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Biota of the Baltic Sea
The distribution of marine and freshwater organisms is hindered by low and fluctuating salinity of the Baltic Sea, and thus the number of species in the sea is lower than in marine environment with normal salinity. Many species live under the conditions of constant salinity and temperature stress, which results in increased sensitivity to environmental changes. The abundance and speed of growth of marine species in the Baltic Sea reduces along with the reduction of salinity in East and North direction.
Vegetation of the Baltic Sea is poor and consists mostly of Algae. Limited number of flowering plants (pond water-crowfoot - Ranunculus peltatus, fan-leaved water crowfoot - Ranunculus circinatus, coon's tail - Ceratophyllum demersum, water milfoil - Myriophyllus spicatum, etc.) are considered as secondary marine organisms.
Animals of the Baltic Sea consist of organisms introduced at different eras: brackish and marine glacial relicts (descendants of species that migrated to Yoldia Sea), marine boreal species and freshwater species from inland waters. Due to short existence no endemic animal species have been established in the Baltic Sea.
There are ca 440 species of invertebrates living in the Baltic Sea, only marine organisms include medusae or yellyfish (Scyphozoa), ctenophores or comb-jellies (Ctenophora), mud dragons (Kinorhyncha), priapulids (Priapulida), nemertines or ribbon worms (Nemertea) and bristle worms (Polychaeta).
Estonian waters contain 30 fish species of marine origin. There are 10 species of highly migratory fish. About 20 species of freshwater fish is found in coastal waters.
Sea is essential for many bird species, most of them are waders (Charadriiformes) and waterfowl (Anseriformes). Migratory routes pass the Baltic Sea. Most abundant migratory species include long-tailed duck (Clangula hyemalis), mallard (Anas platyrhynchos), barnacle goose (Branta leucopsis) and bean goose (Anser fabalis).
Mammals in the Baltic Sea are pinnipeds (grey seal - Halicherus grypus and ringed seal - Phoca hispida) and cetacean (harbour porpoise - Phocaena phocaena).
Estonian fishes
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