Three artificial reefs have been built off the shore of Waita in Kitakyusyu, Fukuoka Prefecture, which is to prevent the erosion of the seashore. During the construction, we started researching on the effects of these artificial reefs for the sands stability and the nursery ground, continuing for four years through its completion.
Although there are natural seaweed beds around this sea area, we were unable to observe any seaweed on the artificial reefs when two of them had been set up. Right after the third reef was placed, however, seaweed (Sargassum) beds began to spread.
Therefore, we examined if there was any correlation between changes of nearshore currents caused by the third one and the growth of seaweed on natural or artificial reefs. As a result, we suggest that the changes of currents improved the growth of seaweed beds.
