Studies on the formation of natural and artificial seaweed beds - II. The formation of Sargassum beds on artificial substrata by transplanting seedlings of S. horneri (TURNER) C. AGARDH and S. muticum (YENDO) FENSHOLT.

Seedlings of S. horneri and S. muticum were grown on Nori nets in an indoor tank up to 26mm in frond length for 81 days and 17mm for 69 days, respectively. The seedlings on the net were transplanted to a floating raft at Higashiura. S. horneri rapidly grew up to a maximum frond length of 231cm until December with a maximum frnd weight of 578g (wet weight) in April next year. S. muticum also grew up rapidly to a maximum frond length of 386cm and a maximum frond weight of 414g until april next year. Both species gradually decayed from May to June. From November to April next year, S. horneri grew at a CGR of 3.7kg/net/day, reaching a maximum standing crop of 785kg (dry weight)/net, and S. muticum. grew at a CGR of 1.3-1.7kg/net/day, reaching a maximum standing crop fo 193kg (dry weight)/net. N and P contents of the two species reached a maximum in April. N content was not so different in both species. However, P content was twice as much in S. horner as in S. muticum. Standing stocks of N and P per net reached respectively 28.2kg and 3kg in S. horneri, and 6.4kg and 0.3kg in S. muticum. Thus, it is apparent that the artificial beds of the two species of Sargassum can be used to clean the seawater and also be utilized as a source of marine biomass as well as for supplying nursery or feeding grounds of important animals in fisheries.