Ascophyllum | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Clade: | Diaphoretickes |
Clade: | SAR |
Clade: | Stramenopiles |
Phylum: | Gyrista |
Subphylum: | Ochrophytina |
Class: | Phaeophyceae |
Order: | Fucales |
Family: | Fucaceae |
Genus: | Ascophyllum Stackhouse, 1809 |
Species: | A. nodosum |
Binomial name | |
Ascophyllum nodosum | |
Distribution |
Ascophyllum nodosum is a large, common cold water seaweed or brown alga (Phaeophyceae) in the family Fucaceae. Its common names include knotted wrack, egg wrack, feamainn bhuí, rockweed, knotted kelp and Norwegian kelp. It grows only in the northern Atlantic Ocean, along the north-western coast of Europe (from the White Sea to Portugal) including east Greenland [1] and the north-eastern coast of North America. Its range further south of these latitudes is limited by warmer ocean waters. [2] It dominates the intertidal zone. [3] [4] Ascophyllum nodosum has been used numerous times in scientific research and has even been found to benefit humans through consumption. [5]
Ascophyllum nodosum is the only species in the genus Ascophyllum. The original name (basionym) was Fucus nodosus Linnaeus 1753. The species was transferred to the genus Ascophyllum (as Ascophylla) by Stackhouse (Papenfuss 1950), under the name Ascophyllum laevigata (Guiry and Guiry 2020). The combination Ascophyllum nodosum was made by Le Jolis (1863). [6]
Ascophyllum nodosum has long tough and leathery fronds, [7] irregularly dichotomously branched [8] fronds with large, egg-shaped air bladders set in series at regular intervals along the fronds and not stalked. The air bladders create a way for fronds broken by wave exposure or other causes to be dispersed and regrow in other areas. [9] While the fronds can reach up to 2 m, the length depends on wave exposure: the length increases with water velocity until a certain point, then decreases as waves become more intense. [9] The fronds can reach 2 m in length and are attached by a holdfast to rocks and boulders. In rare cases, the fronds can reach 6m long. [6] The fronds are olive-green, [10] olive-brown in color and somewhat compressed, but without a midrib. [11]
Each individual plant is dioecious, either male or female. [7] The gametes are produced in the spring [7] in conceptacles embedded in yellowish receptacles on short branches. [2] [12] A year after the plant is fertilized and forms a zygote, the first frond grows, and at the beginning of year 2, an air bladder forms, which creates a way to age the plants. [9]
Several different varieties and forms of this species have been described, including the two below.
Ascophyllum nodosum is found mostly on sheltered sites on shores in the midlittoral, where it can become the dominant species in the littoral zone. [4]
The species is found in a range of coastal habitats from sheltered estuaries 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 and Fucus serratus . Its distribution is also limited by salinity, wave exposure, temperature, desiccation, and general stress. [15] [16] [17] It may take approximately five years before becoming fertile. Ascophyllum nodosum is an autotroph, meaning that it makes its own food by photosynthesis, like other plants and algae. The air bladders on A. nodosum serve as a flotation device, which allows sunlight to reach the plant better, aiding photosynthesis. [6]
Excess sperm can be released during the reproduction of Ascophyllum nodosum, which can then act as a food source for plankton consumers. The coverage created by mats of A. nodosum can serve as protection for several marine species, including barnacles (Semibalanus balanoides) , periwinkles (genus Littorina), and marine isopods. [9]
Phlorotannins in A. nodosum act as chemical defenses against the marine herbivorous snail, Littorina littorea . [18]
Polysiphonia lanosa (L.) T.A. Christensen is a small red alga, commonly found growing in dense tufts on Ascophyllum whose rhizoids penetrate the host. [19] It is considered by some as parasitic; however, as it only receives structural support from knotted wrack (not parasitically), it acts as an epiphyte.
This species has been recorded in Europe from Ireland, the White Sea, [21] the Faroe Islands, [22] Norway, [23] Britain and Isle of Man, [24] Netherlands, [25] and North America from the Bay of Fundy, Nova Scotia, Baffin Island, Hudson Strait, Labrador, and Newfoundland. [1] [2] The southern boundary of A. nodosum ends around Long Island, NY, on account of higher water temperatures when traveling farther south. [6] It has been recorded as an accidental introduction near San Francisco, California, and eradicated as a potential invasive species. [26]
The consumption of Ascophyllum nodosum has been proven to have dental benefits in humans, [27] [28] dogs [29] [30] and cats. [30] In addition to dental benefits, A. nodosum can reduce inflammation and speed up healing, especially after a serious injury. [6] Brown algae contains fucoidans, which are sulfated, fucose-rich polymers. Fucoidans block selectins, which are receptors on white blood cells that allow those cells to enter a tissue, causing inflammation. Since the fucoidans block inflammation, A. nodosum can be considered an anti-inflammatory. [5]
Ascophyllum nodosum extracts can be used to control body weight in obese mice. [31] There is potential for these extracts to be efficient in humans, but most studies focus on the effects in small rodents, so more testing needs to be done. [32]
Ascophyllum nodosum is harvested for use in alginates, fertilisers, and the manufacture of seaweed meal for animal and human consumption. Due to the high level of vitamins and minerals that bioaccumulate in A. nodosum, it has been used in Greenland as a dietary supplement. [6] It was also been used for certain herbal teas, particularly kelp teas. [6] [33] It has long been used as an organic and mainstream fertilizer for many varieties of crops due to its combination of both macronutrients, (N, P, and K) and micronutrients (Ca, Mg, S, Mn, Cu, Fe, Zn, etc.). It also contains cytokinins, auxin-like gibberellins, betaines, mannitol, organic acids, polysaccharides, amino acids, and proteins which are all very beneficial and widely used in agriculture. [34] Ireland, Scotland and Norway have provided the world's principal alginate supply. [35] [36]
Ascophyllum nodosum is frequently used as packaging material for baitworm and lobster shipments from New England to various domestic and international locations. [37] Ascophyllum itself has occasionally been introduced to California, and several species frequently found in baitworm shipments, including Carcinus maenas and Littorina saxatilis , may have been introduced to the San Francisco Bay region this way. [37]
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. [38] [39] It has been used in this way for over fifty years, and studies have shown that A. nodosum absorbs cobalt, cadmium, lead, and indium metal ions out of the water. It has also been used to track environmental radioactivity. [6]
Ascophyllum nodosum contains the phlorotannins tetraphlorethol C and tetrafucol A. [40]
Ascophyllum nodosum is commercially harvested in several countries, including Norway, Ireland, Scotland, France, Iceland, Canada and in USA. In some countries such as Ireland, A. nodosum has been harvested for centuries and the harvest has been maintained at sustainable levels since the late 1940s. [41] Harvest can be done manually: on foot at low tide using a knife or sickle or from a boat using a cutter rake. It can also be harvested mechanically using specifically designed boats. In some countries, a bed of A. nodosum will be harvested intensively (>50% of the biomass removed) and left fallow for 3-5 years. In Canada and in Cobscook Bay, Maine, USA, only between 17-25% of the biomass of a management sector can be harvested annually. Under this harvest regime, beds can recover their harvested biomass within a year [42] [43] , and no long term impact of the harvest on the biomass or morphology of A. nodosum has been observed [44] [45] . Several studies have looked at the impact of the harvest on associated species and have found only limited short-term impacts [46] [47] [48] .
Opponents of its wild harvest point to the alga's high habitat value for over 100 marine species, [49] including benthic invertebrates, [50] commercially important fish, [51] wild ducks, [52] shorebirds, [53] and seabirds. [54]
Fucus vesiculosus, known by the common names bladderwrack, 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 Sea and the Atlantic and Pacific Oceans. It was the original source of iodine, discovered in 1811, and was used extensively to treat goitre, a swelling of the thyroid gland related to iodine deficiency.
Brown algae are a large group of multicellular algae comprising the class Phaeophyceae. They include many seaweeds located in colder waters of the Northern Hemisphere. Brown algae are the major seaweeds of the temperate and polar regions. Many brown algae, such as members of the order Fucales, commonly grow along rocky seashores. Most brown algae live in marine environments, where they play an important role both as food and as a potential habitat. For instance, Macrocystis, a kelp of the order Laminariales, may reach 60 m (200 ft) in length and forms prominent underwater kelp forests that contain a high level of biodiversity. Another example is Sargassum, which creates unique floating mats of seaweed in the tropical waters of the Sargasso Sea that serve as the habitats for many species. Some members of the class, such as kelps, are used by humans as food.
Strangford Lough is a large sea lough or inlet in County Down, in the east of Northern Ireland. It is the largest inlet in Ireland and the wider British Isles, covering 150 km2 (58 sq mi). The lough is almost fully enclosed by the Ards Peninsula and is linked to the Irish Sea by a long narrow channel at its southeastern edge. The main body of the lough has at least seventy islands along with many islets (pladdies), bays, coves, headlands and mudflats. It is part of the Strangford and Lecale Area of Outstanding Natural Beauty. Strangford Lough was designated as Northern Ireland's first Marine Conservation Zone in 2013, and has been designated a Special Area of Conservation for its important wildlife.
Fucus is a genus of brown algae found in the intertidal zones of rocky seashores almost throughout the world.
Caulerpa is a genus of seaweeds in the family Caulerpaceae. They are unusual because they consist of only one cell with many nuclei, making them among the biggest single cells in the world.
Alaria esculenta is an edible seaweed, also known as dabberlocks or badderlocks, or winged kelp, and occasionally as Atlantic Wakame. It is a traditional food along the coasts of the far north Atlantic Ocean. It may be eaten fresh or cooked in Greenland, Iceland, Scotland and Ireland. It is the only one of twelve species of Alaria to occur in both Ireland and in Great Britain.
Fucus serratus is a seaweed of the north Atlantic Ocean, known as toothed wrack, serrated wrack, or saw rack.
Fucoidan is a long chain sulfated polysaccharide found in various species of brown algae. Commercially available fucoidan is commonly extracted from the seaweed species Fucus vesiculosus (wracks), Cladosiphon okamuranus, Laminaria japonica and Undaria pinnatifida (wakame). Variant forms of fucoidan have also been found in animal species, including the sea cucumber.
Fucus spiralis is a species of seaweed, a brown alga, living on the littoral shore of the Atlantic coasts of Europe and North America. It has the common names of spiral wrack and flat wrack.
Pelvetia canaliculata, the channelled wrack, is a very common brown alga (Phaeophyceae) found on the rocks of the upper shores of Europe. It is the only species remaining in the monotypic genus Pelvetia. In 1999, the other members of this genus were reclassified as Silvetia due to differences of oogonium structure and of nucleic acid sequences of the rDNA.
Wrack is part of the common names of several species of seaweed in the family Fucaceae. It may also refer more generally to any seaweeds or seagrasses that wash up on beaches and may accumulate in the wrack zone.
Elsie May Burrows was an English botanist who made significant contributions to British postwar phycology. Her primary area of research was macroalgal ecology, focusing particularly on Fucus, a genus of brown algae, and Chlorophyta, a division of the green algae.
Polysiphonia is a genus of filamentous red algae with about 19 species on the coasts of the British Isles and about 200 species worldwide, including Crete in Greece, Antarctica and Greenland. Its members are known by a number of common names. It is in the order Ceramiales and family Rhodomelaceae.
Turbinaria is a genus of brown algae (Phaeophyceae) found primarily in tropical marine waters. It generally grows on rocky substrates. In tropical Turbinaria species that are often preferentially consumed by herbivorous fishes and echinoids, there is a relatively low level of phenolics and tannins.
Littorina fabalis is a species of sea snail, a marine gastropod mollusk in the family Littorinidae, the winkles or periwinkles.
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 phloroglucinol (polyphloroglucinols). As they are called tannins, they have the ability to precipitate proteins. It has been noticed that some phlorotannins have the ability to oxidize and form covalent bonds with some proteins. In contrast, under similar experimental conditions three types of terrestrial tannins apparently did not form covalent complexes with proteins.
The epithallium or epithallus is the outer layer of a crustose coralline alga, which in some species is periodically shed to prevent organisms from attaching to and overgrowing the alga.
Fucus distichus or rockweed is a species of brown alga in the family Fucaceae to be found in the intertidal zones of rocky seashores in the Northern Hemisphere, mostly in rock pools.
Fucus gardneri is a species of seaweed, a brown alga living on the littoral shore of the Pacific coasts of North America. It has the common names of rockweed and bladderwrack.
Susan Brawley is an American marine ecologist at the University of Maine known for her research on algae, especially algal reproduction. She was elected a fellow of the American Association for the Advancement of Science in 2012.
This article incorporates CC BY-2.5 text from the reference [37]
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