Gonionemus vertens
Date of introduction and origin
Gonionemus vertens was first reported from north-east
England in 1913 and probably originates from the western Pacific
(China, Korea or Japan) via Portugal (Edwards 1976).
Method of introduction
Transport on ships' hulls in the polyp stage (Carlton 1985)
from the western Pacific Ocean in the 19th century may be the
mechanism of introduction. Edwards (1976) suggested that it may
have arrived much earlier from Japan with importations of Japanese
oysters Crassostrea gigas 500 or more years ago; he also
discusses other shipping- and seaplane-associated methods of
transport.
Reasons for success
This species seems to thrive in temperate to warm-temperate
regions.
Rate of spread and methods involved
This species shows a variable, generally moderate rate of
spread. It is thought to have been initially introduced to Europe
in Portugal where the population was localised due to currents,
temperatures and salinities. It was exported from 1867 onwards from
Portugal to France, again with oysters in the polyp stage. This has
probably allowed the spread to other European countries including
the British Isles since France was a major oyster exporter (Edwards
1976). It can also disperse in the hydromedusae stage in water
currents and ballast water.
Distribution
It has a patchy distribution around British coasts and, in a
new area, is usually first noted in aquaria; it is also found on
other western European coasts.
Factors likely to influence spread and distribution
Its spread is likely to have been influenced by movements of
oysters, shipping and marginal spread of established
populations.
Effects on the environment
Unknown.
Effects on commercial interests
Unknown.
Control methods used and effectiveness
None used.
Beneficial effects
None known.
Comments
It is unlikely that the venom of Gonionemus vertens
is as harmful to humans as in much studied Gonionemus
populations of Far-Eastern Russian waters (see Cornelius (1995) and
references therein).
References
Agassiz, A. 1865. North American Acalephae. Illustrated
Catalogue of the Museum of Comparative Zoology at Harvard
College, 2: 1-234.
Carlton, J.T. 1985. Transoceanic and interoceanic dispersal of
coastal marine organisms: the biology of ballast water.
Oceanography and Marine Biology. An Annual Review,
23: 313-371.
Cornelius, P.F.S. 1995. North-west European thecate
hydroids and their medusae, Laodiceidea to haleciidae: keys and
notes for the identification of the species. Linnean Society
of London, Estuarine and Coastal Sciences Association and Field
Studies Council. (Synopses of the British Fauna (new series), No.
50.)
Edwards, C. 1976. A study in erratic Distribution the
occurrence of the medusa Gonionemus in relation to the
distribution of oysters. Advances in Marine Biology,
14: 251-284.
Acknowledgements (contributions from questionnaire)
Dr P.F.S. Cornelius, The Natural History Museum, London.