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4 A. M. MANNINO AND P. BALISTRERI

Figure 4. C. cylindracea stolon (a), area colonised by C. cylindracea (b), C. cylindracea intermingled with other algae (c) and a bridge
created by the stolons of C. cylindracea (d).

C. cylindracea, with a number of macroalgal species rang- Currently, 16 NIS and three cryptogenic species have
ing from 8 to 12. Moreover, it seems that C. cylindracea been recorded till now, and maritime traffic has certainly
takes advantage when native communities are suffering. A spearheaded their introduction and spread (Mannino,
relationship between frond length and substrate typology Balistreri, and Yokeş 2014; Mytilineou et al. 2016; Balistreri
was also observed with longer fronds observed on sand et al. 2017; Mannino and Balistreri 2017; Mannino et al.
substrates. Since higher coverage values were observed 2017). The presence of NIS in the Egadi Islands MPA, but
in areas where the anchorage of boats is permitted, we also in other MPAs (e.g. Cecere, Petrocelli, and Saracino
hypothesise that the anchorage activities, mostly carried 2005) confirms that MPAs, despite their recognised role
out by pleasure boats, may also favour the spread of C. as promising management tool for protection of local bio-
cylindracea. diversity, are not immune from NIS invasions. However,
Even though the project ended in 2016, we are still NIS have been largely disregarded in marine conservation
receiving a huge quantity of records, photos and infor- plans (Giakoumi et al. 2016). The expansion of NIS by
mation on this IAS. During the project we also received recreational vessels represents an actual risk for MPAs,
records and information concerning other NIS and cryp- which are popular tourist destinations.
togenic species (see Carlton 1996; species that cannot be In agreement with Evans, Barbara, and Schembri
classifed with confdence among native nor among intro- (2015) and Schembri et al. (2015), we posit that the regular
duced ones) such as the ‘spotted sea hare’ Aplysia dac- and heavy maritime traffic between Sicily and the Egadi
tylomela (Rang, 1828), the ‘harpoon weed’ Asparagopsis Islands MPA, particularly Favignana, may have contrib-
armata (Harvey, 1855), ‘the red sea plume’ A. taxiformis uted to the arrival of sessile taxa often recorded in foul-
((Delile) Trevisan de Saint-Léon, 1845), the tube-build- ing communities. Therefore, Sicily and the surrounding
ing sabellid Branchiomma bairdi (McIntosh, 1885), the islands may represent an important center of secondary
‘blue spotted cornet fish’ Fistularia commersoni (Rüppel, dispersal for the Egadi Islands MPA.
1838) and the ‘nomad jellyfish’ Rhopilema nomadica NIS and cryptogenic species are likely to continue to
(Galil, Spannier & Ferguson, 1990) (Figure 5). It has been expand, and further arrivals are to be expected. For this
observed that the increase of sedimentation among the reason, in areas more vulnerable to marine biological
stolons of C. cylindracea, also favoured the settlement of invasions, like Sicily and its MPAs, regular monitoring
the biofouler worm Branchiomma bairdi. and surveillance programs are strongly needed in order