Bodden
A lagoon is a shallow bay-like coastal body of water in a ground moraine landscape that was partially flooded after the glacial period . The name Bodden is probably of Low German origin and means "ground" or "ground", which refers to the shallow depth of these waters. Bodden are characteristic of the southern Baltic Sea , where they are typically separated from the open sea by elongated islands and peninsulas and form lagoons .
Emergence
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During the eustatic postglacial, Holocene sea level rise, which was also accompanied by a lowering of the earth's crust , a flat, undulating ground moraine landscape on the southern edge of the Baltic Sea basin was partially permanently flooded, so that an irregular coastline with protrusions and bays was created. The bays on this coast corresponded to so-called tongue basins , which were dug into its base by the inland ice during the last glacial period , and partly also deeper ground moraines. They were the forerunners of today's Bodden. Because the ice has already disappeared and the glacial relief was already subaeric to a certain degree before it was flooded , the lagoon coast is one of the ingression coasts .
Due to currents parallel to the coast , eroded sediment elsewhere can subsequently be deposited on the projections and on islands that are immediately in front of the newly formed lagoon coast. This process is called coastal adjustment . The resulting spits can connect the projections and islands with each other, so that elongated islands and peninsulas arise, which cut off individual bays or a whole series of neighboring bays ( bay chain ) from the open sea and transform them into a lagoon . This coastal morphology with inner coastal waters (lagoons) and outer coastal waters is also known as the double coast . The lagoons on the Baltic Sea coast have a lower salinity than the adjacent open sea areas, since flowing waters continuously supply fresh water and the exchange of water with the open sea can only take place via the flood channels.
More than 30 mostly smaller, shallower bays on the southwestern Baltic coast are called Wiecken , derived from the Old Norse language . These are either located within a Bodden or on the outer coast.
Examples
Bodden waters can be found in the southern Baltic Sea in Western Pomerania between the Fischland and the island of Usedom , including:
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Darß-Zingster Boddenkette | Bodstedter Bodden, Barther Bodden, Grabow, Koppelstrom and Saaler Bodden, |
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West Rügen Boddenkette | Kubitzer Bodden, Schaproder Bodden, Udarser Wiek and Vitter Bodden |
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North Rügen Bodden | Breetzer Bodden, Breeger Bodden, Lebbiner Bodden, Großer and Kleiner Jasmunder Bodden, Rassower Strom, Wieker Bodden |
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Greifswalder Bodden | Rügischer Bodden, Hagensche Wiek and Danish Wiek |
| Peenestrom | Achterwasser and Krumminer Wiek |
Flora and fauna
Because the Baltic Sea already a brackish sea with a relatively low salt content , the particularly strong isolated lagoons among the lagoons are almost salt-free and have the character of freshwater lakes . These lagoons are densely covered with reeds on their banks and thus offer habitats for many species of birds that are bound to freshwater. Typical fish species that are important for commercial fishing are pike , pikeperch , perch and eel .
A special habitat on the West Pomeranian lagoon coast is the windwatt . The shallowest coastal areas sometimes dry for weeks and can then be flooded again for days when the wind directions or wind strengths change. In the dry phases, in the more open, more marine-influenced bays, the salt concentration in the soil ( substrate ) of the tidal flats can fluctuate significantly: after rainfall it drops significantly and in summer drought with high evaporation it increases significantly. The dry areas also heat up strongly during the day in summer to cool down again at night. Very few invertebrate species can live under these extreme conditions, but they are all the more common. They form the food source for many wader species, such as avocets and sanderlings . The Windwatt also offers important resting places for migratory birds such as the crane and many species of geese . In addition, the mud flats are a safe place to rest for seals.
Among other things, all these ecological peculiarities were reasons for the establishment of the Western Pomerania Lagoon Area National Park between the Darß and the island of Rügen .
Philatelic
On January 2, 2015, the first day of issue, Deutsche Post AG issued a postage stamp worth 85 euro cents with the designation Ostsee - Boddenlandschaft in the Wildes Deutschland stamp series . The design comes from the graphic artist Dieter Ziegenfeuter .
literature
- Günter Schlungbaum, Henning Baudler: The diversity of inner coastal waters on the southern Baltic Sea - an overview from the Flensburg Fjord to the Curonian Lagoon - Part 1: Development history, morphology, hydrology and hydrography , Rostock 2001 digitized
- Günter Schlungbaum, Bernd Kwiattkowski, Mathias Krech: The diversity of inner coastal waters on the southern Baltic Sea - an overview from the Flensburg Fjord to the Curonian Lagoon - Part 2: Diversity of natural and anthropogenic eutrophication processes a discussion on possible ecological quality according to the EU Water Framework Directive , Rostock 2001 Digitized
- Ulf Karsten, Rhena Schumann, Kathrin Witte: Darß-Zingster Bodden waters: Filters between land and sea . In: Biology in Our Time. Vol. 33, No. 1, 2003, pp. 46-55, ISSN 0045-205X .
- Dieter Kelletat: Physical geography of the seas and coasts. Teubner, Stuttgart 1989. ISBN 3-519-03426-3 .
- Ralf-Otto Niedermeyer, Heinz Kliewe, Wolfgang Jahnke: The Baltic Sea coast between Boltenhagen and Ahlbeck - a geological and geomorphological overview with excursion tips . 1st edition. Hermann Haack / Geographisch-Kartographische Anstalt, Gotha 1987 (Geographical modules, booklet 30), ISBN 3-7301-0633-3 .
Web links
- Bodden coast in the online glossary of the MLU service portal Geoinformation, website of the Martin Luther University Halle-Wittenberg
Individual evidence
- ↑ Vorpommersche Boddenlandschaft National Park: Habitats: Bodden waters
- ^ National Park Vorpommersche Boddenlandschaft: Land use in the national park: fishing
- ↑ Vorpommersche Boddenlandschaft National Park: habitats: wind flats