Ascophyllum nodosum is a large, common brown alga, Phaeophyta in the family Fucaceae, being the only species in the genus Ascophyllum. It is seaweed of the northern Atlantic Ocean, also known as Norwegian kelp, knotted Kelp, knotted wrack or egg wrack. It is common on the north-western coast of Europe (from Svalbard to Portugal) including east Greenland  and the north-eastern coast of North America. 
Ascophyllum is very popular amongst the science community and has been claimed to be both the best known seaweed on the planet as well as the most researched by the academic community. 
Ascophyllum nodosum has long fronds with large egg-shaped air-bladders set in series at regular intervals in 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-brown in color and somewhat compressed but without a mid-rib. 
Varieties and forms
Several different varieties and forms of this species have been described.
The species is found in a range of coastal habitats from sheltered estuaries to moderately exposed coasts, often it dominates the inter-tidal zone (although sub-tidal 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 F. serratus. Its distribution is also limited by salinity, wave exposure, temperature, desiccation and general stress. These, and other attributes of the algae are summarized in ,. It may take approximately five years before becoming fertile.
Recorded in Europe from: Faroe Islands,  Norway,  Ireland, Britain and Isle of Man  Netherlands  North America: Bay of Fundy, Nova Scotia, Baffin Island, Hudson Strait, Labrador and Newfoundland.  It has been recorded as an accidental introduction to San Francisco, California, and eradicated as a potential invasive species there. 
Ascophyllum nodosum is harvested for use in alginates, fertilisers and for 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, (eg. N, P, K, Ca, Mg, S) and micronutrients (eg. Mn, Cu, Fe, Zn, etc). It also host to 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 may reduce, or even eliminate, not only bacterial plaque and dental caries but also arteriosclerotic plaque, atherosclerotic plaque, pleural plaque, renal calculus, biliary calculus, and prostatic calculus.
Furthermore, the medicinal and dental uses have been recognized for well over a century.
Because the age of the different parts of A. nodosum can be identified by its shoots, A. nodusum has also been used to monitor concentrations of heavy metals in sea water. A concentration factor for zinc has been reported to be of the order 10 to the fourth.
- ^ a b M. D. Guiry & Wendy Guiry (2006-11-23). "Ascophyllum nodosum (Linnaeus) Le Jolis". AlgaeBase. http://www.algaebase.org/speciesdetail.lasso?species_id=5&sk=0&from=results.
- ^ a b c W. R. Taylor (1962). Marine Algae of the Northeastern Coast of North America. Ann Arbor, University of Michigan Press. ISBN 0-472-04904-6.
- ^ T. L. Senn (1987). Seaweed and Plant Growth. Clemson, S.C.: T.L. Senn. p. 181 pp. ISBN 0-939241-01-3.
- ^ S. Hiscock (1979). "A field key to the British brown seaweeds (Heterokontophyta)". Field Studies 5: 1–44.
- ^ H. Stegenga, J. J. Bolton & R. J. Anderson (1997). Seaweeds of the South African West Coast. Bolus Herbarium Humber 18, University of Cape Town. ISBN 0-7992-1793-X.
- ^ M. J. Lynn (1949). "A rare alga from Larne Lough". Irish Naturalists' Journal 9: 301–304.
- ^ D. C. Gibb (1957). "The free-living forms of Ascophyllum nodosum (L.) Le Jol". Journal of Ecology 45: 49–83. doi:10.2307/2257076.
- ^ O. Morton (2003). "The marine macroalgae of County Donegal, Ireland". Bulletin of the Irish Biogeographical Society 27: 3–164.
- ^ O. Morton (1994). Marine Algae of Northern Ireland. Ulster Museum, Belfast. ISBN 0-900761-28-8.
- ^ J. R. Lewis (1964). The Ecology of Rocky Shores. English Universities Press, London.
- ^ Schonbeck,MW and TA. Norton. 1980. Factors controlling the ower limits of fucoid algae on the shore. J.exp.mar.biol. ecol. 43:131-150
- ^ Seip,K.L.1980. A mathematical model of competition and colonization in a community of marine benthic algae. Ecological modelling 10:77-104
- ^ Seip, K.L. Mathematical models of rocky shore ecosystems. In Jørgensen, SE and Mitch, WJ (Eds) Application of ecological modelling in environmental management, Part B, Chap 13, pp 341-433
- ^ C. A. Maggs (1993). Seaweeds of the British Isles. Vol. I: Rhodophyta. Part 3A. Natural History Museum, London. ISBN 0-11-310045-0.
- ^ F. Børgesen (1903). Botany of the Færöes Part II, pp. 339-532. Det nordiske Forlag Ernst Bojesen, Copenhagen.
- ^ F. E. Round (1981). The Ecology of Algae. Cambridge University Press Cambridge. ISBN 0-521-22583-3.
- ^ F. G. Hardy & M. D. Guiry (2006). A Check-list and Atlas of the Seaweeds of Britain and Ireland. British Phycological Society, London. ISBN 3-906166-35-X.
- ^ H. Stegenga, I. Mol, W. F. Prud'homme van Reine & G. M. Lokhorst (1997). "Checklist of the marine algae of the Netherlands". Gorteria supplement 4: 3–57.
- ^ A. W. Miller, A. L. Chang, N. Cosentino-Manning & G. M. Ruiz (2004). "A new record and eradication of the north Atlantic alga Ascophyllum nodosum (Phaeophyceae) from San Francisco Bay, California, USA". Journal of Phycology 40: 1028–1031. doi:10.1111/j.1529-8817.2004.04081.x.
- ^ J. Norrie & D. A. Hiltz (1999). "Seaweed Extract Research and Applications in Agriculture". Agro food Industry hi-tech.
- ^ L. G. Lewis, N. F. Stanley & G. G. Guist (1988). "Commercial production and applications of algal hydrocolloides". in C. A. Lembi & J. R. Waaland. Algae and Human Affairs. Cambridge University Press, Cambridge. ISBN 0-521-32115-8.
- ^ M. D. Guiry & D. J. Garbary (1991). "Geographical and Taxonomic guide to European Seaweeds of Economic Importance". in M. D. Guiry & Blunden. Seaweed Resources in Europe: Uses and Potential. John Wiley & Sons, England. ISBN 0-471-92947-6.
- ^ (WO/2002/034279) ORAL PREPARATION CONTAINING SEAWEED FOR REDUCTION OF PLAQUE AND CALCULUS
- ^ The London Encyclopaedia or Universal Dictionary of Science, Art, Literature and Practical Mechanics 1829 - Vol. IX - F to Garter. Pages 663 - 665
- ^ Seip,K.L. 1979. A mathematical model for the uptake of heavy metals in benthic algae. Ecological modelling 6: 183-197
- ^ Melhus, A.,KL Seip, HM Seip and S. Myklestad. 1978. A preliminary study of the use of benthic algae as biological indicators of heavy metal pollution in Sørfjorden, Norway. Environ. pollut (15):101107