Solieria chordalis

Division: Rhodophyta
Class: Rhodophyceae
Order: Gigartinales
Species name: Solieria chordalis (Agardh) J. Agardh
Synonyms: None
Common name: None
Date of introduction and origin
Solieria chordalis was introduced around 1976 from northern France into Falmouth Harbour (Cornwall), and the Fleet and Weymouth Bay (Dorest) (Farnham & Jephson 1977).
Method of introduction
It was possibly transported on ships' hulls (Farnham 1980), although perhaps also on ballast stones in recent historical times. Weed-rafting of stones may also have been a natural mechanism for dispersal across the Channel (W.F. Farnham pers. comm.).
Reasons for success
It spreads using vegetative regeneration from basal, rhizoidal systems. (indeed no fertile gametophytes have been found), so despite lack of sexual reproduction, the asexual methods are very effective.
Rate of spread and methods involved
It has spread slowly. A disjunct distribution is suggestive of remote dispersal methods such as shipping (Farnham 1980).
Currently it is found in western Wales, Dorset and Cornwall (Hiscock & Maggs 1984). Elsewhere in Europe it is found in France (Farnham 1980), Spain and in the western Mediterranean (South & Tittley 1986; I. Tittley, pers. comm.).
Factors likely to influence spread and distribution
Effects on the environment
None known.
Effects on commercial interests
Control methods used and effectiveness
None used.
Beneficial effects
It could be cultivated to produce carrageenan.
Previously it was considered that, as well as Solieria chordalis on the south coast, Solieria filiformis was present in Milford Haven, South Wales. However, W.F. Farnham (pers. comm.) indicates that the Milford Haven population (Farnham 1980; Farnham & Irvine 1979) was misidentified and is probably better referred to as S. chordalis (the only known species of this genus in Britain).
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. 1979. Discovery of members of the red algal family Solieriaceae in the British Isles. British Phycological Journal, 14: 123.
Farnham, W.F., & Jephson, N.A. 1977. A survey of the maerl beds of Falmouth (Cornwall). British Phycological Journal, 12: 119.
Hiscock, S. 1986. A field guide to the British Red Seaweeds. Field Studies Guide. Ocassional Publication 13.
Hiscock, S., & Maggs, C.A. 1984. Notes on the distribution and ecology of some new and interesting seaweeds from south-west Britain. British Phycological Journal, 19: 73-87.
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)
Dr C.A. Maggs, Queen's University of Belfast.
Dr W.F. Farnham, University of Portsmouth.
Mr I. Tittley, Natural History Museum, London.