(Zibrowius 1980; Taviani et al. 2005). However, the advent of the new deep-sea
exploration technologies has highlighted the richness of the Mediterranean deep-sea
environments (Angiolillo and Canese 2018). As a result, large and highly structured
CWC communities characterized by a significant coral growth and colonies density
have been found in specific areas, such as the northern Ionian Sea, the Southwestern
Adriatic Sea, the Strait of Sicily, the Sardinia Channel, the most westerly part of the
Gulf of Lions submarine canyon system and the Alboran Sea (Orejas et al. 2009;
Chimienti et al. 2018).
Radiocarbon ages of these reef-forming coral species revealed that they proliferated in the Alboran Sea during the last glacial-interglacial transition and the Early
Holocene (ca.13–10 ka BP) with pronounced growth periods (Fink et al. 2013).
After a subsequent period of coral absence, cold-water corals recolonized this basin
during the Mid-Holocene (about 5.4 ka BP). According to Fink et al. (2013), that
period of sustained cold-water coral growth in this area was closely linked to phases
of high marine productivity. In more recent times, changes in hydrodynamic conditions have produced a shift from a CWC community dominated by Desmophyllum
pertusum to other dominated by Madrepora oculata and dendrophylliid corals
(Stalder et al. 2015). These authors pointed that their data suggest that M. oculata,
and in particular dendrophylliids, show a higher tolerance to environmental changes
than D. pertusum, whose upper limit of thermal tolerance is near 15
C (Gori et al.
2014).
According to Pardo et al. (2011), nowadays white cold-water corals generate
three distinct habitats widespread along the Alboran Sea: reefs and colonies of live
corals, dead coral reefs and extensive bottoms covered with coral debris (rubbles),
allowing the existence and settlement of different species and biocenosis. Dead
corals predominate, while small reef patches of living colonies appear scattered in
seamounts and escarpments, mainly observed from ca. 200–600 m depth, with the
dominance of Madrepora oculata on most of the locations. Specifically, up to date,
living CWC have been observed in the following sites of the Alboran Sea:
– Avempace Bank: isolated, living colonies of M. oculata at 350–360 m depth
(Pardo et al. 2011).
– El Idrissi Bank: isolated colonies of M. oculata at about 400 m depth (Hebbeln
et al. 2009).
– Alboran Ridge: living colonies of M. oculata deeper than 400 m (Templado et al.
2006).
– Seco de los Olivos: living colonies of Desmophyllum pertusum, M. oculata and
specimens of D. dianthus below 220 m depth (Pardo et al. 2011). The highest
densities were found between 300 and 500 m on rocky walls with steep slopes,
but they extend down to 650 m (de la Torriente et al. 2018). These cold-water
corals appeared intermixed with diverse communities where occur other
scleractinians as Dendrophyllia cornigera, Caryophyllia calveri or the Atlantic
species Anomocora fecunda.
– Catifas Bank (W Cabliers): living colonies of M. oculata and D. pertusum at
about 360–460 m in depth (Pardo et al. 2011).
10 Invertebrates: The Realm of Diversity
389
exploration technologies has highlighted the richness of the Mediterranean deep-sea
environments (Angiolillo and Canese 2018). As a result, large and highly structured
CWC communities characterized by a significant coral growth and colonies density
have been found in specific areas, such as the northern Ionian Sea, the Southwestern
Adriatic Sea, the Strait of Sicily, the Sardinia Channel, the most westerly part of the
Gulf of Lions submarine canyon system and the Alboran Sea (Orejas et al. 2009;
Chimienti et al. 2018).
Radiocarbon ages of these reef-forming coral species revealed that they proliferated in the Alboran Sea during the last glacial-interglacial transition and the Early
Holocene (ca.13–10 ka BP) with pronounced growth periods (Fink et al. 2013).
After a subsequent period of coral absence, cold-water corals recolonized this basin
during the Mid-Holocene (about 5.4 ka BP). According to Fink et al. (2013), that
period of sustained cold-water coral growth in this area was closely linked to phases
of high marine productivity. In more recent times, changes in hydrodynamic conditions have produced a shift from a CWC community dominated by Desmophyllum
pertusum to other dominated by Madrepora oculata and dendrophylliid corals
(Stalder et al. 2015). These authors pointed that their data suggest that M. oculata,
and in particular dendrophylliids, show a higher tolerance to environmental changes
than D. pertusum, whose upper limit of thermal tolerance is near 15
C (Gori et al.
2014).
According to Pardo et al. (2011), nowadays white cold-water corals generate
three distinct habitats widespread along the Alboran Sea: reefs and colonies of live
corals, dead coral reefs and extensive bottoms covered with coral debris (rubbles),
allowing the existence and settlement of different species and biocenosis. Dead
corals predominate, while small reef patches of living colonies appear scattered in
seamounts and escarpments, mainly observed from ca. 200–600 m depth, with the
dominance of Madrepora oculata on most of the locations. Specifically, up to date,
living CWC have been observed in the following sites of the Alboran Sea:
– Avempace Bank: isolated, living colonies of M. oculata at 350–360 m depth
(Pardo et al. 2011).
– El Idrissi Bank: isolated colonies of M. oculata at about 400 m depth (Hebbeln
et al. 2009).
– Alboran Ridge: living colonies of M. oculata deeper than 400 m (Templado et al.
2006).
– Seco de los Olivos: living colonies of Desmophyllum pertusum, M. oculata and
specimens of D. dianthus below 220 m depth (Pardo et al. 2011). The highest
densities were found between 300 and 500 m on rocky walls with steep slopes,
but they extend down to 650 m (de la Torriente et al. 2018). These cold-water
corals appeared intermixed with diverse communities where occur other
scleractinians as Dendrophyllia cornigera, Caryophyllia calveri or the Atlantic
species Anomocora fecunda.
– Catifas Bank (W Cabliers): living colonies of M. oculata and D. pertusum at
about 360–460 m in depth (Pardo et al. 2011).
10 Invertebrates: The Realm of Diversity
389