Page 11 - ArcipelagoEgadi

8 m, depth and mean sea surface temperature was 14.5ºC In August 2014, sampling of the two Siganid spe-
(Fig. 15). Only the total length (TL) could be provided as cies was performed on the island of Lipsi (37.303299°N,
the specimen was partially predated, showing 77 cm of 26.751428°E), Dodecanese group of islands, in the
TL. Interestingly, the capture of another specimen 30 km Southeast of the Aegean Sea, Greece. Fish communities
southwards (38.17395ºN, 0.58601ºW), was mentioned at 8 sites (Table 2) were recorded to assess Siganus spp.
by the same fisherman, but this information could not be habitat preference. The habitats assessed were rocky al-
verified as the specimen was not preserved. gal beds, seagrass meadows and sand. The species rich-
ness and diversity of algae at these sites were measured.
Anyhow, the establishment of Fistularia commer- Local artisanal fishermen’s daily catches were also as-
sonii in the SW Mediterranean was suspected, since the sessed to denote Siganus spp. presence further offshore.
species was also documented in areas such as the Balearic
Islands (Mas et al., 2009), and more recently at Cabo de Siganus spp. were dominant in the local artisanal
Palos (Martinez, 2015). fishermen’s catch, with S. luridus comprising 54.5% of
the total catch in the month of August 2014, and 74.9%
Summarizing, the sporadic detection of the species in of the total herbivore catch. This bears socio-econom-
the western Mediterranean, coupled with low abundance ic implications as Siganus spp. in the region have low
during the last 7-8 years, indicate that the Fistularia commercial value (around 5€/kg). It was found that S.
commersonii have not had the ability to become inva- luridus (Fig. 16) and S. rivulatus (Fig. 17) favour rocky
sive in the area presumably due to environmental fea- algal habitats, with S. rivulatus also frequenting seagrass,
tures. However, since the species has been detected on a though not to the same extent.
yearly basis, future tropicalization of the Mediterranean
Sea could render this area more suitable for F. com- At Kamares, the site with the lowest abundance of
mersonii, in the same way that other native species are Siganus spp. present, it was also noted that there was a
expanding their distribution range in the North-western lack of the invasive alga species, Caulerpa cylindracea
Mediterranean due to warming of the sea. Despite the lat- Sonder supporting the idea that this alga is one of the
ter, monitoring programs for F. commersonnii and other preferred food sources of Siganus spp. (Stergiou, 1988;
targeted invasive species will be needed to prevent fur-
ther impacts on the ecosystem.

2.8. Siganus luridus and Siganus rivulatus in the Coastal
Waters of Lipsi Island, Dodecanese, Greece

By S. Carden-Noad and M. Drakulić

Siganus luridus (Rüppell, 1829) and Siganus rivula-
tus (Forsskål, 1775) are invasive Lessepsian fish species,
native to the Red Sea. The first records of their presence
in the Mediterranean are from the early 1900s. These
invasive species are thought to be altering the natural
food web of the rocky infralittoral zone by overgrazing
and outcompeting native herbivores such as Sarpa sal-
pa (Linnaeus, 1758) and Boops boops (Linnaeus, 1758)
(Stergiou, 1988; Azzurro et al., 2007; Giakoumi, 2014).

Table 2: List of infralittoral sites with number of Siganus spp. Fig. 16: Siganus luridus over rocky algal substrate in Lipsi
present. coastal waters

Site Coordinates Number Number of Fig. 17: School of Siganus rivulatus in Lipsi coastal waters.
of S. S. rivulatus
luridus present
present

Giofito 37.280556°N, 26.771667°E 42 2

Lendou 37.299722°N, 26.763056°E 33 1

Platis 37.313611°N, 26.739722°E 28 0
Gialos

Gatis 37.293611°N, 26.750000°E 93 2

Moschato 37.321667°N, 26.724167°E 13 18

Vroulia 37.318056°N, 26.723889°E 42 5

Katsadia 37.281944°N, 26.771944°E 34 18

Kamares 37.305278°N, 26.787778°E 19 6

482 Medit. Mar. Sci., 16/2, 2015, 472-488