MapGES 2022 Cruise Report: Exploration and mapping of deep-sea biodiversity in the Azores, summer 2022

Main objective: MapGES 2022 is the continuation of our long-term strategy to map deep-sea biodiversity and identify Vulnerable Marine Ecosystems (VMEs) in the Azores using the Azor drift-cam video system. This year, we operated from the RV Arquipélago and were lucky to finally explore some long-awaited areas such as the Diogo de Teive and Cachalote seamounts, the Flores island slopes (western Azores), but also the Girard, Maria Celeste, Formigas and Margrette seamounts and the island slopes of Santa Maria (eastern Azores). As in other MapGES cruises, the objectives were to (i) map benthic communities inhabiting unexplored seamounts, ridges and island slopes, (ii) identify new areas that fit the FAO definition of what constitutes a Vulnerable Marine Ecosystem (VME); and (iii) determine distribution patterns of deep-sea benthic biodiversity in the Azores region. The results of this cruise, when added to the previous contributions, will help identify what are the main environmental drivers that determine the spatial distribution of deep-sea benthic fauna in the Azores. This cruise also provided valuable information in the context of Good Environmental Status (GES), Marine Spatial Planning (MSP) and provided new insights on how to sustainably manage deep-sea ecosystems.

Methodology: We performed several underwater video transects along the seafloor with the Azor drift-cam, a low-cost drifting camera system designed and developed at IMAR & Okeanos (University of the Azores), which allows the recording of high-quality underwater video images of the seabed down to 1000 m depth. The system was deployed from the research vessel RV Arquipélago, owned by the Government of the Azores.

Scientific team in Leg 1: Telmo Morato (chief scientist), Sérgio Gomes, Luís Rodrigues, Guilherme Gonçalves, Inês Carneiro

Scientific team in Leg 2: Telmo Morato and Carlos Dominguez-Carrió (chief scientists), Sérgio Gomes, Luís Rodrigues, Guilherme Gonçalves, Manuela Ramos

Cruise summary: The MapGES 2022 survey was divided in 2 legs, which were planned to explore very distant areas of the Azores, namely the eastern and western group of islands (Table 1, Figure 1). Overall, ~130 dives were accomplished in 22 sampling areas, which include 11 seamounts and the slopes of 5 different islands (Tabel 2). During Leg 1, from 6^th to 23^rd July 2022, we performed 62 dives with the Azor drift-cam, covering 36.3 km of the seafloor and producing 60:33 hours of video footage, 3.31TB of disc space. This leg surveyed the deep-sea benthic communities dwelling on the slopes of Flores island and Diogo de Teive and Cachalote seamounts on board of the research vessel Arquipélago, together with some dives around Faial, Pico and São Jorge islands. During, Leg 2, from 14^th to 28^th August 2022, we performed 72 dives with the Azor drift-cam, covering 35 km of the seafloor and producing 69:38 hours of video footage, 3.82TB of disc space. This leg surveyed the slopes around Santa Maria island, as well as several seamounts on their vicinity, some located on the easternmost part of the Azores archipelago. Leg 2 explored for the first time the seamounts of Albatroz do Meio, Girard, Maria Celeste and Margrette seamounts, and collected new information on the shallower areas of Formigas seamount, for which data was still lacking to complete the exploratory dives done in previous surveys.

Main achievements:

1. During the MapGES 2022 cruise we accomplished of more than 130 underwater video transects between 190 and 1099 m depth with the Azor drift-cam, adding up to around 130 new hours of underwater video footage of seabed habitats. The presence of many lost 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. These collateral fishing impacts, i.e., preventing the acquisition of deep-sea biodiversity data to inform management deserve to be better quantified. 
2. Deep-sea exploration with the Azor drift-cam confirmed that Diogo de Teive seamount may classify as a near-natural or pristine area. The Portuguese Hydrographic Institute mapped this seamount in 2019 and found that it was much shallower than previous maps indicated. Because of the lack of known fishing events, we classified Diogo de Teive as a potential near-natural or pristine area. During the dives performed in Leg 1, we found many large and intact colonies of the coral Callogorgia verticillata that showed no signs of impacts from fishing activity, and we also encountered large schools of the wreckfish Polyprion americanus. More exploration may be needed, but this area should be kept in the list of priority areas for conservation in the Azores.
3. We explored the Cachalote seamount with the Azor drift-cam, after almost 4 years of waiting. The Portuguese Hydrographic Institute also mapped this seamount back in 2018 and revealed its flat-topped structure. The benthic communities showed a clear vertical stratification, with extensive gardens of Narella bellissima and Narella versluysi at depths between 700 m and 900 m, with areas characterized by the bamboo coral Acanella arbuscula. At 500-600 m depth, coral gardens of Callogorgia verticillata and Viminella flagellum were observed, together with many other species of corals and sponges. We also drifted over some alfonsinos, silver roughy, wreckfish, and saw lost fishing lines, both on the deeper dives and also on the summit. Although there were quite a few large Callogorgia verticillata colonies, many of them showed signs of fishing impacts, such as broken or missing branches.
4. We also explored the deep sea around Flores island, the westernmost point of the Azores and Europe, but siting on the North American Plate. We were stunned by two very dense patches of large pink and white bubblegum corals (Paragorgia cf. johnsoni) that resemble those observed in the Gigante Western Ridge. These areas are good candidates for breaking the record of the densest bubblegum coral garden in the Azores. The coral gardens seemed to be in reasonably good conditions, despite the fact that many colonies showed signs of impacts, some even found lying broken over the seafloor. We were also stunned by the diverse fauna colonizing the steep walls that can be found around Flores island, where large corals resembling Paramuricea were filmed, as well as by the diverse benthic communities observed with several species of corals and sponges, including Acanthogorgia sp., Dentomuricea cf. meteor, white and yellow Viminella flagellum, Elatopathes abietina and Leiodermatium sp.
5. Deep-sea exploration with the Azor drift-cam of several isolated seamounts located between the islands of Pico and Santa Maria (Albatroz do Meio, Girard, Maria Celeste) for which no information regarding their benthic communities was previously available. The images recorded revealed a diverse benthic ecosystem characterized by (among several other assemblages) dense coral gardens of Narella versluysi, Narella bellissima and Candidella imbricata, aggregations of Stylasterids, large Callogorgia verticillata colonies and sponge grounds with the barrel sponge Pheronema carpenteri, as well as extensive areas with deposits of coral rubble.
6. We completed the first visual survey to the slopes of Santa Maria island, with a total of 30 dives carried out with the Azor drift-cam at depths between 200 and 1070 m depth, covering the whole perimeter of the island. The habitats explored host rich benthic communities, with black corals of the genus Leiopathes on its deepest areas, coral gardens of Narella versluysi and Narella bellissima and sponge grounds with Pheronema carpenteri at intermediate depths, and coral gardens with Viminella flagellum and Callogorgia verticillata, as well as aggregations of giant sponges of the genus Characella, in the shallowest areas explored, among several other assemblages.
7. We explored areas below 600 m depth inside the Marine Protected Area (MPA) of Formigas seamount to complete the exploratory work performed in deeper areas during the MedWaves cruise in 2016. The dives unveiled one of the largest and densest aggregations of the primnoid coral Callogorgia verticillata ever recorded in the Azores, which was found on the northern slopes of Formigas seamount. Although the area has been protected for several years, we were surprised by the amount of lost or abandoned fishing lines observed laying over the seabed.
8. We performed the first dives ever on Margrette seamount, the easternmost part of the Azores archipelago shallower than 1000 m depth, and hence that can be surveyed with the Azor drift-cam. Margrette seamount appeared to be a very complex area in terms of its geological morphology, with several vertical walls that complicated the exploratory work performed.
9. Discovered dense and diverse coral gardens and sponge grounds whose presence was unknown to science and that may fit the FAO criteria to be considered Vulnerable Marine Ecosystems (VMEs).