Colpomenia peregrina

Division: Chromophyta
Class: Phaeophyceae
Order: Dictyosiphonales
Species name: Colpomenia peregrina (Sauvageau) Hamel
Synonyms: Colpomenia sinuosa (Mertens ex Roth) Derbès et Solier var. peregrina Sauvageau
Common name: Oyster thief
 
Date of introduction and origin
Colpomenia peregrina was introduced in 1907 from France into Cornwall and Dorset (Cotton 1908). This species occurs naturally in the Pacific Ocean and was introduced from the Pacific coast of North America.
 
Method of introduction
It was introduced to France from the Pacific coast of America with juvenile American oysters Crassostrea virginica. There was natural migration from France to Britain, and it may also have been introduced unintentionally with commercial oysters from France.
 
Reasons for success
This species lacks predators and has a rapid growth rate.
 
Rate of spread and methods involved
It has spread throughout Britain from southern England in 1907 to the Isle of Man by 1923, the Outer Hebrides by 1936 and the Orkneys by 1940 (Lund 1949; Norton 1976; Wilkinson 1975), marginally by natural means of dispersion.
 
Distribution
It is distributed throughout Britain although populations are larger on western coasts. In Europe it is found from Iberia to southern Norway. It has a world-wide distribution in temperate waters (South & Tittley 1986).
 
Factors likely to influence spread and distribution
Temperature and other conditions for reproduction affect its spread.
 
Effects on the environment
It has negligible effects on the environment.
 
Effects on commercial interests
When growing attached to oysters it floats away with the oyster when the air-filled thalli grow large enough, hence its name of oyster thief (Farnham 1980) but this does not occur in England.
 
Control methods used and effectiveness
None used.
 
Beneficial effects
None known.
 
Comments
It is found almost world-wide in temperate areas. There is some debate as to whether Colpomenia peregrina and C. sinuosa are separate species or variants of a single species.
 
References
Cabioc'h, J., Floc'h, J.H., Toquin, A. le., Boudouresque, C.F., Meinesz, A. & Verlaque, M. 1992. Guide des alguesdes mers d'Europe. Paris and Lausanne, Delachaux & Nestlé.
 
Cotton, A.D. 1908. Colpomenia sinuosa in Britain. Journal of Botany, London, 46: 82-83.
 
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.)
 
Lund, S. 1949. Remarks on some Norwegian marine algae. Blyttia, 7: 56-64.
 
Norton, T.A. 1976. The marine algae of the eastern border counties of Scotland. British Phycological Journal, 11: 19-27.
 
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).
 
Wilkinson, M. 1975. The marine algae of Orkney. British Phycological Journal, 10: 387-397.
 
Acknowledgements (contributions from questionnaire)
Mr I. Tittley, Natural History Museum, London.