Date of introduction and origin
Undaria pinnatifida was found attached to floating
pontoons in the Hamble estuary in the Solent, Hampshire on 15 June
1994 (Fletcher & Manfredi 1995). It is native to the west coast
of Japan. Its introduction to Europe was initially to France where
it was found in 1971 in Etang de Thau, a saltwater lagoon on the
Mediterranean coast (Perez, Lee & Juge 1981; Boudouresque,
Gerbal & Knoepffler-Peguy 1985).
Method of introduction
The most likely vector for the initial introduction of
Undaria pinnatifida to Europe was imported spat of Pacific
oysters Crassostrea gigas (Perez, Lee & Juge 1981;
Boudouresque, Gerbal & Knoepffler-Peguy 1985). However, because
of its commercial importance, subsequent introductions in France
were intentional, and attempts were made in 1981 to cultivate
plants on rope in the Mediterranean (Perez, Lee & Juge 1981)
and later, since 1983, successful attempts at cultivation have been
made on the Atlantic coast at several sites in Brittany (Perez,
Kaas & Barbaroux 1984; Perez et al. 1988;
Boudouresque, Gerbal & Knoepffler-Peguy 1985; Castric-Fey,
Girard & L'Hardy-Halos 1993; Wallentinus in press). This alga
was also reported from Spain in 1990, having been introduced with
imported oysters (Wallentinus in press).
Its introduction from France to Britain is thought to have
been on ships' hulls (Fletcher & Manfredi 1995). Such spread
via boats using ports in the English Channel was predicted by Hay
Reasons for success
It produces millions of spores with motile periods of up to 5
hours and has a propensity for colonising floating objects
(Fletcher & Manfredi 1995) which suggests it can easily be
spread locally by natural dispersion and more remotely through the
agency of shipping.
Five reasons likely to give competitive edge over native
species were listed by Fletcher & Manfredi (1995) from
observations on introduced populations in Brittany and the
- its behaviour as an opportunistic weed and its ability to
rapidly colonise new or disturbed substrata and artificial floating
- its occurrence in dense, vigorous stands on benthic shores,
forming a thick canopy over the subordinate biota;
- its occupancy of a wide range of shores varying in
- its extensive vertical distribution, from low tide level down
to 15 m in suitably clear waters;
- the extended period of reproductive spore formation and release
observed in introduced populations.
Rate of spread and methods involved
Short distance, marginal spread occurs by natural reproductive
processes; while spread along the coast and probably across the
Channel is likely to be associated with shipping and coastal boat
traffic (Hay 1990; Fletcher & Manfredi 1995; Wallentinus in
In British waters it was first found in the Hamble estuary in
the Solent but has more recently been found at scattered locations
on the Isle of Wight, in Torquay in Devon, in a marina on Jersey in
the Channel Isles (R.L. Fletcher pers. comm.). Elsewhere in Europe
it occurs on the French Mediterranean coast, on the north and south
coasts of Brittany, and on the Atlantic coast of Spain around Ria
de Arosa (Wallentinus in press).
Factors likely to influence spread and distribution
Fletcher & Manfredi (1995) predicted that coastal boating
traffic would be the means of significant spread of this species in
northern European waters.
Effects on the environment
It may cause displacement of other native species (Fletcher
& Manfredi 1995).
Effects on commercial interests
Undaria is a commercially important edible species.
It is a fouling agent.
Control methods used and effectiveness
It is planned to remove all subsequently occurring plants from
the marina pontoons in the Hamble. However, this is thought
unlikely to eradicate the species or halt its local spread
(Fletcher & Manfredi 1995).
Undaria is a commercially important species,
cultivated for food (Guiry & Blunden 1991).
The intentional introduction of Undaria to the north
coast of France and its continued farming has been considered
extensively and sanctioned by the International Council for the
Exploration of the Sea. Proposals to introduce this species to
Ireland were rejected (Wallentinus in press).
Boudouresque, C.F., Gerbal, M., & Knoepffler-Peguy, M.
1985. L'algue japonaise Undaria pinnatifida (Phaeophyceae,
Laminariales) en Méditerranée. Phycologia, 24:
Castric-Fey, A., Girard, A., & L'Hardy-Halos, M. Th. 1993.
The distribution of Undaria pinnatifida (Phaeophyceae,
Laminariales) on the coast of St. Malo (Brittany, France).
Botanica Marina, 36: 351-358.
Fletcher, R.L., & Manfredi, C. 1995. The occurrence of
Undaria pinnatifida (Phaeophyceae, Laminariales) on the
south coast of England. Botanica Marina, 38:
Guiry, M.D., & Blunden, G. eds.1991. Seaweed
resources in Europe: uses and potential. Chichester, John
Wiley & sons.
Hay, C.H. 1990. The dispersal of sporophytes of Undaria
pinnatifida (Phaeophyta: Laminariales) found in a New Zealand
harbour. New Zealand Journal of Botany, 25:
Perez, R., Durand, P., Kaas, R., Barbaroux, O., Barbier, V.,
Vinot, C., Bourgeau-Causse, M., Leclerq, M., & Moigne, J.Y.
1988. Undaria pinnatifida on the French coast. Cultivation
method, biochemical composition of the sporophyte and the
gametophyte. In: Algal Biotechnology, ed. by T.
Staedler, J. Mollion, M.C. Verdus, Y. Karamanos, H. Morvan, &
D. Christiaen) 315-328. London, Elsevier.
Perez, R., Lee, J.Y., & Juge, C. 1981. Observations sur la
biologie de l'algue japonaise Undaria pinnatifida (Harvey)
Suringar introduite accidentellemente dans l'Etang de Thau.
Science et Pêche, 315: 1-12.
Perez, R., Kaas, R., & Barbaroux, O. 1984. Culture
expérimentale de l'algue Undaria pinnatifida sur les côtes
de France. Science et Pêche, 343: 3-15.
Wallentinus, I. In press. Status of introductions of
non-indigenous marine species to north Atlantic waters:
introductions and transfers of plants. ICES co-operative
Acknowledgements (contributions from questionnaire)
Dr R.L. Fletcher, University of Portsmouth.