Environmental control of gametogenesis in Laminaria saccharina. III. The effects of different iodine concentrations, and chloride and iodide ratios

Abstract

A study was made of the effects of different concentrations of iodide and iodate, and chloride/iodide ratios on meiospore germination, morphology, and gametogenesis of Laminaria saccharina gametophytes in axenic cultures, using a synthetic seawater medium under optimal light, temperature, nitrate, and phosphate conditions.Iodide and iodate were not essential for antheridial and oogonial production, but a small addition of iodine had a stimulatory effect. At low concentrations, iodide was more effective than iodate. At high concentrations, iodate had a less inhibitory effect than iodide. Inhibition occurred at iodine concentrations 60 000 times greater than that in natural seawater. This inhibition diminished with increasing chloride concentrations. The natural chlorinity of seawater might counteract adverse iodine effects on the marine algae thus allowing them to accumulate high concentrations of iodine.