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From Wikipedia, the free encyclopedia

Kelp on rocky beach in Freycinet, Tasmania
Scientific classification
Kingdom: Chromalveolata
Phylum: Heterokontophyta
Class: Phaeophyceae
Order: Laminariales
Migula, 1909[1]


Kelp (raw)
Nutritional value per 100 g (3.5 oz)
Energy 180 kJ (43 kcal)
Carbohydrates 9.6 g
Sugars 0.6 g
Dietary fiber 1.3 g
Fat 0.6 g
Protein 1.7 g
Thiamine (Vit. B1) 0.1 mg (8%)
Riboflavin (Vit. B2) 0.2 mg (13%)
Niacin (Vit. B3) 0.5 mg (3%)
Pantothenic acid (B5) 0.6 mg (12%)
Vitamin B6 0.0 mg (0%)
Folate (Vit. B9) 180 μg (45%)
Vitamin C 3.0 mg (5%)
Calcium 168.0 mg (17%)
Iron 2.8 mg (22%)
Magnesium 121.0 mg (33%)
Phosphorus 42.0 mg (6%)
Potassium 89 mg (2%)
Sodium 233 mg (10%)
Zinc 1.2 mg (12%)
Percentages are relative to US recommendations for adults.
Source: USDA Nutrient database

Kelp are large seaweeds (algae) belonging to the brown algae (class Phaeophyceae) and are classified as the order Laminariales. There are about 300 different genera. Some species can be very long and form kelp forests.

Kelp fisheries is a branch of fisheries science that deals with the study of and uses of large seaweeds of the brown algae group that are commonly called kelp.

Scientists group them in the kingdom plantae

Kelp grows in underwater "forests" (kelp forests) in shallow oceans. It requires nutrient-rich water below about 20 °C (68 °F). It is known for its high growth rate — the genera Macrocystis and Nereocystis grow as fast as half a metre a day, ultimately reaching 30 to 80 m.[2]

Through the 19th century, the word "kelp" was closely associated with seaweeds that could be burned to obtain soda ash (primarily sodium carbonate). The seaweeds used included species from both the orders Laminariales and Fucales. The word "kelp" was also used directly to refer to these processed ashes.[3]



In most kelp, the thallus (or body) consists of flat or leaf-like structures known as blades. Blades originate from elongated stem-like structures, the stipes. The holdfast, a root-like structure, anchors the kelp to the substrate of the ocean. Gas-filled bladders (pneumatocysts) form at the base of blades of American species, such as Nereocystis lueteana (Mert. & Post & Rupr.)[2] and keep the kelp blades close to the surface, holding up the blades by the gas they contain.

Growth and reproduction

Growth occurs at the base of the meristem, where the blades and stipe meet. Growth may be limited by grazing. Sea urchins, for example, can reduce entire areas to urchin barrens. The kelp life cycle involves a diploid sporophyte and haploid gametophyte stage. The haploid phase begins when the mature organism releases many spores, which then germinate to become male or female gametophytes. Sexual reproduction then results in the beginning of the diploid sporophyte stage, which will develop into a mature individual.

Commercial uses

Alaskan beach kelp

Bongo kelp ash is rich in iodine and alkali. In great amount, kelp ash can be used in soap and glass production. Until the Leblanc process was commercialized in the early 1800s, burning of kelp in Scotland was one of the principal industrial sources of soda ash (predominantly sodium carbonate).[4] Alginate, a kelp-derived carbohydrate, is used to thicken products such as ice cream, jelly, salad dressing, and toothpaste, as well as an ingredient in exotic dog food and in manufactured goods[citation needed]. Giant kelp can be harvested fairly easily because of its surface canopy and growth habit of staying in deeper water.

Kelp is also used frequently in seaweed fertiliser, especially in the Channel Islands, where it is known as vraic.

Kombu (Saccharina japonica and others), several Pacific species of kelp, is a very important ingredient in Japanese cuisine. Kombu is used to flavor broths and stews (especially dashi), as a savory garnish (tororo konbu) for rice and other dishes, as a vegetable, and a primary ingredient in popular snacks (such as tsukudani). Transparent sheets of kelp (oboro konbu) are used as an edible decorative wrapping for rice and other foods.[5]

Kombu can be used to soften beans during cooking, and to help convert indigestible sugars and thus reduce flatulence.[6]

Because of its high concentration of iodine, brown kelp (Laminaria) has been used to treat goiter, an enlargement of the thyroid gland caused by a lack of iodine, since medieval times.[7]

As a possible renewable energy source

See also: Biomass energy, Algae fuel

Kelp has a high rate of growth and its decay is quite efficient in yielding methane, as well as sugars that can be converted to ethanol. It has been proposed that large open-ocean kelp farms could serve as a source of renewable energy.[8] Unlike some biofuels such as corn ethanol, kelp energy avoids "food vs fuel" issues and does not require irrigation.

Kelp in history and culture

During the Highland Clearances, many Scottish Highlanders were moved off their crofts, and went to industries such as fishing and kelping (producing soda ash from the ashes of kelp). At least until the 1820s, when there were steep falls in the price of kelp, landlords wanted to create pools of cheap or virtually free labour, supplied by families subsisting in new crofting townships. Kelp collection and processing was a very profitable way of using this labour, and landlords petitioned successfully for legislation designed to stop emigration. But the economic collapse of the kelp industry in northern Scotland led to further emigration, especially to North America.

Natives of the Falkland Islands are sometimes nicknamed "Kelpers"[9][10]. The name is primarily applied by outsiders rather than the natives themselves.


Overfishing nearshore ecosystems leads to the degradation of kelp forests. Herbivores are released from their usual population regulation, leading to over-grazing of kelp and other algae. This can quickly result in barren landscapes where only a small number of species can thrive.[citation needed]


Kelp in China

Laminaria japonica, the important commercial seaweed, was first introduced into China in the late 1920s from Hokkaido, Japan. Commercial production of kelp harvested from its natural habitat took place in Japan for over a century. Yet mariculture of this algae on a very large commercial scale was realized in China only in the 1950s. Between the 1950s and the 1980s kelp production in China increased from about 60 to over 250,000 dry weight metric tons annually, making China the largest producer of Laminaria.

Prominent species

Species of Laminaria in the British Isles;

  • Laminaria digitata (Hudson) J.V. Lamouroux (Oarweed; Tangle)
  • Laminaria hyperborea (Gunnerus) Foslie (Curvie)
  • Laminaria ochroleuca Bachelot de la Pylaie
  • Laminaria saccharina (Linnaeus) J.V.Lamouroux (sea belt; sugar kelp; sugarwack)

Species of Laminaria world-wide, listing of species at AlgaeBase:[11]

  • Laminaria agardhii (NE. America)
  • Laminaria angustata (Japan)
  • Laminaria bongardina Postels et Ruprecht (Bering Sea to California)
  • Laminaria cuneifolia (NE. America)
  • Laminaria dentigera Klellm. (California - America)
  • Laminaria digitata (NE. America)
  • Laminaria ephemera Setchell (Sitka, Alaska, to Monterey County, California - America)
  • Laminaria farlowii Setchell (Santa Cruz, California, to Baja California - America)
  • Laminaria groenlandica (NE. America)
  • Laminaria japonica (Japan), synonym of Saccharina japonica
  • Laminaria longicruris (NE. America)
  • Laminaria nigripes (NE. America)
  • Laminaria ontermedia (NE. America)
  • Laminaria pallida]] Greville ex J. Agardh (South Africa)
  • Laminaria platymeris (NE. America)
  • Laminaria saccharina (Linnaeus) Lamouroux (Aleutian Islands, Alaska to southern California America)
  • Laminaria setchellii Silva (Aleutian Islands, Alaska to Baja California America)
  • Laminaria sinclairii (Harvey ex Hooker f. ex Harvey) Farlow, Anderson et Eaton (Hope Island, British Columbia to Los Angeles, California - America)
  • Laminaria solidungula (NE. America)
  • Laminaria stenophylla (NE. America)

Other species in the Laminariales that may be considered as kelp

  • Alaria marginata Post. & Rupr. (Alaska and California - America
  • Costaria costata (C.Ag.) Saunders Japan; Alaska, California - America)
  • Durvillea antarctica (New Zealand, South America, and Australia)
  • Durvillea willana (New Zealand)
  • Durvillaea potatorum (Labillardière) Areschoug (Tasmania; Australia)
  • Ecklonia brevipes J. Agardh (Australia; New Zealand)
  • Ecklonia maxima (Osbeck) Papenfuss (South Africa)
  • Ecklonia radiata (C.Agardh) J. Agardh (Australia; Tasmania; New Zealand; South Africa)
  • Eisena arborea Aresch. (Vancouver Island, British Columbia, Montrey, Santa Catalina Island, California - America)
  • Egregia menziesii (Turn.) Aresch.
  • Hedophyllum sessile (C.Ag.) Setch (Alaska, California - America)
  • Macrocystis angustifolia Bory (Australia; Tasmania and South Africa)
  • Pleurophycus gardneri Setch. & Saund. (Alaska, California - America)
  • Pterygophora californica Rupr. (Vancouver Island, British Columbia to Bahia del Ropsario, Baja California and California - America)
  • Saccharina japonica (Japan)


Some animals are named after the kelp, either because they inhabit the same habitat as kelp or because they feed on kelp. These include:

  • Northern kelp crab (Pugettia producta) and graceful kelp crab (Pugettia gracilis), Pacific coast of North America.
  • Kelpfish (blenny) (e.g., Heterosticbus rostratus, genus Gibbonsia), Pacific coast of North America.
  • Kelp goose (kelp hen) (Chloephaga hybrida), South America and the Falkland Islands
  • Kelp pigeon (sheathbill) (Chionis alba and Chionis minor), Antarctic

See also


  1. ^ Migula, W. (1909). Kryptogamen-Flora von Deutschland, Deutsch-Österreich und der Schweiz. Band II. Algen. 2. Teil. Rhodophyceae, Phaeophyceae, Characeae. Gera: Verlag Friedriech von Zezschwitz. pp. i-iv, 1-382, 122 (41 col.) pls. 
  2. ^ a b Thomas, D. 2002. Seaweeds. The Natural History Museum, London, p. 15. ISBN 0 565 09175 1
  3. ^ "Kelp," in Oxford English Dictionary (Second Edition). Oxford University Press, 1989. Retrieved 1 December 2006
  4. ^ Clow, Archibald and Clow, Nan L. (1952). Chemical Revolution. Ayer Co Pub, June 1952, pp. 65–90. ISBN 0-8369-1909-2
  5. ^ Kazuko, Emi: Japanese Cooking, p. 78, Hermes House, 2002, p. 78. ISBN 0-681-32327-2
  6. ^ Graimes, Nicola: The Best-Ever Vegetarian Cookbook, Barnes & Noble Books, 1999, p. 59. ISBN 0-7607-1740-0
  7. ^ Iodine Helps Kelp Fight Free Radicals and May Aid Humans, Too Newswise, Retrieved on July 8, 2008.
  8. ^
  9. ^ [1] definition for "Kelper",
  10. ^ [2] definition for "Kelper"
  11. ^ Laminariales

External links

1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

KELP (in M.E. culp or culpe, of unknown origin; the Fr. equivalent is varech), the ash produced by the incineration of various kinds of sea-weed (Algae) obtainable in great abundance on the west coasts of Ireland and Scotland, and the coast of Brittany. It is prepared from the deep-sea tangle (Laminaria digitata), sugar wrack (L. saccharina), knobbed wrack (Fucus nodosus), black wrack (F. serratus), and bladder wrack (F. vesiculosus). The Laminarias yield what is termed "drift-weed kelp," obtainable only when cast up on the coasts by storms or other causes. The species of Fucus growing within the tidal range are cut from the rocks at low water, and are therefore known as "cut-weeds." The weeds are first dried in the sun and are then collected into shallow pits and burned till they form a fused mass, which while still hot is sprinkled with water to break it up into convenient pieces. A ton of kelp is obtained from 20 to 22 tons of wet sea-weed. The average composition may vary as follows: potassium sulphate, 10 to 12%; potassium chloride, 20 to 25%; sodium carbonate, 5%; other sodium and magnesium salts, 15 to 20%; and insoluble ash from 40 to 50%. The relative richness in iodine of different samples varies largely, good drift kelp yielding as much as 10 to 15 lb per ton of 222 cwts., whilst cut-weed kelp will not give more than 3 to 4 lb. The use of kelp in soap and glass manufacture has been rendered obsolete by the modern process of obtaining carbonate of soda cheaply from common salt (see Iodine).

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Simple English

[[File:|thumb|right|220px|A kelp forest in Monterey.]]

File:Kelp In Freycinet
Kelp on a beach

Kelp is a type of marine seaweed. It is a brown alga. There are many different kinds of kelp. Kelp grow in large forests, usually near the surface of the water. Some kelps grow very fast (up to 30 cm a day). Kelp can reach a length of up to 60 m. The blades are kept afloat by gas-filled bladders.

Kelp plays an important role as food and habitat for fish and other forms. It may be eaten as a vegetable.

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