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Biol. Mar. Medit. (2006), 13 (1): 591-592

P. Gianguzza, B. Zava*, C. Bonaviri, G. Monteverde, A. Palmeri, S. Riggio

Dipartimento di Biologia Animale, Università degli Studi di Palermo,
Via Archirafi, 18 – 90123 Palermo, Italia.
pgiangu@unipa.it

*Wilderness – Studi ambientali, Palermo, Italia.

FIRST RECORD OF CAULERPA TAXIFOLIA (CAULERPALES,
ULVOPHYCEAE) IN THE WESTERN SICILIAN WATERS (ITALY)
PRIMA SEGNALAZIONE DI CAULERPA TAXIFOLIA (CAULERPALES,
ULVOPHYCEAE) PER LE ACQUE DELLA SICILIA OCCIDENTALE

Abstract
We report the first in situ observations of the invasive Caulerpa taxifolia in western Sicilian waters

along the coasts of Favignana Island, at Bue Marino inlet. The settlement of C. taxifolia covers a surface
area of 1.5 ha at depths of between 6 and 22 m and it has colonized soft bottoms covered by Posidonia
oceanica, Cymodocea nodosa and Caulerpa racemosa. Dense clusters of C. taxifolia, with up to 85%
bottom cover in the middle of the bed and 25% cover at the peripheries, indicate that this is an expanding
settlement and future work is needed to investigate temporal fluctuations of this alien species.

Key-words: Caulerpa taxifolia, alien species, Mediterranean Sea.

Introduction
Caulerpa taxifolia (Vahl) C. Agardh is considered one of the major ecological

threats to native marine biodiversity owing to its vegetative growth and population
persistence (Meinesz et al., 1995). In April 2004 the invasive strain of C. taxifolia
was identified for the first time in Western Sicilian waters along the coasts of
Favignana Island, at the Bue Marino inlet (37°55’02’’N; 12°22’13’’E). The present
paper provides qualitative data on the colonization level of this new C. taxifolia
station located in the take zone C of the marine protected area (MPA) of “Egadi
Islands”, where a healthy Posidonia bed is dominating.

Materials and methods
Field mapping of C. taxifolia was undertaken using the method of Vaugelas et

al. (1999). The length of coastline along which C. taxifolia can be observed, and
the surface area colonized were estimated by underwater visual censuses along
100 m × 10 m transects parallel to the shoreline (n=20) at 3, 6 and 18 m depth
respectively. Furthermore, to characterize the C. taxifolia canopy we counted the
number of upright primary fronds present in 25×25 cm quadrates (n=50) hapha-
zardly tossed into the vegetated area. The presence of other vegetation (seagrass
or other algae) or other relevant features were also noted. Field surveys were
carried out on 25-26 June, 28-29 July and 25-26 August 2004.

Results
The new settlement of C. taxifolia affected approximately a coastline surface

equal to 1.5 ha and the depth range of the infestations was 6-22 m. The tropi-