2011; Espinosa et al. 2015). Most of the marine caves studied in the area are small
and shallow, although deeper (below 30 m deep) and longer (approximately 100 m
long) caves have been also described (Navarro-Barranco et al. 2015).
A common biological feature is the so-called biocenosis of semi-dark caves,
where dim light favours the dominance of sessile invertebrates, such as the sponges
Dysidea avara, Sarcotragus spp., Petrosia ficiformis and Chondrosia reniformis, the
anthozoans Astroides calycularis and Parazoanthus axinellae, different species of
gorgonians, the bryozoans Adeonella calveti and Pentapora fascialis and the fishes
Phycis phycis and Conger conger among others. Those species are not exclusive of
cave habitats, being also found in other sciaphilous environments (crevices, overhangs, coralligenous assemblages) or photic habitats but with less coverage by
sessile organisms.
The Cerro Gordo marine cave, located in the coast of La Herradura (Granada), is
the most interesting and studied cave in this area. Due to their extensive length, inner
areas within this cave are characterized by constant conditions of darkness and by
water confinement. Benthic taxa occurring in the innermost part of the cave are
highly specialized species (Fig. 9.15), mainly encrusting sponges and bryozoans,
brachiopods (Novocrania anomala, Megathiris detruncata) or serpulid polychaetes
(Navarro-Barranco et al. 2015).
Unlike sessile communities, other elements of Alboran cave fauna (mainly
crustaceans) are relatively well known in comparison with other Mediterranean
areas. The singularity of mobile epifaunal assemblages inhabiting cave sediments
and hard substrates has been highlighted (Navarro-Barranco et al. 2013, 2014). The
spatial distribution, trophic ecology and colonization patterns of the Amphipoda,
which constitute the best-known cave-dwelling macrofaunal group in this area
(49 species reported until know), have also been explored (Navarro-Barranco
2015; Navarro-Barranco et al. 2015). Dense swarms of the Mediterranean endemic
mysid Hemimysis margalefi can be found inside some of the caves (Rastorgueff et al.
2014), as well as the sponge-feeding molluscs Naria spurca, Luria lurida,
Peltodoris atromaculata and Berthella ocellata or the decapods Stenopus spinosus,
Palaemon serratus, Lysmata seticaudata and Dromia personata. Regarding fishes,
the cardinal fish Apogon imberbis or the leopard-spotted goby (Thorogobius
ephippiatus) are frequent in caves.
Ecological studies conducted in caves in the Alboran Sea have pointed out the
slow rate of colonization, the uniqueness of their species composition and the high
stability of the environmental conditions, supporting the current consideration of
marine caves as highly valuable and sensitive habitats to human perturbation.
Although recent studies conducted within the Cerro Gordo cave have highlighted
its good environmental status, significant temporal variations of the sessile assemblage structure have occurred during the last decade (both at internal and external
cave sectors) (Navarro-Barranco et al. 2015).
Submarine caves are adequately defined in the EU Habitats Directive as “8330
Submerged or partially submerged sea caves” (López-Bedoya and Pérez-Alberti
2009) and are therefore eligible for inclusion in a marine Special Area of Conservation. The major human source of impacts suggested for marine caves are due to
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J. L. Rueda et al.
and shallow, although deeper (below 30 m deep) and longer (approximately 100 m
long) caves have been also described (Navarro-Barranco et al. 2015).
A common biological feature is the so-called biocenosis of semi-dark caves,
where dim light favours the dominance of sessile invertebrates, such as the sponges
Dysidea avara, Sarcotragus spp., Petrosia ficiformis and Chondrosia reniformis, the
anthozoans Astroides calycularis and Parazoanthus axinellae, different species of
gorgonians, the bryozoans Adeonella calveti and Pentapora fascialis and the fishes
Phycis phycis and Conger conger among others. Those species are not exclusive of
cave habitats, being also found in other sciaphilous environments (crevices, overhangs, coralligenous assemblages) or photic habitats but with less coverage by
sessile organisms.
The Cerro Gordo marine cave, located in the coast of La Herradura (Granada), is
the most interesting and studied cave in this area. Due to their extensive length, inner
areas within this cave are characterized by constant conditions of darkness and by
water confinement. Benthic taxa occurring in the innermost part of the cave are
highly specialized species (Fig. 9.15), mainly encrusting sponges and bryozoans,
brachiopods (Novocrania anomala, Megathiris detruncata) or serpulid polychaetes
(Navarro-Barranco et al. 2015).
Unlike sessile communities, other elements of Alboran cave fauna (mainly
crustaceans) are relatively well known in comparison with other Mediterranean
areas. The singularity of mobile epifaunal assemblages inhabiting cave sediments
and hard substrates has been highlighted (Navarro-Barranco et al. 2013, 2014). The
spatial distribution, trophic ecology and colonization patterns of the Amphipoda,
which constitute the best-known cave-dwelling macrofaunal group in this area
(49 species reported until know), have also been explored (Navarro-Barranco
2015; Navarro-Barranco et al. 2015). Dense swarms of the Mediterranean endemic
mysid Hemimysis margalefi can be found inside some of the caves (Rastorgueff et al.
2014), as well as the sponge-feeding molluscs Naria spurca, Luria lurida,
Peltodoris atromaculata and Berthella ocellata or the decapods Stenopus spinosus,
Palaemon serratus, Lysmata seticaudata and Dromia personata. Regarding fishes,
the cardinal fish Apogon imberbis or the leopard-spotted goby (Thorogobius
ephippiatus) are frequent in caves.
Ecological studies conducted in caves in the Alboran Sea have pointed out the
slow rate of colonization, the uniqueness of their species composition and the high
stability of the environmental conditions, supporting the current consideration of
marine caves as highly valuable and sensitive habitats to human perturbation.
Although recent studies conducted within the Cerro Gordo cave have highlighted
its good environmental status, significant temporal variations of the sessile assemblage structure have occurred during the last decade (both at internal and external
cave sectors) (Navarro-Barranco et al. 2015).
Submarine caves are adequately defined in the EU Habitats Directive as “8330
Submerged or partially submerged sea caves” (López-Bedoya and Pérez-Alberti
2009) and are therefore eligible for inclusion in a marine Special Area of Conservation. The major human source of impacts suggested for marine caves are due to
318
J. L. Rueda et al.