Page 43 - Invasive_Species_2013

Mediterranean invasive species factsheet

Similar species Ecological impacts
Caulerpa racemosa var. cylindracea resembles the Caulerpa racemosa var. cylindracea represents an
two native Caulerpa racemosa varieties. It is important threat to the diversity of benthic coastal
particularly similar to C. racemosa var. lamourouxii f. ecosystems (i.e. seagrass beds, maerl beds and
requienii, but in this native variety the surface is coarse sediments), since it alters habitat
much smoother, the bladder-like ramuli are rounded characteristics, competes with native species and
but less inflated and shorter, and the erect fronds changes native benthic communities. This species is
can be partly unbranched, slightly compressed or of now found carpeting many coastal areas. It is
irregular width. The other native variety, Caulerpa considered to be one of the 100 worst invasive
species in the Mediterranean, as it can alter the
racemosa var. turbinata, has the ends of its
physical and chemical conditions of the environment
branchlets flattened.
(including water movement, sediment deposition and
Narrow fronds,
sometimes branched substrate characteristics), as well as causing
profound changes to benthic assemblages of algae
and invertebrates.

Economic impacts

The economic impact of C. racemosa var.
cylindracea has never been quantified, although
there are reports of fishing nets being clogged and
broken by this invasive alga, thereby reducing fish
catches. The monotonous seascape produced by the
dominance of this alga may also reduce the
Rhyzomes
No ramified attractiveness of a site for underwater tourism (such
as spearfishing, scuba diving and free diving).

Caulerpa racemosa lamourouxii
Management options
Prevention: Stronger legislation and local
Club disk shaped Ramuli regulations controlling the activities of the aquarium
trade, shipping, fishing and mariculture are urgently
needed to prevent the further spread of this species.
Eradication: Experimental eradication studies or
programmes for C. racemosa in the Mediterranean
are rare. They have been applied with some
2
effectiveness in small areas (400–1,000 cm ),
especially in restricted areas such as bays and
harbours. The standard procedure is manual removal
of the weed at 3 to 4-week intervals. Nevertheless,
Caulerpa racemosa turbinata C. racemosa fragments tend to recolonize these
areas again after a period of 2 to 18 months.
Brief history of its introduction and
pathways
C. racemosa var. cylindracea is an endemic species Further reading
Verlaque, M., et al. 2000. The Caulerpa racemosa complex
from south-western Australia. The mode of
(Caulerpales, Ulvophyceae) in the Mediterranean Sea.
introduction of the invasive Mediterranean variety of Botanica Marina 43, 49–68.
Caulerpa racemosa var. cylindracea into the
http://www.europe-aliens.org/pdf/Caulerpa_racemosa.pdf
Mediterranean Sea remains speculative; however,
Cebrian E., et al. 2011. Exploring the effects of invasive
maritime traffic (ballast water and ship hull fouling) algae on the persistence of gorgonian populations.
and the aquarium trade are the most likely vectors Biological Invasions DOI: 10.1007/s10530-012-0261-6. Drawings: Juan Varela
for the introduction of this high-impact alga. Klein J, Verlaque M., 2008. The Caulerpa racemosa
C. racemosa can still be found in aquarium stores invasion: a critical review. Marine Pollution Bulletin 56,
205–225.
and is sold by internet retailers.

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