Practical ecological knowledge for the temperate reader.

Macrocystis pyrifera - Giant perennial kelp

Family: Laminariaceae [Wiki]

"Macrocystis is a monospecific genus, the sole species is M. pyrifera. Some individuals are so huge that the thallus may grow to up to 60 m (200 ft).[4]" [Wiki]

"One of the largest of these brown algae is Macrocystis (Fig. 1.8) which may grow up to 150 ft (45· 7 m) long. It appears to have a life of about five years, though individual fronds have only an average age of six months or so (North, 1961), which means that the growth rate is very high; the average rate of elongation of frond apices has been measured at 7·1 cm ± 4·3 cm per day (Sargent and Lantrip, 1952). At a depth of 60 ft. (I8·3m) whole fronds can grow as much as 45 cm per day, and at this rate they represent the most rapid plant growth known. By means of bladders, which are gas-filled and located at the base of the laminae, the fronds are kept floating at the surface of the sea. In view of their great size these seaweeds can have their rooting portion down at depths of 10-15 fathoms (lS·25-27-4m), though they achieve their best growth in depths of about S fathoms (l4·6m)." [Chapman SU]

"M. pyrifera grows in water along the south coast of Argentina and it is frequently deposited on the beach of Bahía de Camarones causing unpleasant odors and a negative impact on local tourism and can be considered an easily available natural waste." [Alvarez BLA]

" of the fastest-growing organisms on Earth, commonly growing to 30 m, and in ideal conditions can grow over 50 cm per day in one season and reach over 50 or 60 m and 100 Kg in mass. Like most kelp species, M. pyrifera is perennial, and has a lifespan of five to eight years. This species will often die back to its holdfast each winter, as much as three quarters of an individual can be lost during the winter season." [Periera ESW]

"The effect of warm water on the rate of decay of Macrocystis is striking, and if the temperature of the water rises much above 20°C whole beds may disappear entirely. Several beds did, in fact, disappear completely as a result of this in the warm summer of 1917 and again later. Destruction appears to be caused by bacterial action at these higher temperatures (see p. 273). In other places the kelp beds exist near sites where wastes are discharged into the sea. Historical records shows that two beds have deteriorated since 1945 because of the local discharge. In addition to the wastes, turbidity in such areas can also be a significant factor as well as sea urchin grazing." [Chapman SU]


"Water extracts of certain algae, e.g. Macrocystis, Gelidium cartilagineum, Pelvetia fastigiata and Egregia laevigata, are toxic to mice (Habekost, Fraser and Halstead, 1955). There is no evidence, however, that consumption of alginate products at normal use age levels (see p. 216) presents any toxicological problems (McNeely and Kovacs, 1975)." [Chapman SU]

Food Use

"In this country the Maoris used to employ certain of the green seaweeds said to be very palatable in salads and soups. They still make use of the red seaweed Porphyra (see p. 98). It is recorded that seaweed meal made from Macrocystis, together with milk from a seaweed-eating cow, produced a very striking speed-up in the development of a four year old child who, at the beginning of the treatment, was not able to sit up and talk." [Chapman SU]

Medicinal Use

"The methanol extracts of the red alga Palmaria palmata and three kelp (Laminaria setchellii, Macrocystis integrifolia, and Nereocystis luetkeana) display antiproliferative effects on the HeLa human cervical adenocarcinoma cell line. The antiproliferative efficacy of these algal extracts was positively correlated with the total polyphenol contents suggesting a causal link related to extract content of phlorotannins (Yuan and Walsh, 2006)." [????]

"Brown algae thallus serves chiefly as a source of iodine. The drug has also been demonstrated to have an influence on the immune system, as well as antiviral qualities. In a study with 400 women, the daily intake of 5.5 g of macrocystis powder over a period of 6 to 8 weeks led to an elevation of hemoglobin levels of 86% over normal values. Although licensed as a substance to aid weight loss, no adequate experimental data are available to support that effect." [PDR]

"Unproven Uses: Folk medicine uses include weight reduction. The drug is used as a commercial pharmaceutical preparation in the U.S. for anemia in pregnancy. In Japan the drug is used for hypertension." [PDR]

"No health hazards are known in conjunction with the proper administration of designated therapeutic dosages." [PDR]

"Brown Kelp should not be used by individuals with a familial disposition to thyroid illness or hyperthyroidism." [PDR]

"Long-term administration of daily dosages that exceed 150 micrograms iodine carry with them the danger of worsening an existing hyperthyroidism. Quantities over 300 micrograms iodine per day can precipitate hyperthyroidism." [PDR]

"Mode of Administration: Brown Kelp preparations are available for internal use. Storage: Store in tightly sealed container." [PDR]

Chemical Composition

Macrocystis pyrifera [Qin BSFA]

Water 10%–11% Copper 0.003%
Ash 33%–35% Chromium 0.0003%
Protein 5%–6% Manganese 0.0001%
Cellulose 6%–7% Silver 0.0001%
Alginic acid and other carbohydrates
Vanadium 0.0001%
Sodium 5.5% Lead 0.0001%
Calcium 2.0% Chlorine 11%
Strontium 0.7% Sulfur 1.0%
Magnesium 0.7% Nitrogen 0.9%
Iron 0.08% Phosphorus 0.29%
Aluminum 0.025% Iodine 0.13%
Lithium 0.01% Boron 0.008%
Rubidium 0.001% Bromine 0.0002%
Monosaccharide Compositions of Fucoidan

Macrocystis pyrifera - Fucose, galactose, sulfate (Black et al. (1953) [Qin BSFA]

Alginate Production

"The giant Macrocystis grows along the shores of eastern and southern Australia and Tasmania where it is now being harvested as a source of alginates." [Chapman SU]

"The rather inadequate data for Macrocystis from Hoagland (I 916), presented in Table 6.6, show that plants from the south contain considerably more algin than those from farther north. This result is probably related to higher metabolic activity in the warmer southern waters. It is comparable to a somewhat similar phenomenon mentioned previously (p. 22) for iodine, potash and nitrogen." [Chapman SU]

"Also in the southern hemisphere a factory was established in Tasmania, using Macrocystis, in 1964 (Pownall, 1964) but it has since closed. More recently a new company, Kelp Industries Pty, has been formed, but this is purely for the collection and export of dried Macrocystis to Alginate Industries of Great Britain. Export commenced in 1975 and there has been a steady increase since then". [Chapman SU]

"Most of the extractions performed by scientists then were in mild acidic conditions with temperature variations, and subsequently ethanol precipitation. It is interesting to note that Hoagland and Lieb (1915) (Table 3.2) used sodium carbonate to pretreat the seaweed, Macrocystis pyrifera, prior to extraction using hydrochloric acid, and the extract was found to be mainly alginic acid and some fucose-sulfate. This is consistent to what was discussed previously (section “Brown Seaweeds and its Polysaccharides”), where alginate is water soluble in sodium form, that is, the sodium carbonate converts the alginate in the M. pyrifera into sodium alginate. The HCl used for the extraction then converts the sodium alginate into alginic acid, which was then extracted." [Kim SP]

"Alginate is a linear polysaccharide polymer of b-d-mannuronic acid and a-lguluronic acid. The commercially available alginates are derived primarily from brown seaweed, which include: Laminaria hyperborea, Ascophyllum nodosum, and Macrocystis pyrifera (Goh et al., 2012). An extraction method for alginate is outlined in Figure 9.4. First, acid treatment is used to convert the alginate salts to insoluble alginic acid and to remove external salts and residual formaldehyde. The seaweeds are then stirred for 15 min at room temperature, and the residual solution is then drained. After this, extraction is carried out with water in excess ratio (depending on the species and desired viscosity) at a temperature of 80°C and pH of 10 (maintained by adding sodium carbonate). Following extraction, water is added to reduce viscosity at 75°C and to facilitate the filtration process. The product of filtration, that is, clarified alginate solution, is added simultaneously at synchronized speed with 10% calcium chloride (CaCl2) solution. Recovered calcium alginate is treated with acid at pH 1.8–2.0 to obtain alginate (Hernández- Carmona et al., 2013)." [Tiwari SS]

Use in Dental alginate impressions

"Dental alginate impression materials contain a blend of several ingredients to impart desirable properties during its use in clinical conditions. Alginic acid is a colloidal polysaccharide extracted from cell walls of various species of brown seaweed (Phaeophyceae). Although alginic acid can be extracted from any seaweed, the chemical structure of alginic acid varies from one genus to other. Several brown seaweeds, such as Laminaria, Ascophyllum, Durvillaea, Ecklonia, Lessonia, Macrocystis and Sargassum can be used as a source of raw alginate (Black and Woodward, 1954)." [Kim SP]

Cultivation & Propagation

"In the studies without considering the effects of UVR, diurnal photosynthesis of macroalgae was depressed in the afternoon on sunny days in Macrocystis pyrifera surface canopy (Gerard, 1986)" [Israel SRGCE]

"Metschnikowia zobellii is a dominant yeast on surfaces of decomposing macroalgae from the kelp Macrocystis pyrife (Van Uden and Branco 1963)." [Raghukumar FCME]

"In recent times, seaweed protein has been extracted and used as fish feed. In Australia, the brown seaweed Macrocystis pyrifera and the red seaweed Gracilaria edulis have been used as abalone feed (McHugh, 2003)." [Tiwari SS]

"Macrocystis pyrifera is also harvested along the Mexican coast. Starting with 10000 tons (10160 tonnes) wet weight in 1956 the annual harvest in 1974 was 37000 tons (37 580 tonnes) and it is probably still increasing." [Chapman SU]

"In the U.S., the giant kelp, Macrocystis pyrifera is used (Figure 7.13); it is harvested from large offshore beds off the coasts of California and Mexico. Around 50,000 tons wet weight are gathered each year using ships equipped with cutting machinery. Macrocystis has the distinction of being the largest macroalgae in the world; the largest attached plant recorded was 65 m long and the plants are capable of growing at up to 50 cm day". [Barsanti Algae]

"The concept of the kelp farm (Wilcox and Leese, 1976) has been developed to ensure adequate supplies of algae that can be harvested economically. At the present time attention is centred around the large Pacific kelp, Macrocystis pyrifera, (Fig. 1.8), which grows in extensive beds that are regularly harvested off the Pacific USA. The algal genus also occurs off the coasts of South Africa, South America, Australia and New Zealand. Experimental work in California (North, 1974) has shown that plants can be cultured and nets innoculated with sporelings, or larger plants can be readily transferred to nets. However, Macrocystis is not the only large brown alga that can or could be harvested mechanically." [Chapman SU]

"In the case of Macrocystis, which has been unsuccessfully exploited in Tasmania for algin production, experiments have shown that it can be grown successfully outside its present distribution area in the West Indies (La Croix) and in the English Channel. In the case of France the plants were removed before maturity and reproduction because of opposition to its introduction. The use of any of the large algae for farming immediately raised the problem of a potential 'weed' species that could change an existing ecosystem. For this reason it will be wisest to restrict kelp farms to ocean areas where the alga grows naturally." [Chapman SU]

"Initial experiments using Macrocystis on nets attached near the shore resulted in problems with ocean currents, wave action and shipping. However, they did demonstrate the value of locating farms in areas where there was natural upwelling of nutrients or in areas where upwelling could be generated artificially. Jackson (1977) showed that low nutrients in surface waters provide the primary limiting factor. At St. Croix the test plants grown in upwelling water grew better than comparable plants in California". [Chapman SU]

"The advantage of Macrocystis and other large brown algae is that they are immune to frost or drought and in the case of Macrocystis individual frond life is 6 months so that 2-3 crops per year are feasible. It is estimated that a 100000 acre (40469 ha) farm would produce 15-45 x 109 ft3 (42·48-126·62 x 107 m3 ) methane per year at a cost of S 3-9 per 1000." [Chapman SU]


"Some macroalgal species like Macrocystis pylifera and genera such as Sargassum, Laminaria, Ascophyllum, Ulva, Cladophora, Chaetomorpha, and Gracilaria have been explored as potential methane sources (Filipkowska et al. 2008)." [Demirbas AE]

"Giant kelp (Macrocystis spp.) yields, for instance, have been compared to those of sugar cane (Mann, 1973; Lapointe et al., 1976; Feng et al., 2004; Harger and Neushul, 2009). Biomass increases of 20% per day (Guist et al., 1982), as well as yields of 50 t/ha/year dry weight (Lapointe et al., 1976) and 1750 g C/m2/year (Mann, 1973), were already reported 40 years ago. More recently, rates of 39.7 g dry weight/m2/d have been sustained in intensive tank culture during a period of 4 years (Capo et al., 1999) and yields in excess of 600 t/ha/year fresh weight have been documented (Neori et al., 2004)." [Tiwari SS]


"Brown algae is been used as green manure. Easy availability, low cost, nutritional quality, rich micronutrients (Fe, Cu, Zn, B, Mn, Co and Mo), macronutrients (Ca, K and P), vitamins, growth hormones (auxins, betaines, cytokinins and gibberellins) and chelating property make brown seaweeds an excellent soil conditioner. Species of various seaweeds such as Ascophyllum , Dictyopteris , Durvillaea, Fucus , Laminaria , Macrocystis , Padina and Sargassum (Kumar and Sahoo 2011 ) are being used as a biofertilizer in many coastal countries...." [Sahoo TAW]

"In the southern hemisphere, coast dwellers in New Zealand have made use of algae as manure. Macrocystis pyrifera, Lessonia variegata and Ecklonia radiata are the bottom weed species that have been used, whilst Carpophyllum, Cystophora (Blossevillea) and Sargassum are the principal low-water forms. The cost of driftweed removal in New Zealand is, however, expensive. The principal objection to a more extensive use of seaweed as a manure in New Zealand, and indeed anywhere, is that it is heavy bulky material (it contains 90% water), and, unless dried, it must therefore be utilized near its source. It is, therefore, only profitable to establish an industry in places where large quantities are likely to be continually available. ... Grimmet and Elliott (I 940) prepared a dry manure from New Zealand Macrocystis which contained 17% of potash and 2% of nitrogenous material. The bull kelp, Durvillea, which is also abundant in these waters, would not be a satisfactory alga for manurial purposes since it only contains about 1·75 % potash and 0·7% nitrogen (Aston, 1916). Field experiments carried out in New Zealand have shown that plots fertilized with dried Macrocystis yield crops only slightly inferior to plots treated with an equivalent amount of artificial manure containing 30% of potash salts." [Chapman SU]

"Little (I 948) studied the rate of decomposition of certain large New Zealand brown seaweeds when dug into the soil. Macrocystis, Ecklonia and Durvillea decompose completely within four months, but Carpophyllum is still recognizable after one year. The bulk of the sodium, potassium and chlorine is released in the first fourteen days, so that these elements are made available very rapidly. It is likely therefore that the minor elements will be made available equally rapidly." [Chapman SU]

"In British Columbia mineral and nitrogen content in Macrocystis and Nereocystis is also maximal in December, January and March (Wort, 1955)." [Chapman SU]

"In the case of Macrocystis the availability of the nitrogen decreases on drying, so that it is desirable to use this alga when wet." [Chapman SU]


"Algae are among the most promising biosorbents; due to presence of alginate in their cell wall, brown algae are probably the best. Recently we have published the results of metal biosorption using nonviable biomasses from two brown algae, Macrocystis pyrifera and Undaria pinnatifida (Plaza Cazón et al. 2011, 2012a, b, 2013)." [Alvarez BLA]

Journals of Interest

Use of Other Related Sp.

"Macrocystis angustifolia has been cultivated on an experimental scale in South Africa with a view to eventually growing it for alginate production or abalone feed." [Qin BSFA]


Page last modified on Wednesday, November 17, 2021 9:09 PM