A three-year study was conducted on Undaria pinnatifida (Wakame) using chemical fiber (vinylon) in Amagasaki port in Osaka Bay, a hypertrophic inner bay surrounded by vertical seawalls. 1) Continuous, autonomous growth and generational turnover of Wakame on fiber were observed. 2) First, Mytilus galloprovincialis was dominant on the fiber, same as on the wall; after this was different from that, by a habitat segregation of animals and seaweed on the fiber. 3) The fiber set in shallow water notably decreased in number and its durability deteriorated, but still have the seaweed bed function. 4) In summer, the fiber became shelters for organisms such as demersal fishes. And We held "Growing Citizens' Own Wakame" environmental education program, helped industrial district water purification using organisms.