Ascophyllum

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). ==Description==

Ascophyllum nodosum has long tough and leathery fronds, irregularly dichotomously branched 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. 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. olive-brown in color and somewhat compressed, but without a midrib. Young shoots are yellow, however darken with age. ==Reproduction==

Each individual plant is dioecious, either male or female. 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. • 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 lochs in Scotland and Ireland. ==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. 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. Polysiphonia lanosa (L.) T.A. Christensen is a small red alga, commonly found growing in dense tufts on Ascophyllum whose rhizoids penetrate the host. It is considered by some as parasitic; however, as it only receives structural support from knotted wrack (not parasitically), it acts as an epiphyte. ==Distribution==

, Netherlands This species has been recorded in Europe from Ireland, the White Sea, the Faroe Islands, Norway, Britain and Isle of Man, Netherlands, and North America from the Bay of Fundy, Nova Scotia, Baffin Island, Hudson Strait, Labrador, and Newfoundland. ==Uses==

The consumption of Ascophyllum nodosum has been proven to have dental benefits in humans, dogs and cats. 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. 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. 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. 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 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 and Littorina saxatilis, may have been introduced to the San Francisco Bay region this way. 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. == Chemistry ==

Ascophyllum nodosum contains the phlorotannins tetraphlorethol C and tetrafucol A. ==Harvesting==

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. 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 and 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, and no long-term impact of the harvest on the biomass or morphology of A. nodosum has been observed. Several studies have looked at the impact of the harvest on associated species and have found only limited short-term impacts. Opponents of its wild harvest point to the alga's high habitat value for over 100 marine species, including benthic invertebrates, commercially important fish, wild ducks, and seabirds. ==References==