Effects of Chelated Iron on the Growth of Sargassaceae Species at the Germling and Immature Stages

Sargassaceae species are important macroalgae for maintaining marine environments. Furthermore, biofuel based on Sargassaceae species has become studied recently. However, Sargassaceae species have declined rapidly in coastal areas around Japan, which are called "isoyake", a term meaning barren areas. The development of effective measures to restore these "isoyake" and the construction of Sargassaceae beds are strongly needed. A lack of iron in coastal areas limits the growth of macroalgae, and may cause "isoyake". However, the effects of the iron concentration on the growth of macroalgae, such as species of Sargassaceae, are poorly studied. In this research, the effects of chelated iron on the growth of Sargassaceae species during the germling and immature stages were examined. The addition of Fe-EDTA promoted the growth of four Sargassaceae species during the germling stages. During the germling stage of Sargassum ringgoldianum, the maximum specific growth rate and the saturation constant were estimated to be 0.17 day-1 and 4.3 μg/L, respectively. Additionally, the periodic addition of Fe-EDTA promoted the stable growth of Sargassum horneri during the immature stage.