hexactinellids, such as those of Asconema setubalense, have been reported usually
close to steep escarpments. On the Seco de los Olivos (Fig. 9.21), areas dominated
by this large sponge have been recorded throughout the two main ridges surrounding
the main central guyot (Pardo et al. 2011; de la Torriente et al. 2018) and represents a
dominant accompanying species in the Cabliers cold-water coral reefs (Corbera et al.
2019). Another hexactinellid sponge, the small and stalked Sympagella delauzei,
was recently described from several seamounts of the Alboran Sea, growing on rocks
but also on coral rubble (Boury-Esnault et al. 2015).
Other species forming part of the bathyal sponge communities are Geodia sp.,
Phakellia robusta, P. ventilabrum and the “lollipop” sponges of the genera
Podospongia, Crella and Stylocordyla (de la Torriente et al. 2014, 2018; Gofas
et al. 2014a). The latter small sponges may be abundant on the substrate forming a
dense undergrowth beneath larger sponges and gorgonians. Poecillastra compressa
and Pachastrella monilifera are also key structuring sponges from the circalittoral to
the bathyal in the Alboran Sea (Sitjà and Maldonado 2014).
Dense aggregations of the giant deep-sea oyster Neopycnodonte zibrowii colonizing vertical walls and overhangs have been found on the Djibouti Banks (Hebbeln
et al. 2009) and Seco de los Olivos (de la Torriente et al. 2014), whereas aggregations of the smaller Neopycnodonte cochlear can be found almost everywhere in the
Alboran Sea at shallower depths (80–200 m).
Additionally, other species which may be found on bathyal hard bottoms of the
Alboran Sea are mobile species such as sea urchins (Cidaris cidaris, Gracilechinus
acutus), sea cucumbers (Holothuria spp.), brittle stars (Ophiothrix spp.) and crinoids
(Leptometra phalangium), but they are not restricted to hard bottoms and can also be
found on deep bioclastic gravels. Particularly, dense aggregations of Cidaris cidaris
and Leptometra phalangium were recorded on the Seco de los Olivos (de la
Torriente et al. 2014) and Djibouti Banks (Gofas et al. 2014a), respectively. There
is also a wide representation of crustaceans such as crayfish (Palinurus
mauritanicus), squat lobsters (Munida sp.) and shrimps of the genera Plesionika
(P. edwardsii, P. gigliolii, P. narval) (Aguilar et al. 2008).
The hard bottoms of the bathyal zone are included in the broad concept of “1170
Reefs” (Templado et al. 2009) of the EU Habitats Directive. In addition, the use of
towed dredges and trawl nets in fisheries at depths beyond 1000 m 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). “Submarine canyons”, “Seamounts”,
and “Deep sea corals (Lophelia pertusa and Madrepora oculata beds)” are 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).
Although the Alboran Sea is not within the scope of OSPAR convention, it is worth
taking note that “carbonate mounds”, “coral gardens”, “deep-sea sponge aggregations” and “Lophelia pertusa reefs” are placed on the OSPAR list of threatened
and/or declining species and habitats. Recently in 2013, some progress has been
made in including several species of cold-water corals (M. oculata and D. pertusum)
338
J. L. Rueda et al.
close to steep escarpments. On the Seco de los Olivos (Fig. 9.21), areas dominated
by this large sponge have been recorded throughout the two main ridges surrounding
the main central guyot (Pardo et al. 2011; de la Torriente et al. 2018) and represents a
dominant accompanying species in the Cabliers cold-water coral reefs (Corbera et al.
2019). Another hexactinellid sponge, the small and stalked Sympagella delauzei,
was recently described from several seamounts of the Alboran Sea, growing on rocks
but also on coral rubble (Boury-Esnault et al. 2015).
Other species forming part of the bathyal sponge communities are Geodia sp.,
Phakellia robusta, P. ventilabrum and the “lollipop” sponges of the genera
Podospongia, Crella and Stylocordyla (de la Torriente et al. 2014, 2018; Gofas
et al. 2014a). The latter small sponges may be abundant on the substrate forming a
dense undergrowth beneath larger sponges and gorgonians. Poecillastra compressa
and Pachastrella monilifera are also key structuring sponges from the circalittoral to
the bathyal in the Alboran Sea (Sitjà and Maldonado 2014).
Dense aggregations of the giant deep-sea oyster Neopycnodonte zibrowii colonizing vertical walls and overhangs have been found on the Djibouti Banks (Hebbeln
et al. 2009) and Seco de los Olivos (de la Torriente et al. 2014), whereas aggregations of the smaller Neopycnodonte cochlear can be found almost everywhere in the
Alboran Sea at shallower depths (80–200 m).
Additionally, other species which may be found on bathyal hard bottoms of the
Alboran Sea are mobile species such as sea urchins (Cidaris cidaris, Gracilechinus
acutus), sea cucumbers (Holothuria spp.), brittle stars (Ophiothrix spp.) and crinoids
(Leptometra phalangium), but they are not restricted to hard bottoms and can also be
found on deep bioclastic gravels. Particularly, dense aggregations of Cidaris cidaris
and Leptometra phalangium were recorded on the Seco de los Olivos (de la
Torriente et al. 2014) and Djibouti Banks (Gofas et al. 2014a), respectively. There
is also a wide representation of crustaceans such as crayfish (Palinurus
mauritanicus), squat lobsters (Munida sp.) and shrimps of the genera Plesionika
(P. edwardsii, P. gigliolii, P. narval) (Aguilar et al. 2008).
The hard bottoms of the bathyal zone are included in the broad concept of “1170
Reefs” (Templado et al. 2009) of the EU Habitats Directive. In addition, the use of
towed dredges and trawl nets in fisheries at depths beyond 1000 m 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). “Submarine canyons”, “Seamounts”,
and “Deep sea corals (Lophelia pertusa and Madrepora oculata beds)” are 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).
Although the Alboran Sea is not within the scope of OSPAR convention, it is worth
taking note that “carbonate mounds”, “coral gardens”, “deep-sea sponge aggregations” and “Lophelia pertusa reefs” are placed on the OSPAR list of threatened
and/or declining species and habitats. Recently in 2013, some progress has been
made in including several species of cold-water corals (M. oculata and D. pertusum)
338
J. L. Rueda et al.