The barren ground, known as "isoyake" in Japanese, is a phenomenon of the disappearance of seaweeds caused by certain factors. It is also a serious environmental problem in the conservation of coastal biodiversity and fisheries resources. Since 1971, the Kagoshima Prefectural Fisheries Technology and Development Center (KPFTDC, formerly Kagoshima Prefectural Experimental Station) had been conducting field studies in identified barren grounds so as to introduce some interventions to restore the seaweed communities. The hypothesis was that the seaweed communities were negatively impacted by fish and sea urchin grazing. We reviewed recent studies of the barren ground phenomenon that focused on removing the limiting factors of the growth of seaweed communities. Results of the survey in 2002 and 2003 revealed that the composition of seaweed grazers, water temperature and other environmental factors of the barren grounds showed no significant differences compared to those of the natural seaweed communities. However, the former had higher biomass of grazers compared to the latter. Based on this information, we suggested the possible influence of maximum grazing and its detrimental effects to the primary growth of seaweeds. I also discussed some factors that led to the occurrence of barren grounds and its continuance, and what methods to consider for the optimum restoration of such 'lost' seaweed communities.
