The average number and length of Sargassum plants that have settled on the three types of substrata, carbonated steel-making slag block, granite stone, and cement concrete block, deployed from April 1998 to January 1999 at Koune, the Seto Inland Sea of Japan, were compared.
Results showed that maximum length of Sargassum plants that have settled on the three types of substrata did not vary significantly, so the strength of adhesion of the plants was the same for all substratum types. On the other hand, the average number of plants that have settled on the test pieces of carbonated steel-making slag block was higher than that on the cement concrete block although not significantly different from that on the granite stone. This suggests that carbonated steel-making slag blocks have good potential as seaweed bed substrata.