have been drastically affected by the arrival of some of these species. As previously
mentioned, Asparagopsis armata (Fig. 8.2a) and A. taxiformis (Fig. 8.2b) are two
very characteristic elements and in many cases are the dominant ones of infralittoral
communities, both in photophilic and hemisciaphilous environments. Caulerpa
cylindracea is an exotic species of Australian origin that has spread over much of
the bottoms of Alboran Sea, both on the African coast and on the Iberian Peninsula,
invading habitats as diverse as eulittoral pools, seagrass meadows, infralittoral hard
and soft bottoms, maerl, and coralligenous substrates. The arrival of Rugulopteryx
okamurae (Fig. 8.2d) is especially dramatic. Although its presence in the Alboran
Sea is currently restricted to the westernmost area (both shores of the Strait of
Gibraltar) and isolated sites on the coast of Málaga (Altamirano et al. 2016; García
Gómez et al. 2018), Granada and Almería its development has drastically
transformed the underwater landscape, especially the infralittoral hard bottoms.
This species is the main, and at times almost unique, representative of these “new
communities,” with coverage close to 100% in many cases and with very high
biomass values.
The Alboran Sea has the particularity of coverage on some sandy bottoms of the
infralittoral meadows of all four species of seagrasses found in Europe (Posidonia
oceanica, Cymodocea nodosa, Zostera marina, and Z. noltei), sometimes coexisting
in relatively restricted areas. A good example is Roquetas de Mar in Almería, where
at the end of the twentieth century, the four species were present together in a very
restricted area (Moreno and Guirado 2003). The coexistence of the four species is
very rare in other parts of the Mediterranean, such as at Cala Jonquet on the Costa
Brava (Cebrián et al. 1997). Regrettably, Z. marina has practically disappeared in
recent years from the Alboran Sea (Arroyo et al. 2015) and other localities in the
Mediterranean such as Catalonia (Romero et al. 2015) for various reasons, so it is no
longer possible to find all four species in the same area.
The presence of seagrasses substantially modifies the soft substrates on which
they attach, constituting a new habitat that in many ways is intermediate between
sediments and rocky bottoms. This effect is very noticeable, especially in the
meadows of P. oceanica, which is the largest species and whose presence most
extensively transforms the characteristics of the seabed. The new marine habitat
formed by the meadows consists almost entirely of seagrasses, since the great
majority of the macroalgae do not have the capacity to attach to soft substrates.
The meadows of P. oceanica constitute one of the main climax stages of
Mediterranean coastal ecosystems (Díaz-Almela and Duarte 2008). The meadows
are heterogeneous, with many species of hard bottoms found among the rhizomes of
the seagrasses, while organisms typical of soft substrates can also be found in them,
mainly in sediment-filled channels. Many species live preferentially in these
meadows, and some are exclusive to them, mainly those that live in the foliar
stratum between the leaves. We must not forget that the meadows serve as the
home for many species of commercial interest for their whole lives, or else one phase
of the life cycle, such as the juveniles of many pelagic species (Urra et al. 2013;
Rueda et al. 2015).
8 Seaweeds and Seagrasses: The Marine Forests from the Alboran Sea
263
mentioned, Asparagopsis armata (Fig. 8.2a) and A. taxiformis (Fig. 8.2b) are two
very characteristic elements and in many cases are the dominant ones of infralittoral
communities, both in photophilic and hemisciaphilous environments. Caulerpa
cylindracea is an exotic species of Australian origin that has spread over much of
the bottoms of Alboran Sea, both on the African coast and on the Iberian Peninsula,
invading habitats as diverse as eulittoral pools, seagrass meadows, infralittoral hard
and soft bottoms, maerl, and coralligenous substrates. The arrival of Rugulopteryx
okamurae (Fig. 8.2d) is especially dramatic. Although its presence in the Alboran
Sea is currently restricted to the westernmost area (both shores of the Strait of
Gibraltar) and isolated sites on the coast of Málaga (Altamirano et al. 2016; García
Gómez et al. 2018), Granada and Almería its development has drastically
transformed the underwater landscape, especially the infralittoral hard bottoms.
This species is the main, and at times almost unique, representative of these “new
communities,” with coverage close to 100% in many cases and with very high
biomass values.
The Alboran Sea has the particularity of coverage on some sandy bottoms of the
infralittoral meadows of all four species of seagrasses found in Europe (Posidonia
oceanica, Cymodocea nodosa, Zostera marina, and Z. noltei), sometimes coexisting
in relatively restricted areas. A good example is Roquetas de Mar in Almería, where
at the end of the twentieth century, the four species were present together in a very
restricted area (Moreno and Guirado 2003). The coexistence of the four species is
very rare in other parts of the Mediterranean, such as at Cala Jonquet on the Costa
Brava (Cebrián et al. 1997). Regrettably, Z. marina has practically disappeared in
recent years from the Alboran Sea (Arroyo et al. 2015) and other localities in the
Mediterranean such as Catalonia (Romero et al. 2015) for various reasons, so it is no
longer possible to find all four species in the same area.
The presence of seagrasses substantially modifies the soft substrates on which
they attach, constituting a new habitat that in many ways is intermediate between
sediments and rocky bottoms. This effect is very noticeable, especially in the
meadows of P. oceanica, which is the largest species and whose presence most
extensively transforms the characteristics of the seabed. The new marine habitat
formed by the meadows consists almost entirely of seagrasses, since the great
majority of the macroalgae do not have the capacity to attach to soft substrates.
The meadows of P. oceanica constitute one of the main climax stages of
Mediterranean coastal ecosystems (Díaz-Almela and Duarte 2008). The meadows
are heterogeneous, with many species of hard bottoms found among the rhizomes of
the seagrasses, while organisms typical of soft substrates can also be found in them,
mainly in sediment-filled channels. Many species live preferentially in these
meadows, and some are exclusive to them, mainly those that live in the foliar
stratum between the leaves. We must not forget that the meadows serve as the
home for many species of commercial interest for their whole lives, or else one phase
of the life cycle, such as the juveniles of many pelagic species (Urra et al. 2013;
Rueda et al. 2015).
8 Seaweeds and Seagrasses: The Marine Forests from the Alboran Sea
263