A relict oasis of living deep-sea mussels Bathymodiolus and microbial-mediated seep carbonates at newly-discovered active cold seeps in the Gulf of Cádiz, NE Atlantic Ocean

• Published in: Paläontologische Zeitschrift Vol. 95; no. 4; pp. 793 - 807
• Main Authors: Somoza, Luis, Rueda, José Luis, González, Francisco J., Rincón-Tomás, Blanca, Medialdea, Teresa, Sánchez-Guillamón, Olga, Hoppert, Michael, Vázquez, Juan T., Madureira, Pedro, Santofimia, Esther, López-Pamo, Enrique, Palomino, Desirée, Ortíz, Jose Eugenio, Blanco, Lorena, del Carmen Fernández-Puga, Maria, Fernández-Salas, L. M., Reitner, Joachim
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-12-2021
• Subjects: Earth and Environmental Science; Earth Sciences; Paleontology; Research Paper; Gulf of Cádiz; Mud volcanoes; Cold seeps; Deep-sea mussels; Chemosynthesis-based habitats; Seep carbonates
• ISSN: 0031-0220; 1867-6812
• DOI: 10.1007/s12542-021-00594-3

Extensive beds of the deep-sea mussel
Bathymodiolus mauritanicus
(currently also known as
Gigantidas mauritanicus
) linked to active cold seeps related to fissure-like activity on Al Gacel mud volcano, Gulf of Cádiz, were filmed and sampled for the first time during the oceanographic expedition SUBVENT-2 aboard R/V Sarmiento de Gamboa. Al Gacel mud volcano is one of up to 80 fluid venting submarine structures (mud volcanoes and mud volcano/diapir complexes) identified in the Gulf of Cádiz as result of explosive venting of hydrocarbon-enriched fluids sourced from deep seated reservoirs. This mud volcano is a cone-shaped edifice, 107 m high, 944 m in diameter constituted by mud breccias and, partially covered by pavements of seep carbonates. Extensive beds of this deep-sea mussel were detected at the northern flank at 810–815 m water depth associated with bacterial mats around intermittent buoyant vertical bubble methane plumes. High methane concentrations were measured in the water column above living mussel beds. Other chemosymbiotic species (
Siboglinum
sp.,
Solemya elarraichensis
,
Isorropodon
sp.,
Thyasira vulcolutre
and
Lucinoma asapheus
) were also found in different parts of Al Gacel mud volcano. Al Gacel mud volcano may currently represent one of the most active mud volcanoes in the Gulf of Cádiz, delivering significant amounts of thermogenic hydrocarbon fluids which contribute to foster the extensive chemosynthesis-based communities detected. This finding is of paramount importance for linking extremophile bivalve populations along the North Atlantic, including cold seeps of the Gulf of México, hydrothermal vents of the Mid-Atlantic Ridge and now, detailed documented at the Gulf of Cádiz.