Additionally, several submarine canyons have been studied within the Alboran
basin in the last decade, providing some information of the coralligenous communities inhabiting these systems. Regarding this, La Línea de la Concepción and
Guadiaro submarine canyon heads in the northwestern part of the Alboran shelf
(60–100 m depth) display mixed bottoms composed of rocky boulders, gravels and
biogenic remains that are colonized by the abundant Eunicella verrucosa, together
with Leptogorgia sarmentosa in the case of La Línea canyon, with individuals of
Astrospartus mediterraneus laying on branched gorgonian colonies (Vázquez et al.
2015). Secondary typifying species of these communities include dispersed small
colonies of the cold-water coral Dendrophyllia cornigera, as well as echinoderms
such as Centrostephanus longispinus and Cidaris cidaris or the echiurian Bonellia
viridis. In deeper settings (140–200 m), colonies of Callogorgia verticillata,
Dendrophyllia cornigera and Caryophyllia solitary corals were observed in high
density in coralligenous communities of the Guadiaro canyon (Vázquez et al. 2015).
All coralligenous (and precoralligenous) bottoms can easily be encompassed in
the broadly defined habitat of “1170 Reefs” (Templado et al. 2009) of the EU
Habitats Directive. Furthermore, the use of towed dredges and trawl nets fisheries
over coralligenous bottoms is forbidden under Art. 4 of the Council Regulation
(EC) No 1967/2006 concerning management measures for the sustainable exploitation of fishery resources in the Mediterranean Sea (Council of the European Union
2006). “Coralligenous beds” are also listed as “Essential Marine Habitats (EMH) of
relevance for the management of priority species” by the Scientific Advisory Committee of the General Fisheries Commission for the Mediterranean (General Fisheries Commission for the Mediterranean 2009). A few of the characteristic species,
e.g. the sea urchin Centrostephanus longispinus and more recently several species of
gorgonians and black corals, have been included in Annex 2 of the Barcelona
convention, but this is of limited consequence unless national bylaws enforce
protection in practice. The red coral Corallium rubrum, the most sought after species
in this environment, is of particular concern, and information on its conservation
status and exploitation is thoroughly discussed in Chap. 10.
9.5 Caves
Despite being considered as unique and sensitive habitats requiring protection under
EU Habitats Directive, the number of studies dealing with marine caves and their
biota in the Alboran Sea is scarce, and, as a consequence, this is the Mediterranean
region with the lowest number of marine caves reported (Giakoumi et al. 2013). To
date, all ecological studies have been conducted in the northern part of the Alboran
Sea (mainly in the coast of Granada) (Navarro-Barranco 2015), while the biota of
Moroccan caves remain almost unexplored. Nevertheless, long stretches of the
coastline along the southern margin of the Alboran Sea are composed by limestone
cliffs which likely contain marine caves, some of them already reported at the Cap de
Trois Fourches, Al-Hoceima National Park or Chafarinas Islands (Maldonado et al.
9 Benthic Fauna of Littoral and Deep-Sea Habitats of the Alboran Sea: A. . .
317
basin in the last decade, providing some information of the coralligenous communities inhabiting these systems. Regarding this, La Línea de la Concepción and
Guadiaro submarine canyon heads in the northwestern part of the Alboran shelf
(60–100 m depth) display mixed bottoms composed of rocky boulders, gravels and
biogenic remains that are colonized by the abundant Eunicella verrucosa, together
with Leptogorgia sarmentosa in the case of La Línea canyon, with individuals of
Astrospartus mediterraneus laying on branched gorgonian colonies (Vázquez et al.
2015). Secondary typifying species of these communities include dispersed small
colonies of the cold-water coral Dendrophyllia cornigera, as well as echinoderms
such as Centrostephanus longispinus and Cidaris cidaris or the echiurian Bonellia
viridis. In deeper settings (140–200 m), colonies of Callogorgia verticillata,
Dendrophyllia cornigera and Caryophyllia solitary corals were observed in high
density in coralligenous communities of the Guadiaro canyon (Vázquez et al. 2015).
All coralligenous (and precoralligenous) bottoms can easily be encompassed in
the broadly defined habitat of “1170 Reefs” (Templado et al. 2009) of the EU
Habitats Directive. Furthermore, the use of towed dredges and trawl nets fisheries
over coralligenous bottoms is forbidden under Art. 4 of the Council Regulation
(EC) No 1967/2006 concerning management measures for the sustainable exploitation of fishery resources in the Mediterranean Sea (Council of the European Union
2006). “Coralligenous beds” are also listed as “Essential Marine Habitats (EMH) of
relevance for the management of priority species” by the Scientific Advisory Committee of the General Fisheries Commission for the Mediterranean (General Fisheries Commission for the Mediterranean 2009). A few of the characteristic species,
e.g. the sea urchin Centrostephanus longispinus and more recently several species of
gorgonians and black corals, have been included in Annex 2 of the Barcelona
convention, but this is of limited consequence unless national bylaws enforce
protection in practice. The red coral Corallium rubrum, the most sought after species
in this environment, is of particular concern, and information on its conservation
status and exploitation is thoroughly discussed in Chap. 10.
9.5 Caves
Despite being considered as unique and sensitive habitats requiring protection under
EU Habitats Directive, the number of studies dealing with marine caves and their
biota in the Alboran Sea is scarce, and, as a consequence, this is the Mediterranean
region with the lowest number of marine caves reported (Giakoumi et al. 2013). To
date, all ecological studies have been conducted in the northern part of the Alboran
Sea (mainly in the coast of Granada) (Navarro-Barranco 2015), while the biota of
Moroccan caves remain almost unexplored. Nevertheless, long stretches of the
coastline along the southern margin of the Alboran Sea are composed by limestone
cliffs which likely contain marine caves, some of them already reported at the Cap de
Trois Fourches, Al-Hoceima National Park or Chafarinas Islands (Maldonado et al.
9 Benthic Fauna of Littoral and Deep-Sea Habitats of the Alboran Sea: A. . .
317