Following the Mediterranean path through the Atlantic: the MEDWAVES cruise

The Strait of Gibraltar (SG) and the surrounding areas, Gulf of Cadiz (GoC) in the Atlantic, and Alboran Sea (AS) in the Mediterranean, are key areas to understanding the distribution and connectivity of marine communities, as the SG and the meeting of water masses at the Almeria Oran front represent an oceanographic transition area, connecting the Atlantic Ocean and the Mediterranean Sea. The Mediterranean Outflow Water (MOW) flows out from Gibraltar and extends towards the East of the Atlantic, building a warm and salty water mass which propagates in North West direction from Portugal originating the “Mediterranean Water“ (MW) in the Atlantic. This warm and salty water mass becomes characteristic of the North Atlantic in mid waters (around 1100 m). The occurrence of cold-water coral (CWC) communities in the NE Atlantic has been related to the pathway of the MOW, whereby this current system would have an historical influence on the migration of coral larvae and (re)colonisation of the Atlantic in the post-glacial era. The MEDWAVES (MEDiterranean out flow WAter and Vulnerable EcosystemS) cruise targeted areas under the potential influence of the MOW within the Mediterranean and Atlantic realms. These include seamounts where CWC have been reported but that are still poorly known, and which may act as essential “stepping stones” connecting fauna of seamounts in the Mediterranean with those of the continental shelf of Portugal, the Azores and the Mid-Atlantic Ridge. During MEDWAVES sampling was conducted for two of the case studies of the ATLAS project: Gulf of Cadiz-Strait of Gibraltar-Alboran Sea and Azores. The main goals of MEDWAVES were to: (1) to characterise physically and biogeochemically the MOW Path and understand its interaction with the general Atlantic Meridional Overturning Circulation (AMOC) stream, from the Alboran Sea to the Azores, through the Gulf of Cadiz, and the Ormonde Seamount, exploring the relationship between the oceanographic settings of these target areas and the ecosystems therein and, (2) to characterise communities associated to the transition area, and sample for population genetic analysis aiming at understanding the way the populations located in the target areas contribute or have contributed to connectivity between the Mediterranean Sea and the Atlantic Ocean