Special characteristics of the Baltic Sea
The Baltic Sea differs from the other seas. Its special features make the Baltic Sea at the same time
Young and shallow sea
The Baltic Sea is a very young sea. It was not until in the last ice age when it started to reach its present form. Furthermore, the Baltic Sea is relatively shallow with the average depth only 55 meters. The reason for the shallowness is that the Baltic Sea is situated on top of the tectonic plate and not between them, like the oceans. Still, the bottom of the Baltic Sea is not completely flat for the sea bed is occasionally interrupted by basins and very shallow parts.
ASSIGNMENT 2
Make a line from the development stages of the Baltic Sea and briefly describe the main characteristics of each era.
The large brackish water basin
The water of the Baltic Sea is a mixture of salty and fresh water, brackish water. Only way the Baltic Sea is connected to the North Sea and the Atlantic Ocean is through the shallow and narrow Danish straits. Danish Straits are also only channels for the saline water to stream into the Baltic Sea, whereas fresh water is brought buy rainfalls and about 250 rivers. In conclusion, the salinity of the Baltic Sea differs from 20 per mille in the south to the almost nothing in the North. Brackish water is a challenging environment for many life forms as it is. In the Baltic Sea, winter adds up the challenge with coldness and ice cover.
ASSIGNMENT 3
Find out, how the challenging conditions on the Baltic Sea are affecting its flora and fauna.
The water of the Baltic Sea is stratified
Besides by the salinity level, the water stratifies also by the temperature. On the bottom the water is colder than near the surface. Thermocline is a layer where the temperature changes rapidly. In the autumn the temperature difference between bottom and surface diminishes and thermocline disappears. Halocline on the other hand will appear also in winter.
ASSIGNMENT 4
Describe what the saltwater pulse is. Find out how it affects the Baltic Sea.
Water exchanges slowly
Because the Baltic Sea is a closed sea area and the salt pulses come rarely, the exchange of the water is very slow. It is estimated that it takes about 25-30 years for the whole amount of water to exchange. This is also why all the accumulated nutrients and contaminants remain in the sea for a very long time.
Do you think you already know something about the Baltic Sea? Test your knowledge in the quiz in the Baltic Sea Portal! Baltic Sea Portal Sea Game
More information:
Finnish Environment Institute: Baltic Sea
