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Chemistry and Ecology 251

Downloaded By: [Furnari, G.] At: 10:31 24 May 2010 Figure 1. Seagrasses distribution in Sicily.

the Ionian coasts of Sicily [22,28–31]. In the southern Tyrrhenian Sea it was first observed in
1995 off the island of Vulcano, in the Aeolian Archipelago [32], and at Oliveri-Tindari (Messina)
[30], forming dense prairies ∼2 ha wide, extending from 1 to 27 m depth [27,33]. H. stipulacea
is also common today, mainly in small harbours and sheltered bays along the Tyrrhenian coast
and the Egadi islands, although it is not common along the southern coast of Sicily (author’s
observation). The recent rapid spread of the species has likely been mediated by pleasure boat
traffic and anchoring, and favoured by an increase in seawater temperature [6].

Nanostera noltii is a Zosteracea widely distributed along the coasts of Europe and northern
Africa [2], but not common along the Sicilian coasts, where only small patches of <10 m2 have
occasionally been observed. The species was recorded in a few localities along the north-western
[34] and south-eastern coasts [35] and in a coastal lagoon, the Stagnone di Marsala [36], as well as
the coastal lakes of Ganzirri and Faro [37]. Recently, it has been found in a salt mine near Marsala
(western coast, author’s observation), where high salinity (∼60–70 g·L−1) can be detected in
summer.

The eel-grass Zostera marina, a species adapted to the cold waters of the North Atlantic and
North Pacific, can be found in the Mediterranean in more or less sheltered areas on soft mud or
firm sand [38]. It occurs rarely in Sicily and was detected only near Gela (south-eastern coast),
which is up to date the only location where the species has been recorded in Sicily [35].

Extensive mapping surveys by acoustic instruments (side scan sonar), combined with airborne
and satellite remote sensing methods and true control inspections (remote-operated vehicle; ROV)
have been used to estimate Cymodocea nodosa and Posidonia oceanica coverage and distribution
along Sicilian coasts [39].

Prairies of C. nodosa are frequently observed along the coast of Sicily and colonise ∼19,000 ha.
In term of species coverage, the northern (∼40%) and southern (∼44%) coasts show the higher
values, while the Aeolian Islands host >90% of the C. nodosa prairies of the small Sicilian
islands. Moreover, C. nodosa reaches edaphic climax characterised by dense, extensive prairies at
7–15 m depth [40,41] in some areas of the southern (Gulf of Gela) and northern coasts (Gulfs of
Castellammare and Termini Imerese). This ecological condition is due to peculiar sedimentologic