MACOI - Portuguese Seaweeds Website

Class:

Florideophyceae

Genus:

Ahnfeltia Fries

Species:

Ahnfeltia plicata

Authority:

(Hudson) E.M.Fries

Description:

Original publication: Fries, E.M. (1836). Corpus florarum provincialium Sueciae. I. Floram scanicam. pp. i-xxiv, 193-346. Upsaliae [Uppsala]: excudebant Regiae Acad. Typographi.

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A perennial red seaweed which forms dense, tangled tufts. The fronds are very fine, tough and wiry with irregular or dichotomous branching and up to 21 cm in length. The holdfast is disc-like or encrusting, 0.5 to 2 cm in diameter. The fronds are dark brown when moist and appear almost black when dry. The uppermost branches are often green.

Link for MarLIN

Taxonomic notes: For more information Guiry (1997) recommends consulting Maggs, McLachlan & Saunders (1989).

Name History

Adjective (Latin), folded into pleats or furrows, usually longitudinally (Stearn 1973)

Biogeography

N and NE Atlantic (Greenland to Azores); SW Atlantic (Uruguay); NE Pacific (Alaska to Mexico); NW Pacific (Russia); SE Pacific (Chile); Indian Ocean; Antarctica and the Subantarctic Is.

Life Cycle

Gametophytes horny, cylindrical, blackish fronds, narrow (1 mm diam.), irregularly subdichotomously branched, to 120 mm high, from a thin crustose base of up to 200 mm diam. Branches with rounded axils and blunt, often bleached tips and growing through shell fragments. Tetrasporophyte (Porphyrodiscus-phase) a thin violet crust , generally found in association with the gametophytes.

Uses and compounds

Source of hydrocolloids - source of agar

Ahnfeltia plicata is one of the major seaweeds harvested for commercial agar production as it produces a very high-quality, low-sulfate agar. Agar is used for many purposes. It forms a major component of Asian cooking, often showing up in soups and jellies. As a non-animal derived thickening agent, Ahnfeltia plicata is also widely used for vegan products (such as marshmallows, gummy bears, cosmetics, etc.) in place of gelatin. Agar is also well-known to science students as it is used extensively as a growth medium for bacteria in petri dishes.

Harvesting

Ahnfeltia plicata is harvested mainly off of the coast of the White Sea in Russia where it grows prolifically and forms the basis of the Russian agar industry. While widespread, the alga does not grow in sufficient quantities for harvest in Britain, Ireland, and elsewhere.

Link for Seaweed Industry Association

A Source of so-called Russian Agar (a Carrageenan) (Braune & Guiry, 2011).

References

Braune, W. (2008). Meeresalgen. Ein Farbbildführer zu den verbreiteten benthischen Grün- Braun- und Rotalgen der Weltmeere. pp. [1]-596, 266 pls. Ruggell: A.R.G. Gantner Verlag.

Farnham, W.F. & Fletcher, R.L. (1976). The occurrence of a Porphyrodiscus simulans Batt. phase in the life history of Ahnfeltia plicata (Huds.) Fries. British Phycological Journal 11: 183-190.

Loiseaux-de Goër, S. & Noailles, M.-C. (2008). Algues de Roscoff. pp. [1]-215, col. figs. Roscoff: Editions de la Station Biologique de Roscoff.

Maggs, C.A. & Pueschel, C.M. (1989). Morphology and development of Ahnfeltia plicata (Rhodophyta): proposal of Ahnfeltiales ord. nov.. Journal of Phycology 25: 333-351, 95 figs.

Maggs, C.A., McLachlan, J.L. & Saunders, G.W. (1989). Infrageneric taxonomy of Ahnfeltia (Ahnfeltiales, Rhodophyta). Journal of Phycology 25: 351-368.

Mikami, H. (1965). A systematic study of the Phyllophoraceae and Gigartinaceae from Japan and its vicinity. Memoirs of the Faculty of Fisheries Hokkaido University 5(2): 181-285.

Smith, G.M. (1944). Marine algae of the Monterey Peninsula. pp. i-ix, 1-622, 98 pls. Stanford: Stanford University Press.

Zemke-White, W.L. & Ohno, M. (1999). World seaweed utilisation: an end-of-century summary. Journal of Applied Phycology 11: 369-376.

Habitat:

Marine species, on rock, mid-intertidal to sublittoral, especially common on sand-covered rocks, widely distributed, common.

Common names:

English: Sakhalin agar (Levring, Hoppe & Schmid 1969), Bushy Ahnfelt's Seaweed (Arasaki & Arasaki 1983), Black Scour Weed (Bunker et al. 2010).

French: Fil de fer (Dickinson 1963).

Japanese: Itani (Levring, Hoppe & Schmid 1969), Itanigusa (Arasaki & Arasaki 1983), Kanten (McConnaughey 1985).

Common names used in commerce, often for edible algae
fil de fer {Fr}; landladys wig {Eng}; "wig, landladys"

Type information:

Basionym: Fucus plicatus Hudson

Type locality: England (Dawson 1961: 246). Lectotype: BM (Dixon & Irvine 1977: 213). Notes: An unlocalized, undated Hudson specimen in BM has been chosen as provisional lectotype.