Turku is located between land and sea, on the coast of the Baltic Sea, so its nature is diverse and beautiful. Turku has many different kinds of nature trails and conservation areas, and the presence of the Archipelago Sea brings thousands of small islands and islets – the life at sea – close.
However, the beauty of the nature should not be taken for granted. In order to preserve the diversity of nature also for the following generations, we all should mend our ways.
Coastal habitat types
The conditions of coastal areas are affected in many ways by human activities, both on land and on sea, as well as by natural phenomena. The biggest factors threatening our seaside environments are the eutrophication of the Baltic Sea, building of coastal areas, and the climate change.
More than half of the habitat types of our coasts have been assessed as threatened and a quarter as near-threatened. The threatened habitat types consist of around 5% of the surface area.
Beaches wear out and become eutrophic
As a result of eutrophication, masses of algae and reed drift more and more often to the shore and cover the open sand, which creates a seedbed for vegetation that does not really belong there.
Rosa rugosa, which was originally imported as an ornamental plant, has run wild and is spreading on our coasts uncontrollably. The plants have grown into impenetrable thickets as large as several hectares in some of our finest beaches, and they overpower the original beach vegetation.
The recreative use of the beaches wears them out and destroys their typical vegetation and specialized fauna. Also buildings have been erected on the wide sand dune areas.
More attention should be paid to the care of coastal nature
The condition of the Baltic Sea is crucial also for the sake of the beaches, and there is much to do in order to stop the eutrophication. Overgrowing beaches should be attended to, and the forests and swamps on the post-glacial land uplift coasts that have lost their natural state should be restored.
Over a third of our shores are already populated, and in many places it is difficult to find an unbuilt shore. Building should be planned more carefully for the remaining free shores.
The ancient bedrocks revealed by the ice sheet, with all their bird islets and rock pools, the rocky waterfronts with their meadows, and the ridge islands with their sandy beaches are all part of the internationally unique coastal nature, and their conservation is everyone’s concern.
Marine habitat types
The many problems of the Baltic Sea, worst of all the eutrophication, have had an impact also on the habitat types of marine environments. Half of the underwater habitat types of the Baltic Sea are either endangered or extremely endangered.
The most endangered habitat types are close to us in the Archipelago Sea and the Gulf of Finland, where the human impact on the marine habitats is the greatest. The Gulf of Finland is the most eutrophicated area of the Baltic Sea and it will not be able to withstand the current nutrient load, which is triple compared to the other parts of the Baltic Sea.
The Baltic Sea is a young and ecologically very sensitive sea area. It is the second largest brackish water inland sea in the world by its water volume. In addition to its uniqueness, the Baltic Sea is, unfortunately, one of the most polluted brackish water basins.
The great vulnerability of the Baltic Sea for pollutants and poisons results from its shallowness and shape, small water volume, and poor water turnover. The average depth of the Baltic Sea is only 55 meters, and the time it takes for the entire volume of water to change is estimated to be around 30 years.