Grateloupia filicina

Division: Rhodophyta
Class: Rhodophyceae
Order: Cryptonemiales
Species name: Grateloupia filicina (Lamouroux) C. Agardh var. luxurians A. & E.S. Gepp
Synonyms: Various synonyms exist for this species and variety, see Farnham (1978)
Common name: None
Date of introduction and origin
Grateloupia filicina var. luxurians was first introduced into the Solent before 1947 (Farnham & Irvine 1968; Farnham 1978, 1980). It occurs in the Pacific, Indian, and warmer parts of the Atlantic Oceans (Farnham 1980) and was possibly introduced from around Japan.
Method of introduction
It probably arrived in France at least with oysters as an unintentional associated introduction (C.A. Maggs pers. comm.).
Reasons for success
This species has high reproductive rate and is fertile for much of the year.
Rate of spread and methods involved
Despite the species' high reproductive rate it has spread very slowly.
There are populations of this species in Dorset, Hampshire, Isle of Wight and Sussex (see Farnham (1980) for map). Recently, further populations have been found in Jersey (W.F. Farnham pers. comm.). European populations are present in the Mediterranean and in Brittany.
Factors likely to influence spread and distribution
It is possible that low temperatures in certain parts of Great Britain may affect this species.
Effects on the environment
Unknown, but see under comments.
Effects on commercial interests
It grows in marinas but is unlikely to be a nuisance.
Control methods used and effectiveness
None used.
Beneficial effects
This species is used in the western Pacific as a food and as a source of carrageenan.
The fronds of this seaweed can reach a length of 70 cm (Irvine & Farnham 1983), compared with up to 10 cm for the native variety G. filicina var. filicina. The non-native may be capable of displacing other species, on account of its potential size (R. Mitchell pers. comm.) although there is no inidication of this happening (W.F. Farnham pers. comm.).
Farnham, W.F. 1978. Introduction of marine algae into the Solent, with special reference to the genus Grateloupia. Ph.D. Thesis, Portsmouth Polytechnic.
Farnham, W.F. 1980. Studies on aliens in the marine flora of southern England. In: The shore environment, volume 2: ecosystems, ed. by J.H. Price, D.E.G. Irvine & W.F. Farnham, 875-914. London, Academic Press. (Systematics Association Special Volume, No. 17B.)
Farnham, W.F., & Irvine, L.M. 1968. Occurrence of unusually large plants of Grateloupia in the vicinity of Portsmouth. Nature, 219: 744-746.
Irvine, L.M., & Farnham, W.F. 1983. Halymeniaceae. In: Seaweeds of the British Isles. Volume 1 Rhodophyta part 2A Cryptonemiales (sensu stricto), Palmariales, Rhodymeniales, ed. by L.M. Irvine, 17-51. London, British Museum (Natural History).
Acknowledgements (contributions from questionnaire)
Dr C.A. Maggs, Queen's University of Belfast.