"Experience tidal flats - understand tidal flats"

The Schweenssand nature reserve in the Neuland district is characterized by freshwater mudflats with tidal creeks, sandflats and mudflats. The 35-hectare area lies in the tidal area of the Elbe.

Surface of the tidal flat in Hamburg's Schweenssand nature reserve.

The North Sea coast with the Wadden Sea is one of the world's largest mudflat regions. This picture is from the dike foreland near Obergeorgswerder. Since 2009, the Wadden Sea of the North Sea is a World Heritage Site. Since 2011 also the Hamburg part and since 2014 the Danish part. Wind, waves, tide, salt, brackish or fresh water form a unique habitat in the region.

Mudflats - here on the Entenwerder peninsula - are habitats for many animals ...

... and plants, as here in the dike foreshore near Obergeorgswerder. The Wadden Sea of the North Sea is home to an amazing diversity of life, providing a surprising number of different habitats for over 10,000 species.

Mudflats consist of sand grains of different sizes, which are clearly visible in sandflats such as here on the island of Neßsand. Mixed mudflats contain more silt. It is softer at the surface, but you only sink in a few inches deep. Silt mudflats, on the other hand, are clayey and much less coarse-pored, containing much more water and therefore quite soft. It contains much more organic material than sand mudflats and is gray to black.

Tidal flat soils are subject to constant movement due to the tides. They often have a high lime content due to crushed mussel shells. The photo was taken on the island of Neßsand in the Lower Elbe. It is a protected area where the borders of the federal states of Hamburg, Lower Saxony and Schleswig-Holstein meet.

Tidal flat section in the Schweenssand area. Typical for tidal flat soil are the two layers or horizons, as it is called in soil science. The upper layer is light and only a few millimeters to a few centimeters thick; here the soil is still rich in oxygen. The organic components, together with the oxygen, provide the lighter, brownish to red-orange color. Below this, it becomes much darker, often almost black. Oxygen no longer reaches the soil in this layer. The chemical conversions under reducing conditions produce, among other things, methane and hydrogen sulfide, which is responsible for the typical rotten egg smell.

Priel is, in a sense, a river in the mudflats - a watercourse that does not run dry even at low tide. Here on the protected inland island of Neßsand in the Lower Elbe.

The island of Neuwerk is located in the middle of the Hamburg Wadden Sea National Park (NPHW), which was founded in 1990, and belongs to the district of Hamburg-Mitte - although it is about 120 kilometers away as the crow flies. In the mudflats around the island, many breeding and resting birds in particular feel at home.