and stalked sponges such as Crella pyrula, Podospongia lovenii, Rhizaxinella
elongata, R. gracilis or Stylocordyla sp.
10.3.2 Gorgonians
The so-called gorgonian forests are one of the most emblematic Mediterranean
marine communities, showing a high diversity and great structural complexity.
The nearly 30 species forming these forests have different morphologies, with
sizes varying between a few centimetres and more than 2–3 m high and inhabit a
wide range of environments (Gori et al. 2017). They are typical on hard bottoms, but
some of them are also able to tolerate high levels of sedimentation or to anchor
themselves on soft bottoms and form dense monospecific or multispecific assemblages that can extend over large areas.
Most of the Mediterranean species of gorgonians are present in the Alboran Sea,
as well as some Atlantic species such as Eunicella gazella, E. labiata, E. filiformis,
Filigorgia guineensis, Spinimuricea atlantica or Ellisella paraplexauroides, some of
them coming from northwestern Africa. This fact determines that the bottoms of the
Strait of Gibraltar and the Alboran Sea harbour more species than other Mediterranean or nearby Atlantic areas. Specifically, up to 19 species have been recorded in
the bottoms surrounding the Alboran Island down to 500 m depth (Templado et al.
2006). In contrast, for example, only eight species were found in Tunisian waters
within the depth range of 7–120 m (Ghanem et al. 2018), nine were observed
between 40 and 360 m depth in the Menorca Channel (Grinyó et al. 2016), and
five species were observed in the Algarve coast down to 30 m depth (Cúrdia et al.
2013).
Four gorgonian species are commonly present in shallow areas of the Mediterranean (Gori et al. 2012), namely, Eunicella singularis, E. cavolinii, Paramuricea
clavata and Leptogorgia sarmentosa. In the Alboran Sea, E. cavolinii becomes very
rare, being replaced by another species such as Eunicella labiata (Fig. 10.2). Furthermore, in the Strait of Gibraltar and Chafarinas Islands, the abovementioned
Ellisella paraplexauroides (Fig. 10.2) can be found as shallow as about 20 m.
Eunicella singularis can be considered the most common and abundant gorgonian species and the only one known to host symbiotic algae. It is abundant
throughout the western Mediterranean and Adriatic Sea, is occasionally present in
the eastern Mediterranean and reaches the coasts of the Algarve in the near Atlantic.
This species is common on rocky bottoms in shallow waters, as well as on deeper
coralligenous formations. The extensive distribution of E. singularis on a regional
scale may be related to its tolerance to a wide range of irradiance and abiotic factors,
and it is found commonly on horizontal or sloping bottoms (Linares et al. 2008a;
Gori et al. 2011). In contrast, the emblematic Mediterranean red gorgonian
Paramuricea clavata show a more patchy distribution mainly in the western basin
of the Mediterranean and the Adriatic Sea. It is associated with vertical rocky walls
and occupied a narrow range of light and environmental conditions from about 20 m
10 Invertebrates: The Realm of Diversity
377
elongata, R. gracilis or Stylocordyla sp.
10.3.2 Gorgonians
The so-called gorgonian forests are one of the most emblematic Mediterranean
marine communities, showing a high diversity and great structural complexity.
The nearly 30 species forming these forests have different morphologies, with
sizes varying between a few centimetres and more than 2–3 m high and inhabit a
wide range of environments (Gori et al. 2017). They are typical on hard bottoms, but
some of them are also able to tolerate high levels of sedimentation or to anchor
themselves on soft bottoms and form dense monospecific or multispecific assemblages that can extend over large areas.
Most of the Mediterranean species of gorgonians are present in the Alboran Sea,
as well as some Atlantic species such as Eunicella gazella, E. labiata, E. filiformis,
Filigorgia guineensis, Spinimuricea atlantica or Ellisella paraplexauroides, some of
them coming from northwestern Africa. This fact determines that the bottoms of the
Strait of Gibraltar and the Alboran Sea harbour more species than other Mediterranean or nearby Atlantic areas. Specifically, up to 19 species have been recorded in
the bottoms surrounding the Alboran Island down to 500 m depth (Templado et al.
2006). In contrast, for example, only eight species were found in Tunisian waters
within the depth range of 7–120 m (Ghanem et al. 2018), nine were observed
between 40 and 360 m depth in the Menorca Channel (Grinyó et al. 2016), and
five species were observed in the Algarve coast down to 30 m depth (Cúrdia et al.
2013).
Four gorgonian species are commonly present in shallow areas of the Mediterranean (Gori et al. 2012), namely, Eunicella singularis, E. cavolinii, Paramuricea
clavata and Leptogorgia sarmentosa. In the Alboran Sea, E. cavolinii becomes very
rare, being replaced by another species such as Eunicella labiata (Fig. 10.2). Furthermore, in the Strait of Gibraltar and Chafarinas Islands, the abovementioned
Ellisella paraplexauroides (Fig. 10.2) can be found as shallow as about 20 m.
Eunicella singularis can be considered the most common and abundant gorgonian species and the only one known to host symbiotic algae. It is abundant
throughout the western Mediterranean and Adriatic Sea, is occasionally present in
the eastern Mediterranean and reaches the coasts of the Algarve in the near Atlantic.
This species is common on rocky bottoms in shallow waters, as well as on deeper
coralligenous formations. The extensive distribution of E. singularis on a regional
scale may be related to its tolerance to a wide range of irradiance and abiotic factors,
and it is found commonly on horizontal or sloping bottoms (Linares et al. 2008a;
Gori et al. 2011). In contrast, the emblematic Mediterranean red gorgonian
Paramuricea clavata show a more patchy distribution mainly in the western basin
of the Mediterranean and the Adriatic Sea. It is associated with vertical rocky walls
and occupied a narrow range of light and environmental conditions from about 20 m
10 Invertebrates: The Realm of Diversity
377