Page 45 - Invasive_Species_2013

Mediterranean invasive species factsheet

day and form completely new fronds every other Ecological impacts
day, reaching densities of approximately 5,000 Caulerpa taxifolia appears to be having a major
fronds per square metre. impact in several locations, where it invades a large
number of habitats such as seagrass beds, modifies
Similar species organic and inorganic components of the sediment
This species resembles other Caulerpa species, and potentially threatens biodiversity. A decline in
especially C. sertularioides. C. sertularioides is a biodiversity and in fish biomass have been seen in
more delicate alga with cylindrical branches, areas that C. taxifolia has invaded. For this reason, it
different from the flattened branchlets of C. taxifolia. is important to differentiate it from native species.
Its rising branchlets are also more rounded towards
their tips, compared to the more angular, squared-off Economic impacts
branches of C. taxifolia. Their economic impact has never been quantified,

but the killer algae frequently become entangled in
nets and round anchors, reducing fishing catches.
cylindrical branches The algae also continue to be found in the aquarium
with round tips
trade.

Management options
Prevention: Stronger legislation and local
regulations controlling the activities of the aquarium
trade, shipping and mariculture are urgently needed.

Eradication: Various methods have been proposed
and tested: manual uprooting, a range of underwater
suction devices, physical control with dry ice, hot
water jets, chemicals and underwater welding
devices to boil the plants in situ. The variable, limited
results of these different attempts have precluded the
establishment of any permanent control
Caulerpa sertularoides programmes.

Another possible form of control is the introduction of
Brief history of its introduction and natural predators into the invaded environment.
pathways Several research programmes are testing the use of
Caulerpa taxifolia was accidentally introduced into biological control methods involving the artificial
the Mediterranean from a public aquarium in introduction of grazing mollusc species.
Monaco. Since then, it has spread rapidly due to its
natural vegetative dispersal mechanism, its lack of Further reading
natural grazers and the ease of anthropogenic
http://www.europe-aliens.org/pdf/Caulerpa_taxifolia.pdf
dispersion by boats, anchors, fishing nets and
aquaria. Cottalorda, J. M. et al, 2010. Le Parc national de Port-
Cros: une structure référence dans la mise en oeuvre de
stratégies de contrôle de la Chlorobionte envahissante
Natural dispersion occurs near the central invasion
Caulerpa taxifolia (Valh) C. Agardh. Sci. Rep. Port-Cros
zone, but its wider spread is facilitated by transport natl. Park, Fr., 24: 105-126.
Drawings: Juan Varela
on pleasure boat anchoring equipment and on
fishing nets.

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