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Dieren en planten

Seals   Harbour seal   Food choice   Reproduction of harbour seals   Population in the Wadden Sea   Grey seal   Dolphins   Porpoise   Algae and seaweed   Phaeocystis   Diatoms   Flagellates   Phytoplankton   

Water en land

Water and land   North Sea   In general   Geological history   Southern North Sea   Frisian Front   Central Oystergrounds   Doggersbank   Helgoland   Wadden Sea region   Dutch wadden region   German wadden region   Danish wadden region   

Mens en Milieu

Water currents   Sea currents   Tides and water levels   Matter and materials   Nutrients   Phosphoric compounds   Nitrogen compounds   Silicon compounds   Ecology   Ecosystems   Managing the fish stock   Fish stock North Sea   
North Sea wave, foto fitis, sytske dijksen

North Sea, in general

The North Sea is the sea between Norway, Scotland, England, France, Belgium, the Netherlands, Germany and Denmark. The northern boundary is formed by an imaginary line between the Scottish Shetland and Orkney Islands and the Norwegian mainland. The lower boundary of the North Sea is the line between Calais in France and Dover in England. It is a shallow (30-200 meters) coastal sea of the Atlantic Ocean with an average depth of 90 meters. The sea floor descends from south to north where it develops into a 725-meter deep trough, the Norwegian Trench. The North Sea occupies around 572,000 square kilometres and has a volume of 54,000 cubic kilometer (= 0.16% of the surface of all the world seas together). The average temperature of the water throughout the year is 9.5 °C in the northern North Sea to 11°C along the southern North Sea (the Dutch coast).

  • Transection of the North Sea
    Cross-section through the North Sea, Ecomare

    The North Sea grows gradually deeper in a northwesterly direction. The depth of the water distinguishes the southern, central and northern North Sea. The section south of Dogger Bank is no deeper than 50 meters at most places and belongs to the southern part. The North Sea north of this large shallow area down to a depth of 100 meters belongs to the central section. And the more northerly lying region with depths up to 200 meters is called the northern North Sea. The Norwegian Trench and the Skagerrak form the fourth section of the North Sea.

  • Supply of water for the North Sea
    rainclouds over the sea, foto fitis, sytske dijksen

    The North Sea is supplied with water via several different sources. Every year, 5000 cubic kilometres of water from the Atlantic Ocean flows via the English Channel between England and France into the North Sea. At least 50,000 km° ocean water enters via the northern entrance by the Shetland Islands. The Baltic Sea delivers 500 km° of brackish water yearly and the various rivers contribute 300 km° of fresh water. All the water in the North Sea is refreshed once every two years. Precipitation and evaporation keep each other in balance: 500 millimeter per year evaporates and approximately the same amount is precipitates.

  • Coastal sea
    Wadden Sea, foto fitis, sytske dijksen

    The North Sea, just like most coastal seas, is particularly rich in nutrients. These are carried in by the rivers from the land. In addition, due to its shallowness, sunlight can penetrate to the bottom almost everywhere. This allows for planktonic plants to live in large abundance in the North Sea. This overabundance on plant materials provides sufficient food for maintaining the many types of organisms in the North Sea. The North Sea also has many coastal areas which are even richer in nutrients; the best example of this is the Wadden Sea.

  • Natural processes
    Waves, Ecomare

    The sea is alive. Due to the climate, the tides, the sea currents and the supply of water from the rivers, the sea is continually subject to changes. Life in the sea has adapted to this. The ecosystem of the North Sea is so complex that scientists still regularly run into puzzles: for example, the fish stocks remain unpredictable year after year.