Marine ecosystems in the Baltic Sea are characterised by a sensitive balance affected by many interrelated factors. Ecosystems are shaped by changes in the inorganic environment as well as biological factors.
Physical and chemical conditions including acidity, salinity and the quality of the sea bed all limit the range of organisms that can thrive in each area. Marine organisms within any area form food webs, and regulate the occurrence of other species through competition factors. Every single marine species forms part of a wider web.
The ecosystems of the Baltic Sea are unique, due to its low salinity. Both saltwater and freshwater species can adapt to thrive here. But this also makes the Baltic’s ecosystems sensitive to changes caused by man. The waters of the Baltic are highly stratified due to variations in salinity, and in summer also in temperature. The ecosystems found in different water layers at different depths may vary greatly. The Baltic’s northerly location and the consequent pronounced seasonal changes give Baltic marine ecosystems distinct rhythmic cycles.
