Accumulation, effects on growth, and localization of zinc in Padina gymnospora (Dictyotales, Phaeophyceae)

Young plants of Padina gymnospora were exposed to 10, 20, 100, 1000 or 5000 ug zinc per litre as zinc sulphate in seawater under laboratory conditions for 21 d. The accumulation of zinc increased approximately linearly with the zinc concentration in the water and a steady state was not reached even for high concentrations. Analytical electron microscopy techniques to determine the localization of zinc in the cells showed it to be present as dense granules along cell walls, starting 15 to 25 cells away from the thallus apex but being absent in the cytoplasm of viable cells.