Vanadium an essential element for some marine macroalgae.

In some marine algae cultivated axenically in the artificial medium ASP6 F2 (pH 8.3) vanadium at 1-100 μg l(-1) increases the fresh weight. In the multicellular brown algaFucus spiralis 10 μg V I(-1) enhances the fresh weight by about 400% while in the green algaEnteromorpha compressa the yield is increased by 90%. Red algae do not respond to vanadium. InFucus morphological effects are displayed in more frequent branching and/or broader blades. No significant increase in the chlorophyll content could be demonstrated at the early stage at which these morphological effects first appeared. Later the chlorophyll content increased.