Meeting point for marine and freshwater species

The Baltic Sea ecosystem is a unique mixture of marine and freshwater species. Species number is relatively low: the Baltic Sea is geologically young. There has not been simply enough time for species to be able to adapt to restrictive conditions: low salinity and drastically varying seasonal conditions.

“Ah-oo” says the eider, typical bird in the Baltic Sea. Eider is a true marine species like its main food, blue mussel. Blue mussel requires salty water and therefore is not met in the Bothnian Bay with low salinity.

Salinity restricts marine species. Freshwater species, on the contrary, have to tackle too high salinity in many areas of the Baltic Sea. There are certain tolerance limits for each. Freshwater species stay close to river estuaries whereas true marine species avoid those areas.

Underwater valleys and mountains

Salinity, temperature and sea bottom characteristics are the main factors affecting the species habiting underwater areas.

Underwater Baltic Sea is not monotonous world: there is topographic variation from valleys to hills, and depending on this, salinity, temperature and other characteristics, a wide spectrum of different habitats. Our knowledge of bottom habitats is still scarce.

Nature above the sea level show rich variation as well from sandy beaches to pastures with rich flora, such as Elder-flowered orchid (Dactylorhiza sambucina), and from rugged pine forests to lush coppices. Some areas are pristine and still raising from the sea.

Nature at risk

According to HELCOM, over 60 species in the Baltic Sea are threatened or declining. The major forces shedding dark clouds over the Baltic Sea nature are: eutrophication, risk of oil spills, construction of wind farms, marine traffic and underwater gravel digging. Not to mention nasty intruders – alien species.

Diverse nature – a health insurance for the Baltic Sea

Why is it important to cherish the biodiversity? Besides the diverse nature is a value of its own, it is a “health insurance” for the Baltic Sea. Some species, key species, such as bladderwrack, eelgrass or blue mussel, are of special importance of being true cornerstones of many habitats, and nursing many other species.

Healthy ecosystem with wide variety of species is more tolerant against disturbances – either natural or human. Moreover, it recovers faster. And not to mention all the other “ecosystem services” the healthy Baltic Sea with all its inherent species offers: recreation, food production and climate control!

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