Page 9 - ArcipelagoEgadi

During a free diving underwater photographic survey
on 5-6 December 2014 in a coastal area of the Greek is-
land of Kastelorizo, four specimens of an exotic echinoid
were observed and photographed. The studied marine
area is just parallel to the shore, narrow and about 200
meters long. It is located close to the port of the island
(36.152916°N, 29.591658°E) and is characterized by a
rocky substrate. The specimens observed during the day
were semi-shielded on rocky bottom and open crevices at
a depth of only 3-5 meters. One specimen was observed
and photographed again in the same area during a similar
survey on 2-3 May 2015.
After close examination of the photographic material
and based on external morphological aspects, the speci-
mens were recognized as the needle-spined urchins Di-
adema setosum (Fig. 12).
The conspicuous characteristic of the species is the
unusual long spines, absent from the swallow water echi-
noids of Greece. The specimens also had at least four
white spot markings on the inter-ambulacrals just above
the ambitus (Fig. 13). According to Coppard & Campbell
Fig. 12: Specimen of Diadema setosum in an open crevice.
Fig. 13: At least 4 white spot markings are obvious on the test Ocean, the East African coast and the Red Sea. After
of this specimen.
480 Medit. Mar. Sci., 16/2, 2015, 472-488
(2006), the white spot markings are evident during the
day and night on Diadema setosum instead of the similar
markings on the test of the closely related D. savignyi
(Michelin, 1845) which are typically visible only during
the night. All specimens observed had only dark (almost
black) spines but no gray ones, instead of the both dark
and gray spines of the specimens mentioned by Yapici et
al. (2014) in Turkish waters.
Yokes & Galil (2006) mention that possible vectors
for the indroduction of this species into the Mediterranean
Sea include larval transport through the Suez Canal, ship-
ping, and aquarium trade. They also underline the ur-
chin’s venomous spines that may cause painful injuries
to swimmers.
Although the occurrence of Diadema setosum in
Kastellorizo, Greece, could be expected after its appear-
ance in the nearby Turkish coastal area of Kaş Peninsula
(Yokes & Galil, 2006), its presence around the island is
documented here after about a decade. This is probably
due to the scarce scientific investigation of the area and
this underlines the urgent need for a more thorough ef-
fort to monitor the rapid expansion of alien species. The
latter is of significant importance for taking management
measures for the eradication of unwanted invasive spe-
cies in due time.
The finding of Diadema setosum adds a new alien echi-
noderm to Hellenic waters, after the previously invento-
ried species Ophiactis savignyi (Müller & Troschel, 1842)
and Synaptula reciprocans (Forsskǻl, 1775) (Zenetos et
al., 2011 and references therein).
2.5. Goniobranchus annulatus invading the South-
Eastern Aegean Sea (Greece)
By G. Kondylatos and M. Corsini-Foka
Goniobranchus annulatus (Eliot, 1904), a nudi-
branch of distinctive colour pattern, inhabits the Indian
its first occurrence in the Mediterranean, in a rock pool
on the island of Salamina, Saronikos Gulf, Greece in
2004 (Daskos & Zenetos, 2007), the species has been
found along the Mediterranean coasts of Turkey, at
Beldibi, Antalya (2008), at Çevlik Harbor (2009) and in
Iskenderun Gulf (2008-2009); in Cyprus, at Dhekelia,
Larnaca, (2009); in various locations off Israel (2009-
2011) (Pasternak et al., 2011 and references within); in
Lebanon (Crocetta et al., 2013); and in Greece, island of
Kastelorizo, in 2010 (Zenetos et al., 2011).
On the 10th of May 2015, more than 10 specimens of
the nudibranch were observed along a distance of 30-40
m, over the rocky substrate covered by green, red and
brown algae, within a depth range of 2-12 m, during snor-
keling and free diving. 7 live samples, 3-5 cm in length,
were collected by hand and transported to the facilities of
the Hydrobiological Station of Rhodes, where they suc-