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
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
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
JAPAN CLOSE-UP, January 2003, published by PHP