LEG 1 - Princesa Alice Bank and Seamounts North of Graciosa

1. Were able to visit eight unexplored geomorphological structures in the Azores EEZ – Sedlo W, Sedlo, Borda, São Jorge NE, Princesa Alice W, Princesa Alice SW, Picos S do Princesa Alice, plus the Gaillard seamount and an area West of Picos S do Princesa Alice. We also visited some areas that have already been explored but were in need of extra video data namely João Leonardes, Serreta Mar, Mar da Fortuna, and São Jorge NW.
2. During the MapGES 2023 RV Arquipélago Leg 1 cruise we accomplished 64 underwater video transects and the deepest dive ever at 1 125 m depth with the Azor drift-cam, adding up to around 62 hours of new underwater video footage of seabed habitats. As in previous years, the presence of some fishing lines made our deep-sea exploration challenging. After having the Azor drift-cam caught on several lines, we managed to get free with only minor damages. This collateral fishing impact is preventing the acquisition of deep-sea biodiversity data to inform management deserve to be better quantified.
3. We explored the Sedlo seamount with the Azor drift-cam. From 2002–2005, Sedlo was the focus of a multidisciplinary EU project, OASIS (Oceanic Seamounts: An Integrated Study), which showed highly complex hydrographical patterns with anticyclonic circulation around its three summits, driven principally by Taylor column formation. This seamount was speculated to accommodate one the Azores’ most important spawning ground for orange roughy, with higher abundances between 1 000 and 1 200 m.
4. Deep-sea explorations with the Azor drift-cam added supporting evidence to consider Sedlo seamount as an Essential Fish Habitat. We found areas that are home to the highly endangered deep-sea fish orange roughy Hoplostethus atlanticus and discovered that Sedlo and other neighbouring seamounts host a high number of deep-sea shark species, some of which rarely observed in the Azores. We also discovered large aggregations of the black coral Leiopathes expansa on the summit of the Sedlo W, with most specimens of relatively small sizes. This area seemed to be a good candidate for being considered a Vulnerable Marine Ecosystem and should be kept in the list of priority areas for conservation in the Azores.
5. We also explored Borda, João Leonardes, Gaillard seamount, north of Graciosa Island. Along with Sedlo, these seamounts seem to host slightly unique deep-sea benthic communities when compared to other areas in the Azores EEZ explored so far with black corals Leiopathes expansa and Parantipathes hirondelle, the bamboo coral Acanella arbuscula, stylasterids of the genus Errina, the sea urchin Cidaris cidaris, and lamellate sponges of the genus Phakellia among others.
6. We started exploring the morphological features south of Princesa Alice peak. Most dives covered soft and mix sediments with relatively low biodiversity and abundance, although some areas hosted high densities of Narella Bellissima and Narella versluysi, while others were dominated by patches of Pheronema carpenter and other sponges (e.g., Asconema sp.). We also observed some sparse colonies of cold-water such as corals Narella versluysi, Hemicorallium Niobe, H. tricolor, Acanella arbuscula, Chrysogorgya sp., cf. Leptopsammia, cf. Candidella imbricata, and Flabellum sp., and some deep-sea sponges such as cf. Regadrella, and specimens from the genus Geodia, along with some shrimps Aristaeopsis edwardsiana, sea-urchins Cidaris cidaris and deep-sea fishes such as Mora moro, Synaphobranchus kaupii, Helicolenus dactylopterus, Hoplostethus mediterraneus, Gephyroberix darwinii, Dalatias licha, and one Trachyscorpia cristulata.

LEG 2 - Hard Rock Café, Kurchatov, and Seamounts in the Central and Eastern Azores

7. Were able to visit ten unexplored geomorphological structures in the Azores EEZ – Hard Rock Café, Kurchatov SE, Albatroz N, Ferraria N, Ferraria Mar, Sauerwein, Mar da Prata, Mar da Prata N, Grande Norte and one seamount around Princesa Alice (De Guerne). We also visited four areas that have already been explored but needed extra video data namely the Isolado, Kurchatov N, Kurchatov SW, and Mar da Prata S. We visited also the Perestrelo Bartolomeu area, for which some information already existed, and the Petrov area, which turned out to be deeper than the maps indicated.
8. During the MapGES 2023 Leg2 of the Arquipélago Cruise we accomplished 79 underwater video transects, in one of which we discovered the highest vertical wall ever filmed with Azor drift-cam, with about 230 m height. This cruise added up around 79 hours of new underwater video footage of seabed habitats. As in previous years, the presence of some fishing lines made our deep-sea exploration challenging, especially in the shallower dives performed around São Miguel Island (e.g., Mar da Prata and Grande Norte). However, after having the Azor drift-cam caught on several lines, we managed to successfully get free with only minor damages, and without losing any system.
9. The Hard Rock Café seamount was finally explored with the Azor drift-cam. The hydrographic Institute mapped this seamount in 2020 but given its location 210 nautical miles from the natural starting point of the MapGES cruises (Horta) and given its position to the north of the Azores archipelago (normally more affected by adverse weather conditions), the visit to this seamount was being postponed a few years ago. After all conditions were met, the Hard Rock Café was visited. It is a geomorphological structure that, due to its characteristics, was from the first moment on the list of the first options for the expansion of the Azores Marine Park, hence the doubled importance of this visit.
10. We also visited a seamount named Petrov. This area does not yet have high-resolution bathymetry data, so we tried to prospect the area looking for a peak between 300 m and 1,000 m depth. However, after launching the Azor drift-cam in search of a shallower peak we were unable to reach the bottom. All sonars on board indicated depths between 1,900 m and 2,500 m deep, indicating that this area is much deeper than current nautical charts demonstrate and highlight, once again, the importance of carrying out multibeam bathymetry surveys in the Azores.
11. Deep-sea explorations with the Azor drift-cam added supporting evidence to consider Hard Rock Café and Isolado, Essential Fish Habitats. We found that these areas were both home to the highly endangered deep-sea fish orange roughy (Hoplostethus atlanticus) and both exhibited large schools of the wreckfish (Polyprion americanus). These areas also showed a high number of deep-sea shark species, some of which were rarely observed in the Azores. Although these areas showed low abundances in terms of benthic megafauna, we detected some frequent colonies of the slow-growing black corals Antipathes dichotoma and Leiopathes expansa.
12. Most seamounts on the way to and around São Miguel Island, such as Albatroz N, Ferraria N, Ferraria Mar, Mar da Prata and Grande Norte host interesting deep-sea benthic communities with deeper areas demonstrating abundant coral gardens of both Narella versluysi and Narella bellissima, sometimes, in aggregation with Callogorgia verticillata, Acanthogorgia sp. or Leiopathes expansa. Shallower areas were mainly characterized by large gardens of Viminella flagellum, sometimes associated with Callogorgia verticillata and other times with frequent and large Dentomuricea.
13. The Sauerwein ridge, between the islands of São Miguel and Santa Maria, had surprisingly low biodiversity, highlighting once again the need to better understand the reasons that explain the spatial distribution patterns of benthic communities to better inform management and conservation of these vulnerable ecosystems.
14. Although the Grande Norte seamount was clearly the area with the highest intensity of bottom fishing, where we observed several lost bottom longlines, the benthic communities observed appeared to be in good environmental condition, displaying large aggregations of Callogorgia verticillata. These observations add to the evidence that hook-and-line fishing produces much smaller impacts when compared to other fishing gear.
15. We continued exploring the morphological features around Princesa Alice, namely De Guerne. Most dives covered soft and mixed sediments with relatively low biodiversity and abundance, with only some occasional corals of the species Acanella arbuscula, Parantipathes hirondelle and Elatopathes abietina, and dispersed Acanthogorgia sp.