind stress and cloud bursts. Comparison to historical information revealed that primary productivity of microphytobenthos may vary at least fivefold due to variations in environmental conditions. Therefore, ongoing changes in environmental conditions and especially extreme events because of climate change will not only lead to changes in spatiotemporal patterns of benthic primary production but also to changes in biodiversity of life under water and ecosystem services in

The COVID-19 pandemic reminds us that our health is vulnerable to immediate threats emerging from the ecosystems we inhabit. More insidious global threats include the increasingly overt consequences of climate change, biodiversity loss, and pollution. As the largest connected ecosystem on Earth, the global ocean exerts a greater influence than any other on our climate and weather, affecting global food production and international trade. Much more importantly, human health is intricately linked to “ocean health.”

Whilst the demand for nutritious and sustainable seafood is increasing, fishing yields are declining due to overfishing and climate change. The inshore aquaculture of marine molluscs—e.g., the suspension-feeding cockle Cerastoderma edule for NW Europe—might be an alternative practice if cost-effective and nature-based technology enhances growth and survival. Our inshore experiments revealed that increasing the seawater residence time resulted in improved water quality. The reduction in sediment loads and stimulation of pelagic microalgal growth resulted in enhanced shell growth and meat content of the wild cockles seeded into the system. Shorter residence times resulted also in an increase in benthic microalgae, but the concurrent increase in silt content of the sediment appeared to hamper effective filtration by cockles. The growth conditions (with respect to the water and sediment quality) for the inshore cultivation of cockles can indeed be improved by means of ecological engineering, suggesting that the inshore aquaculture of marine shellfish can provide sustainable food and income for coastal communities, in particular when the shellfish farms are located in low-lying salinized coastal areas where common agriculture practices are no longer profitable. The involvement of the shellfishery industry was and will be crucial for studying and understanding the complex practice of cockle cultivation.

Intertidal areas in the Oosterschelde estuary decreases due to a disturbed sediment-balance caused by construction of a storm surge barrier and two compartmentalization dams. The intertidal area provide valuable foraging ground for the benthivore wader populations of the East-Atlantic Flyway. In 2019 seven nourishments were constructed at the Roggenplaat intertidal shoal to mitigate loss of foraging area and preserving wader populations. We study abundance of waders at the Roggenplaat prior to nourishment construction in a spatial and temporal manner and its relation with environmental factors to be able understand natural distribution of the waders and to evaluate the selected nourishment locations regarding interference with natural wader distribution. Relation between wader abundance and environmental factors like exposure time, food availability, and sediment composition increases understanding of the impact of drivers behind natural patterns in wader abundance. This study uses intertidal shoal covering bird counts that are obtained by counting from a boat that makes three two-hour tours (period 1, 2 and 3) around the Roggenplaat on 25 counting days. Bird counts were executed from one hour after high tide up to one hour after low tide. All waders that are protected by Nature2000 regulations for the Oosterschelde are studied. Environmental data of the Roggenplaat were obtained by combining tide gauge and LIDAR measurements for exposure time and collecting field samples at 113 stations for benthic infauna abundance and sediment composition. Spatial hotspot maps of foraging wader density were created for each period to find most important foraging ground of each species. Hotspots of foraging behavior were related to spatial differences in environmental conditions by comparing mapped data. The results show that significant temporal differences are present within a tidal cycle since less birds are counted from one hour after high tide up to three hours before low tid

In de Waddenzee komen twee soorten zeegras voor, namelijk klein zeegras (Zostera noltii) en groot zeegras (Zostera marina). Beide soorten kunnen een eenjarige en een meerjarige levenscyclus vertonen, waarbij ze respectievelijk met zaden en wortelstokken de winter overleven. Na een periode van zeer lage abundantie, als gevolg van ziekten in de jaren dertig en eutrofiëring in de jaren tachtig, lijkt het zeegras in de noordelijke delen van de trilaterale Waddenzee zich te herstellen, onder meer als het resultaat van een verbetering van de waterkwaliteit. In de zuidelijke delen van de Waddenzee zijn zeegrasvelden echter nog schaars en hebben ze een lage dichtheid. Hoewel zeegras in de Nederlandse Waddenzee enig herstel leek te hebben doorgemaakt, is het huidige oppervlak van de zeegrasvelden (ca. 3 km2) nog steeds maar een fractie (<3%) van het oppervlak dat geschikt lijkt te zijn voor het voorkomen van zeegras (ongeveer 130 km2). Dit vraagt om nader onderzoek naar omgevingsfactoren die de uitbreiding van zeegras in de Nederlandse Waddenzee mogelijk beperken., In this study, previous findings and assumptions on the importance of exposure time, sediment stability and ammonia for seagrass occurrence in the Dutch Wadden Sea are confirmed and (further) quantified.

Estuarine food webs are generally considered to be supported by marine pelagic and benthic primary producers and by the import of dead organic matter from the open sea. Although estuaries receive considerable amounts of freshwater phytoplankton and organic compounds from adjacent rivers, the potential contribution of these living and dead matter to estuarine food webs is often assumed to be negligible and, therefore, not examined. Based on stable isotope analyses, we report the importance of freshwater suspended particulate organic matter (FW-SPOM) for fuelling estuarine food webs in comparison to estuarine SPOM and microphytobenthos. This previously neglected food source contributed 50–60% (annual average) of food intake of suspension-feeding bivalves such as cockles (Cerastoderma edule), mussels (Mytilus edulis) and Pacific oysters (Magallana gigas) at the Balgzand tidal flats, an estuarine site in the western Wadden Sea (12–32 psu). For these species, this proportion was particularly high in autumn during strong run-off of SPOM-rich freshwater, whilst estuarine SPOM (20%-25%) and microphytobenthos (15%-30%) were relatively important in summer when the freshwater run-off was very low. These findings have implications for our understanding of the trophic interactions within coastal food webs and for freshwater management of estuarine ecosystems.

Food availability and food stock depletion by foraging populations can have substantial effects on the population size. How these aspects combine is rarely studied on long time scales, considering the complexity of ecological systems and the challenges to collect all relevant data. Migratory red knots (Calidris canutus) have been studied in the Western Dutch Wadden Sea over 24 years (from 1993 until 2017), and so has their and food availability. Here, we examine the relationships between numbers of red knots and their food in the Western Wadden Sea. First, the relation between red knot population size in the Vlie tidal basin and the availability of edible sizes of the preferred prey species (Limicola balthica) and an alternative prey (Cerastoderma edule) in is considered. The effect of prey quality, defined as the flesh to shell ratio of the prey, on the red knot population size is also taken into account. Furthermore, the relation between red knot numbers and elimination of prey in edible size classes in the Vlie tidal basin is analysed. To validate the relations between red knots and their food, the total available prey biomass and total calculated prey elimination are compared with the theoretical energy requirements of all red knots counted in the Vlie tidal basin each year. The numbers of red knots correlated positively with the amount of preferred prey (L. balthica) available, whereas there was no such relationship for the alternative prey (C. edule). Moreover, the number of red knots counted yearly correlated positively with mean quality of the preferred prey. This implies that any change in the availability of high-quality L. balthica will affect the red knot population. With increasing numbers of red knots, the calculated elimination of the edible size classes of L. balthica also increased, whereas there was no relationship with the estimated elimination of the alternative prey. The fraction of L. balthica eliminated was constant with the yearly number of r

Plastic pollution abounds in our oceans, resulting in a number of deleterious consequences for marine organisms. The transfer of microplastics (plastic particles measuring < 5 mm) between trophic levels through predator-prey interactions has become an important aspect of marine pollution research. This study aims to investigate microplastic ingestion in prey fish species, in order to provide further understanding of the potential for microplastic transfer between trophic levels. Sprat (Sprattus sprattus) and sandeel (Ammodytidae), together with a small number of other prey species, were analysed for ingested microplastics. The fish were collected from a number of locations in the North Sea. 291 sprat and 297 sandeels were analysed using both dissection and KOH dissolution to extract potential plastic. 12 and 5 microplastic particles were retrieved from the sprat and sandeels respectively. According to FT-IR analysis these were composed of a range of polymers including polyethylene (PE), polymethyl methacrylate (PMMA) and polypropylene (PP). Furthermore, sprat from both the winter and summer seasons were compared. Results show that summer sprat contained more plastic than the winter sprat, suggesting seasonal variation in microplastic ingestion by sprat in the North Sea. Microplastic characterisation by colleagues revealed that FT-IR is essential for determining whether a sample is ultimately plastic or not. One problem that occurs from analysing microplastic ingestion in a laboratory environment is the potential for atmospheric fallout of microfibres. The variation in the methods used by researchers to minimise or avoid air-borne contamination makes it difficult to compare microplastic results. This emphasises the need for studies to report fibrous and non-fibrous microplastics separately so as to allow proper comparison between studies. Although fibres were recovered from the samples during analysis, they were not taken into account in the ingestion results as t

Long-term field observations of nitrogen [N] and phosphorus [P] concentrations were used to construct nutrient budgets for the western Dutch Wadden Sea between 1976 and 2012. Nutrients come into the western Dutch Wadden Sea via river runoff, through exchange with the coastal zone of the North Sea, neighbouring tidal basins and through atmospheric deposition (for N). The highest concentrations in phosphorus and nitrogen were observed in the mid-1980s. Improved phosphorus removal at waste water treatment plants, management of fertilization in agriculture and removal of phosphates from detergents led to reduced riverine nutrient inputs and, consequently, reduced nutrient concentrations in the Wadden Sea. The budgets suggest that the period of the initial net import of phosphorus and nitrogen switched to a net export in 1981 for nitrogen and in 1992 for phosphorus. Such different behaviour in nutrient budgets during the rise and fall of external nutrient concentrations may be the result of different sediment-water exchange dynamics for P and N. It is hypothesized that during the period of increasing eutrophication (1976–1981) P, and to a lesser degree N, were stored in sediments as organic and inorganic nutrients. In the following period (1981–1992) external nutrient concentrations (especially in the North Sea) decreased, but P concentrations in the Wadden Sea remained high due to prolonged sediment release, whilst denitrification removed substantial amounts of N.From 1992 onwards, P and N budgets were closed by net loss, most probably because P stores were then depleted and denitrification continued. Under the present conditions (lower rates of sediment import and depleted P stores), nutrient concentrations in this area are expected to be more strongly influenced by wind-driven exchange with the North Sea and precipitation-driven discharge from Lake IJssel. This implies that the consequences of climate change will be more important, than during the 1970s and 1980s.

Quantifying exchange of particulate matter between coastal and open waters is an important and often unresolved issue. Here, we apply phytoplankton order richness as an innovative marine tracer to identify the geographic position of a coastal exchange zone in the SE North Sea, including its variability in time and space. Previous observations on dynamics of suspended particulate matter accumulation resulted in a hypothesized boundary between coastal waters (including the Wadden Sea) and open North Sea waters, the so-called ‘line-of-no-return’. Our study along two transects (Terschelling, Noordwijk) in the Dutch coastal zone showed seasonality patterns in phytoplankton order richness, both for diatoms and flagellates. The coastal Wadden Sea was found to be clearly different from the open North Sea, implying that seasonality in Wadden Sea phytoplankton is at least partly driven by local environmental conditions. Seasonality in flagellates was found to be more uniform than seasonality in diatoms. Stations in the coastal North Sea to a distance of 10 km (Terschelling) to 20 km (Noordwijk) from the shore appeared to be at the inside of the ‘line-of-no-return’. Our findings indicate that this approach is a useful aid in exploring mixing of particulate matter between coastal and open waters and to study the responses of phytoplankton communities to environmental drivers.

In this study, we have compared three methods to determine the exposure times of intertidal flats in the DutchWadden Sea. The first method was based on a triangulation (TRIA) of the sea level elevations measured at thetidal gauges surrounding the Dutch Wadden Sea, following Rappoldt et al. (2004); for the second, method numericalsimulations with the General Estuarine Transport Model (GETM) were used, and the third method (HYBRID)is a combination of the previous two. The first two methods showa good agreement for thewestern DutchWadden Sea, an area where the density of intertidal flats is low. However, the results of TRIA and GETM showdifferences of as much as 20% for the much shallower eastern part of the DutchWadden Sea.To explore the influence of the number and distribution of tidal gauge stations on these differences, virtual tidalgauges were added to the existing network of tidal gauge stations, based on model results. An analysis showedthat there is limited added value to an even large (three-fold) increase in the number of tide gauges, largely becauseof the highly non-linear behavior of the tidal wave in themodel compared to the linear approach adoptedin the triangulation method.The third approach (HYBRID) was developed by combining the previous two methods. Tidal prediction was obtainedfrom applying a Least Squares Harmonic Analysis on the Sea Level Height (SLH) in the simulation withGETM at every grid point. Moreover, the unpredictable part, e.g. the set-ups or set-downs induced by windsfrom the North Sea or the European continent, was determined by applying the triangulation method to thewind-induced SLH observed at the tidal gauge stations. This wind-induced SLH was defined as the observedsea level height minus the tidal prediction and its long-term mean value. This combination of methods offers anewapproach to determine exposure times in theWadden Seamore accurately than eithermethod individually.

Fluctuations in species composition can have major effects on the functionality of an ecosystem; however, studying such impacts is often complicated because fluctuations coincide with changes in other parts of the ecosystem. In this study, we explored long-term (1975 to 2014) changes in predator-prey interactions following concurrent changes in predatory epibenthic fish and crustaceans as well as their prey, macrozoobenthic bivalves and polychaetes, in the western Wadden Sea. Historical and recent invasions have resulted in an increase in relatively large and long-lived bivalves (Mya arenaria, Ensis directus, Crassostrea gigas) which have found a size refuge from epibenthic predators in the Wadden Sea. While bivalves dominated the macrozoobenthic biomass, polychaetes were the main food source of epibenthic predators, with the invasive polychaete Marenzelleria viridis probably becoming an important food source during the early 2000s. Food requirements of epibenthic crustaceans, mainly Crangon crangon, almost doubled from 5 to 10 g ash-free dry mass (AFDM) m-2 yr-1, and requirements of epibenthic fish decreased by more than 80%, mainly due to the local disappearance of Pleuronectes platessa. While the overall food requirements of the epibenthic predators stayed more or less constant, the edible fraction of the macrozoobenthic biomass increased from 5 to 20 g AFDM m-2 until the 2000s and decreased to 10 g AFDM m-2 thereafter. This was the result of changes in native (Nereis diversicolor and Heteromastus filiformis) and invasive (M. viridis) polychaetes. These findings illustrate that coinciding species-specific changes and interactions of both predators and prey should be taken into account to determine the impact of invasions on the food web structure and functioning of coastal systems.

Over the last decades, significant changes in the distribution and abundance of fish species are observed in the North Sea region. The ongoing warming trend of the Wadden Sea might drive cold-water species out of the Wadden Sea by exceeding their optimum performance temperature and might give an opportunity for warm-water species to perform well. In the context of the physiology of fish species and temperature conditions of the Wadden Sea, a mechanism is developed to explain changes in the distribution of several fish species. The species of interest are two demersal flatfish species and two contrasting pelagic fish species, respectively, plaice (Pleuronectes platessa L.), flounder (Platichthys flesus L.), Atlantic herring (Clupea harengus L.) and European anchovy (Engraulis encrasicolus L.). Projected temperature conditions of a general estuarine transport model (GETM) of the Dutch Wadden Sea were implemented into a dynamic energy budget (DEB) model, resulting in monthly potential growth maps for the years 2009-2011 of two sizes classes of the four fish species. Summer temperatures exceeded several species-specific optimum temperatures in large parts of the Wadden Sea within the study period, whereby high temperatures limit growth. Growth reduction was not projected in every year since there was interannual variability in temperature-related growth. If temperatures keep rising, which is projected, optimum temperatures will be exceeded more frequently and more pronounced in the Wadden Sea. The observed changes in fish species distribution can be temperature driven since several cold-water species live at their upper thermal limit, besides, temperature conditions become more favorable for warm-water species.

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Dynamic Energy Budget (DEB) models are often used to describe growth in bivalve species. Ingestion rate determines the amount of energy assimilated and therefore the amount of energy allocated to growth, maintenance, and reproduction. Gills and palps are involved in the ingestion of food as their size determines clearance rate and selection efficiency. In bivalves, gills create a water current from which particles are filtered and palps sort these particles into edible and non-edible. Gill and palp sizes are phenotypically flexible and depend on environmental conditions. So far, variation in gill and palp size has not been incorporated in DEB models, even though they could greatly affect the amount of energy assimilated. Therefore, this research aims at linking environmental conditions to variation in gill and palp size in cockles (Cerastoderma edule) and incorporates this into a standard DEB model to estimate growth for cockles that adjusted their feeding apparatus to optimize food intake. Data on variation in feeding morphology has been collected under different conditions in the Dutch Wadden Sea. DEB models were applied to three different sites to compare variation in growth under different environmental conditions with and without flexibility in the feeding morphology. Results indicate that variation in gill size is mostly explained by shell length and exposure time while variation in palp size relates to shell length, median grain size, exposure time and density. Model estimates for cockle growth show a reduced growth under low Chlorophyll a and high Suspended Particulate Matter concentrations. In addition, it is beneficial for cockles to adjust their palp size, as this result in increased growth, while adjusting gill size seem to negatively affect growth. Therefore, it is concluded that flexibility in feeding morphology influences the growth of cockles and should not be ignored when modelling bivalve growth.

The ongoing daily sampling programme of the fish fauna in the Dutch Wadden Sea using fixed gear was analysed for the years 1960–2011. Spring sampling caught immigrating fish from the coastal zone and autumn samples reflected emigration of young-of-the-year. In total 82 fish species were caught with no clear trend in biodiversity. In both spring and autumn total daily catch fluctuated and peaked in the late 1970s. From 1980 to the present catches of both pelagic and demersal species showed a 10-fold decrease in total biomass. Mean individual biomass decreased in spring between 1980 and the present from about 150 to 20 g wet weight. No trend was found in autumn mean individual biomass which fluctuated around 20 g wet weight. The trophic structure remained constant for both the demersal and benthopelagic fish fauna from 1980 to 2011, whilst the trophic position of pelagic fish in spring fell from about 3.9 to 3.1. Min/max auto-correlation factor analysis showed similar trends in spring and autumn species biomass time series: the first axis represented a decrease from the 1960s followed by stabilization from the mid-1990s. The second trend showed an increase with a maximum around 1980 followed by a steady decrease in spring and a decrease and stabilization from 2000 in autumn. It is argued that the most likely explanatory variables are a combination of external factors: increased water temperature, habitat destruction in the coastal zone (sand dredging and beach nourishment, fishing) and increased predation by top predators for the first trend, and large-scale hydrodynamic circulation for the second trend. We conclude that both the trophic structure of the coastal zone fauna and the nursery function of the Wadden Sea have been reduced since the 1980s. Our findings corroborate that ecological change in coastal ecosystems has not only occurred in the past but still continues.