Grateloupia doryphora
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.