New Technology Helps Restore Barren Seafloors

The Ocean Greenery research group, an industry-academic research group of 14 members, succeeded in demonstrating through their experiments that a mixture of iron/steel slag and humic material is effective for preventing "isoyake," or rocky-shore denudation, which is considered to be one of the causes of the recent decline in fish catches in Japan, the group announced on September 21, 2005.

Isoyake is a phenomenon observed in seabeds where useful seaweeds such as kelp and soft seaweed disappear, and rocky beds become smothered in white tiny seaweed known as calcareous algae. The isoyake phenomenon has been spreading along the coasts of Japan and has become a serious issue.

Professor Masayoshi Sadakata at Kogakuin University, the leader of the group, has been conducting basic studies to reverse isoyake since 1999 and has confirmed in laboratory experiments that fulvic acid-Fe, a complex produced from mixing a substance containing bivalent iron (e.g., iron and steel slag) and fermented wood chips can facilitate the growth of seaweed, including kelp and sea lettuce.

Three corporations in the group, Nishimatsu Construction Co., Nippon Steel Corp., and Eco Green Co., jointly conducted a field experiment in November 2004 along the Shaguma Coast in Mashike, Hokkaido, where isoyake had been devastating shores for years. "Yashi units," or palm fiber bags filled with a mixture of iron/steel slag and humic matter, were buried on the seafloor around 25 meters offshore. A year later, in an area of about 30 meters further away from the bags, kelp and other seaweed were found growing several times more thickly than usual. The group will continue studying the effects of this method, including the duration of efficacy, and impacts on material cycling and ecosystems along the coast.



Posted: 2005/12/31 08:30:45 AM
Japanese version