Fucus spiralis Linnaeus

Fucus spiralis Linnaeus

Description: Spiralled Wrack, Fucus spiralis, is the uppermost species of Fucus that occurs on the shore. The frond lacks bladders (Fucus vesiculosus) and does not have a serrated edge (Fucus serratus); it is sometimes spiralled. This species has recently had another, common species segregated from it, Fucus guiryi. For characters to distinguish the two species, go to the description of this entity.

Fucus serratus L.

Fucus serratus L.

Description: Dichotmously branched fronds arising from a small disc via a short stipe; distinct midrib. Plants to 300 mm with terminal, compressed receptacles with warty conceptacles. This is the "Serrated wrack" of the lower shore in the north-eastern Atlantic. It is easily recognised by its saw-toothed frond, and a lack of swollen receptacles (see below).

Habitat: Zone forming on sheltered and semi-exposed shores from about MTL down to about MLWN where it meets the kelp zone.
Distribution: Widely distributed on all coasts of Britain and Ireland. Spain north to Spitsbergen.
Usage: Fucus serratus is used in Ireland and France for the production of seaweed extracts for cosmetics, and for seaweed baths.
Similar species: Fucus vesiculosus generally has paired vesicles and does not have a saw-toothed edge; Fucus spiralis has inflated terminal receptacles with a sterile rim,
Link: AlgaeBase

FUCUS

Fucus is northern-hemisphere genus of macroscopic marine seaweeds called wracks. It includes a relatively small number of species. Fucus vesiculosus is perhaps the best-known species (below), is known to have a number of useful compounds. The plants consist of a flattened, dichotomously-branched thallus which has a small stipe and a holdfast. The blade usually has a locally-thickened area which is centrally placed called a midrib. Air bladders are found in some species and these help to keep the plant afloat when submerged.
There is no conducting tissue in Fucus: it is unecessary as the plant is small enough to be able to manufacture food locally. In these brown algae the plants are always diploid and meiosis takes place before the gametes are formed. Gamete production takes place in specialised crypt-like structures called conceptacles which are borne in fertile, swollen areas at the tips of the plants: these are called receptacles. It is very easy to confuse these two terms. Some species of Fucus, such as Fucus spiralis, are monoecious with both sexes occurring on one plant; most are dioecious with each sex being found on different plants. Some monoecious species may have both sexes in one conceptacle whilst others may have them in separate conceptacles.
The male reproductive structures (left, in section) are called antheridiophores which are branched, tree-like structures that line the conceptacles. The antheridiophores have terminal inflated antheridia on their branches; these undergo meiosis and form 64-128 biflagellate male gametes (antherozoids).
Oogonia, the female reproductive structures (below, in section), are bore on short stalks and after meiosis to form 8 nuclei (one meiosis and one mitosis) the oogonium then cleaves to form 8 large, non-motile eggs. Gametes are usually released into the water on the rising tide. Exposure to air causes dessication and the gametes are squeezed onto the surface of the receptacle, and are then washed off and mixed by the inoming tide. The female egg liberates a volatile hydrocarbon, fucoserraten (a compound with 8 carbon atoms) which attracts the male antherozoids; these cluster around the egg and spin it; one penetrates the complex series of coats around the egg and karyogamy (nuclear fusion) occurs. The zygotic cell settles down and germinates to form a new diploid thallus. Strictly speaking, the so-called gametophyte thallus in Fucus is a sporophyte that undergoes meiosis just before gametes are formed. This is the reason why some textbooks refer to the male gametangia as 'microsporangia' and the female gametangia as 'megasporangia'. Fucus species are found in the upper, mid, and lower intertidal in the colder waters of the northern Atlantic and northern Pacific. The genus is absent from the southern hemisphere.

PHAECOPHYCEAE : BROWN ALGAE

CHARACTERISTIC 

The brown colour of these algae results from the dominance of the xanthophyll pigment fucoxanthin, which masks the other pigments, Chlorophyll a and c (there is no Chlorophyll b), beta-carotene and other xanthophylls. Food reserves are typically complex polysaccharides, sugars and higher alcohols. The principal carbohydrate reserve is laminaran, and true starch is absent (compare with the green algae). The walls are made of cellulose and alginic acid, a long-chained heteropolysaccharide.
There are no known unicellular or colonial representatives; the simplest plant form is a branched, filamentous thallus. The kelps are the largest (up to 70 m long) and perhaps the most complex brown algae, and they are the only algae known to have internal tissue differentiation into conducting tissue; there is, however, no true xylem tissue as found in the 'higher' plants.
Most brown algae have an alternation of haploid and diploid generations. The haploid thalli form isogamous, anisogamous or oogamous gametes and the diploid thalli form zoospores, generally by meiosis. The haploid (gametangial) and diploid (sporangial) thalli may be similar (isomorphic) or different (heteromorphic) in appearance, or the gametangial generation may be extremely reduced (Fucales). The brown Giant Kelp Macrocystis pyrifera (top) is harvested off the coasts of California for feeding abalone. It used to be used for alginate extraction, but this now mostly comes from Atlantic Ascophyllum nodosum and Laminaria hyperborea. Alginates, derivatives of alginic acids, are used commercially for toothpastes, soaps, ice cream, tinned meats, fabric printing, and a host of other applications. It forms a stable viscous gel in water, and its primary function in the above applications is as a binder, stabilizer, emulsifier, or moulding agent. Saccharina japonica, formerly Laminaria, and other species of the genus are grown on ropes in China, Korea and Japan for food and alginate production. Undaria pinnatifida is also cultivated in Japan, Korea and China for production of Wakame, a valuable food kelp. Small amounts are also grown in Atlantic France for the European market.


About 16,000 tonnes of Ascophyllum nodosum (above, Feamainn bhuí in Irish, referring to the yellow colour in summer) are harvested each year in Ireland, dried and milled in factories at Arramara Teo., Cill Chiaráin (Kilkerrin), Co. Galway; and some 3,000 t of the resulting seaweed meal is exported and processed in Scotland for the production of alginic acid. Laminaria hyperborea stipes (sea rods) are harvested in Norway and used to be collected in drift in Scotland and Ireland. The rods are used for the manufacture of high-grade alginates. Other brown algae are used for the extraction of agricultural sprays ('liquid seaweed extracts'). These extracts are used at low concentrations on crops and their hormone-like activities are thought to be due to betaines, cytokinenins, etc. In some areas, like the west of Ireland and Scotland, kelps and other brown algae are gathered as a fertiliser for land

There are about 1800 species of brown algae, and most are marine. In general, brown algae are larger and more species are found in colder waters. Virtually all the biomass worldwide comes from a relatively small number of species in the orders Laminariales and Fucales. The total wholesale value of dried brown algae worldwide collected in the wild or cultivated is less than $100 million dollars.

WHAT ARE SEAWEEDS?

What are seaweeds?

Marine macroalgae, or seaweeds, are plant-like organisms that generally live attached to rock or other hard substrata in coastal areas. They belong to three different groups, empirically distinguished since the mid-nineteenth century on the basis of thallus color: brown algae (phylum Orchrophyta, class Phaeophyceae; see right for a large brown kelp, Durvillaea in New Zealand), red algae (phylum Rhodophyta; below Gelidium in Ireland), and green algae (phylum Chlorophyta, classes Bryopsidophyceae, Chlorophyceae, Dasycladophyceae, Prasinophyceae, and Ulvophyceae; bottom, Ulva howensis in Lord Howe Island off eastern Australia). Distinguishing these three phyla, however, involves more substantial differences than colour. In addition to the pigmentation, they differ considerably in many ultrastructural and biochemical features including photosynthetic pigments, storage compounds, composition of cell walls,presence / absence of flagella, ultrastructure of mitosis, connections between adjacent cells, and the fine structure of the chloroplasts. They originated through different evolutionary processes (primary endosymbiosis for green and red algae, secondary endosymbiosis for brown algae, and for this reason they are now classified in different kingdoms (green algae and red algae in the Kingdom Plantae, and brown algae in the Kingdom Chromista).

Red and brown algae are almost exclusively marine, whilst green algae are also common in freshwater (rivers and lakes), and even in terrestrial (rocks, walls, houses, and tree bark in damp places) situations. Many of these algae are very ancient organisms, and although lumped together as "algae", are not really very closely related, having representatives in 4 of the 5 or 6 kingdoms of organisms.


Seaweeds are far more complex organisms than generally realised. Many have specialised tissues and growth forms. They may have very complicated sex, with many of them producing sex pheremones ( chemicals that attract males or male gametes), and with many different types of sex organs. Red algae have the most complicated sex known in plants. Kelps are known to have quite rapid translocation, something that is not credited to algae in many textbooks. There is even growing evidence of root-like structures in some wracks that reach deep into rocks, and which may be important in the "weathering" of rocks in the intertidal. Generally, seaweeds and many algae have holdfasts : basal structures that do exactly what the name suggests-hold fast to the rock. Seaweeds must produce  some amazing adhesives as quite small holdfasts seem to be sufficient for quite large plants. On the right you can see the small holdfast (about1 cm across) of an Ascophyllum nodosum (Egg Wrack) clump about 2 m in length.



AlgaeBase dynamic species counts shows that there are about 9,300 species of seaweeds, of which 6,000 are red agae (Rhodophyta), 1,800 are browns and 1,500 are greens (about 800 species of Byropsidophyceae, 50 species of Dasycladophyceae, and 250 marine Ulvophyceae. Up-to-date numbers are given by AlgaeBase.

SEAWEED

This site is a source of general information on all aspects of seaweeds. Seaweeds are marine algae: saltwater-dwelling, simple organisms that fall into the somewhat outmoded, but still useful, category of "plants". Most of them are the green (about 1500 species), brown (about 1800 species) or red (about 6200 species) kinds, samples of which are each illustrated on this page, and most are attached by holdfasts, which generally just have an anchorage function, although a particularly efficient one.

Colourful Seaweed in Galway Rockpool

This underwater movie is about a minute long and shows a seaweed-dominated rockpool in the lower intertidal of Galway Bay near Spiddal. The pool is lined with the fronds of Corallina officinalis (pink), with scattered stands of Chondrus crispus (Carrageen Moss, fan-shaped, purple-red) and Cryptopleura ramosa (delicate, crimson-red), occasional plants of Ulva (Sea Lettuce), young plants of Sea-thong (Himanthalia elongata, yellow brown) forming a tree-like canopy; there are occasional plants of Sea Oak (Halidrys siliquosa brownish-yellow). Oxygen bubbles can be seen escaping as the movie clip progresses.

Do you know any seaweeds?

Most people know two general categories of seaweeds: wracks (members of the brown algal order Fucales such as Fucus) and kelps (members of the brown algal order Laminariales such as Laminaria), and many have heard of Carrageen or Irish Moss (usually a red alga, Chondrus crispus) and Dulse or Dillisk (also a red alga, Palmaria palmata). Seaweeds make up the Sargasso Sea, a large ocean gyre in the western Atlantic where drift plants of several species of the genus Sargassum accumulate. Seaweeds are particularly important ecologically: they dominate the rocky intertidal in most oceans, and in temperate and polar regions cover rock surfaces in the shallow subtidal. Although only penetrating to 8-40 m in most oceans, some are found to depths of 250 m in particularly clear waters (Mediterranean, Caribbean, Brazil). The Giant Kelp (Macrocystis) is one of the largest plants in the world, which in western North America forms an important association with the newly revived Sea Otter.

Yummy Seaweed?

Seaweeds are found throughout the world's oceans and seas and none is known to be poisonous. Many are actually nice to eat and even considered a great delicacy in many Asian countries. Some recent, healthy recipes can be found here. Seaweeds are used in many maritime regions for industrial applications and as a fertiliser. The major direct use of these plants as food is in Japan, China and Korea, and in the Indian Ocean where seaweed cultivation has become a major coastal industry. The main food species grown by aquaculture in these countries are Nori or Zicai (Porphyra, a red alga), Kombu, Kunbu or Haidai (Laminaria or Saccharina: brown algae) and Wakame (Undaria, also a brown alga). In Japan alone, the total annual production value of nori amounts to more than US$2 billion, one of the most valuable crops produced by aquaculture in the world. In most western countries, seaweed consumption is relatively restricted and there has not been any great pressure to develop mass cultivation techniques. On this site, seaweed aquaculture, particularly nori, a Japanese red seaweed, is described in detail.

Uses of Seaweed

Industrial utilisation of seaweed is mostly centred on the extraction of phycocolloids (marine hydrocolloids), and, to a much lesser extent, certain fine biochemicals. Fermentation and pyrolysis and the use of seaweed as biofuels are not an option on an industrial scale at present, but are possible options for the future, particularly as conventional fossil fuels run out. Seaweeds are being used in cosmetics, and as organic fertilisers. They have the potential to be much more widely used as a source of long- and short-chained biochemicals with medicinal and industrial uses. Marine algae may also be used as energy-collectors and potentially useful substances may be extracted by fermentation and pyrolysis. Seaweed extracts appear in the oddest of places; you almost certainly have eaten some sort of seaweed extract in the last 24 hours as many processed foods such as chocolate milk, yoghurts, health drinks, and even the highest-quality German beers contain seaweed polysaccharides such as agars, carrageenans and alginates! Seaweed baths have been popular in Ireland and Britain since Edwardian times, and seaweed wraps and treatments have become more poular in the last few years. A recent innovation is the apparent incorporation of seaweed into a fibre, although some commentators have cast doubt on the presence of any seaweed in fabrics advertised as such.

THE NUTRITIONAL AND MEDICINAL VALUE OF SEAWEEDS USED IN CHINESE MEDICINE

THE NUTRITIONAL AND MEDICINAL VALUE OF SEAWEEDS
USED IN CHINESE MEDICINE

by Subhuti Dharmananda, Ph.D., Director, Institute for Traditional Medicine, Portland, Oregon

There are four seaweeds commonly used in Chinese medicine:

• Laminaria (kelp), a brown algae and Ecklonia (the more commonly used item), a green algae as sources of kunbu (Laminaria is sometimes called haidai, to distinguish it from Ecklonia or other sources)
• Sargassum, a brown algae, as the source of haizao
• Pyrphora, a red algae, as the source of zicai

These seaweeds will be discussed briefly in this article.

SEAWEED'S NUTRITIONAL VALUE (1)

Seaweed draws an extraordinary wealth of mineral elements from the sea that can account for up to 36% of its dry mass. The mineral macronutrients include sodium, calcium, magnesium, potassium, chlorine, sulfur and phosphorus; the micronutrients include iodine, iron, zinc, copper, selenium, molybdenum, fluoride, manganese, boron, nickel and cobalt.

Seaweed has such a large proportion of iodine compared to dietary minimum requirements, that it is primarily known as a source of this nutrient. The highest iodine content is found in brown algae, with dry kelp ranging from 1500-8000 ppm (parts per million) and dry rockweed (Fucus) from 500-1000 ppm. In most instances, red and green algae have lower contents, about 100-300 ppm in dried seaweeds, but remain high in comparison to any land plants. Daily adult requirements, currently recommended at 150 µg/day, could be covered by very small quantities of seaweed. Just one gram of dried brown algae provides from 500-8,000 µg of iodine and even the green and red algae (such as the purple nori that is used in Japanese cuisine) provides 100-300 µg in a single gram.

The amounts of seaweed ingested as food in Japan, or in supplements, is often considerably more than 1 gram a day. Studies show that the human body adapts readily to higher iodine intake, where the thyroid gland is the main tissue involved in use of iodine (it is a component of thyroid hormones). Huge portions of the world population get insufficient iodine because the land, plants, and animals that serve as common dietary sources are very low in iodine. In many countries, iodine is added to table salt to assure adequate levels are attained. However, some developing countries are still catching up and suffering from the effects of low iodine intake. China is has the largest population with a history of low iodine intake, followed by India.

Aside from iodine, seaweed is one of the richest plant sources of calcium, but its calcium content relative to dietary requirements pales in comparison to the iodine. The calcium content of seaweeds is typically about 4-7% of dry matter. At 7% calcium, one gram of dried seaweed provides 70 mg of calcium, compared to a daily dietary requirement of about 1,000 mg. Still, this is higher than a serving of most non-milk based foods.

Protein content in seaweed varies somewhat. It is low in brown algae at 5-11% of dry matter, but comparable in quantitative terms to legumes at 30-40% of dry matter in some species of red algae. Green algae, which are still not harvested much, also have a significant protein content, i.e., up to 20% of dry matter. Spirulina, a micro-alga, is well known for its very high content, i.e., 70% of dry matter.

Seaweed contains several vitamins. Red and brown algae are rich in carotenes (provitamin A) and are used, in fact, as a source of natural mixed carotenes for dietary supplements. The content ranges from 20-170 ppm. The vitamin C in red and brown algae is also notable, with contents ranging from 500-3000 ppm. Other vitamins are also present, including B₁₂, which is not found in most land plants.

Seaweed has very little fat, ranging from 1-5% of dry matter, although seaweed lipids have a higher proportion of essential fatty acids than land plants. Green algae, whose fatty acid make-up is the closest to higher plants, have a much higher oleic and alpha-linoleic acid content. Red algae have a high EPA content, a substance mostly found in animals, especially fish. Seaweed has a high fiber content, making up 32% to 50% of dry matter. The soluble fiber fraction accounts for 51-56% of total fibers in green (ulvans) and red algae (agars, carrageenans and xylans) and for 67-87% in brown algae (laminaria, fucus, and others). Soluble fibers are generally associated with having cholesterol-lowering and hypoglycemic effects.

Seaweeds: Ecklonia (upper left); Porphyra (middle left); Sargassum (lower left); Laminaria (right)

FOOD USES

Probably the most widely known seaweed used for food is Porphyra, which literally means purple (see sample leaf below), reflecting its color in nature. The Chinese name is zicai, which means purple vegetable. It is classified among the red algae, which have red to purple pigments. Upon processing to yield the food, which is known in Japan as nori, the red pigments are lost and the final product has a dark greenish color. Nori is used to wrap sushi and for making numerous snacks. The other common food item is the low cost but highly nutritious kelp (kunbu in Chinese; kombu in Japanese). Kombu is usually sold in 5-6-inch dried pieces and can be found in health food stores and Japanese groceries (see sample package below). It is also sold as kombu that cooks quickly, vinegared, shaved kombu that needs little or no cooking, boiled, soy sauce flavored kombu, lightly pickled kombu, and powdered kombu that can be sprinkled on food or used in drinks. Dried kombu needs to be simmered for at least 20 minutes to soften it and flavor the liquid. If used only for flavoring stock, the kombu itself is removed from the liquid at the end of cooking and discarded. A third seaweed widely used in Japan is known as wakame (from Undaria pinnatifida). See the Appendix for information about seaweed utilization in Japan.

MEDICINAL USES

Seaweeds have a salty taste that is an indication that the material can disperse phlegm accumulation, particularly as it forms soft masses, include goiter, the thyroid swelling that indicates severe iodine deficiency. Following are the descriptions of the seaweeds from Oriental Materia Medica (2):

Kunbu (Laminaria and Ecklonia)

• Essence and Flavor: Salty, Cold
  
• Channel Entered: Liver, Stomach, Kidney
  
• Actions: Softens hardness, disperses accumulation, resolves phlegm, cleanses heat
  
• Applications: Scrofula, goiter, tumor, edema, accumulation, testicular pain and swelling

Haizao (Sargassum)

• Essence and Flavor: Bitter, Salty, Cold
  
• Channel Entered: Liver, Stomach, Kidney
  
• Actions: Disperses accumulated phlegm, disperses goiter and tumor, delivers water, cleanses heat
  
• Applications: Scrofula, goiter, tumor, edema, testicular pain and swelling

Zicai (Porphyra)

• Essence and Flavor: Sweet, Salty, Cold
  
• Channel Entered: Lung
  
• Actions: Resolves phlegm, softens hardness, dispels heat, promotes diuresis
  
• Applications: Goiter, beriberi [leg swelling], edema, urinary infection, sore throat

The descriptions for kunbu and haizao are quite similar. Yang Yifan (3) wrote about the differences between these commonly used seaweeds:

Haizao and Kunbu are salty and cold, and enter the liver, lung, and kidney meridians. Both can clear heat, transform phlegm, soften hardness, and dissipate nodules. They can also promote urination and reduce edema. In clinical practice, they are often used together to treat nodules such as goiter and scrofula.

There are some differences between the two herbs. Haizao is stronger in transforming phlegm and dissipating nodules, and it is more suitable for treating goiter and scrofula. Kunbu is stronger in softening hardness and reducing congealed blood; it is more suitable for treating liver-spleen enlargement, liver cirrhosis, and tumors.

One of the best known formulas with the seaweeds is Haizao Yuhu Tang, or the Sargassum Decoction for the Jade Flask (4). This formula of 12 ingredients includes Sargassum, Ecklonia, and Laminaria. It was used to treat a condition of goiter which was so severe it made the throat look like a large flask. However, these seaweeds have been adopted into formulas for treating other soft swellings, including ovarian cysts, breast lumps, lymph node swellings, lipomas, and fat accumulation from simple obesity.

REFERENCES

1. Secretariat of the Pacific Community Coastal Fisheries Programme, Seaweed's nutritional value, Fisheries Information Newsletter #95, October-December 2000.
2. Hsu HY, et al., Oriental Materia Medica: A Concise Guide, 1986 Oriental Healing Arts Institute, Long Beach, CA.
3. Yang Yifang, Chinese Herbal Medicines: Comparisons and Characteristics, 2002 Churchill-Livingstone, London
4. Bensky D and Barolet R, Chinese Herbal Medicine: Formulas and Strategies, 1990 rev. ed., Eastland Press, Seattle, WA.

APPENDIX: JAPAN AND SEAWEED

Following is an outline report on Japanese utilization of seaweed and seaweed products, with data from 1998, except as noted, thanks to the Fisheries Information Newsletter (1).

• Japan is the world's largest seafood producer, importer and consumer. Annual seafood expenditures totaled 36,425 yen (~$300 U.S.) per capita.
• Total fresh seaweed production was 623,286 tons for all types of seaweed. But, this is far less than Japan uses for certain seaweeds, particularly those used for industrial processing of specialty seaweed products.
• Today, Japan is the leading importer of seaweed, while Korea is the premier exporter-with Japan as its main customer.
• Japanese imports stood at a total of 71,800 tons of fresh seaweed produce valued at over $150 million dollars. It consisted of 40,900 tons of Undaria (a seaweed that grows in the Pacific, from Korea to Japan to Australia) imported from China and Korea worth $65.3 million dollars, plus other varieties worth $38 million dollars.
• Exports of seaweed from Japan were 1214 tons of miscellaneous seaweed, i.e., processable raw seaweed, dried kombu and nori worth $12 million dollars, plus 59 million dried Porphyra sheets (as used for making sushi) worth $4.6 million dollars. The exports are mainly sold to the USA and Taiwan.
• There are at least 21 seaweed species used daily in food preparation in Japan. The Japanese consume an average of 4 kg per capita every year (~11 grams per day). There is also a large industry built around the three common colloid compounds derived from seaweed: agar, alginate, and carrageenan. These are used to provide thickening and texture to foods, and for other uses.
• The agar industry started in Japan over 400 years ago in mountainous regions where, in cold winters, agar would set into a gel. Japan now imports the raw material, the seaweeds Gracilaria and Gelidium, from Chile and South Africa, for a yearly output of 1000-1500 tons of agar in 1994.
• Alginate extraction in Japan is carried out using Ecklonia and Durvillea imported from Chile and South Africa. The alginate obtained is high-quality material and is used in specific biotech applications. The use of Laminaria spp. for kombu, moreover, has resulted in the import of another raw material so as to extract alginates. Overall production of alginate is about 1000-1500 tons per year (1994 figures).
• The carrageenan industry is mainly based on direct imports of seaweeds (1,718 tons in 1994). Carragenophytes are also imported from Southeast Asian aquafarms (yielding Eucheuma and Kappaphycus) and from wild stocks in North and South America and Europe (yielding Chondrus and Gigartina).

Seaweed Farming in Japan

Seaweed farming is highly developed in Japanese coastal areas. The main species grown there are Porphyra (nori), Laminaria (kombu) and Undaria (wakame). These alone have accounted for 98% of overall Japanese seaweed production since 1984. The balance is made up of minor traditional (Monostroma, Enteromorpha and Cladosiphon) or experimental (Meristotheca and Grateloupia) crops or wild stock harvests.

Nori

Nori is a traditional food used, for example, to make sushi, which has been a highly profitable crop over the past century. Since the reproduction cycle's summer phase was discovered by Dr Kathleen Drew-Baker, farming has become easier and more lucrative - so much so that no imports have occurred since 1976. Porphyra cultivation is the largest sub-industry in Japanese aquafarming, employing 16,800 workers. In 1998, output stood at 10,326 million nori sheets, i.e. equivalent to 396,615 tons of fresh produce.

Kombu

Kombu is the most widely sold seaweed in Japan. It is an "all-purpose" product although it is most commonly used for bean-curd soup with kombu.

Wild stock still accounts for a major share of output. Several species of the genus Laminaria are used in the Japanese food industry. Laminaria japonica takes the lion's share of kombu production with a raw-material tonnage of 141,875.

Wakame

Undaria pinnatifida cultivation is a relatively recent development in Japan and wakame is served as a luxury food on Japanese and Korean tables. It is highly sought after for bean-curd soup or salads. Raw-material production, standing at 73,508 tons, is unable to meet Japanese demand for wakame.

Undaria pinnatifida (wakame)