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Macrocystis pyrifera


Macrocystis pyrifera

Giant kelp
Scientific classification
Kingdom: Chromalveolata
Phylum: Heterokontophyta
Class: Phaeophyceae
Order: Laminariales
Family: Laminariaceae
Genus: Macrocystis
Species: M. pyrifera
Binomial name
Macrocystis pyrifera
(L.) C.Ag.[1]
  • Fucus pyrifer L.
  • Laminaria pyrifera (L.) Lamouroux
  • M. humboldtii (Bonpland) C.Ag.
  • M. planicaulis C. Agardh
  • M. pyrifera var. humboldtii Bonplan.

Macrocystis pyrifera, commonly known as giant kelp or giant bladder kelp, is a species of kelp (large brown algae), and one of four species in the genus Macrocystis. Giant kelp is common along the coast of the eastern Pacific Ocean, from Baja California north to southeast Alaska, and is also found in the southern oceans near South America, South Africa, and Australia. Individual algae may grow to more than 45 metres (148 ft) long at a rate of as much as 2 feet (61 cm) per day. Giant kelp grows in dense stands known as kelp forests, which are home to many marine animals that depend on the algae for food or shelter. Humans harvest kelp for it is rich in iodine, potassium, and other minerals, but the primary product obtained from giant kelp is alginate.


  • Description 1
  • Growth 2
  • Ecology 3
  • Aquaculture 4
  • Gallery 5
  • Notes 6
  • References 7
    • Further reading 7.1


M.pyrifera is the largest of all algae. The stage of the life cycle that is usually seen is the sporophyte, which is perennial and individuals persist for many years.The giant kelp receives its name from its incredible size. Individuals may grow to up to 50 metres (160 ft) long.[2] The stalks arise from a holdfast and branch three or four times from near the base. Blades develop at irregular intervals along the stipe, with a single pneumatocyst (gas bladder) at the base of each blade.[3]

A related and similar-looking, but smaller species, M.integrifolia, grows to only to 6 metres (20 ft) long. It is found on intertidal rocks or shallow subtidal rocks along the Pacific coast of North America (British Columbia to California) and South America.[4][5]


M.pyrifera is one of the fastest-growing organisms on Earth.[6][7] They can grow at a rate of 0.6 metres (2 ft) a day to reach over 45 metres (148 ft) long in one growing season.[4][8][9]

Juvenile giant kelp grow directly upon their parent female gametophyte. To establish itself, a young kelp produces one or two primary blades, and begins a rudimentary holdfast, which serves to anchor the plant to the rocky bottom. As the kelp grows, additional blades develop from the growing tip, while the holdfast enlarges and may entirely cover the rock to which it is attached.

Growth occurs with lengthening of the stipe (central stalk), and splitting of the blades. At the growing tip is a single blade, at the base of which develop small gas bladders along one side. As the bladders and stipe grow, small tears develop in the attached blade. Once the tears have completed, each bladder supports a single separate blade along the stipe, with the bladders and their blades attached at irregular intervals.[10][11]


M.pyrifera is found in North America (Alaska to California), South America, South Africa, New Zealand, and southern Australia.[12] It thrives in cooler waters where the ocean water temperature remains below 70 °F (21 °C).[9]

Where the bottom is rocky and affords places for it to anchor, giant kelp forms extensive kelp beds with large "floating canopies".[4] When present in large numbers, giant kelp forms kelp forests that are home to many marine species who depend upon the kelp directly for food and shelter, or indirectly as a hunting ground for prey. Both the large size of the kelp and the large number of individuals significantly alter the availability of light, the flow of ocean currents, and the chemistry of the ocean water in the area where they grow.[13]

In high-density populations, giant kelp individuals compete with other individuals of the species for space and resources. Giant kelp may also compete with Pterygophora californica in these circumstances.[14][15]

Where surface waters are poor in nutrients, nitrogen in the form of amino acids is translocated up the stipe through sieve elements that very much resemble the phloem of vascular plants.[16][17] Translocation of nutrients along the stipe may be as rapid as 60 centimetres (24 in) per hour.[11] Most translocation occurs to move carbon-rich photosynthate, and typically transfers material from mature regions to actively growing regions where the machinery of photosynthesis is not yet fully in place. Translocation also moves nutrients downward from light-exposed surface fronds to sporophylls (reproductive fronds) at the base of the kelp, where there is little light and thus little photosynthesis to produce food.


M.pyrifera has been utilized for many years as a food source;[18][19] it also contains many compounds such as iodine, potassium, other minerals vitamins and carbohydrates and thus has also used as a dietary supplement.[20][21] In the beginning of the 20th century California kelp beds were harvested as a source for soda ash.[18][22][23] With commercial interest increasing significantly during the 1970s and the 1980s this was primarily due to the production of alginates, and also for biomass production for animal feed due to the energy crisis during that period.[22][23][24] However the commercial production for M.pyrifera never became realty. With the end of the energy crisis and the decline in prices of alginates, the research into farming Macrocystis also declined.[19]

The demand for M.pyrifera is increasing due to the newfound uses of these plants such as fertilizers, cultivation for bioremediation purposes, abalone and sea urchin feed.[19][25] There is current research going into utilizing M.pyrifera as feed for other aquaculture species such as shrimps.[25][26] Recently, M.pyrifera has been examined as a possible feedstock for conversion into ethanol for biofuel use.[27]



  1. ^ Agardh 1820
  2. ^ Hoek et al. 1995, p. 201
  3. ^ Kain 1991
  4. ^ a b c Abbott & Hollenberg 1976
  5. ^ AlgaeBase: Species: Macrocystis integrifolia
  6. ^ Fenner, Bob The Brown Algae
  7. ^ White & Plaskett 1982, page 8
  8. ^ Cribb 1953
  9. ^ a b Davis 1991, p. 21
  10. ^ Mondragon & Mondragon 2003
  11. ^ a b Prescott 1968, pp.226-227
  12. ^ AlgaeBase: Species: Macrocystis pyrifera
  13. ^ Lobban & Harrison, p. 158
  14. ^ Reed 1990
  15. ^ Reed et al. 1991
  16. ^ Lobban & Harrison, pp. 151-153
  17. ^ Hoek et al. 1995, p. 204
  18. ^ a b Abbott 1996
  19. ^ a b c Gutierrez et al. 2006
  20. ^ Bushing 2000
  21. ^ Connor 1989, p. 58
  22. ^ a b Neushul 1987
  23. ^ a b Druehl et al. 1988
  24. ^ Gerard 1987
  25. ^ a b Buschmann et al. 2006
  26. ^ Cruz et al. 2009
  27. ^ Wargacki et al. 2012


  • Abbott, I A & G J Hollenberg. (1976) Marine Algae of California. California: Stanford University Press. ISBN 0-8047-0867-3
  • Abbott, I. A. (1996). Ethnobotany of seaweeds: clues to uses of seaweeds. Hydrobiologia, 326-327(1), 15-20.
  • Agardh, C A. (1820) Species algarum rite cognitae, cum synonymis, differentiis specificis et descriptionibus succinctis. Vol. 1, Part 1, pp. [i-iv], [1]-168. Lund: Berling.
  • Buschmann, A., Varela, D., Hernández-González, M., & Huovinen, P. (2008). Opportunities and challenges for the development of an integrated seaweed-based aquaculture activity in Chile: determining the physiological capabilities of Macrocystis and Gracilaria as biofilters. Journal of Applied Phycology, 20(5), 571-577.
  • Buschmann, A. H., Hernández-González, M. C., Astudillo, C., Fuente, L. d. l., Gutierrez, A., & Aroca, G. (2005). Seaweed cultivation, product development and integrated aquaculture studies in Chile. World Aquaculture, 36(3), 51-53.
  • Bushing, William W (2000) Giant Bladder Kelp .
  • Druehl LD, Baird R, Lindwall A, Lloyd KE, Pakula S (1988) Longline cultivation of some Laminareaceae in British Columbia. Aquacult. Fish Management 19, 253–263.
  • Chaoyuan, W., & Guangheng, L. (1987). Progress in the genetics and breeding of economic seaweeds in China. Hydrobiologia, 151-152(1), 57-61.
  • Connor, Judith & Charles Baxter. (1989) Kelp Forests. Monterey, California: Monterey Bay Aquarium. ISBN 1-878244-01-9
  • Cribb, A B. (1953) (L.) Ag. in Tasmanian watersMacrocystis pyrifera Australian Journal of Marine and Freshwater Research 5 (1):1-34.
  • Cruz-SuÁRez, L., Tapia-Salazar, M., Nieto-LÓPez, M., Guajardo-Barbosa, C., & Ricque-Marie, D. (2009). Comparison of Ulva clathrata and the kelps Macrocystis pyrifera and Ascophyllum nodosum as ingredients in shrimp feeds. Aquaculture Nutrition, 15(4), 421-430.
  • Davis, Chuck. (1991) California Reefs. San Francisco, California: Chronicle Books. ISBN 0-87701-787-5
  • Fishery and Aquaculture Statistics. (2007). Retrieved from
  • Gutierrez, A., Correa, T., Muñoz, V., Santibañez, A., Marcos, R., Cáceres, C., et al. (2006). Farming of the Giant Kelp Macrocystis Pyrifera in Southern Chile for Development of Novel Food Products. Journal of Applied Phycology, 18(3), 259-267.
  • Hoek, C van den; D G Mann & H M Jahns. (1995) Algae: An Introduction to Phycology. Cambridge: Cambridge University Press. ISBN 0-521-30419-9
  • Huisman, J M (2000) Marine Plants of Australia. University of Western Australia Press. ISBN 1-876268-33-6
  • Kain, J M (1991) Culivation of attached seaweeds in Guiry, M D & G Blunden (1991) Seaweed Resources in Europe: Uses and Potential. John Wiley and Sons.
  • Lobban, C S & P J Harrison. (1994) Seaweed Ecology and Physiology. Cambridge: Cambridge University Press. ISBN 0-521-40334-0
  • Macchiavello, J., Araya, E., & Bulboa, C. Production of Macrocystis pyrifera (Laminariales;Phaeophyceae) in northern Chile on spore-based culture. Journal of Applied Phycology, 1-7.
  • Mariculture of Seaweeds. (2010). Retrieved from
  • Mondragon, Jennifer & Jeff Mondragon. (2003) Seaweeds of the Pacific Coast. Monterey, California: Sea Challengers. ISBN 0-930118-29-4
  • Neushul M (1987) Energy from marine biomass: The historicalrecord. In: Bird KT, Benson PH (eds), Seaweed Cultivation for Renewable Resources, Elsevier Science Publishers, Amsterdam, 1–37.
  • North, W J, G A Jackson, & S L Manley. (1986) "Macrocystis and its environment, knowns and unknowns." Aquatic Biology 26:9-26.
  • Prescott, G W. (1968) The Algae: A Review. Boston: Houghton Mifflin Company.
  • Reed, D C. (1990) "The effects of variable settlement and early competition on patterns of kelp recruitment." Ecology 71:776-787.
  • Reed, D C, M Neushul, & A W Ebeling. (1991) "Role of settlement density on gametophyte growth and reproduction in the kelps Pterygophora californica and Macrocystis pyrifera (Phaeophyceae)." Journal of Phycology 27:361-366.
  • Simenstad, C.A., Estes, J.A. and Kenyon, K.W., 1978. Aleuts, sea otters, and alternatestable state communities. Science, 200: 403-411.
  • Wargacki, A.J., Leonard, E., Win, M.N., Regitsky, D.D., Santos, C.N.S., et al. (2012). An engineered microbial platform for direct biofuel production from brown macroalgae. Science, 335(1), 308-313.
  • Westermeier, R., Patiño, D., Piel, M. I., Maier, I., & Mueller, D. G. (2006). A new approach to kelp mariculture in Chile: production of free-floating sporophyte seedlings from gametophyte cultures of Lessonia trabeculata and Macrocystis pyrifera. Aquaculture Research, 37(2), 164-171.
  • Westermeier, R., Patiño, D., & Müller, D. G. (2007). Sexual compatibility and hybrid formation between the giant kelp species Macrocystis pyrifera and M. integrifoliat (Laminariales, Phaeophyceae) in Chile. Journal of Applied Phycology, 19(3), 215-221.
  • White, L P & L G Plaskett, (1982) Biomass as Fuel. Academic Press. ISBN 0-12-746980-X

Further reading

  • Connor, Judith & Charles Baxter. (1989) Kelp Forests. Monterey, California: Monterey Bay Aquarium. ISBN 1-878244-01-9
  • Davis, Chuck. (1991) California Reefs. San Francisco, California: Chronicle Books. ISBN 0-87701-787-5
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