Abstract
Using investigations of their distribution, grown status, and grown environments, this study was conducted to elucidate the actual growth of Phyllospadix japonicus Makino (endangered species) at the Shichiriga-hama coast, Kanagawa prefecture, where artificial beach nourishment is conducted. Line surveys and surface surveys revealed that the Phyllospadix japonicus Makino distribution is about 2.5 km in the coastal direction and 20-150 m in the offshore direction. They inhabit T.P. -0.8 - -2.7 m deeper than the subtidal zone. The bottom sediment of their area of distribution is a rock bed covered by 1-3-cm-thick sand gravel. Artificial beach nourishment was introduced 4,500m3 in the past 4 years. Although extension of sand of the artificial beach nourishment up to their growth range is conceivable, results of a grain size composition survey re-vealed that Phyllospadix japonicus Makino distribution area has not decreased.
