Macrocystis pyrifera
Encyclopedia
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 (147.6 ft) long at a rate of as much as 2 feet (61 cm) per day. Giant kelp grows in dense stands known as kelp forest
s, which are home to many marine animals that depend on the algae for food or shelter. Humans harvest kelp for its rich iodine
, potassium
, and other minerals, but the primary product obtained from giant kelp is alginate.
, and 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. Giant kelp receives its name from its incredible size. Individuals may grow to up to 50 metres (164 ft) long. 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.
A related and similar-looking, but smaller species, M.integrifolia, grows to only to 6 metres (19.7 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.
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.
(Alaska
to California
), South America
, South Africa
, New Zealand
, and southern Australia
. It thrives in cooler waters where the ocean water temperature remains below 70 °F (21.1 °C).
Where the bottom is rocky and affords places for it to anchor, giant kelp forms extensive kelp beds with large "floating canopies". When present in large numbers, giant kelp forms kelp forest
s 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.
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.
Where surface waters are poor in nutrients, nitrogen
in the form of amino acid
s is translocated up the stipe through sieve elements that very much resemble the phloem
of vascular plant
s. Translocation of nutrients along the stipe may be as rapid as 60 centimetres (23.6 in) per hour. 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 sporophyll
s (reproductive fronds) at the base of the kelp, where there is little light and thus little photosynthesis to produce food.
, potassium
, other minerals vitamins and carbohydrates and thus has also used as a dietary supplement . In the beginning of the 20th century California kelp beds were harvested as a source for potash
. 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 . 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.
The demand for M.pyrifera is increasing due to the new found uses of these plants such as fertilizer
s, cultivation for bioremediation
purposes, abalone
and sea urchin
feed. There is current research going into utilizing M.pyrifera as feed for other aquaculture species such as shrimps.
Kelp
Kelps are large seaweeds belonging to the brown algae in the order Laminariales. There are about 30 different genera....
(large brown algae
Brown algae
The Phaeophyceae or brown algae , is a large group of mostly marine multicellular algae, including many seaweeds of colder Northern Hemisphere waters. They play an important role in marine environments, both as food and for the habitats they form...
), and one of four species in the genus Macrocystis
Macrocystis
Macrocystis is a genus of kelp . 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 individual stipes may persist for many years...
. Giant kelp is common along the coast of the eastern Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, from Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
north to southeast Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
, and is also found in the southern oceans near South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, and Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. Individual algae may grow to more than 45 metres (147.6 ft) long at a rate of as much as 2 feet (61 cm) per day. Giant kelp grows in dense stands known as kelp forest
Kelp forest
Kelp forests are underwater areas with a high density of kelp. They are recognized as one of the most productive and dynamic ecosystems on Earth. Smaller areas of anchored kelp are called kelp beds....
s, which are home to many marine animals that depend on the algae for food or shelter. Humans harvest kelp for its rich iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
, potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
, and other minerals, but the primary product obtained from giant kelp is alginate.
Description
M.pyrifera is the largest of the brown algaeBrown algae
The Phaeophyceae or brown algae , is a large group of mostly marine multicellular algae, including many seaweeds of colder Northern Hemisphere waters. They play an important role in marine environments, both as food and for the habitats they form...
, and the largest of all algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
. The stage of the life cycle that is usually seen is the sporophyte
Sporophyte
All land plants, and some algae, have life cycles in which a haploid gametophyte generation alternates with a diploid sporophyte, the generation of a plant or algae that has a double set of chromosomes. A multicellular sporophyte generation or phase is present in the life cycle of all land plants...
, which is perennial and individuals persist for many years. Giant kelp receives its name from its incredible size. Individuals may grow to up to 50 metres (164 ft) long. The stalks arise from a holdfast
Holdfast
A holdfast is a root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, stalked crinoids, benthic cnidarians, and sponges, to the substrate. ...
and branch three or four times from near the base. Blades develop at irregular intervals along the stipe, with a single pneumatocyst
Pneumatocyst
In phycology, a pneumatocyst is a large float containing gas found in brown algae. An organism may have more than one. They provide buoyancy to lift the blades toward the surface, allowing them to receive more sunlight for photosynthesis....
(gas bladder) at the base of each blade.
A related and similar-looking, but smaller species, M.integrifolia, grows to only to 6 metres (19.7 ft) long. It is found on intertidal rocks or shallow subtidal rocks along the Pacific coast of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
(British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
to California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
) and South America.
Growth
M.pyrifera is one of the fastest-growing organisms on Earth. They can grow at a rate of two feet a day to reach over 45 metres (147.6 ft) long in one growing season..Juvenile giant kelp grow directly upon their parent female gametophyte
Gametophyte
A gametophyte is the haploid, multicellular phase of plants and algae that undergo alternation of generations, with each of its cells containing only a single set of chromosomes....
. To establish itself, a young kelp produces one or two primary blades, and begins a rudimentary holdfast
Holdfast
A holdfast is a root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, stalked crinoids, benthic cnidarians, and sponges, to the substrate. ...
, 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
Stipe (botany)
In botany, a stipe is a stalk that supports some other structure. The precise meaning is different depending on which taxonomic group is being described....
(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.
Ecology
M.pyrifera is found in North AmericaNorth America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
(Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
to California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
), South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, and southern Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. It thrives in cooler waters where the ocean water temperature remains below 70 °F (21.1 °C).
Where the bottom is rocky and affords places for it to anchor, giant kelp forms extensive kelp beds with large "floating canopies". When present in large numbers, giant kelp forms kelp forest
Kelp forest
Kelp forests are underwater areas with a high density of kelp. They are recognized as one of the most productive and dynamic ecosystems on Earth. Smaller areas of anchored kelp are called kelp beds....
s 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.
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
Pterygophora californica
Pterygophora californica is a large species of kelp, commonly known as stalked kelp or southern palm kelp. It is the only species in its genus Pterygophora . It grows in shallow water on the Pacific coast of North America where it forms part of a biodiverse community in a "kelp forest".-Description:P...
in these circumstances.
Where surface waters are poor in nutrients, nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
in the form of amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
s is translocated up the stipe through sieve elements that very much resemble the phloem
Phloem
In vascular plants, phloem is the living tissue that carries organic nutrients , in particular, glucose, a sugar, to all parts of the plant where needed. In trees, the phloem is the innermost layer of the bark, hence the name, derived from the Greek word "bark"...
of vascular plant
Vascular plant
Vascular plants are those plants that have lignified tissues for conducting water, minerals, and photosynthetic products through the plant. Vascular plants include the clubmosses, Equisetum, ferns, gymnosperms and angiosperms...
s. Translocation of nutrients along the stipe may be as rapid as 60 centimetres (23.6 in) per hour. Most translocation occurs to move carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
-rich photosynthate, and typically transfers material from mature regions to actively growing regions where the machinery of photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
is not yet fully in place. Translocation also moves nutrients downward from light-exposed surface fronds to sporophyll
Sporophyll
A sporophyll is a leaf that bears sporangia. Both microphylls and megaphylls can be sporophylls. In heterosporous plants, sporophylls bear either megasporangia , or microsporangia...
s (reproductive fronds) at the base of the kelp, where there is little light and thus little photosynthesis to produce food.
Aquaculture
M.pyrifera has been utilized for many years as a food source ; it also contains many compounds such as iodineIodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
, potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
, other minerals vitamins and carbohydrates and thus has also used as a dietary supplement . In the beginning of the 20th century California kelp beds were harvested as a source for potash
Potash
Potash is the common name for various mined and manufactured salts that contain potassium in water-soluble form. In some rare cases, potash can be formed with traces of organic materials such as plant remains, and this was the major historical source for it before the industrial era...
. 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 . 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.
The demand for M.pyrifera is increasing due to the new found uses of these plants such as fertilizer
Fertilizer
Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...
s, cultivation for bioremediation
Bioremediation
Bioremediation is the use of microorganism metabolism to remove pollutants. Technologies can be generally classified as in situ or ex situ. In situ bioremediation involves treating the contaminated material at the site, while ex situ involves the removal of the contaminated material to be treated...
purposes, abalone
Abalone
Abalone , from aulón, are small to very large-sized edible sea snails, marine gastropod molluscs in the family Haliotidae and the genus Haliotis...
and sea urchin
Sea urchin
Sea urchins or urchins are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. They inhabit all oceans. Their shell, or "test", is round and spiny, typically from across. Common colors include black and dull...
feed. There is current research going into utilizing M.pyrifera as feed for other aquaculture species such as shrimps.
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