Page 81 - Invasive_Species_2013

Mediterranean invasive species factsheet

Similar species Economic impacts
This oyster resembles another Mediterranean alien The economic impact of this invasive species is
species, Spondylus groschi, but the latter’s larger unknown. It is a valuable species for seashell
number of main ribs (6–16 compared with 6–7 in S. collectors, with a small trading market. In Lebanon it
spinosus), the homogeneous shape of its spines is also harvested and sold for food in restaurants.
(large and flat like a palette knife) and their colour
(compared with white spines in S. spinosus) Management options
distinguish these two non-native species.
A suggested prevention action is to conduct public
awareness campaigns combined with monitoring.
Control actions are feasible only in specific
All spines are similar in
shape – like palette knife circumstances, such as when individuals are
localized in a very confined area. Fouling
communities on recreational boats and ships can be
removed, but larvae can soon re-establish previous
densities. These bivalves are also strongly attached
to the sea bottom and their eradication implies the
removal of part of the local benthic communities and
their substratum. This procedure clearly has a
considerable impact and must be shown to be
justifiable by means of an environmental impact
assessment, as in the case of the other alien bivalve
Chama pacifica.

Spondylus groschi Further reading
Shabtay, A., 2011. The invasive oyster Spondylus spinosus
Schreibers, 1793 in the Israeli Mediterranean coast. PhD
thesis, Tel Aviv University, 97pp.
Brief history of its introduction and http://www.ciesm.org/atlas/Spondylusspinosus.html
pathways
Native to the Indo-Pacific and Red Sea, the spiny
oyster was first recorded in the Mediterranean in
1988 in Israel, subsequently spreading to the
Turkish and Lebanese coasts; it is presently
confined to the eastern Mediterranean Sea. It is
presumed that it arrived via the Suez Canal and its
further dissemination was assisted by ships.

Ecological impacts

The spiny oyster, either alone or together with the
jewel box oyster, Chama pacifica, can form dense
aggregations that produce solid reefs at some sites,
completely replacing native oyster species.
Competition and reduced plankton availability
Drawings: Juan Varela
caused by decreased water flow can also slow down
the growth of other benthic organisms.

78 Monitoring Marine Invasive Species in Mediterranean MPAs: A strategy and practical guide for managers