Date of introduction and origin
Thalassiosira punctigera was first detected in English waters
(Plymouth, Devon) in 1978 (Wallentinus in press; G.R. Hasle pers.
comm.). Its origin is unknown although it had only previously been
recorded from the North Pacific and South Atlantic Oceans, plus one
record from the Carribean (Hasle 1983).
Method of introduction
The method of introduction is unknown, but ballast transport
cannot be ruled out and imported oysters have also been
hypothesised as a potential vector (Rincé & Paulmier 1986;
Wallentinus in press).
Reasons for success
Unknown.
Rate of spread and methods involved
It was reported from English waters and Helgoland in 1978;
Norway in 1979; Netherlands in 1981 (Marine Biological Association
1979; Hasle 1990; Smayda 1990). Its method of spread is
unknown.
Distribution
It is found in the English Channel and North Sea (Wallentinus
in press).
Factors likely to influence spread and distribution
Unknown.
Effects on the environment
Unknown.
Effects on commercial interests
Unknown.
Control methods used and effectiveness
None used.
Beneficial effects
None known.
Comments
It is an extremely variable species with regard to size and
valve structure (Hasle 1983). It was very abundant in the English
Channel in the period 1980-1981 but has subsequently been
considered to have an insignificant role (Boalch 1987).
References
Boalch, G.T. 1987. Changes in the phytoplankton of the western
English Channel in recent years. British Phycological Journal, 22:
225-235.
Hasle, G.R. 1983. Thalassiosira punctigera (Castr.) comb.
nov., a widely distributed marine planktonic diatom. Nordic Journal
of Botany, 3: 593-608.
Hasle, G.R. 1990. Diatoms of the Oslo fjord and the Skagerrak.
Species new to the area: immigrants or overlooked in the past?
Blyttia, 48:33-38.
Marine Biological Association. 1979. Report of the Council for
1971-1972. Journal of the Marine Biological Association of the
United Kingdom, 52: 1067-1102.
Rincé, Y., & Paulmier, G. 1986. Donnée nouvelles sur la
distribution de la diatomée marine Coscinodiscus wailesii Gran
& Angst (Bacillariophyceae). Phycologia, 25: 73-79.
Smayda, T.J. 1990. Novel and nuisance phytoplankton blooms in
the sea: evidence for a global epidemic. In: Toxic marine
phytoplankton, Granéli, E, Sundström, B., Elder, L., &
Anderson, D.M. eds. Proceedings of the Fourth International
Conference on Toxic Marine Phytoplankton, 26-30 June 1989, Lund,
Sweden. Elsevier, New York, p29-40.
Wallentinus, I. In press. Status of introductions of
non-indigenous marine species to north Atlantic waters:
introductions and transfers of plants. ICES co-operative research
report.
Acknowledgements (contributors)
Prof. G.R. Hasle, University of Oslo.