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Presented at Biodiversity Next in Leiden, 23th October 2019 in "CP06 Contributed papers: Data extraction, literature and collections", moderated by Ely Wallis.

An important goal of the ATLAS project is to improve our understanding of the ocean transport pathways and connectivity of water masses at basin and regional scales relevant for benthic marine ecosystems. The MEDWAVES cruise (21st September-26th October, 2016) aimed to better understand the characteristics of the Mediterranean Outflow Water (MOW) and its potential influence in the occurrence, composition and distribution of deep-sea benthic communities from the Mediterranean to the Azores. Among the geomorphological features targeted in MEDWAVES, two Atlantic seamounts were included: Ormonde (Portuguese continental shelf) and Formigas Bank (close to the Azores Archipelago). During MEDWAVES, the geomorphology and oceanography of the areas was characterised. Further submarine video transects were conducted by means of a Remotely Operated Vehicle (ROV). The transects were performed in the different flanks of the seamounts aiming to characterise the benthic communities considering different geographical orientations and the influence of water masses. The characteristics of the video transects allowed to perform a methodology for video analysis based on still images. The images were taken directly from the video recordings at regular length intervals based on the positioning of the ROV, generating a set of images that allowed for comparisons between different areas. To make such comparisons robust, a thorough filtering was carried out based on the position of the parallel laser beams on screen. Only images that had a similar area observed were selected, in which all megabenthic organisms are currently being identified to the lowest possible taxon. It is expected that this protocol can be used for the video processing in all benthic communities surveyed during MEDWAVES. Some examples of coral garden habitats and sponge grounds identified in these areas are presented. This proposed methodology and preliminary results represent the first steps in a larger study that aims to: (1) characterise the megabenthic communities, the species diversity and their distribution in Ormonde Seamount and Formigas Bank, (2) evaluate the influence of substrate type, flank orientation and the characteristics of the water masses in the patterns observed, and (3) do a comparison between both seamounts to determine differences in their biological composition.

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 Cold-water corals (CWCs) 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 has been conducted in two of the case studies of ATLAS: Case study 7 (Gulf of Cádiz-Strait of Gibraltar-Alboran Sea) and Case study 8 (Azores). The initially targeted areas in the Atlantic were: the Gazul Mud volcano, in the Gulf of Cádiz (GoC) area, included in the case study 7, and the Atlantic seamounts Ormonde (Portuguese shelf) and Formigas (by Azores), both part of the case study 8. In the Mediterranean the targeted areas were The Guadiaro submarine canyon and the Seco de los Olivos (also known as Chella Bank) seamount. Unfortunately it was not possible to sample in Guadiaro due to time constraints originated by adverse meteorological conditions which obligate us to reduce the time at sea focusing only in 4 of the 5 initially planned areas. MEDWAVES was structured in two legs; the first leg took place from the 21st September (departure from Cádiz harbour in Spain) to the 13th October 2016 (arrival in Ponta Delgada, São Miguel, Azores, Portugal took place the 8th of October due to the meteorological conditions that obligated to conclude the first leg earlier as planned). during the Leg 1 sampling was carried out in Gazul, Ormonde and Formigas. The second leg started the 14th October (departure from Ponta Delgada) and finished the 26th October (arrival in Málaga harbour, Spain). MEDWAVES had a total of 30 effective sampling days, being 6 days not operative due to the adverse meteorological conditions experienced during the first leg which forced us to stay in Ponta Delgada from the 08th to the 13th October. During MEDWAVES the daily routine followed a similar scheme, depending of course on the weather and sea conditions. The main activity during the day, starting early in the morning (around 08:00 AM, once the night activities were finished), was the ROV deployment. Generally a single ROV dive of around 8 hours was performed, however in several occasions two dives were carried out in the same day (see General station list, Appendix II). After the ROV (and sometimes between two dives) the Box Corer and/or Van Veen Grab and/or Multicore was deployed. After these activities, during the night CTD-Rosette deployments and MB was conducted. Accordingly to this schema the scientific personnel worked in the day or in the night watch. A total of 215 sampling stations have been covered in MEDWAVES, using the following sampling gears: Multibeam echosounder, CTD-Rosette, LADCP, Box Corer, Van Veen Grab, Multicorer and a Remotely Operated Vehicle (ROV). Table 1 sumamrised the number of sampling stations conducted with each gear in each sampling zone. Additionally MB surveys have been conducted during the transits between areas.

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 Cold-water corals (CWCs) 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 has been conducted in two of the case studies of ATLAS: Case study 7 (Gulf of Cádiz-Strait of Gibraltar-Alboran Sea) and Case study 8 (Azores). The initially targeted areas in the Atlantic were: the Gazul Mud volcano, in the Gulf of Cádiz (GoC) area, included in the case study 7, and the Atlantic seamounts Ormonde (Portuguese shelf) and Formigas (by Azores), both part of the case study 8. In the Mediterranean the targeted areas were The Guadiaro submarine canyon and the Seco de los Olivos (also known as Chella Bank) seamount. Unfortunately it was not possible to sample in Guadiaro due to time constraints originated by adverse meteorological conditions which obligate us to reduce the time at sea focusing only in 4 of the 5 initially planned areas. MEDWAVES was structured in two legs; the first leg took place from the 21st September (departure from Cádiz harbour in Spain) to the 13th October 2016 (arrival in Ponta Delgada, São Miguel, Azores, Portugal took place the 8th of October due to the meteorological conditions that obligated to conclude the first leg earlier as planned). during the Leg 1 sampling was carried out in Gazul, Ormonde and Formigas. The second leg started the 14th October (departure from Ponta Delgada) and finished the 26th October (arrival in Málaga harbour, Spain). MEDWAVES had a total of 30 effective sampling days, being 6 days not operative due to the adverse meteorological conditions experienced during the first leg which forced us to stay in Ponta Delgada from the 08th to the 13th October. During MEDWAVES the daily routine followed a similar scheme, depending of course on the weather and sea conditions. The main activity during the day, starting early in the morning (around 08:00 AM, once the night activities were finished), was the ROV deployment. Generally a single ROV dive of around 8 hours was performed, however in several occasions two dives were carried out in the same day (see General station list, Appendix II). After the ROV (and sometimes between two dives) the Box Corer and/or Van Veen Grab and/or Multicore was deployed. After these activities, during the night CTD-Rosette deployments and MB was conducted. Accordingly to this schema the scientific personnel worked in the day or in the night watch. A total of 215 sampling stations have been covered in MEDWAVES, using the following sampling gears: Multibeam echosounder, CTD-Rosette, LADCP, Box Corer, Van Veen Grab, Multicorer and a Remotely Operated Vehicle (ROV). Table 1 sumamrised the number of sampling stations conducted with each gear in each sampling zone. Additionally MB surveys have been conducted during the transits between areas.

In September 2011 a marine geological survey, the FAIVI (Features of Acores and Italian Volcanic Islands) cruise, was carried offshore the Terceira Island aboard the French R/V L'Atalante, in the framework of the Eurofleet program. One of the targets of the FAIVI cruise was the study of the Terceira volcanic edifice, particularly the area offshore the NW sector of the island (Serreta Ridge). Here an intermediate-depth submarine eruption occurred in 1998-2001, producing a consistent amount of lava balloons, i.e. balloon-like structures consisting of a thin lava shell surrounding a closed hollow interior, normally corresponding to a single large vesicle, or a few large convoluted vesicles, floating on the sea (Gaspar et al., 2003; Kueppers et al., 2012). Lava balloons are fairly unusual products of submarine eruptions. To date, balloon-like products have only been documented at Pantelleria, Italy in 1891 (Riccò, 1982; Washington, 1909), Mauna Loa, Hawaii in 1877 (Moore et al., 1985); Socorro Island, Mexico in 1993 (Siebe et al., 1995); at the 1998-2001 Serreta eruption offshore Terceira island (Azores) (Gaspar & Wallenstein, 1999) and, very recently offshore El Hierro, Canary Islands in October 2011 (Troll et al., 2012). Their genesis, in the framework of shallow-intermediate-depth submarine eruptions, is still poorly understood although several efforts have been made to improve the knowledge of the mechanisms producing such basaltic floating scorias (Kueppers et al., 2012). In order to reconstruct the style of eruption producing lava balloons and associated volcaniclastic deposits at Serreta, the investigations focused on: i) the identification and characterization of the emission vent(s) associated to the 1998-2001 submarine eruption; ii) the characterization of related deposits dispersal and grain size and, iii) the quantification of physical parameters of the eruptive event from the characteristics of sampled products (e.g., volatile contents, cooling rate). Here, we present preliminary results of the FAIVI cruise and attempt a first comparison with the 1891 eruption at Pantelleria, object of recent marine geological studies (Conte et al., submitted). As a first result, the FAIVI survey allowed to reconstruct with unprecedented detail the bathymetry offshore Terceira Island and, particularly, in the Serreta Ridge area. The latter is characterized by several volcanic features such as linear eruptive centres, volcanic cones and lava flows. Furthermore, bathymetric backscatter data and seafloor samples (collected through rock- and gravity- coring, grabbing and dredging) were preliminary analyzed on board and gave the following results: 1) The main vent of 1998-2001 Serreta eruption was identified; it is a half-cone, some 150 m high with a diameter of 700 m, resting on the top of the Serreta Ridge at 250-300 m water depth. 2) Most samples collected in the area surrounding the vent have been interpreted as related to the 1998-2001 Serreta eruption. They include, in fact, a large amount of fresh, highly vesciculated basaltic scoria, with the typical layered vescicularity observed in the lava balloon crust recovered intact during the 1998-2001 eruption. Material sampled from the top of Serreta Ridge encompasses different types, from large scoriaceous blocks (up to 60 cm length) of black fresh basalt characterized by numerous, large, highly convoluted vesicles with smooth internal walls, to fragments of scoriaceous material with dimensions

The Gulf of Cádiz (GoC) represents an area of socioeconomic and scientific importance for oceanographic, geological and biological processes. An interesting feature of the GoC is the presence of a large amount of mud volcanoes (MVs) and diapirs that display different seepage, seabed types, oceanographic settings and biological communities. Detailed exploration of some MVs is still needed for detecting Vulnerable Marine ecosystems (VMEs) that seem to be rare in other areas of the GoC, improving the current knowledge on its biodiversity and ecological attributes. During different expeditions (MEDWAVES-ATLAS, INDEMARES-CHICA 0610 & 0412 and ISUNEPCA 0616) carried out in different years, biological samples and videos were obtained in Gazul MV (Spanish Margin of the GoC). The study of those samples and videos has revealed the presence of several ecologically important VMEs (e.g. 3 species of reef framework-forming corals, coral gardens including solitary scleractinians, gorgonians and antipatharians, as well as deep-sea sponge aggregations and chemosynthesis-related structures) and a large number of species occurring in this MV, including new records for the European margin, threatened species and non-previously described species. The combination of different environmental and anthropogenic factors allowed the present-day persistence of these VMEs in the GoC. Some of Gazul MV biological and ecological attributes fit several criteria of the Convention on Biological Diversity for EBSA description (e.g. 1,3,4,6) that, together with those of other areas of the GoC, may contribute to the future potential nomination of an EBSA in this area of the NE Atlantic.