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Bearded seal

Knowledge repository

Scientific name: Erignathus barbatus
Family: Phocidae
Size: 2 - 2,5 meters
Weight: 250 – 300 kilos
Habitat: Arctic
Endangered status: not endangered

See also

  • baardrob

"Bearded seals get their name from their... moustache!"

External characteristics of the bearded seal

Do you know how the bearded seal got its name? Bearded seals have a bunch of thick and long whiskers. When these are dry, the ends of these whiskers curl. It looks like they have a thick moustache.

Bearded seals have a broad head that appears a bit flat when viewed from above. Their eyes are relatively small and close to eachother. They have a large, broad muzzle with the cheeks appearing to droop a little. Their nostrils are wide apart and quite large1,3.

The head is quite small in relation to their body. Bearded seals have a large, long body. Adult animals are between 2 and 2.5 meters long, with an average weight between 250 and 300 kilograms3.

Gender differences

The females sometimes grow a bit larger than the males. But otherwise the females and males are difficult to tell apart. They both have a gray-brown color, sometimes with a rust-colored head and flippers. Because their fingers are all the same length, bearded seals' flippers appear almost square in shape. The nails are wide and short1,2.

Did you know...

Did you know: If there is iron in the seabed, some seal species can develop a rust-colored coat on the head and flippers. This is quite common in bearded seals, but also the common seal (Phoca vitulina) here in the Netherlands sometimes has this!

Distribution and status

Bearded seals are members of the family true seals (Phocidae), and belong to the subfamily of northern true seals (Phocinae). They live in the Arctic. Their remote habitat and way of life make it very difficult to conduct long-term research. As a result, little is known about their behavior.

This seal species has two subspecies. The Eastern bearded seal (Erignathus barbatus barbatus) and the Western bearded seal (Erignathus barbatus nauticus). The first one lives in the Atlantic part of the North Pole. The Western bearded seal also lives in the North Pole, but on the Pacific side1.

It is estimated that there are more than 500,000 bearded seals. They are considered non-threatened, but global warming is causing significant changes in their habitat1. They depend on sea ice during mating season, so its reduction is disadvantageous to the bearded seal population. So they are not in trouble yet. But melting ice caps will mean less and less space for bearded seals to mate and nurse pups2.

Diet and foraging

Bearded seals mainly hunt benthos. Benthos is a collective name for organisms that live in and on the seabed. Their diet is varied. They eat crabs, shrimps, shellfish, squid and fish. They prey on these animals in shallower waters, usually diving around 100 meters deep. Younger, less experienced animals sometimes go a lot deeper (up to 450 meters). Bearded seals can stay underwater for 25 minutes, but most dives don't last more than 10 minutes3.3.

Behaviour of the bearded seal

Bearded seals are not very social. They prefer to spend their time alone. Females also like to be alone when they have and nurse their pups. However, it is not strange to see them lying next to each other on the ice. They prefer not to go into the water during moulting. Then they can often be found in small groups on the ice.

Bearded seals rest close to water. They do this so that they can flee quickly if necessary. So the best places to rest are along the water's edge on the pack ice, on ice floes or around breathing holes on the sea ice3.

Did you know...

Did you know that bearded seals prevent their favorite breathing holes from freezing? They do this by scraping the ice with their short but strong claws. 1

Reproduction in bearded seals

Little is known about this species, both about mating behaviour and about the period of birth. For example, we don't know how long the pregnancy of bearded seals lasts.

Mating behaviour

When they are between 5 and 7 years old, bearded seals become sexually mature. That means that they are adults and can therefore have pups.

Bearded seals mate in the water. Because of this, little is known about their mating behaviour. We do know that males “sing” during the mating season. They do this to attract females and to scare off other males. Their singing usually consists of sharp, whistling sounds. These start very high and then become lower in pitch3.

Birth and nursing period

The pups are born between March and early May on ice floes in shallow water. The pups are around 1.30 meters at birth and then weigh an average of 35 kilos. They have dense, light gray fur and a layer of subcutaneous blubber.

Did you know that most bearded seal pups enter the water with their mother within a few hours of birth? They probably do this to avoid polar bears in the area3.

During the nursing period, the pup spends about half of the time on the ice sleeping. The rest of the time, mother and pup will be in the water together. So bearded seal pups learn to swim and dive from their mother, something most other seal species do not do3.

The milk that the pup gets from the mother is about 50 percent fat. This helps the pup gain weight quickly. The nursing period lasts between 18 and 24 days. At the end of this period, the bearded seal pup can weigh 100 kilos. So pups gain 60-70 kilos in this short time! The mother then leaves her weaner to mate2,3.

Enemies of the bearded seal

Bearded seals are often on the menu of polar bears. Orcas, Greenland sharks and even walruses also sometimes hunt young bearded seals.

These seals are also hunted by humans. Traditional seal hunting is an important source of food, fuel and equipment for native people.

Bearded seals were also hunted commercially in Russia. Between 1950 and 1960, more than 10,000 bearded seals were killed. That has now been greatly reduced. Now only a few hundred animals are allowed to be killed each year. However, the only sources on this are from the Russian government, so it is not clear whether these numbers are correct and whether those rules are also being followed3,4.

1 (Shirihai & Jarrett, 2021 [2006])

2 (NOAA, 2022)

3 (Kovaks, 2018)

4(Cameron et al., 2010)

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  • Classification

  • Characteristics bearded seal

  • Gender differences

  • Distribution and status

  • Diet and foraging

  • Behaviour of the bearded seal

  • Reproduction in bearded seals

  • Enemies of the bearded seal

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Zeehond met melanisme


Knowledge repository

Have you ever seen a black seal? That would be very special because black coloured seals are quite rare. These seals have melanism, which makes them completely black from head to toe. In this article you can read all about what melanism is and learn what a melanistic seal looks like.

See also

  • Melanism

  • Melanistische zeehond

  • Zwarte zeehond

  • Melanisme is het tegenovergestelde van albinisme

What is melanism?

Having melanism means too much of the pigment melanin is produced. This is caused by an abnormality in genes. The pigment melanin is found in humans and animals in the skin, eyes and hair. The more melanin you have, the darker your skin color, eyes and hair are.

The amount of melanin you naturally have can vary per person/animal, but it is quite unique to produce both an excess of melanin (melanism) and no melanin at all (albinism).

Black seals in the Netherlands

Seals that are completely black are called melanistic. These seals have completely black fur and black nails. As far as we know, we have taken care of at least 10 melanistic seals in Pieterburen.

The most recent one came to us in January ,2016. We see that seals with melanism behave the same as all other seals and are no more sensitive or weaker than the rest. We, therefore release seals with melanism back into the sea with confidence.

Watch this video

Curious what a melanistic seal looks like? Then watch the short video below of seal Pepper at our Sealcentre:

Melanism is rare

It is almost never the case that you see a completely black seal. It is difficult to say exactly how little melanism occurs in the seals in the sea. We have only seen melanism in grey seals, not in common seals (yet).

Zwarte zeehond - melanisme

Melanism in other animals

Melanism does not only occur in seals. There are also melanistic foxes, chickens, frogs, guinea pigs and house cats. A very well-known example of a melanistic animal is the black panther.

Did you know...

The black panther is not a separate animal species, but is a collective name for all melanistic felines?

In most cases, the completely black animals are in the minority in felines, but in the feline jaguarundi about 80 percent are melanistic animals [1].

Advantages or disadvantages of melanism

Melanism can be beneficial and/or disadvantageous for animal species and individual. For scientists, melanism is an interesting topic. If animals can differ in appearance, does black fur have certain advantages or disadvantages? It often happens that the colour and/or pattern of the coat matches the colours of the environment.

White pups

Think, for example, of a seal pup with a white coat lying on the ice in the North Pole. This way he is less noticeable to predators who would love to eat the pup. On the other hand, it also works to their advantage for predators. A polar bear is colored white for the same reason, so that seals are less likely to see it coming when it goes to hunt them. If you have the color of your environment, it works like a protective color: you stand out less which increases your chance of survival.

For that reason, melanism should not occur in the North Pole. According to this theory, black animals would stand out in such a snow-white environment. The result: they are eaten earlier and therefore even rarer. The fewer black animals there are, the less likely they are to reproduce and pass on their genes that provide the black coat.

Melanistic advantage in the Netherlands

For a seal in the Netherlands, a black fur has no advantage or disadvantage in any case. This is because the seal is at the very top of the Wadden Sea food chain. That is so because there is no other animal that eats the seal.

Also, there are no other reasons that can cause melanistic seals to increase or decrease. The number of black seals in the seal population depends entirely on how many of these melanistic seals reproduce.

Did you know...

Animals can change colour when their environment changes? A special and well-known example of this is the pepper-and-salt butterfly [2].

Adapt to the environment

The name says it all: the pepper-and-salt butterfly was white with black. But in the 19th century (1800-1899) completely black specimens of this species suddenly appeared in England. These black butterflies are very noticeable when they were on a light tree trunk. Why did more black butterflies appear at that time if that seems to be a disadvantage?

In this century, the Industrial Revolution was in full swing. Due to the large spread of factories and machines, there was a lot of air pollution. The black soot in the air precipitated, turning buildings and trees black. Suddenly you didn't stand out as a black butterfly. In cities, the ratio turned around. Black butterflies of the pepper-and-salt butterfly were mainly found there, while the light variant occurred in nature reserves.

Depending on various factors, such as your environment, melanism can therefore work in your favor! Can you think of in which nature reserves a black seal has an advantage compared to a grey seal?


  2. Majerus, Michael E. N. (2008). “Industrial Melanism in the Peppered Moth, Biston betularia: An Excellent Teaching Example of Darwinian Evolution in Action”.Evolution: Education and Outreach 2 (1): 63–74. doi:10.1007/s12052-008-0107-y

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Seal mother also let pups be

Knowledge repository

Research in the Dollard has been ongoing since 2015. In all these years, several results have been achieved. We have learned more about the behaviour of seal mothers and their pups. We have also been able to use the results to adjust our rehabilitation policy: we now observe seal pups longer and catch fewer pups. Below we share the insights we've gained so far.

See also

  • Pup roept

  • Zeehond - moeder en pup zogen

  • Onderzoek in de Dollard

First insights

We used to think that a seal pup lying alone along the shore had been abandoned by its mother. They were also called 'howlers', because of the sound they made. But were they really abandoned? Our researchers have followed several mothers over the past few years. They looked at how long it took them to return to their pups.

Thus, we found that puppies were regularly left alone for a while (see the picture below). Some mothers even stayed away for eight hours. Then they would reappear and give their pup milk. This means that a pup alone is not necessarily abandoned. Seal mothers also have to look after themselves and hunt for food. It is quite normal that she cannot be with her pup all the time.

Veldonderzoek - observatiemuur in de Dollard

Peculiar behaviour of seal mothers and pups

The researchers also looked at the behaviour of mothers and their pups as well as pups of other mothers. They found out that the pups not only drink from their own mother, but also join in drinking from other mothers. Not all mothers allow this; there are mothers who only give milk to their own pup (see image below). But there are also very social mothers, who let dozens of other pups suckle. One mother gave milk to 33 different pups!

Zeehonden rusten uit op drooggevallen zandbank

Seal pups cannot survive on the milk of other mothers alone. For the first 7-11 days of their life, the pup drinks from its own mother, after which the mother sometimes lets other pups drink from her. If a pup loses their mother within that first 7-11 days time, they can get milk from other mothers. This does not mean that the abandoned pup will survive with only milk from other mothers. In fact, the pup gets most of its milk from its own mother. So other seal mothers cannot replace their own mothers, but collectively they can care for several pups. It is like a daycare centre for seals.

Less rehabilitation, more observation

This research has allowed us to change our seal rehabilitation rules. Thanks to these discoveries, seal guards observe pups that are alone for up to 24 to 48 hours. This is a lot longer than before. This gives pups a greater chance of staying with their mothers. Only pups who have really lost their mothers are now taken in.

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Blind seals

Knowledge repository

Did you ever wonder how a blind seal survives in the wild? Seals are used to hunting with low visibility. Most seal species look for their food dozens, sometimes even hundreds, of metres underwater. Light does not penetrate as deeply into the sea. As a result, seals often hunt in the dark. Although their eyes are large and see more underwater than we do, it is the whiskers that are indispensable when hunting.

See also

Whiskers of a seal

Seals have very sensitive whiskers, which allow them to detect the smallest movements in water. As such, they find their way through the water current and feel the vibrations given off by fish. These are picked up by the hundreds of nerves in each whisker. Minutes after a fish has swum away, a seal can still detect it. This is because a seal's whiskers are not smooth, as a dog's or cat's whisker, but ribbed. Therefore, they glide smoothly through the water.

This allows Blind, the blind seal seen for years by our researchers in the Dollard, to find enough food without seeing anything.

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Whiskers of a seal

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Maternity strategy of seals

Knowledge repository

One of the studies that our researchers conduct in the Dollard, is to analyse ten seal mothers. Over several years, they look at whether their mothering strategy changes. For example, they look at whether she feeds more or fewer pups from other mothers and whether she always feeds the same pups or whether this varies. In addition, they study whether the seal mothers give milk each other’s pups. These things combined is called maternity strategy. 

See also

Zeehond - moeder en pup zogen

Allonursing, what is it?

Allonursing means that a seal gives mothermilk to a pup that is not their own. But why would a seal mother give milk to another pup? The causes and function of allonursing in seals remain mysterious, as giving milk takes an enormous amount of energy for the mother seal. There is also an increased risk of transmission of pathogens between mothers and other pups. It is therefore a crucial research subject.

Why do mother seals conduct allonursing?

There are five hypotheses that could explain why seals nurse their other pups:

  1. Allonursing is the result of misguided parental behaviour.
  2. Seal mothers alternate to nurse each other's pups.
  3. Females nurse foreign pups for additional health benefits.
  4. Females feed foreign pups to discharge milk not drunk by their own.
  5. Inexperienced seals spontaneously give milk without reproducing, or because they have lost their young. In order to improve their mothering.

Dit onderzoek doen we tijdens onze observatie in de Dollard: de periode waarin gewone zeehonden hun pups krijgen. Er worden filmpjes gemaakt van de moeders die melk geven. Met photo identification kunnen we de verschillende pups herkennen.

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Philopatry in seals

Knowledge repository

Philopatry means that an animal stays with a certain area or returns to it. In the study of Sealcentre Pieterburen about this topic, we examine birth philopatry. This means that the seal would return to their birthplace to breed.

See also

Research on birth philopatry

Our research team studies whether pups from the previous season return to the Dollard to breed and whether this also happens every year. Each seal pup is identified at birth. We do this with the photos we take every year of every seal that comes on the beach, so we can see if they have returned. This method is called photo identification.

Disturbance impacts the results

We also look at several factors that may influence this result. If a seal is severely disturbed several times by noise or dogs running loose, it may become stressed and remember that the place is not safe and therefore won’t return. This is also the reason why our research team does its research from a distance, behind a wall with holes in it. The seals do not see us.

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Field research into behaviour of seals

Knowledge repository

With the research we conduct in the field, we study and analyse the behaviour of seal mothers and pups in the wild. An example of this is our ongoing research in the Dollard area. On this page you learn everything about studying seals in the wild.

See also

  • Field research

  • Wetenschappers bij kijkmuur Dollard

  • Camera door observatiemuur - veldonderzoek

  • Veldonderzoek - zeehonden door kijkmuur observeren

Working with the tides

Met het veldonderzoek is ons team afhankelijk van eb en vloed. Onze onderzoekers zijn vier uur voordat het vloed is aanwezig bij de kijkwand. Met laagwater rusten zeehonden op drooggevallen zandbanken in de zee, maar als het vloed wordt verplaatsen ze zich naar de kust. Tijdens vloed zijn de zeehonden het beste van dichtbij te zien. Drie uur na vloed zijn ze klaar met observeren. Ze bestuderen in deze tijd het gedrag van de zeehonden.

Research equipment

Do you know what all the research team needs? The team carries various materials to make the investigation run smoothly. For example::

  • Cameras for the photo identification of seals
  • Lenses
  • Batteries and SD cards
  • Tripods on which the cameras can be placed
  • Field notepad and pens
  • Tides time table and weather forecast
  • A lot of patience

    They also take materials that can be useful when a seal needs to be taken care of after observation. The seal is then taken in a large basket. Below are the materials that are needed for a seal rescue:

    • Towels
    • Scrubs and overals
    • Jar, funnel, tubes, water, ORS
    • A scale
    • Blue spray to mark the pups (in the rest of the province Groningen the colour orange is used)
    • Plastic bags for rubbish
    • Gloves, masks and blue shoes

    Wrap-up observation day

    At the end of the day, the team returns to the Sealcentre to officially close the observation day. The collected data are transferred to a hard disk. All important events such as births, marked animals or pickups are written down in the notebook. Lastly, an update is given to the rest of the team.

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    How do you identify a seal?

    Knowledge repository

    There are two ways to identify a seal. The first way is the 'capture-mark-recapture' method. This involves capturing a seal and marking it with a spray. We prefer to avoid this method. Because capturing a seal is very stressful. Stress changes the seal's behaviour and thus the results of the study.

    See also

    Foto identification of seals in the Dollard

    Our researchers therefore use the method photo identification. They take a photo of all seals coming out of the water. They do this immediately because the seal's fur is still wet. On the wet fur, the seal's pattern can be seen more clearly. For each photo, our researchers circle what strikes them most about the seal. Think patterns or scars. If the pattern matches photos taken before, we know it is the same seal.

    To make this process faster and easier, they work with programme Photo-ID. A photo of a seal is put into the programme. The programme examines this photo and recognises the seal's patterns. Then the photo is automatically matched to one of the seals in the list.

    Pattern is unique for every seal

    Below is an example of how we can recognise seals. Near the arrows are prominent spots. As you can see in the photo, the fur has changed colour, but the spots are still visible. The arrow below his flipper points to three dots that are the same in both photos. The arrow to his head indicates a kind of white spot with four dots. Besides the programme automatically recognising the photos, it is important for us to double-check for accuracy ourselves. After all, we already have 400 seals in the database.

    Hoe herken je een zeehond?

    Identifying a seal

    In the summer of 2021, there was a seal in De Onlanden – an area in the province of Drenthe. A special event, because you don't often see a seal in fresh water. After many hours of taking photos from a great distance, we managed to get a good picture of its tag number (this is on a small label on its rear flipper) and spot pattern. It turned out to be an old friend of us. The seal has a tag number 20-115. That's how we knew it was seal Thor. We also put the photo in the photo-ID programme. Through Bea and Marga's research, every seal that has been at the centre has been photographed.

    Zeehond Thor in de opvang
    Zeehond Thor in De Onlanden

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    Knowledge repository

    You have probably heard of the word 'albino'. Most likely, you think of white rats or white rabbits with red eyes. There are also people with albinism. But did you know that there are also albino seals? In this article you can read about what albinism means and what it looks like in seals.

    See also

    What is albinism?

    Albinism, the opposite of melanis , is a rare disorder in which little or no pigment melanin is made at all [1]. Without pigment, the skin color, hair and eyes look different. Usually, albino animals have red eyes and white fur, but that is not always the case. There are multiple forms of albinism with differences in hair, skin and eye color.

    As far as we know, we have treated at least seven albino seals in our Sealcentre. Seal Sealas the most recent case of this (2017). 

    Partially albino?

    We have had different forms of albino seals in the sanctuary. One of the variations is called ocular albinism. Seal Sealas is a good example of this. In ocular albinism, it is mainly the eyes that lack the pigment melanin. That is why these albino seals have red eyes, but no white fur, for example. The fur is lighter in color than that of the congeners.

    Albino zeehond in Pieterburen

    Albino seals are sensitive to light

    Albino seals are more sensitive to light and therefore behave differently. We saw the seal Sealas close her eyes above water to protect her eyes from the sun (see photo 4). The sun is dangerous for the sensitive skin and eyes of albino animals. It doesn't matter much for a seal to hunt, because seals hunt underwater and their whiskers are more important than their eyes. But above water, they are more at risk of sun damage.


    There is also leucism. In leucism, the pigment melanin is produced, but it is not expressed in the coat or skin. This means that only the coat is lighter in color and the eyes are normally colored. The eyes of these seals are in any case less sensitive to the sun than those of albino seals. In 2009, we captured a leucistic seal, appropriately named Golden Queen.

    Leucisme bij zeehonden

    Watch this video

    Would you like to see what an albino seal looks like? Then watch the video below of seal Sealas at our centre:

    1. Fertl, D., & Rosel, P. E. (2009). Albinism. Encyclopedia of Marine Mammals, 24–26. doi:10.1016/b978-0-12-373553-9.00006-7 

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    The values of the Wadden Sea

    Knowledge repository

    The Wadden Sea is heritage. That means we think the area is important. It has a special value for us. We want to pass on the values of the Wadden Sea to future generations. So we want to protect the area. Do you? And why?

    See also

    • Zeehondenmoeder en pup

    • Wadden Sea

    • Zeehondenpup

    • Scholeksters

    What does the Wadden Sea mean to you?

    The Wadden Sea is extremely important to us. Not just because it is the habitat of the seals. But many other animals and plants also depend on the Wadden Sea. Furthermore many people depend on the Wadden Sea; they live on the coast or on the islands and eat the fish that are caught there. We also think the Wadden Sea is simply very beautiful. These are the values of the Wadden Sea for us.

    Many people find the Wadden Sea important. This differs per person: different people have different values. Some people find the Wadden Sea especially important because many birds make a stop in the Wadden Sea area on their migration from the Arctic to Africa. Other people especially like the wide landscape and walking in the mud. And other people find it very special that the landscape is constantly changing; after all, the Wadden Sea is different every hour.

    UNESCO World Heritage

    As so many people think that the Wadden Sea has special values, UNESCO recognizes the Wadden Sea as a World Heritage Site. This means that UNESCO believes that the Wadden Sea is important for everyone in the world: it has an Exceptional Universal Value. UNESCO has determined that by a criteria of ten points. The Wadden Sea meets the last three of those ten criteria.

    Criterion 8: Geological processes

    The Wadden Sea is constantly changing. Ebb and flow alternate: twice a day the Wadden Sea changes from sea to land and back again. Together with the wind, the tide ensures that sand and silt disappear in some places, while remain in other places. The tide makes the area very dynamic. Islands, sandbanks, arbours, channels, salt marshes and dunes are formed, shifted and broken down again. That process goes on constantly, in most places without human intervention. It happens almost nowhere in the world that an area can form itself in this way. It is very special that this is possible in the Wadden Sea.

    Criterion 9: Ecological and biological processes

    Many different plants and animals live in the Wadden Sea. Many of these plants and animals occur in large numbers. In other words, there is a large biodiversity and a large biomass. Many animal and plant species like places where two areas merge. In the Wadden Sea, land turns into sea and fresh water turns into salt. That is why many animals and plants feel like home there.

    The Wadden Sea is especially important for migrating birds who stop there during their journey from, for example, Greenland to West Africa. They find a lot of food here. The Wadden Sea is therefore also extremely important for life in other places in the world where other animal and plant species depend on these migrating birds.

    Criterion 10: Biodiversity

    Up to 10,000 species of plants and animals live in the Wadden Sea. Because there is so much food for birds, up to 6.1 million birds can live in the Wadden Sea at the same time. Up to 12 million birds pass through the area every year. In addition to having plenty of food, there is little disturbance to birds, allowing them to rest in peace during their long journeys from the north to the south of the planet and back again. Some species fly all the way from northern Greenland, Canada and Russia via the Wadden Sea to western and southern Africa, such as the Bissagos Islands in Guinea-Bissau and Banc d'Arguin in Mauritania.

    Did you know...

    The Wadden Sea is not only important for biodiversity in the Netherlands, Germany and Denmark, but The Wadden Sea is important for a huge part of the world? 

    Conservation of the Wadden Sea

    Because of these geological, ecological and biological processes and the large biodiversity and mass, UNESCO believes that the Wadden Sea should be protected. We wholeheartedly agree with that. The Wadden Sea is extremely important. Not only in itself, but also because many species and areas in other places on Earth depend on this area. In addition, attention to geological, biological and ecological processes and biodiversity is important for everyone important. After all, the existence of everyone in the world depends on it. Yet the Wadden Sea is still threatened in various ways. That is why we are committed to a healthy and sustainable future for the Wadden Sea.

    Rijksdienst voor het Cultureel Erfgoed. Waddenzee: Uitzonderlijke Universele Waarden (OUVs). 2019.
    Wadden Sea World Heritage. One Wadden Sea: One Global Heritage.

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