Abstract
This investigation was aimed the creation of new growth grounds for seaweeds on the breakwaterfor the sake of the environmental-friendly utilization of port structures. The Port of Omaezaki, Shizuoka Prefecture, was selected as a survey field. The survey was carried out at the inside and outside of a seawall covered with wave-dissipating caissons and the slit caissons set up at the end of seawall. Seaweeds, including Ecklonia cava, ware confirmed to grow on artificial structures, in only a case of protection using net from herbivorous fishes, such as rabbitfish, Siganus fuscescens, and the slit caisssons, hich can protect more easily from hervivorous fishes, are more useful ordinary wave-diwssipating caissons. Many young frond, probably derived from mother thallus transplanted, ware found on the wave chamber floor of the slit caisson. The slit caisson is also useful as a place which supply zoospores.
