distributed all along the western Mediterranean coasts during the Pleistocene and
was still quite common until the end of the nineteenth century. Since then, its
populations have drastically decreased (Templado et al. 2004). Currently, it is
considered extinct on the European continental coasts except for some localities of
southern Spain (see Luque et al. 2018 for an updated review). Nowadays the main
populations are restricted to the North African coasts, from the Strait of Gibraltar to
Tunisia. Otherwise, some relict populations persist in certain island enclaves around
Corsica, Sardinia and Sicily.
According to data compiled by Luque et al. (2018), more than 90% of specimens
of P. ferruginea are concentrated along the coasts of the Alboran Sea, mainly on the
African side, where its populations are quite scattered and fragmented. The main
populations (with several thousands of adult limpets) are located in Ceuta (Strait of
Gibraltar), Melilla, Chafarinas Islands, Habibas, Rachgoun and Plana islands (western coast of Algeria) and Zembra Island (Tunisia). Conversely, along the more than
700 kilometres of Andalusian coastline between the Strait of Gibraltar and Cabo de
Gata, estimated numbers do not reach 8000 specimens (CMA 2014).
The decline of this limpet is attributed to human impact, such as overharvesting,
development of coastal infrastructures (and the consequent degradation and fragmentation of the habitat) and marine pollution (Templado et al. 2004; Moreno and
Arroyo 2008; Luque et al. 2018). Patella ferruginea is currently considered in
danger of extinction and was included in 1992 as a “species in need of strict
protection” in Annex IV of the Habitats Directive (92/43/CEE), in 1996 as an
“endangered or threatened species” within Annex II of the Barcelona Convention,
as “strictly protected” in 1996 in Annex II of the Bern Convention and as “in danger
of extinction” in the Spanish Catalogue of Endangered Species (see Sect. 10.5).
10.1.2 Ellisella paraplexauroides
The gorgonian Ellisella paraplexauroides (Fig. 10.2) is one of the largest colonial
invertebrates in the Mediterranean Sea and the only member of the genus Ellisella
(Anthozoa, Alcyonacea, Ellisellidae) recorded in European waters (Grasshoff 1992).
It forms brick-red candlestick like colonies, to just over 2 m high with ramifications
arising from a common short stem and heading parallel upwards.
Ellisella paraplexauroides is an Atlantic-Mediterranean species rarely found in
the Mediterranean (Templado et al. 2006; Arroyo et al. 2008; Angiolillo et al. 2012).
In the Atlantic, the species occurs along the west coast of Africa (from Angola to
Morocco) and off the Canary islands (Brito and Ocaña 2004), while in the Mediterranean, most of the records (reviewed by Angiolillo et al. 2012) are restricted to the
Gibraltar Strait (Arroyo et al. 2008; Ocaña et al. 2009) and Alboran Sea (Templado
et al. 2006; Arroyo et al. 2008). Inward into the Mediterranean, only isolated
colonies have been reported off Algeria and Tunisia, Naples (doubtful record) and
Pantelleria Island (data compiled by Angiolillo et al. 2012).
10 Invertebrates: The Realm of Diversity
361
was still quite common until the end of the nineteenth century. Since then, its
populations have drastically decreased (Templado et al. 2004). Currently, it is
considered extinct on the European continental coasts except for some localities of
southern Spain (see Luque et al. 2018 for an updated review). Nowadays the main
populations are restricted to the North African coasts, from the Strait of Gibraltar to
Tunisia. Otherwise, some relict populations persist in certain island enclaves around
Corsica, Sardinia and Sicily.
According to data compiled by Luque et al. (2018), more than 90% of specimens
of P. ferruginea are concentrated along the coasts of the Alboran Sea, mainly on the
African side, where its populations are quite scattered and fragmented. The main
populations (with several thousands of adult limpets) are located in Ceuta (Strait of
Gibraltar), Melilla, Chafarinas Islands, Habibas, Rachgoun and Plana islands (western coast of Algeria) and Zembra Island (Tunisia). Conversely, along the more than
700 kilometres of Andalusian coastline between the Strait of Gibraltar and Cabo de
Gata, estimated numbers do not reach 8000 specimens (CMA 2014).
The decline of this limpet is attributed to human impact, such as overharvesting,
development of coastal infrastructures (and the consequent degradation and fragmentation of the habitat) and marine pollution (Templado et al. 2004; Moreno and
Arroyo 2008; Luque et al. 2018). Patella ferruginea is currently considered in
danger of extinction and was included in 1992 as a “species in need of strict
protection” in Annex IV of the Habitats Directive (92/43/CEE), in 1996 as an
“endangered or threatened species” within Annex II of the Barcelona Convention,
as “strictly protected” in 1996 in Annex II of the Bern Convention and as “in danger
of extinction” in the Spanish Catalogue of Endangered Species (see Sect. 10.5).
10.1.2 Ellisella paraplexauroides
The gorgonian Ellisella paraplexauroides (Fig. 10.2) is one of the largest colonial
invertebrates in the Mediterranean Sea and the only member of the genus Ellisella
(Anthozoa, Alcyonacea, Ellisellidae) recorded in European waters (Grasshoff 1992).
It forms brick-red candlestick like colonies, to just over 2 m high with ramifications
arising from a common short stem and heading parallel upwards.
Ellisella paraplexauroides is an Atlantic-Mediterranean species rarely found in
the Mediterranean (Templado et al. 2006; Arroyo et al. 2008; Angiolillo et al. 2012).
In the Atlantic, the species occurs along the west coast of Africa (from Angola to
Morocco) and off the Canary islands (Brito and Ocaña 2004), while in the Mediterranean, most of the records (reviewed by Angiolillo et al. 2012) are restricted to the
Gibraltar Strait (Arroyo et al. 2008; Ocaña et al. 2009) and Alboran Sea (Templado
et al. 2006; Arroyo et al. 2008). Inward into the Mediterranean, only isolated
colonies have been reported off Algeria and Tunisia, Naples (doubtful record) and
Pantelleria Island (data compiled by Angiolillo et al. 2012).
10 Invertebrates: The Realm of Diversity
361