Despite being a large charismatic species, very little is known about its basic
biology and ecology. In most of its distribution area, this gorgonian seems to be
located on shelf bottoms mainly in the depth range of 50–200 m. Nevertheless, in the
Canary Islands has been recorded at the extreme depths of 690 m (Brito and Ocaña
2004), while in the Strait of Gibraltar area and around the Chafarinas Islands can be
found as shallow as 15–20 m depth (Ocaña et al. 2009; Maldonado et al. 2013).
Scattered colonies have been found in the deep shelf around the Alboran Island
(Templado et al. 2006; Gofas et al. 2014) between 70 and 200 m depth and in the
Seco de los Olivos (also known as Chella Bank) below 80 m depth (Aguilar et al.
2008; de la Torriente et al. 2014). Likewise, some colonies were photographed and
sampled from 80 to 94 m depth on the northeast coasts of Pantelleria Island
(Angiolillo et al. 2012).
The occurrence of Ellisella paraplexauroides around the Chafarinas Islands is
noteworthy. This species dominates the underwater rocky landscape from about
17–20 m deep with an average density of 0.5 colonies m
À2 (maximum, 5 colonies
m
À2 ) (Maldonado et al. 2013). These authors pointed out that this unique population
requires serious conservation attention owing to considerable damage caused by
small-scale fishing operations. Likewise, Otero et al. (2017) highlight that this
gorgonian should be considered “vulnerable” in the Mediterranean basin, since its
populations are concentrated around the few sites mentioned and have suffered a
drastic decline over recent decades. This decline is mainly related to the impact of
unregulated and illegal fisheries, particularly the use of benthic gillnets, trawling
gear and longlines. These authors also draw attention to the exceptional value of the
population of E. paraplexauroides of Chafarinas Islands. In fact, this species was
included in 2013 in Annex II of the Barcelona Convention, among other gorgonians
and corals (see Sect. 10.5), and listed as “vulnerable” in the IUCN Red List.
10.1.3 Astroides calycularis
Another conspicuous and emblematic species of the Alboran Sea is the scleractinian
coral Astroides calycularis (Figs. 10.2 and 10.3), known as “Mediterranean orange
coral” because of the deep orange colour of its coenosarc and polyps (Zibrowius
1995). This species is also well represented in few sectors of the Tyrrhenian Sea,
Sicily and Malta and on the Zembra Island in Tunisia, but the greatest concentration
and distribution of colonies occurs in the Strait of Gibraltar and Alboran Sea. It
barely extends into Atlantic waters beyond the Strait of Gibraltar, and its known
western limit of distribution is located at La Caleta, Cadiz City (Moreno et al.
2008a).
⁄
ä
Fig. 10.2 (continued) coral Astroides calycularis and the yellow coral Leptopsammia pruvoti (22 m
depth) [Luis Sánchez Tocino]
10 Invertebrates: The Realm of Diversity
363
biology and ecology. In most of its distribution area, this gorgonian seems to be
located on shelf bottoms mainly in the depth range of 50–200 m. Nevertheless, in the
Canary Islands has been recorded at the extreme depths of 690 m (Brito and Ocaña
2004), while in the Strait of Gibraltar area and around the Chafarinas Islands can be
found as shallow as 15–20 m depth (Ocaña et al. 2009; Maldonado et al. 2013).
Scattered colonies have been found in the deep shelf around the Alboran Island
(Templado et al. 2006; Gofas et al. 2014) between 70 and 200 m depth and in the
Seco de los Olivos (also known as Chella Bank) below 80 m depth (Aguilar et al.
2008; de la Torriente et al. 2014). Likewise, some colonies were photographed and
sampled from 80 to 94 m depth on the northeast coasts of Pantelleria Island
(Angiolillo et al. 2012).
The occurrence of Ellisella paraplexauroides around the Chafarinas Islands is
noteworthy. This species dominates the underwater rocky landscape from about
17–20 m deep with an average density of 0.5 colonies m
À2 (maximum, 5 colonies
m
À2 ) (Maldonado et al. 2013). These authors pointed out that this unique population
requires serious conservation attention owing to considerable damage caused by
small-scale fishing operations. Likewise, Otero et al. (2017) highlight that this
gorgonian should be considered “vulnerable” in the Mediterranean basin, since its
populations are concentrated around the few sites mentioned and have suffered a
drastic decline over recent decades. This decline is mainly related to the impact of
unregulated and illegal fisheries, particularly the use of benthic gillnets, trawling
gear and longlines. These authors also draw attention to the exceptional value of the
population of E. paraplexauroides of Chafarinas Islands. In fact, this species was
included in 2013 in Annex II of the Barcelona Convention, among other gorgonians
and corals (see Sect. 10.5), and listed as “vulnerable” in the IUCN Red List.
10.1.3 Astroides calycularis
Another conspicuous and emblematic species of the Alboran Sea is the scleractinian
coral Astroides calycularis (Figs. 10.2 and 10.3), known as “Mediterranean orange
coral” because of the deep orange colour of its coenosarc and polyps (Zibrowius
1995). This species is also well represented in few sectors of the Tyrrhenian Sea,
Sicily and Malta and on the Zembra Island in Tunisia, but the greatest concentration
and distribution of colonies occurs in the Strait of Gibraltar and Alboran Sea. It
barely extends into Atlantic waters beyond the Strait of Gibraltar, and its known
western limit of distribution is located at La Caleta, Cadiz City (Moreno et al.
2008a).
⁄
ä
Fig. 10.2 (continued) coral Astroides calycularis and the yellow coral Leptopsammia pruvoti (22 m
depth) [Luis Sánchez Tocino]
10 Invertebrates: The Realm of Diversity
363