Management-free techniques for restoration of Eisenia and Ecklonia beds along the central Pacific coast of Japan

Abstract

Because of the importance of seaweed resources for conservation of thecoastal environment, the provision of habitats of commercially importantspecies and because of use as human food, a study was carried out on bedsof Eisenia bicyclis and Ecklonia cava. This included the mostimportant environmental factors and the development of techniques forrestoration and long-term maintenance of the beds. At a site chosen fordetailed study, the Eisenia and Ecklonia bed was influenced bymany factors, including desiccation, rainfall, low salinity, low light intensity,turbidity, accumulation of suspended sediments, cover by adhering animals,wave and current action and grazing pressure. The distribution of suchseaweed beds is also limited locally by the size and hardness of rock on thebottom, and by fluctuations in the sand level at the base of the reefs.The management-free technique of creating Eisenia and Ecklonia beds is based on an understanding of the factors limiting the localdistribution of the beds. Conditions for seaweed growth can then beartificially enhanced by coastal engineering. Suggestions to enhance Eisenia and Ecklonia bed restoration using management-freetechniques include raising the bottom, elevating substrata above the sandybottom, and providing substrata of a shape suitable for the attachment ofkelp.