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Biodiversity Journal, 2017, 8 (1): 105-112 Monograph

Preliminary data on the occurrence of alien macroalgae in

the vermetid reef along the coasts of Favignana Island (South-

ern Tyrrhenian Sea)

Paolo Balistreri* &Anna Maria Mannino

Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche, Sezione di Botanica ed Ecologia vegetale, Universita
di Palermo, Via Archirafi 38, 90123 Palermo, Italy; e-mail: requin.blanc@hotmail.it; annamaria.mannino@unipa.it
’Corresponding author

ABSTRACT Intertidal vermetid reefs are highly diverse systems that provide numerous habitats for animal

and vegetal species, leading to an increase of intertidal biodiversity. These habitats, particu-
larly vulnerable to environmental changes and human activities, are now experiencing high
mortality in several areas of the Mediterranean Sea. Since alien macroalgae are nowadays
considered one of the most serious threats to biodiversity and natural ecosystem functioning,
we provide a first baseline assessment of the occurrence of alien species in the vermetid reef
along the coasts of the Island of Favignana (Egadi Islands Marine Protected Area). Surveyes

carried out in 2015 revealed the only presence of Caulerpa cylindracea Sonder (Bryopsidales
Caulerpaceae). The alga, exclusively recorded within the cuvettes, showed low values of
abundance (class 1: cover <10%) except for San Giuseppe and Punta Longa localities where
the values of abundance fell within the class 3 (cover <40% and >20%). No significant cor-
relations were highlighted between the abundance values of C. cylindracea and those of the
dominant macroalgae inhabiting the cuvettes.

KEY WORDS Alien macroalgae; Favignana Island; southern Tyrrhenian Sea; vermetid reef.

Received 20.04.2016; accepted 23.08.2016; printed 30.03.2017
Proceedings of the 3rd International Congress “Biodiversity, Mediterranean, Society”, September 4th-6th 2015, Noto-
Vendicari (Italy)

INTRODUCTION phyta, 30 to the Ochrophyta, and one is a seagrass
species (Tracheophyta) (Verlaque et al., 2015). At

The Mediterranean Sea is one of the most present, 52 non-indigenous macroalgae are reported

severely affected areas by biological invasions, from the Italian coasts, 6 Chlorophyta, 9 Ochro-
a “sea under siege” (Galil, 2000; Boudouresque et phyta, 36 Rhodophyta and 1 aquatic angiosperm

al., 2005; Rilov & Galil, 2009). The number of alien (Sfriso & Marchini, 2014). Among them the invas-
marine species reported so far ranges from more ive taxa belonging to the genus Caulerpa (Bryop-

than 600 to nearly 1 .000 (Zenetos et al., 2012; Galil sidales Caulerpaceae), Caulerpa racemosa var.
& Goren, 2014). As far as marine macrophytes are cylindracea (Sonder) Verlaque, Huisman et Boudour-

concerned, a total of one hundred and thirty three esque, thereafter reinstated to its species rank as C.
species have been listed as possible aliens; of these, cylindracea Sonder (Belton et al., 2014), C. taxi-
23 belong to the Chlorophyta, 79 to the Rhodo- folia (Vahl) C. Agardh and C. taxifolia (Vahl) C.