Gulf of Cádiz


The Gulf of Cadiz is the arm of the Atlantic Ocean between Cabo de Santa Maria, the southernmost point of Mainland Portugal and Cape Trafalgar at the western end of the Strait of Gibraltar. Two major rivers, the Guadalquivir and the Guadiana, as well as smaller rivers, like the Odiel, the Tinto, and the Guadalete, reach the ocean here.
The Gulf of Cadiz is located in the north-eastern Atlantic Ocean between 34°N and 37°15′N and 6°W to 9°45′W. It is enclosed by the southern Iberian and northern Moroccan margins, west of Strait of Gibraltar.

Geology

The geological history of the Gulf of Cadiz is intimately related to plate tectonic interaction between Southern Eurasia and North Africa and is driven by two major mechanisms:
It is now well established that the whole area is under compressive deformation and that mud volcanism and processes associated with the escape of hydrocarbon-rich fluids sustain a broad diversity of chemosynthetic assemblages. The accretionary wedge formed by subduction represents an extensive area which encompasses over forty mud volcanoes, at depths ranging from , and active methane seepage has been documented on several locations.

Biota

The occurrence of chemosymbiotic biota in the extensive mud volcano fields of the Gulf of Cadiz was first reported in 2003. There were found mainly pogonophoran worms, but also gastropods and bivalves, polychaetes, crustaceans and echinoderms. There were also recorded dead corals of genera Madrepora and Lophelia. The chemosymbiotic bivalves collected from the mud volcanoes of the Gulf of Cádiz were reviewed in 2011. There were reported the following species of chemosymbiotic bivalves of Solemyidae: Acharax gadirae, Solemya elarraichensis; Mytilidae: Bathymodiolus mauritanicus, Idas sp.; Lucinidae: Lucinoma asapheus; Thyasiridae: Thyasira vulcolutre, Spinaxinus sentosus; Vesicomyidae: Isorropodon perplexum, Isorropodon megadesmus, Callogonia cyrili, Christineconcha regab, Laubiericoncha chuni and Pliocardia sp. There is high degree of endemism within chemosymbiotic bivalve assemblages.