Page 2 - CatraEgadi2006

Table l. Geographic data of each of the Egadi islands

Area in km2 Favignana Levanzo Marettimo
Coastline in km
Altitude in m 19.32 5.82 12
Distance from W coast 33 15 19
of Sicily in km 314 278 686
16 15 38

Very few studies have been undertaken to date on the phytobenthos of the Egadi
islands. The first data on both the benthic alga! flora and vegetation of the main
islands of the archipelago were given by Giaccone ( 1970) and Giaccone & Sortino
( 1974), respectively. Sortino et al. ( 1976) gave additional information on the flora
of Favignana Island in their phytosociological study of the community with
Phyllariopsis brevipes (as Phyllaria reniformis) in the western Mediterranean Sea,
while more recently Giaccone et al. (1993) referred to materia! collected from
Favignana.

In order to get a more complete knowledge of macroalgal biodiversity currently
occurring at the marine protected area of the Egadi islands, the benthic alga! flora of
the three main islands of the archipelago was studied.

Materials and methods

Floristic sampling was carried out on rocky substrata in May/June an d September/October 200 l in
order to also record seasonal species. A total of l06 samples were collected (58 in spring and 48 in
autumn) along Il transects perpendicular to the shore (5 at Favignana, 4 at Levanzo, 2 at Marettimo)
(Fig. l, Table 2) an d between the midlittoral zone to 40 m depth (lower infralittoral zone). Following
Boudouresque & Cinelli ( 1976), depths were estimated with reference to the "biologica! zero"
corresponding to the border between mid- and infralittoral zones. The infralittoral zone was studied
by SCUBA diving. The collected materia! was preserved in 5% Formalin in seawater for later study
in the laboratory. Youcher specimens were deposited in the Herbarium of the Department ofBotany
of the University of Catania (CAT). For both basionyms and type localities of each species, both
Guiry & Nic Dhonncha (2005) and Si!va (2005) were consulted.

Results and discussion

In l 06 samples collected from the three islands, a total of 285 species were found,
comprising 200 Rhodophyta (70.18%), 58 Ochrophyta (=Phaeophyceae) (20.35%)
and 27 Chlorophyta (9.47%). Of these, 57 species were present only at Favignana,
21 at Levanzo and 18 at Marettimo while 118 were present in the three islands, 47 at
Favignana and Levanzo, 19 at Favignana and Marettimo and only 8 at Marettimo
and Levanzo. From a comparison with the literature data it appears that the present
floristic richness is only slightly higher than that reported previously [268 species,
consisting of 165 (61.57%) Rhodophyta, 72 (26.87%) Ochrophyta and 31 (11.57%)
Chlorophyta]. The number of species sampled at present and in the past from the

490