Page 14 - Mannino_Balistreri_2017

234 Mannino & Balistreri: An updated overview of invasive Caulerpa taxa ...

species requires long periods of study (Boudouresque & Verlaque 2012).
For a better understanding of the invasive potential and spread dynamics of alien
species such as Caulerpa ones, a quick sighthing of any newly colonized area is fundamen-
tal (Klein & Verlaque 2008). Moreover, the establishment of regular monitoring programs,
as also prescribed by the Marine Strategy Framework Directive (MSFD), including public
awareness campaigns (e.g. the Project “Caulerpa cylindracea – Egadi Islands” sponsored
by the Department of Biological Chemical and Pharmaceutical Sciences and Technologies,
University of Palermo and the Egadi Islands Marine Protected Area), citizen science ini-
tiatives (e.g. “Seawatchers” available at http://www.observadoresdelmar.es/?idioma=en),
online databases or networks such as ELNAIS (Ellenic Network on Aquatic Invasive
Species) by the Hellenic Centre for Marine Research (HCMR), available at
http://elnais.hcmr.gr, regular surveys and mapping by scientists, are welcome and neces-
sary in order to assess the spread dynamics of those invasive species that raise serious con-
cern. All these activities are fundamental to manage continuous spillover effects, especial-
ly in the areas which are more vulnerable to marine biological invasions and along the pro-
tected coasts. All information, regularly updated, would allow the creation of permanent
observatories and warning systems of detection and if possible of control, but also the
planning of suitable management activities.
Lastly, the Mediterranean region, which is described as one of the main climate change
“hot-spots” (Giorgi 2006), should become warmer and drier during the 21st century, mir-
roring the global ocean tendency with an increase of about 3.1 °C predicted in the coming
century (Ben Rais Lasram & al. 2010). Undoubtedly, the distribution of marine species,
alien and native, in the Mediterranean Sea is currently changing as a consequence of sea-
warming. Tropical species are expanding in the southern Mediterranean areas whereas the
northern Mediterranean areas are being more and more occupied by thermophilic indige-
nous species (Bianchi 2007). The possibility of a gradual westward expansion of tropical
species has been already predicted by Por (1990). The abundance, distribution and geo-
graphic expansion of thermophilic species, alien or indigenous (the so-called phenomenon
of “tropicalization”, Bianchi & Morri 2003) are expected to increase, as a consequence of
sea warming, Atlantic flux, lessepsian migration and human activities. Climate changes,
making the Mediterranean Sea a favourable biogeographic area, will certainly facilitate the
expansion of alien Caulerpa species within this Sea, and directly affect the indigenous
macrophyte-dominated ecosystems (e.g. Harley & al. 2012), further confirming that mon-
itoring programs are of great importance to gauge the spread dynamics of these marine
alien species.

Acknowledgements
Authors are indebted to Marc Verlaque for useful suggestions and constructive comments which
greatly improved the manuscript and Michèle Perret-Boudouresque for bibliographic assistance.
They also thank all students for their invaluable field help, Rossella Barone, Sergio Calascibetta,
Vincenzo Di Martino, Pietro Gandolfo, Michele Gristina, Gianluca Neri, Alessandro Pagano, Andrea
Ruggeri, Egidio Tiralongo, Marco Toccaceli and Sergio Zanoni for providing information, records
and photos.