2022 Volume 78 Issue 2 Pages I_37-I_42
For utilizing the FSB as a large marine algal reef, the biological affinity for marine algal was verified from a settlement test in the laboratory and a block installation test in the actual sea area. The growth rate of Sargassum horneri on the FSB test piece by the laboratory experiment was almost the same as those other pieces of concrete and natural stone. In addition, a small block (30 cm square, 30 kg) was installed in the actual sea area (Uchiura bay, Chiba), and changes in the amount of marine algae settlements to the block surface were observed. The amount of marine algae settlements per unit area of the FSB surface 10 months after installing was equal to or greater than that of the concrete block, and stable marine algae settlement on the FSB was confirmed even in the actual sea area. Furthermore, the concentration of heavy metals contained in the deposited marine algae during the laboratory experiment and the actual sea area installing test was measured. As a result, the heavy metal content of marine algae settlement to the FSB was not significantly different from that of other materials such as concrete and natural stone. These values were lower than those of natural marine algae, and these results also clarify the possibility using of FSB as marine algal reef material.
