Ocean farming is one of the unique agricultural technologies that Japan can boast of to the world, perhaps best represented by seaweed cultivation including the farming of nori and kombu. Among seaweed and algae that have important properties is one that has lately garnered a lot of attention, namely mozuku.

Six varieties of mozuku, a fine threadlike seaweed, are eaten or used in food preparation in Japan, and the variety native to the Ryukyu Islands known as Okinawa mozuku is rich in sugars, growing as long as 30 centimeters. Today mozuku produced in Okinawa Prefecture represents more than 90% of the Japanese mozuk market.

Mozuku has long been valued in Okinawa for use in yakuzen-style cuisine (health food using traditional Chinese medicinal herbs) and it has also been believed that the act of washing mozuku keeps women's hands soft and moist. The reason for this can be found in the slimy composition of mozuku, and is due to the physiological effects of the polysaccharide known as fucoidan.

The introduction of fucoidan derived from mozuku into artificially cultivated cancer cells results in the death of most of the cancer cells after a 24-hour period. Biotechnology Research Laboratories of Takara together with the Research Institute for Glycotechnology Advancement have been able to show that fucoidan has the ability to cause a variety of cancer cells to self-destruct.

More progress in research by these labs concentrating on the antitumor properties of fucoidan has ascertained that fucoidan causes certain types of rapidly growing cancer cells to self-destruct, including human acute promyelocytic leukemia cells, human stomach cancer cells, human colon cancer cells, and cancer cells of the descending colon. Moreover, normal cells were hardly affected by this self-destruction.

Already, at Hokugan Co. in Okinawa vitamins and purified drinking water containing mozuku-derived fucoidan have been readied for the marketplace, and the company has begun to communicate to the public the wonderful properties of the ingredient, and to promote development of more new products using mozuku. When powdered, fucoidan extracted from mozuku can be appropriated for use as a medicinal substance or health food, and can also contribute to productivity of mozuku farming, since powdering the substance enables the use of broken or crushed mozuku that otherwise has to be rejected for cooking use.

The exact mechanism of the pharmacological effects of fucoidan that seem to rival anti-cancer drugs is not yet fully understood. Fucoidan itself is a common component of brown seaweed like kombu and wakame as well, but their compositions are different, and depending on the source of the fucoidan, as yet unknown physiological effects can also be expected to be found.

The unique seaweed farming culture of Japan can now plan new strategies for seaweed product development and commercialization in conjunction with continued research into the functionality and properties of seaweed.

Repopulating Eelgrass Leads to Revival of Ocean Environment

At Hinase-cho on the Seto Inland Sea about an hour from Okayama City, a reclamation project is underway to restore eelgrass beds.

Eelgrass, or amamo, is a seaweed widely distributed in the temperate zones of the northern hemisphere, growing in the sandy bottoms of bays and inlets where the waves' action is gentle. It is very thin and grows to length of 1 or 2 meters.

Areas of abundant growth of eelgrass are called eelgrass beds. These beds actually fulfill a variety of functions. First off, since they provide shade in areas where the ocean flow is gentle, many varieties of fish gather here. Many varieties of plankton also can be found at eelgrass beds, so they form an excellent feeding ground for the fish. Also, through photosynthesis the eelgrass absorbs carbon dioxide and releases oxygen, thus contributing to improvement of the environmental quality of the seawater and the ocean bottom. Eelgrass beds remove vast amounts of nitrogen from the atmosphere, so from spring to summer which is the time of thickest growth for eelgrass, they aid in slowing down the eutrophication process and helping control red algae bloom.

Eelgrass beds are intimately related to the maintenance of fruitful fishing grounds and precious fish habitats. In coastal areas the amount of fish caught per year is actually dropping, so commercial fishermen that use small pound nets along the coasts together with junior members of fishermen's associations have started a reclamation plan that would somehow revive this important eelgrass resource. After trial and error at the local fishery experimentation station, in 1992 a joint effort with Nihon Shokusei, a Tsuyama company known for its work in embankment forestation, the group developed an eelgrass bed reclamation technology utilizing a sandbagging-style seeding technique.

The sandbagging-style seeding technique consists of embedding soil, fertilizer and eelgrass seeds into a woven mat about one meter square, like a flat cushion, which is then sunk down to lay across the ocean bottom. The mat is woven of alternating cotton and biodegradable plastic fiber. After two months on the bottom, the cotton decays, leaving spaces between the fibers for the seedlings to grow through. The biodegradable plastic fiber also breaks down completely in two to three years.

As of now, about three years into the eelgrass reclamation project, the area has seen the return of the ainame rock trout, tanago Japanese bitterling, hiiragi ponyfish and yoshiebi greasyback shrimp. The future challenge will be the revival of the peripheral environment so that eelgrass can propagate naturally. From the reforestation of the sea to call back disappearing fish species, to the applied scientific development of seaweed properties-in as much as ocean farming has as yet many unexplored facets, it carries within great future potential.

JAPAN CLOSE-UP, January 2003, published by PHP