least 60% of the surface occupied by this habitat must be included in Nature 2000
Special Areas of Conservation in order to consider their protection as sufficient
(European Commission 2007: 43).
There are scanty nineteenth- and twentieth-century reports of Posidonia as far
west as the bay of Algeciras, particularly from the Gibraltar harbour (Bull et al.
2010), and that could explain old records in that area of molluscs commonly linked
to Posidonia meadows and nowadays absent from the area (e. g. Tricolia speciosa,
Cardites antiquatus). Surveys in the Calahonda SAC (Málaga) show an alarming
extension of dead Posidonia rhizomes now overgrown by macroalgal communities
or covered by sand, pointing to ongoing decline of this emblematic species in the
westernmost part of its distribution range (García Raso et al. 2010).
9.4.3 Kelp Forests
Large brown algae such as Laminaria ochroleuca, Saccorhiza polyschides and
Phyllariopsis spp., widely distributed along the Atlantic coasts, reach some parts
of the Alboran Sea. Surprisingly, despite the great animal diversity that lives in this
complex habitat, the fauna that inhabits the kelp forest of the Strait of Gibraltar and
Alboran Island has not been studied in detail. The only available data comes from the
observations made during the Fauna IV campaign in the Laminaria/Saccorhiza
forests surrounding the Alboran Island between 25 and 50 m in depth (Fig. 9.10).
These data were included in a chapter within the book on the marine vegetal
communities of Andalusia (Luque and Templado 2004) and later in the monograph
of the fauna and flora of Alboran (Templado et al. 2006).
Few animal species can be found on the smooth blades of these large algae,
possibly because they segregate antifouling substances and for being very beaten by
the strong currents, which may make the larvae settlement difficult. Among these
few species, the most outstanding is the bryozoan Membranipora membranacea
(exclusive of the blades of Laminariales), the anemone Alicia mirabilis and the
colonial ascidians of the genus Botryllus. Sometimes the sea urchin Sphaerechinus
granularis can be found eating these blades, although their preferred food are
encrusting red algae of the basal layer of the kelp forests. The limpet Patella
pellucida, which is an obligate associate of the kelp, has not been seen on the
kelps of the Alboran Sea, being reported only from Tangiers (Gofas et al. 2011).
The basal stratum of these forests (Fig. 9.10) is often composed of encrusting red
algae and is inhabited by a rich community of sciaphilous species dominated by
sponges and ascidians, often with a coverage close to 100%. Among the most
conspicuous species are several gorgonians (Eunicella verrucosa, Eunicella gazella,
Eunicella labiata, Leptogorgia sarmentosa) intermingled with the kelp. The white
gorgonian Eunicella verrucosa may reach a high density (up to 20 colonies/m
2 ),
although the size of their colonies is relatively small. Other frequent sessile species
are the serpulid worms Serpula vermicularis and Protula intestinum, the octocorals
Alcyonium acaule and Parerythropodium coralloides (the latter usually on the
9 Benthic Fauna of Littoral and Deep-Sea Habitats of the Alboran Sea: A. . .
309
Special Areas of Conservation in order to consider their protection as sufficient
(European Commission 2007: 43).
There are scanty nineteenth- and twentieth-century reports of Posidonia as far
west as the bay of Algeciras, particularly from the Gibraltar harbour (Bull et al.
2010), and that could explain old records in that area of molluscs commonly linked
to Posidonia meadows and nowadays absent from the area (e. g. Tricolia speciosa,
Cardites antiquatus). Surveys in the Calahonda SAC (Málaga) show an alarming
extension of dead Posidonia rhizomes now overgrown by macroalgal communities
or covered by sand, pointing to ongoing decline of this emblematic species in the
westernmost part of its distribution range (García Raso et al. 2010).
9.4.3 Kelp Forests
Large brown algae such as Laminaria ochroleuca, Saccorhiza polyschides and
Phyllariopsis spp., widely distributed along the Atlantic coasts, reach some parts
of the Alboran Sea. Surprisingly, despite the great animal diversity that lives in this
complex habitat, the fauna that inhabits the kelp forest of the Strait of Gibraltar and
Alboran Island has not been studied in detail. The only available data comes from the
observations made during the Fauna IV campaign in the Laminaria/Saccorhiza
forests surrounding the Alboran Island between 25 and 50 m in depth (Fig. 9.10).
These data were included in a chapter within the book on the marine vegetal
communities of Andalusia (Luque and Templado 2004) and later in the monograph
of the fauna and flora of Alboran (Templado et al. 2006).
Few animal species can be found on the smooth blades of these large algae,
possibly because they segregate antifouling substances and for being very beaten by
the strong currents, which may make the larvae settlement difficult. Among these
few species, the most outstanding is the bryozoan Membranipora membranacea
(exclusive of the blades of Laminariales), the anemone Alicia mirabilis and the
colonial ascidians of the genus Botryllus. Sometimes the sea urchin Sphaerechinus
granularis can be found eating these blades, although their preferred food are
encrusting red algae of the basal layer of the kelp forests. The limpet Patella
pellucida, which is an obligate associate of the kelp, has not been seen on the
kelps of the Alboran Sea, being reported only from Tangiers (Gofas et al. 2011).
The basal stratum of these forests (Fig. 9.10) is often composed of encrusting red
algae and is inhabited by a rich community of sciaphilous species dominated by
sponges and ascidians, often with a coverage close to 100%. Among the most
conspicuous species are several gorgonians (Eunicella verrucosa, Eunicella gazella,
Eunicella labiata, Leptogorgia sarmentosa) intermingled with the kelp. The white
gorgonian Eunicella verrucosa may reach a high density (up to 20 colonies/m
2 ),
although the size of their colonies is relatively small. Other frequent sessile species
are the serpulid worms Serpula vermicularis and Protula intestinum, the octocorals
Alcyonium acaule and Parerythropodium coralloides (the latter usually on the
9 Benthic Fauna of Littoral and Deep-Sea Habitats of the Alboran Sea: A. . .
309