The bottom of the Wadden Sea is crawling with life. Mussel banks form by far the richest area, where large amounts of mussels and other plants and animals make up a richly laid table for many birds and fish. In addition to shellfish, worms, tiny laver spire snails and shrimp-like Corophium are enormously numerous in these shallow parts of the Wadden Sea.
Compared to the North Sea, fish profit in deeper parts from the large amounts of food and the warmer temperatures. Most of the fish species that swim in the Wadden Sea do not live there permanently. Many North Sea fish use the Wadden Sea as a nursery. Plaice or herring are only here during their youngest months. Before they become adults, they migrate to the North Sea. This is just the opposite for flounder, which spend their juvenile years in the North Sea and adult lives in the Wadden Sea. Some fish, such as sea and river lampreys, only use the Wadden Sea as a 'bridge' to move between the sea and the rivers. Around 20 species of fish live their whole life in the Wadden Sea. Examples are the bottom dwellers eelpout and bull rout.
Marine mammals, such as the harbour seal, the grey seal and the porpoise, profit from the rich fish life in the Wadden Sea. Harbor seals are completely adapted to the dynamic sea, where their haul out and rest areas submerge under water twice a day. During high tide, they hunt in the flooded Wadden Sea or the adjacent North Sea. More than 30,000 harbor seals live in the Wadden Sea. Therefore, there is a good chance to spot them from the dikes, dunes or ferries as they swim or rest on a sandbank. Grey seals were gone for many decades but are slowly returning. During the period that they loose their hair, more than 2000 grey seals can be found in the Wadden Sea. These seals regularly swim back and forth to the British coast. Porpoises also swim in the Wadden Sea as well as the North Sea. The northern Wadden Sea region is very popular for female adults with their young. That is why a special reserve has been established by Sylt and Amrum.
Watch the movie 'Harbor seals in the Wadden Sea' (© Cinedesign/Kaufner)
The large amount of food and tranquility that dominates here makes the Wadden Sea particularly important for breeding, moulting and overwintering birds. They like to breed in the salt marshes and dunes or on the grasslands and beaches. The majority of the nesting birds consist of gulls, such as the lesser black-backed gull and the herring gull. But also large numbers of waders breed in the wadden region. The Wadden Sea is by far the most important nesting area for the spoonbill, avocet, sandwich tern and gull-billed tern.
Probably even more important than the role as breeding grounds is the role the Wadden Sea fulfills as winter home and tanking station for migrating birds. Because so many birds use the wealth, tranquility and space in this region, there are times when 6.1 million birds are present in the Wadden Sea. In total, 10-12 million migrating birds pass through every year, consisting of waders, geese, ducks and gulls.
Large amounts of shelducks and eiders moult in the Wadden Sea. In the summer, almost 80% of the European shelducks gather in Dithmarschen off the island Trischen, to replace their flight feathers. In this period, they are unable to fly for a number of weeks and are very dependent upon this undisturbed area. Without the Wadden Sea, various European bird species would become threatened animals or even extinct.