Asparagopsis armata
Division: Rhodophyta
Class: Rhodophyceae
Order: Bonnemaisoniales
Species name: Asparagopsis armata Harvey
Synonyms: Falkenbergia rufolanosa (Harvey) Schmitz (part of life cycle)
Common name: Harpoon weed
Date of introduction and origin
Asparagopsis armata was first recorded in 1949 on Lundy in the Bristol Channel. The Falkenbergia phase was recorded by Harvey & Drew (1949); the gametangial condition of Asparagopsis armata was first recorded from Cornwall by Drew (1950). It had been introduced from mainland Europe. It was first recorded in Ireland in 1939 (Valéra 1942). The species originates from Australia and/or possibly New Zealand.
Method of introduction
It was introduced to mainland Europe, possibly as an associated unintentional introduction with oysters (it was first recorded in Algeria in 1923) (Feldman & Feldman 1942), then probably introduced to Britain and Ireland by rafting and floating.
Reasons for success
The species has a lack of predators and a rapid growth rate. It is also an opportunist.
Rate of spread and methods involved
The species was present in Ireland in 1939, Lundy in 1949, Plymouth (Devon) in 1950, Start Point (south Devon) in 1953 and the Solent in 1973, and arrived in Shetland by 1973 (Irvine et al. 1975).
It is distributed throughout the British Isles although uncommon on the east coast (Irvine et al. 1975). European populations can be found from the western Mediterranean to Shetland and it is especially common on the coast of Spain (South & Tittley 1986).
Factors likely to influence spread and distribution
Lethal temperatures and temperature required for reproduction are likely to restrict distribution. The hooked branches are likely to spread by attachment onto floating objects (Farnham 1980).
Effects on the environment
Effects on commercial interests
Control methods used and effectiveness
None used.
Beneficial effects
None known.
There are two macroscopic phases to the life cycle of Asparagopsis armata, the filamentous habit being very similar in appearance to that of Bonnemaisonia hamifera but readily distinguished at the cellular level (D.A. Birkett pers. comm.).
Drew, K.M. 1950. Occurrence of Asparagopsis armata Harv. on the coast of Cornwall. Nature, 166: 873-874.
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.)
Feldmann, J., & Feldmann, G. 1942. Récherches sur les Bonnemaisoniacées et leur alternances de générations. Annales de Science Naturelle (Botanie) Sér II, 3: 75-175.
Harvey, C.C., & Drew, K.M. 1949. Occurrence of Falkenbergia on the English coast. Nature, 164: 542-543.
Hiscock, S. 1986. A field guide to the British Red Seaweeds. Field Studies Guide. Ocassional Publication 13.
Irvine, D.E.G., Guiry, M.D., Tittley, I., & Russell, G. 1975. New and interesting marine algae from the Shetland Isles. British Phycological Journal, 10: 57-71.
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).
Valéra, M. de. 1942. A red alga new to Ireland: Asparagopsis armata Harvey on the west coast. Irish Naturalists' Journal, 8: 30.
Acknowledgements (contributions from questionnaire)
Mr I. Tittley, Natural History Museum, London.