 The special thing about the Baltic Sea is that its water is neither salt nor fresh, but what usually is called brackish water. The Baltic Sea is actually the biggest sea with brackish water on earth. In the northern parts of the sea the water is almost fresh, but the water gets more salty the more you get to the south. This is because all the northern rivers with their fresh water runs into the Baltic Sea. The reason why the water is more salty in the southern parts of the sea is due to the fact that sometimes, about every 10-20 years, salt water from the Cattegatt is pressed into the Baltic Sea when storms rage in the proper direction. The last time this happened was in 1993. On average it takes about 30 years for the water to be completely renewed. Since salt water is heavier than fresh water, it's also more salty at the bottom of the sea. There are two separate layers which never completely mix with each other. These two layers meet at about 60-80 metres. Because of the brackish water, few species can live in the Baltic Sea and most of those which do have the same salt content as the salt content in the water. It's their ability to keep their salt- and water balance that decides whether they can live in the Baltic Sea or not. Because of this, the animals of the Baltic Sea get smaller than their relatives in other seas and also more sensitive to poisons and pollution. If a major change in the salt content of the sea occurs, the animals wouldn't be able to handle it. If they on the other hand can get the time it takes for them to adapt, it could succeed. The problem is that this process can take several thousand years. The water that reaches the Baltic Sea by the rivers has passed an area inhabited by 85 million people. Most of them live in Poland, but Sweden and Finland pollutes more per person, so we just have the luck to be fewer. The countries that pollutes the Baltic Sea don't necessarily have to be the ones nearby. It can also be pollution from cars and the factory chimneys that can be transported a long way with the winds and end up raining down over the Baltic Sea. Forestry and agriculture is also one of the threats. All the fertilizers and the things that we syringe our fields with is taken with the rain-water through the ground and out to the sea. This goes for our lawns and golf-courses as well. Not to mention all the waste water from the factories around the Baltic Sea that adds to the pollution. The good thing is that the pollution of the Baltic Sea is decreasing, but we still need to do many things to quicken the decreasing process. One way is to forbid the use of several harmful substances, for example PCB and weed-killers, or to change them into less harmful variants. Other ways are to compost, to recycle and to simply decrease the pollution from cars and the agriculture. What threats are there to water life in your area and what is done to prevent them?
And finally some facts about the sea: Area: 377,400 km2
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