Complete Name : Undaria pinnatifida (Harvey) Suringar 1873
Taxonomy : Chromista » Chromophycota » Phaeophyceae » Laminariales » Alariaceae » Undaria pinnatifida
Authors : Stephan Gollasch
Last Updated : October 30th, 2006

Wakame, Japanese kelp.

Alaria pinnatifida - Harvey, 1860
Alaria amplexicaulis - Martens, 1866
Ulopteryx pinnatifida - (Harvey), Kjellman, 1885

This marine brown alga grows on hard substrates and reaches up to 3 m in length (sporophyte stage).

• Dispersal Mechanisms
  • Ametophytes with water currents.
• Reproduction
  • The species has a heteromorphic, diplohaplontic annual life cycle with a large sporophyte and microscopic female and male gametophytes. In Europe the sporophyte is usually less than 1 m in the Mediterranean Sea. Some introduced populations show more than one generation during a year. Vegetative reproduction by fragmentation is unknown.
• Known Predators/Herbivores
  • A high number of species prey upon the algae, e.g. harpacticoid copepods, amphipods, sea urchins and fish. Further, bacteria and phycomycetes attack the plant.
• Resistant Stages (seeds, spores etc.)
  • The gametophytes may undergo a dormancy period. Especially at low light, they are capable of surviving adverse conditions as thick-walled resting stages.

• Native (EUNIS Code)
  • A3: Sublittoral rock and other hard substrata. It grows at hard bottom habitats from approx. 1-15 m depth.
• Habitat Occupied in Invaded Range (EUNIS Code)
  • A3: Sublittoral rock and other hard substrata. Hard bottom habitats from ca. 1-18 m depth. Seems to prefer artificial substrates.
• Habitat Requirements
  • Growth of sporophytes was documented in NE Japan from 4-25 °C where plants appear in winter and disappear in summer. Optimum growth for young sporophytes is 20 °C. Microscopic gametophytes may survive -1 to 30 °C. Light requirements for sporophyte photosynthesis vary seasonally (120-500 µE m-2 s-1 or less). Gametophytes are able to survive in darkness > 6 months. Salinities above 27 PSU are necessary for growth of sporophytes and gametophyte development. Zoospores attach above 19 PSU.

Unintentional introduction with oyster imports from Japan to the French Mediterranean coast. From here it was intentionally transferred to Brittany. Records in or near ports indicate that secondary dispersal may have been caused by vessels.

• Native Range
  • Northwestern Pacific shores, i.e. coasts of Japan, (excluding northern and eastern Hokkaido), Korea, northeastern China, southeast Russia.
• Known Introduced Range
  • Its first record outside the native range was in the French Mediterranean coast. From here it was intentionally transferred to three sites in Brittany in 1983 for farming, and more sites were tested thereafter. In 1987 reproducing individuals were found on mussel lines near the Ouessant seaweed farm. Natural recruitment was observed in St. Malo and in the Rance estuary. In northern Spain it was reported from Ria Ariosa in 1990, later it was found along the N Spanish Atlantic coast down to the Portuguese border. Some records are known from Portuguese estuaries. First finding in southern United Kingdom was in 1994, thereafter on the Channel Islands. In 1999 the species was reported from Zeebrugge, Belgium and in the Netherlands (near Yerseke and near Strijenham). These findings are the northernmost in Europe. Records from the Mediterranean Sea are sporadic (e.g. in the Venice lagoon).
• Trend
  • Spreading.

known distribution area (in CGRS grid squares; in countries; along coast)

	eradicated
	extinct
	not present; eradicated
	native distribution range in CGRS grid squares
	native range
	assumed native range
	infrequent distribution
	key distribution area
	not established

• Ecosystem Impact
  • In some regions it is the dominant seaweed and several co-occurring species decrease when it becomes abundant.
• Health and Social Impact
  • Unknown.
• Economic Impact
  • It prefers artificial substrates and due to its fouling behaviour, frequent cleaning of aquaculture equipment and boats is required. In the Netherlands it grows mainly on Crassostrea gigas, but also on mussels. Being slippery, it causes problems for fishermen harvesting oysters. During mass developments further detrimental impacts may occur, which may impair aquaculture harvests.

• Prevention
  • Hulls of ships should only be cleaned out of the water and detached organisms should be disposed out of the reach of the sea. U. pinnatifida should not be used as a display organism in public aquaria. Even if the water is treated, a risk remains that fertile parts may reach the sea. Scientific experiments within field conditions should not be undertaken where the alga has not yet been found.
• Mechanical
  • One problem with eradication efforts is that the microscopic gametophytes are very tolerant and not visible to the naked eye. In several cases attempts at manual eradications were unsuccessful or showed a limited efficacy.
• Chemical
  • Trials with herbicides and antifouling paints showed that some toxins are efficient at preventing zoospore germination or at causing gametophyte mortality.
• Biological
  • Unknown.

The following contributors have provided records in the DAISIE database for this species.

The following experts registered themselves as having knowledge about this species or its family.

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Boudouresque CFM, Gerbal M, Knoepffler-Peguy M (1985) L´algue japonnaise Undaria pinnatifida (Phaeophyceae, Laminariales) en Méditerranée. Phycologia 24:364-366

Floc’h J-Y, Pajot R, Wallentinus I (1991) The Japanese brown alga Undaria pinnatifida on the coast of France and its possible establishment in European waters. Journal of the Conseil International pour l´Exploration de la Mer 47: 379-390

Wallentinus I (2006) Alien Species Alert: on Undaria pinnatifida (Wakame or Japanese kelp). Annex 9. In Gollasch S, Kieser D (eds) Report of the Working Group of Introductions and Transfers of Marine Organisms, Oostend, Belgium, 16-17 March 2006. ICES CM 2006/ACME:05, pp 292-327 [available at www.ices.dk]

(selected from Wallentinus 2006):

Casas GN, Piriz ML (1996) Surveys of Undaria pinnatifida (Laminariales, Phaeophyta) in Golfo Nuevo, Argentina. Hydrobiologia 326-327:213-215

Castric-Fey A, Girard A, L’Hardy-Halos MT (1993) The distribution of Undaria pinnatifida (Phaeophyceae, Laminariales) on the coast of St. Malo (Brittany, France). Botanica Marina 36:351-358

Cecere EA, Petrocelli S (2004) Floristic and biogeographic considerations about the benthic macroalgal flora in the gulf of Taranto Biogeographia 25:7-18

Curiel D, Bellemo G, Marzocchi M, Scattolin M, Parisi G (1998) Distribution of introduced Japanese macroalgae Undaria pinnatifida, Sargassum muticum (Phaeophyta) and Antithamnion pectinatum (Rhodophyta) in the Lagoon of Venice. Hydrobiologia 385:17-22

Dumoulin E, De Blauwe H (1999) Het bruinwier Undaria pinnatifida (Harvey) Suringar, (Phaeophyta: laminariales) aangetroffen in de jachthavenvan Zeebruge met gegevens over het voorkomen in Europa en de wijze van verspreiding. De Strandvlo 19(4):182-188

Hay CH (1990) The dispersal of sporophytes of Undaria pinnatifida by coastal shipping in New Zealand and implications for further dispersal of Undaria in France. British Phycological Journal 25:301-314

Hewitt CL, Campbell ML, McEnnulty F, Moore KM, Murfet NB, Robertson B, Schaffelke B (2005) Efficacy of physical removal of a marine pest: the introduced kelp Undaria pinnatifida in a Tasmanian Marine Reserve. Biological Invasions 7:251-263

Kim YS, Nam KW (1997) Temperature and light responses on the growth and maturation of gametophytes of Undaria pinnatifida (Harvey) Suringar in Korea. Journal of the Korean Fisheries Society 30:505-510

Matsuyama K (1983) Photosynthesis of Undaria pinnatifida Suringar f. distans Miyabe et Okamura (Phaeophyceae) from Oshoro Bay. I. Seasonal changes of photosynthetic and respiratory rates. Sci. Rep. Hokkaido Fish. Exp. Stn. 25:187-193

Morita T, Kurashima A, Maegawa M (2003) Temperature requirements for the growth of young sporophytes of Undaria pinnatifida and Undaria undarioides (Laminariales, Phaeophyceae). Phycological Research 51(4):266-270

Santiago Caamaño J, Duran Neira, C, Acuña Castroveijo R (1990) Aparicion de Undaria pinnatifida en las coastas de Galicia (España). Un nuevo caso en la problematica de introduccion de especies foraneas. Inf. Tec. Del Centro de Investigaciones Submarinas 3, pp 44

Schaffelke B, Campbell ML, Hewitt CL (2005) Reproductive phenology of the introduced kelp Undaria pinnatifida (Phaeophyceae, Laminariales) in Tasmania, Australia. Phycologia 44:84-94

Stegenga H (1999) Undaria pinnatifida in Nederland gearriveerd. Het Zeepard 59:71-73

Thornber CS, Kinlan BP, Graham MH, Stachowicz JJ (2004) Population ecology of the invasive kelp Undaria pinnatifida in California: environmental and biological controls on demography. Marine Ecology Progress Series 268:69-80

Wallentinus I (1999) Introduction and transfer of plants. In: Munro ALS, Utting SD, Wallentinus I (eds) Status of introductions of non-indigenous marine species to North Atlantic waters 1981-1991. ICES Cooperative Research Reports 231. pp 1-43

Wallentinus I (2002) Introduced marine algae and vascular plants in European aquatic environments. In: Leppäkoski E, Gollasch S, Olenin S (eds) Invasive Aquatic Species of Europe: Distributions, Impacts and Management. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp 27-54

Zhang DM, Miao GR, Pei LO (1984) Studies on Undaria pinnatifida. Hydrobiologia 116/117:263-265