MORPHOLOGICAL VARIATION OF NORTHERN BALTIC FUCUS-VESICULOSUS ALONG THE EXPOSURE GRADIENT

A study of inter-population variation in vegetative morphology of Fucu s vesiculosus L. populations from SW Finland has been carried out and the variation is described and quantified. The taxonomic status of an unusual population from Virolahti the eastern part of Gulf of Finland has also been assessed. Five populations of Fucus vesiculosus were sam pled at peak fertility time from shores of different wave exposure. Ni ne vegetative characters were measured and analysed using principle co mponent analysis and stepwise discriminant analysis. The plant width, distance between dichotomies, plant length, midrib and stipe width wer e the five most important distinguishing characters. The plants were c lassified with accuracy of 70% into the correct population. The morpho logy of Fucus vesiculosus appears to vary within a small scale due to the local factor, exposure: shorter plants with narrow fronds are foun d on exposed shores and plants from more exposed shores lack bladders. Reduced salinity level could partly explain the existence the dwarf m orph of Fucus from eastern part of Gulf of Finland. However, it would be difficult to justify taxonomic recognition of any of these populati ons on morphology.