Grateloupia doryphora

Division: Rhodophyta
Class: Rhodophyceae
Order: Cryptonemiales
Species name: Grateloupia doryphora (Montagne) Howe
Synonyms: Halymenia doryphora Montague, Halymenia lanceola
J. Agardh, Grateloupia lanceola (J. Agardh) J. Agardh etc. (see Farnham 1978).
Common name: None
 
Date of introduction and origin
Grateloupia doryphora was first collected in 1969 from Southsea, Hampshire (Farnham & Irvine 1973). It may have originated in the Atlantic or Pacific (W.F. Farnham pers. comm.).
 
Method of introduction
Probably associated with oyster mariculture, at least in France (W.F. Farnham pers. comm.).
 
Reasons for success
Lack of grazers (C.A. Maggs pers. comm.), sheltered growth conditions, high level of nutrients in water, tolerance to lowered salinities and elevated seawater temperatures in the summer (Farnham 1980) account for its success.
 
Rate of spread and methods involved
It has spread slowly, probably through marginal dispersal (up to 30 miles) by natural means (W.F. Farnham and I. Tittley, pers. comms.), perhaps by movement of plants attached to small stones.
 
Distribution
In England it occurs off Bognor Regis and elsewhere in the sublittoral, West Sussex, and along the Hampshire coast to Lepe in the Solent (Farnham 1980). It is now found around the Isle of Wight, in the Fleet Lagoon, Dorset, and Jersey (W.F. Farnham pers. comm.). The only known mainland European populations are in Portugal (South & Tittley 1986) and, more recently, it has been discovered in Brittany.
 
Factors likely to influence spread and distribution
Water turbidity and competition from indigenous sublittoral algae and probably discourage extensive development in the sublittoral (Farnham 1980).
 
Effects on the environment
Unknown.
 
Effects on commercial interests
This species is used in the Pacific as a food and as an industrial source of carrageenan.
 
Control methods used and effectiveness
None.
 
Beneficial effects
None known.
 
Comments
Where the two co-exist, G. doryphora usually out competes the other non-native, G. filicina var. luxurians (W.F. Farnham pers. comm.). The ribbon-like blades of this seaweed can reach a size of 100 cm by 20 cm, but are usually much smaller (Irvine & Farnham 1983).
 
References
Farnham, W.F., & Irvine, L.M. 1973. The addition of a foliose species of Grateloupia in the British marine flora. British Phycological Journal, 8: 208-209.
 
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.)
 
Irvine, L.M. 1983. Seaweeds of the British Isles, volume 1, Rhodophyta part 2A, Cryptomeniales (sensu stricto) Palmariales, Rhodymeniales. London, British Museum (Natural History).
 
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.. L.M. Irvine, 17-51. London, British Museum (Natural History).
 
South, G.R., & Tittley, I. 1986. A checklist and distributional index of the benthic marine algae of the North Atlantic Ocean. St. Andrews & London, Huntsman Marine Laboratory & British Museum (Natural History).
 
Acknowledgements (contributions from questionnaire)
Mr I. Tittley, Natural History Museum, London.
Dr W.F. Farnham, University of Portsmouth.