Ocean Circulation over Formigas and Ormonde Seamounts

• Main Authors: Mosquera Giménez, Ángela, Vélez-Belchí, Pedro, Piñeiro, Safo, Fajar, Noelia, Rivera, Jesús, Caínzos, Verónica, Santiago, Rocío, Álvarez Rodríguez, Marta, Balbín, Rosa, Jiménez Aparicio, Juan Antonio, Aparicio-González, Alberto
• Format: Lecture
• Language: English
• Published: Zenodo 2018
• Subjects: North Atlantic; Stepping Stones
• Online Access: https://doi.org/10.5281/zenodo.1252328

ATLAS work package 1 presentationat ATLAS 3rd General Assembly Seamounts constitute an obstacle to the free ocean flow, modifying the pattern of circulation. As a result of these alterations, a variety of hydrodynamical processes and phenomena may take place at seamounts, such as Taylor columns/caps. These oceanographic effects may turn seamounts into very productive ecosystems with high biodiversity. Under these conditions seamounts provide a particularly good environment for the settlement of some organisms, acting as stepping stones and contributing to their dispersal. In this study, we verify if these oceanographic effects explain the presence of cold-water corals of Mediterranean origin in the Atlantic. To achieve this, three seamounts in the path of the Mediterranean Outflow Water (MOW) through the Eastern North Atlantic were selected: the Gazul mud volcano, the Ormonde seamount and the Formigas seamount. In order to determine the hydrographic and dynamical conditions at each one of the three locations, CTD, LADPC and biochemical observations were carried out. Taylor columns were not observed in any of the three sampled areas. Although we found suggestions of upwelling/downwelling systems, their effect was barely noticed in the circulation pattern. The oceanographic processes in those areas are more influenced by the vertical distribution of water masses, which determine the stability of the water column. Moreover, the high values of the Brunt-Väisälä frequency around the MOW halocline can lead to the formation of internal waves. These perturbations in the water column can enhance the vertical mixing, producing suspension, which, in turn, could affect the vertical distribution of cold-water corals.