|Kelp on rocky beach in Freycinet, Tasmania|
|Nutritional value per 100 g (3.5 oz)|
|Energy||180 kJ (43 kcal)|
|Dietary fiber||1.3 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.
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.
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.) and keep the kelp blades close to the surface, holding up the blades by the gas they contain.
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.
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). 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. Giant kelp can be harvested fairly easily because of its surface canopy and growth habit of staying in deeper water.
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.
Kombu can be used to soften beans during cooking, and to help convert indigestible sugars and thus reduce flatulence.
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.
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. Unlike some biofuels such as corn ethanol, kelp energy avoids "food vs fuel" issues and does not require irrigation.
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.
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.
Scuba diver in kelp forest
Blue Rockfish in kelp forest
Anemone and starfish in kelp forest
An underwater shot of a Kelp forest.
A Kelp forest.
A fish swimming in a Kelp Forest as seen at the Monterey Bay Aquarium.
A view of the Kelp Forest Exhibit at the Monterey Bay Aquarium from the upstairs level.
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.
Species of Laminaria in the British Isles;
Other species in the Laminariales that may be considered as kelp
Some animals are named after the kelp, either because they inhabit the same habitat as kelp or because they feed on kelp. These include:
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).
[[File:|thumb|right|220px|A kelp forest in Monterey.]]
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.