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''Ascophyllum nodosum'' is a large, common cold water seaweed or
brown alga 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 an ...
( Phaeophyceae) in the
family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Fucaceae The Fucaceae are a family of brown algae, containing six genera: *''Ascophyllum'' Stackhouse – one species *''Fucus'' L. – 15 species *'' Hesperophycus'' Setchell & Gardner – one species *'' Pelvetia'' Decne. & Thur. – one species *'' Pel ...
, being the only
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
in the
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
''Ascophyllum''. It is a seaweed that only grows in the northern
Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
, also known in localities as feamainn bhuí, rockweed, Norwegian kelp, knotted kelp, knotted wrack or egg wrack. It is common on the north-western coast of
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...
(from the
White Sea The White Sea (russian: Белое море, ''Béloye móre''; Karelian and fi, Vienanmeri, lit. Dvina Sea; yrk, Сэрако ямʼ, ''Serako yam'') is a southern inlet of the Barents Sea located on the northwest coast of Russia. It is s ...
to
Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...
) including east
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland i ...
and the north-eastern coast of North America, its range further south of these latitudes being limited by warmer ocean waters.


Description

''Ascophyllum nodosum'' has long tough and leathery fronds,Bunker, F.StP., Maggs, C.A., Brodie, J.A. and Bunker, J.A. 2017. ''Seaweeds of Britain and Ireland.'' Second Edition. Wild Nature Press, Plymouth, UK. irregularly dichotomously branched
frond A frond is a large, divided leaf. In both common usage and botanical nomenclature, the leaves of ferns are referred to as fronds and some botanists restrict the term to this group. Other botanists allow the term frond to also apply to the lar ...
s with large, egg-shaped air bladders set in series at regular intervals along the fronds and not stalked. The fronds can reach 2 m in length and are attached by a holdfast to rocks and boulders. The fronds are olive-green, olive-brown in color and somewhat compressed, but without a midrib.


Reproduction

Its life history is of one diploid plant and
gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...
s. Each individual plant is either male or female. The gametes are produced in the spring in
conceptacles Conceptacles are specialized cavities of marine and freshwater algae that contain the reproductive organs. They are situated in the Receptacle (botany), receptacle and open by a small ostiole.Boney, A.D. (1969). ''A Biology of Marine Algae''. Hutch ...
embedded in yellowish receptacles on short branches.


Varieties and forms

Several different varieties and forms of this species have been described. * ''Ascophyllum nodosum'' var. ''minor'' has been described from
Larne Lough Larne Lough, historically Lough Larne (), is a sea loch or inlet in County Antrim, Northern Ireland. It lies between the Islandmagee peninsula and the mainland. At its mouth is the town of Larne. It is designated as an area of special scientif ...
in
Northern Ireland Northern Ireland ( ga, Tuaisceart Éireann ; sco, label= Ulster-Scots, Norlin Airlann) is a part of the United Kingdom, situated in the north-east of the island of Ireland, that is variously described as a country, province or region. Nort ...
. Free-floating forms of this species are found in, for example, ''A. n. mackaii'' Cotton, which is found at very sheltered locations, such as at the heads of
sea loch ''Loch'' () is the Scottish Gaelic, Scots and Irish word for a lake or sea inlet. It is cognate with the Manx lough, Cornish logh, and one of the Welsh words for lake, llwch. In English English and Hiberno-English, the anglicised spel ...
s in
Scotland Scotland (, ) is a Countries of the United Kingdom, country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a Anglo-Scottish border, border with England to the southeast ...
and
Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...
.


Ecology

''Ascophyllum nodosum'' is found mostly on sheltered sites on shores in the midlittoral, where it can become the dominant species in the
littoral zone The littoral zone or nearshore is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely inundated), to coastal a ...
. The species is found in a range of coastal habitats from sheltered
estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environmen ...
to moderately exposed coasts, and often it dominates the intertidal zone (although subtidal populations are known to exist in very clear waters). However, it is rarely found on exposed shores, and if it is found, the fronds are usually small and badly scratched. This seaweed grows quite slowly, 0.5% per day, carrying capacity is about 40 kg wet weight per square meter, and it may live for 10–15 years. It may typically overlap in distribution with ''
Fucus vesiculosus ''Fucus vesiculosus'', known by the common names bladder wrack, black tang, rockweed, sea grapes, bladder fucus, sea oak, cut weed, dyers fucus, red fucus and rock wrack, is a seaweed found on the coasts of the North Sea, the western Baltic Se ...
'' and ''
Fucus serratus ''Fucus serratus'' is a seaweed of the north Atlantic Ocean, known as toothed wrack or serrated wrack. Description and reproduction ''Fucus serratus'' is a robust alga, olive-brown in colour and similar to '' Fucus vesiculosus'' and ''Fucus spi ...
''. Its distribution is also limited by salinity, wave exposure, temperature, desiccation, and general stress. It may take approximately five years before becoming fertile.
Phlorotannin Phlorotannins are a type of tannins found in brown algae such as kelps and rockweeds or sargassacean species, and in a lower amount also in some red algae. Contrary to hydrolysable or condensed tannins, these compounds are oligomers of phloro ...
s in ''A. nodosum'' act as chemical defenses against the marine herbivorous snail, ''
Littorina littorea The common periwinkle or winkle (''Littorina littorea'') is a species of small edible whelk or sea snail, a marine gastropod mollusc that has gills and an operculum, and is classified within the family Littorinidae, the periwinkles.Reid, David ...
''. '' Polysiphonia lanosa'' (L.) T.A. Christensen is a small
red alga Red algae, or Rhodophyta (, ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority ...
, commonly found growing in dense tufts on ''Ascophyllum'' whose
rhizoid Rhizoids are protuberances that extend from the lower epidermal cells of bryophytes and algae. They are similar in structure and function to the root hairs of vascular land plants. Similar structures are formed by some fungi. Rhizoids may be uni ...
s penetrate the host. It is considered by some as
parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...
; however, as it only receives structural support from knotted wrack (not parasitically), it acts as an epiphyte.


Distribution

This species has been recorded in Europe from
Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...
, the
White Sea The White Sea (russian: Белое море, ''Béloye móre''; Karelian and fi, Vienanmeri, lit. Dvina Sea; yrk, Сэрако ямʼ, ''Serako yam'') is a southern inlet of the Barents Sea located on the northwest coast of Russia. It is s ...
, the
Faroe Islands The Faroe Islands ( ), or simply the Faroes ( fo, Føroyar ; da, Færøerne ), are a North Atlantic island group and an autonomous territory of the Kingdom of Denmark. They are located north-northwest of Scotland, and about halfway bet ...
,
Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and the ...
,
Britain Britain most often refers to: * The United Kingdom, a sovereign state in Europe comprising the island of Great Britain, the north-eastern part of the island of Ireland and many smaller islands * Great Britain, the largest island in the United King ...
and
Isle of Man ) , anthem = "O Land of Our Birth" , image = Isle of Man by Sentinel-2.jpg , image_map = Europe-Isle_of_Man.svg , mapsize = , map_alt = Location of the Isle of Man in Europe , map_caption = Location of the Isle of Man (green) in Europe ...
,
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...
, and North America from the Bay of Fundy,
Nova Scotia Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland". Most of the population are native Eng ...
, Baffin Island,
Hudson Strait Hudson Strait (french: Détroit d'Hudson) links the Atlantic Ocean and Labrador Sea to Hudson Bay in Canada. This strait lies between Baffin Island and Nunavik, with its eastern entrance marked by Cape Chidley in Newfoundland and Labrador ...
,
Labrador , nickname = "The Big Land" , etymology = , subdivision_type = Country , subdivision_name = Canada , subdivision_type1 = Province , subdivision_name1 ...
, and Newfoundland. It has been recorded as an accidental introduction near
San Francisco San Francisco (; Spanish for " Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the fourth most populous in California and 17th ...
, California, and eradicated as a potential invasive species.


Uses

''Ascophyllum nodosum'' is harvested for use in
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 ...
s,
fertiliser 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, and the manufacture of seaweed meal for animal and human consumption. It has long been used as an organic and mainstream fertilizer for many varieties of crops due to its combination of both
macronutrient A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excre ...
s, ( N, P, and K) and micronutrients ( Ca, Mg, S, Mn, Cu, Fe, Zn, etc.). It also contains
cytokinin Cytokinins (CK) are a class of plant hormones that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and le ...
s, auxin-like
gibberellin Gibberellins (GAs) are plant hormones that regulate various developmental processes, including stem elongation, germination, dormancy, flowering, flower development, and leaf and fruit senescence. GAs are one of the longest-known classes of plan ...
s,
betaine A betaine () in chemistry is any neutral chemical compound with a positively charged cationic functional group, such as a quaternary ammonium or phosphonium cation (generally: onium ions) that bears no hydrogen atom and with a negatively charge ...
s,
mannitol Mannitol is a type of sugar alcohol used as a sweetener and medication. It is used as a low calorie sweetener as it is poorly absorbed by the intestines. As a medication, it is used to decrease pressure in the eyes, as in glaucoma, and to lo ...
, organic acids, polysaccharides,
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 a ...
s, and proteins which are all very beneficial and widely used in agriculture. Ireland, Scotland and Norway have provided the world's principal alginate supply. ''Ascophyllum nodosum'' is frequently used as packaging material for baitworm and lobster shipments from
New England New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the Can ...
to various domestic and international locations. ''Ascophyllum'' itself has occasionally been introduced to California, and several species frequently found in baitworm shipments, including ''
Carcinus maenas ''Carcinus maenas'' is a common littoral crab. It is known by different names around the world. In the British Isles, it is generally referred to as the shore crab, or green shore crab. In North America and South Africa, it bears the name europ ...
'' and '' Littorina saxatilis'', may have been introduced to the San Francisco Bay region this way.


Toxicological uses

Because the age of the different parts of ''A. nodosum'' can be identified by its shoots, it has also been used to monitor concentrations of heavy metals in seawater. A concentration factor for zinc has been reported to be of the order 104.


Chemistry

''Ascophyllum nodosum'' contains the phlorotannins tetraphlorethol C and
tetrafucol A Tetrafucol A is a fucol-type phlorotannin found in the brown algae '' Ascophyllum nodosum'', '' Analipus japonicus'' and '' Scytothamnus australis''. In ''A. japonicus'', 5'-bromo- and 5'-chlorotetrafucol-A can also be detected. References ...
.


Harvesting controversy

Controversy exists over impacts of commercial harvesting of ''A. nodosum'' for use in garden or crop
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 and livestock feed supplements in North America and Europe. Some research has been focused on bycatch and impact on intertidal zone communities. Opponents of its wild harvest point to the algae's high habitat value for over 100 marine species, including benthic
invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
s, commercially important fish, wild ducks, shorebirds, and
seabird Seabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same enviro ...
s. Shoreland owners in
Maine Maine () is a state in the New England and Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Canadian provinces of New Brunswick and Quebec to the northeast and ...
, as well as federal, state, and local agencies in the United States, have placed their conservation lands off limits to rockweed removal. Rockweed harvesters point to the value of the seasonal jobs created by the harvest operation, and also highlight the differences in impact of different harvesting methods such as machine v hand harvesting.


References

This article incorporates CC BY-2.5 text from the reference


External links

* * * {{Taxonbar, from=Q1415896 Fucales Fucales genera Edible seaweeds Monotypic brown algae genera Taxa named by John Stackhouse Fucaceae