''Macrocystis pyrifera'', commonly known as giant kelp or bladder kelp, is a species of

kelp Kelps are large brown algae seaweeds that make up the order Laminariales. There are about 30 different genera. Despite its appearance, kelp is not a plant - it is a heterokont, a completely unrelated group of organisms. Kelp grows in "underwa ...

(large

brown algae Brown algae (singular: alga), comprising the class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Brown algae are the major seaweeds of the temperate and po ...

), and one of four species in the genus ''

Macrocystis ''Macrocystis'' is a monospecific genus of kelp (large brown algae). This genus contains the largest of all the phaeophyceae or brown algae. ''Macrocystis'' has pneumatocysts at the base of its blades. Sporophytes are perennial and the indi ...

''. Despite its appearance, it is not a

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...

; it is a

heterokont Heterokonts are a group of protists (formally referred to as Heterokonta, Heterokontae or Heterokontophyta). The group is a major line of eukaryotes. Most are algae, ranging from the giant multicellular kelp to the unicellular diatoms, which a ...

. Giant kelp is common along the coast of the northeastern

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

, from

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

north to southeast

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

, and is also found in the southern oceans near

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

, and

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

. Individual algae may grow to more than long at a rate of as much as per day. Giant kelp grows in dense stands known as

kelp forest Kelp forests are underwater areas with a high density of kelp, which covers a large part of the world's coastlines. Smaller areas of anchored kelp are called kelp beds. They are recognized as one of the most productive and dynamic ecosystems on Ea ...

s, which are home to many marine animals that depend on the algae for food or shelter. The primary commercial product obtained from giant kelp is

alginate Alginic acid, also called algin, is a naturally occurring, edible polysaccharide found in brown algae. It is hydrophilic and forms a viscous gum when hydrated. With metals such as sodium and calcium, its salts are known as alginates. Its colour ...

, but humans also harvest this species on a limited basis for use directly as food, as it is rich in

iodine Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...

potassium Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...

, and other minerals. It can be used in cooking in many of the ways other sea vegetables are used, and particularly serves to add flavor to bean dishes.

Description

''Macrocystis pyrifera'' is the largest of all

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

. The stage of the life cycle that is usually seen is the

sporophyte A sporophyte () is the diploid multicellular stage in the life cycle of a plant or alga which produces asexual spores. This stage alternates with a multicellular haploid gametophyte phase. Life cycle The sporophyte develops from the zygote pr ...

, which is perennial and individuals persist for many years. Individuals may grow to up to long or more. The kelp often grows even longer than the distance from the bottom to the surface as it will grow in a diagonal direction due to the ocean current pushing against the kelp.Hoek ''et al.'' 1995, p. 201 The stalks arise from a basal meristem, with as many as 60 stalks in older well protected plants. Blades develop at irregular intervals along the stipe, with a single

pneumatocyst In phycology, a pneumatocyst is a floating structure that contains gas found on brown seaweed. A seaweed's thallus may have more than one. They provide buoyancy to lift the blades toward the surface, allowing them to receive more sunlight for p ...

(gas bladder) at the base of each blade.Kain 1991 At the base of each stalk a cluster of blades that lack pneumatocysts, instead they develop small sacks on the blade that release the biflagellated

zoospore A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Diversity Flagella types Zoospores may possess one or ...

s these are the sporophylls. A related and similar-looking, but smaller species, '' M. integrifolia'', grows to only long. It is found on intertidal rocks or shallow subtidal rocks along the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

coast of

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

(

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

) and South America.Abbott & Hollenberg 1976 In New Zealand ''M. pyrifera'' is found in the subtidal zone of southern North Island, the South Island, Chatham, Stewart, Bounty, Antipodes, Auckland and Campbell Islands. The species can be found on rock and on sheltered open coasts.

Growth

Juvenile Giant kelp (Macrocystis pyrifera)

''Macrocystis pyrifera'' is one of the fastest-growing organisms on Earth.White & Plaskett 1982, page 8 They can grow at a rate of a day to reach over long in one growing season.Davis 1991, p. 21 Juvenile giant kelp grow directly upon their parent female

gametophyte A gametophyte () is one of the two alternation of generations, alternating multicellular organism, multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has on ...

. 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.Mondragon & Mondragon 2003Prescott 1968, pp.226-227

Ecology

''Macrocystis pyrifera'' is found in

(

, and southern Australia. It thrives in cooler waters where the ocean water temperature remains mostly below . The species is also found near

Tristan da Cunha Tristan da Cunha (), colloquially Tristan, is a remote group of volcanic islands in the South Atlantic Ocean. It is the most remote inhabited archipelago in the world, lying approximately from Cape Town in South Africa, from Saint Helena ...

in the Mid-South Atlantic Ocean. Where the bottom is rocky and affords places for it to anchor, giant kelp forms extensive

kelp bed Kelp forests are underwater areas with a high density of kelp, which covers a large part of the world's coastlines. Smaller areas of anchored kelp are called kelp beds. They are recognized as one of the most productive and dynamic ecosystems on Ea ...

s with large "floating canopies". When present in large numbers, giant kelp forms

s that are home to many marine species that 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. 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.Reed 1990Reed ''et al.'' 1991 Where surface waters are poor in nutrients,

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

in the form of

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

s is translocated up the stipe through sieve elements that very much resemble the

phloem Phloem (, ) is the living biological tissue, tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose, to the rest of the plant. This tran ...

vascular plant Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They ...

s. Translocation of nutrients along the stipe may be as rapid as per hour. Most translocation occurs to move

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...

-rich photosynthate, and typically transfers material from mature regions to actively growing regions where the machinery of

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

is not yet fully in place. Translocation also moves nutrients downward from light-exposed surface fronds to

sporophyll A sporophyll is a leaf that bears sporangia. Both microphylls and megaphylls can be sporophylls. In heterosporous plants, sporophylls (whether they are microphylls or megaphylls) bear either megasporangia and thus are called megasporophylls, or ...

s (reproductive fronds) at the base of the kelp, where there is little light and thus little photosynthesis to produce food.

Aquaculture

''Macrocystis pyrifera'' has been utilized for many years as a food source;Abbott 1996Gutierrez ''et al.'' 2006 it also contains many compounds such as

, other minerals vitamins and carbohydrates and thus has also been used as a dietary supplement.Bushing 2000Connor 1989, p. 58 In the beginning of the 20th century California kelp beds were harvested as a source for

soda ash Sodium carbonate, , (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield moderately alkaline solutions ...

.Abbott 1996Neushul 1987Druehl ''et al.'' 1988 With commercial interest increasing significantly during the 1970s and the 1980s this was primarily due to the production of

s, and also for biomass production for animal feed due to the energy crisis during that period.Neushul 1987Druehl ''et al.'' 1988Gerard 1987 However the commercial production of ''M. pyrifera'' never became reality. With the end of the energy crisis and the decline in prices of alginates, the research into farming ''Macrocystis'' also declined. The demand for ''M. pyrifera'' is increasing due to the newfound uses of these plants such as

fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...

s, cultivation for

bioremediation Bioremediation broadly refers to any process wherein a biological system (typically bacteria, microalgae, fungi, and plants), living or dead, is employed for removing environmental pollutants from air, water, soil, flue gasses, industrial effluent ...

purposes, abalone and sea urchin feed.Buschmann ''et al.'' 2006 There is current research going into utilizing ''M. pyrifera'' as feed for other aquaculture species such as shrimps.Cruz ''et al.'' 2009 Recently, ''M. pyrifera'' has been examined as a possible feedstock for conversion into ethanol for biofuel use.Wargacki ''et al.'' 2012

Conservation

In recent years, the kelp forests have decreased dramatically throughout Japan, Chile, Korea, Australia and North America. Harvesting of kelp as a food source and other uses may be the least concerning aspect to its depletion. In the Northwest Pacific kelp forests in waters near large population centres may be most affected by the sewer/stormwater discharge. The natural phenomenon known as

El Niño El Niño (; ; ) is the warm phase of the El Niño–Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (approximately between the International Date L ...

cycles warm, tropical water from the South Pacific to Northern waters. This has been known to kill off ''M. pyrifera,'' due to its need for cold waters it would usually find in the North Pacific Ocean. In California, El Niño also brought along a population bloom of purple sea urchins which feed on the giant kelp. By the late 2000s most of the onshore giant kelp in California was practically nonexistent.

Tasmania

Off the coast of

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

, kelp forests have been significantly affected by several factors, including warming waters, shifting of the

East Australian current The East Australian Current (EAC) is a warm, southward, western boundary current that is formed from the South Equatorial Current (SEC) crossing the Coral Sea and reaching the eastern coast of Australia. At around 15° S near the Australian co ...

(EAC), and invasion of long-spine sea urchins. Locals have noticed significant effects on the population of abalone, a food source for the

Aboriginal Tasmanians The Aboriginal Tasmanians ( Palawa kani: ''Palawa'' or ''Pakana'') are the Aboriginal people of the Australian island of Tasmania, located south of the mainland. For much of the 20th century, the Tasmanian Aboriginal people were widely, an ...

for thousands of years. These changes have also affected the

oyster Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but not ...

farming industry. By saving oysters that have survived disease outbreaks, they have been able to continue their way of life. It was estimated that by 2019, 95 per cent of the giant kelp forests along Tasmania's east coast had been lost within just a few decades. Some of this loss was attributed by locals to the harvesting of the forests by Alginates Australia, which opened its factory near

Triabunna Triabunna is a rural residential locality in the local government area (LGA) of Glamorgan–Spring Bay in the South-east LGA region of Tasmania. The locality is about north-east of the city of Hobart. The has a population of 905 for the state ...

in 1963, shutting down operations 10 years later as uneconomical. However, expert in

marine ecosystem Marine ecosystems are the largest of Earth's aquatic ecosystems and exist in waters that have a high salt content. These systems contrast with freshwater ecosystems, which have a lower salt content. Marine waters cover more than 70% of the sur ...

s Craig Johnson says that the loss of the forests "is almost certainly the result of

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...

". Water temperatures along the east coast of Tasmania have been rising at nearly four times the average rate globally. The EAC brings warmer waters, which are also nutrient-poor compared to the previously usual cold water around the coast. Common kelp ('' Ecklonia radiata'') is better at nitrogen storage than giant kelp, so has been taking over the areas formerly occupied by giant kelp. ''Macrocystis pyrifera'' has become Australia’s first federally-listed endangered marine community. Scientists and conservationists are continuously looking into ways to restore the once heavily populated species to its original state. Methods include

artificial reef An artificial reef is a human-created underwater structure, typically built to promote marine life in areas with a generally featureless bottom, to control erosion, block ship passage, block the use of trawling nets, or improve surfing. Many ...

s, reducing numbers of purple sea urchins in overpopulated areas, and planting roots along the ocean floor. Scientists had built 28 artificial reefs off

Maria Island Maria Island or 'wukaluwikiwayna' in alawa kani) is a mountainous island located in the Tasman Sea">island.html" ;"title="alawa kani) is a mountainous island">alawa kani) is a mountainous island located in the Tasman Sea, off the east coast of ...

by 2019, and were hopeful of bringing the kelp forests back.

Gallery

File:Alger, Macrocystis pyrifera, Nordisk familjebok.png, File:Giantkelp2 300.jpg, File:CAS Macrocystis 2.JPG, File:CAS Macrocystis 4.JPG, File:Kelpharvest 300.jpg, File:Seaweed, Santa Cruz Harbor.JPG, File:Paralabrax clathratus - Tokyosealifepark - 2019 1 8.webm,

Notes

References

*Abbott, I A & G J Hollenberg. (1976) ''Marine Algae of California.'' California: Stanford University Press. *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. -iv 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. *Cribb, A B. (1953
''Macrocystis pyrifera'' (L.) Ag. in Tasmanian waters
''Australian Journal of Marine and Freshwater Research'' 5 (1):1-34. *Cruz-Suarez, L. Elizabeth; 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. * tp://ftp.fao.org/docrep/fao/012/i1013t/i1013t.pdf ''Fishery and Aquaculture Statistics'' (2007). retrieved from ftp.fao.org*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. *Huisman, J M (2000) ''Marine Plants of Australia.'' University of Western Australia Press. * Kain, J M (1991) ''Cultivation 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. *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 https://web.archive.org/web/20101226110745/http://aquanic.org/species/documents/6_Algae_3__Culturing.pdf *Mondragon, Jennifer & Jeff Mondragon. (2003) ''Seaweeds of the Pacific Coast.'' Monterey, California: Sea Challengers. *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.

External links

* {{Authority control Laminariaceae Flora of the Pacific Marine biota of North America Flora of California Flora of Northwestern Mexico Flora of Southwestern Mexico Flora of the West Coast of the United States Species described in 1820 Flora of Tasmania Flora of Victoria (Australia) Flora of South Australia Flora without expected TNC conservation status