抄録
Communities of algae have disappeared from the shallow waters along the Japan Sea coastline in southwest Hokkaido. A large number of studies have been made on coralline flats, it has been shown that the consumption of algae by sea urchins is an important factor affecting the formation of coralline flats, and is closely related to the physical environment of coastal areas. Recent investigations have shown that algae communities have formed at the region surrounded by sand and gravel in coralline flats. The effects of drift sand on the consumption of algae by sea urchin are experimentally studied. The smaller sand diameter is, and the larger fluid velocity is, the harder sea urchin moves to algae due to drift sand. Therefore consumption of algae by sea urchin decreases under these conditions. Strongylocentrotus intermedius dislikes drift sand more than Strongylocentrotus nudus, so consumption of algae by Strongylocentrotus intermedius decreases.
