Photosynthetic properties of Fucus vesiculosus (Phaeophyceae) from different depths and sites in the Bothnian Sea.

The Baltic Sea is a species-poor ecosystem where marine species coexist with freshwater species. The Baltic Sea offers low salinity, low content of inorganic carbon, long cold winters and no tides.One of the few marine species that can be found in the Baltic, is the brown alga Fucus vesiculosus, which is regarded as ecologically the most important alga in this area. The aim of the present thesis was to examine physiological (photosynthesis and growth) differences between F. vesiculosus in the Bothnian Sea (northern Baltic) and the Atlantic. Measurements were performed with plants in their natural seawaters and under changed conditions of salinity, temperature, nutrients and inorganic carbon concentrations.