eutrophication, the eulittoral becomes dominated by cyanobacteria (Templado et al.
2012) or other fast-growing filamentous algae.
8.4.3 Infralittoral Zone
The infralittoral zone is permanently submerged. Its upper limit is defined by the
absence of species that cannot tolerate emersion, and the lower limit is delimited by
the disappearance of seagrasses and photophilic algae. In this zone, water is not a
limiting factor, hydrodynamism becomes less pronounced, and salinity is almost
constant. The type of substrate and the light gradient are the main factors that
influence the development of different communities. It is a habitat of enormous
complexity and heterogeneity that shelters a great diversity of biological communities. Rocky substrates with strong irradiance support communities of photophilic
algae. It has very diverse communities rich in species, and under optimum conditions, up to four strata can be distinguished depending on the biotypes of its
components.
Depending on the degree of hydrodynamism, it is possible to differentiate
between communities of exposed or sheltered areas. The former are established in
the upper levels at shallow depths where wave action is important. In the Alboran
Sea, this community is represented by Cystoseira tamariscifolia forests (Fig. 8.7a).
Except on Alboran Island (Templado et al. 2006) and the Chafarinas Islands, it does
not usually form a continuous belt; instead scattered, small forests are restricted to
areas with strong hydrodynamism. According to the degree of coverage, the basal
layer of the incrusting C. tamariscifolia communities is usually formed by
Mesophyllum alternans or Lithophyllum incrustans (Gofas et al. 2014). In addition,
other species such as Ellisolandia elongata, Jania rubens, Hypnea musciformis,
Osmundea pinnatifida, Laurencia spp., Gelidium spp., or Valonia utricularis are
present. On Alboran Island, in areas more protected from the action of the waves,
Cystoseira tamariscifolia is replaced by species such as Cystoseira compressa and
Gelidium latifolium, sometimes accompanied by Cystoseira balearica,
C. sauvageauana, C. elegans, or C. foeniculacea (Gofas et al. 2014). When the
availability of light is reduced, a cover of sciaphilous algae develops, such as
Hildenbrandia crouaniorum, Plocamium coccineum, Pterocladiella capillacea,
Peyssonnelia rubra, Cladophora pellucida, Bryopsis plumosa, B. cupressina, Valonia utricularis, and Codium spp.
In sheltered areas, a very diverse community of photophilic algae develops. This
community covers a large part of the rocky surfaces of the Alboran Sea coastline and
constitutes one of the most easily observed landscape units. This biocenosis would
correspond to a forest dominated by Fucales, with various species of Cystoseira as
characteristic and dominant elements, and in certain environments also by Sargassum vulgare (Gofas et al. 2014). On Alboran Island, Cystoseira tamariscifolia is
replaced by C. nodicaulis. The latter species appears between 3 and 4 m depth and
extends to something more than 10 m. However, these communities dominated by
8 Seaweeds and Seagrasses: The Marine Forests from the Alboran Sea
259
2012) or other fast-growing filamentous algae.
8.4.3 Infralittoral Zone
The infralittoral zone is permanently submerged. Its upper limit is defined by the
absence of species that cannot tolerate emersion, and the lower limit is delimited by
the disappearance of seagrasses and photophilic algae. In this zone, water is not a
limiting factor, hydrodynamism becomes less pronounced, and salinity is almost
constant. The type of substrate and the light gradient are the main factors that
influence the development of different communities. It is a habitat of enormous
complexity and heterogeneity that shelters a great diversity of biological communities. Rocky substrates with strong irradiance support communities of photophilic
algae. It has very diverse communities rich in species, and under optimum conditions, up to four strata can be distinguished depending on the biotypes of its
components.
Depending on the degree of hydrodynamism, it is possible to differentiate
between communities of exposed or sheltered areas. The former are established in
the upper levels at shallow depths where wave action is important. In the Alboran
Sea, this community is represented by Cystoseira tamariscifolia forests (Fig. 8.7a).
Except on Alboran Island (Templado et al. 2006) and the Chafarinas Islands, it does
not usually form a continuous belt; instead scattered, small forests are restricted to
areas with strong hydrodynamism. According to the degree of coverage, the basal
layer of the incrusting C. tamariscifolia communities is usually formed by
Mesophyllum alternans or Lithophyllum incrustans (Gofas et al. 2014). In addition,
other species such as Ellisolandia elongata, Jania rubens, Hypnea musciformis,
Osmundea pinnatifida, Laurencia spp., Gelidium spp., or Valonia utricularis are
present. On Alboran Island, in areas more protected from the action of the waves,
Cystoseira tamariscifolia is replaced by species such as Cystoseira compressa and
Gelidium latifolium, sometimes accompanied by Cystoseira balearica,
C. sauvageauana, C. elegans, or C. foeniculacea (Gofas et al. 2014). When the
availability of light is reduced, a cover of sciaphilous algae develops, such as
Hildenbrandia crouaniorum, Plocamium coccineum, Pterocladiella capillacea,
Peyssonnelia rubra, Cladophora pellucida, Bryopsis plumosa, B. cupressina, Valonia utricularis, and Codium spp.
In sheltered areas, a very diverse community of photophilic algae develops. This
community covers a large part of the rocky surfaces of the Alboran Sea coastline and
constitutes one of the most easily observed landscape units. This biocenosis would
correspond to a forest dominated by Fucales, with various species of Cystoseira as
characteristic and dominant elements, and in certain environments also by Sargassum vulgare (Gofas et al. 2014). On Alboran Island, Cystoseira tamariscifolia is
replaced by C. nodicaulis. The latter species appears between 3 and 4 m depth and
extends to something more than 10 m. However, these communities dominated by
8 Seaweeds and Seagrasses: The Marine Forests from the Alboran Sea
259