MapGES 2026 Cruise Report: Exploration and mapping of deep-sea biodiversity in the Azores on board the MT Physeter

Description

Main objectives: MapGES 2026 continues our longstanding commitment to map deep-sea biodiversity and identify Vulnerable 
Marine Ecosystems (VMEs) in the Azores with the Azor drift-cam imagery system. Our 2026 expedition aimed to enhance the data collected in previous surveys by conducting new video transects along the deep slopes of Santa Maria Island and in the Pico W seamount (locally known as Baixa da Bóia). This fieldwork focused mostly on the acquisition of new data from deep areas previously under-studied. Our ultimate goal is to achieve a comprehensive understanding of the deep-sea fauna dwelling on the slopes, banks, and seamounts in these areas. Like previous MapGES cruises, our objectives included: (i) mapping benthic communities in previously unexplored seamounts, ridges, and island slopes; (ii) identifying new areas that meet the FAO definition of Vulnerable Marine Ecosystems; and (iii) determining the distribution patterns of deep-sea benthic biodiversity in the Azores. The results of this cruise, added to previous contributions, help identify the environmental drivers that determine the spatial distribution of deep-sea benthic biodiversity in the Azores. It also provides valuable information in the context of Good Environmental Status (GES), Marine Spatial Planning (MSP), the new Nature Restoration Regulation (NRR), and new insights into how to sustainably manage deep-sea ecosystems.

Methodology: We conducted several underwater video transects along the seafloor using the Azor drift-cam, a cost-effective  drifting camera system developed by the Azores Deep-Sea Research group (ADSR) at the University of the Azores. This system is capable of recording high-quality underwater video images of the seabed, and it was deployed from the MT Physeter. In each sampling area, we performed a representative number of dives using the video system, ranging from approximately 1,000 m to the shallowest point of each geomorphological feature. To capture representative variability of the bathymetric gradient, major geomorphological features, and substrate types, the video transects were designed using the highest-resolution bathymetric data available. This transect design was additionally adjusted to allow the camera system to drift from deeper to shallower regions. This methodology was designed to ensure optimal image quality by maximizing light incidence and minimizing attenuation in the water column, a challenge typically encountered during descending transects. Each transect with the Azor drift-cam was planned for approximately 60 to 120 minutes on the seafloor, with the system drifting over benthic habitats at an average speed of 0.2 to 0.5 knots. Under favourable conditions, each working day facilitated 3 to 4 dives, corresponding to approximately 3 kilometres of seafloor explored daily.

Cruise summary: The MapGES 2026 cruise aboard MT Physeter consisted of 1 leg, aiming at exploring and revisiting slopes  surrounding Santa Maria Island. A total of 33 successful dives were conducted out of 34 planned, covering 5 sampling areas from 1 st July to 16th July 2026. These deployments surveyed the deep-sea benthic communities inhabiting the slopes of the multiple geomorphological structures around Santa Maria Island. Throughout this survey, we also tested some add-ons on our structure, such as the new DJI Osmo Pro 5 action-cam and the attempt to use a 1700m umbilical cable. Several deep dives (>1000 m) were performed during this leg with no major problems across the components of the drift-cam. Many of the transects performed covered soft substrate bottoms, represented by large extensions of sandy sediments even on relatively steep slopes, rocky outcrops, and shallow sectors. During this year’s survey, we observed diverse communities of benthic  invertebrates and fish, from which we may highlight impressive and extensive aggregations of the primnoid corals Candidella imbricata, Narella versluysi and N. Bellissima, the notably large specimens of the octocoral Callogorgia verticillata and a variety of black corals including Leiopathes expansa, Phanopathes erinaceus and Antipathes dichotoma. Also, frequent and extensive fields of the bird’s nest sponge Pheronema carpenteri were seen around the whole Island slopes, and it was possible to record the long-lived and, uncommon on Island slopes, Hoplosthetus atlanticus.

Main achievements: 

  1. During the MapGES 2026 survey conducted aboard the MT Physeter, 34 stations were completed using the  Azor drift-cam. The stations spanned depths ranging from 60 to 1148 m, encompassing a broad spectrum  of depth strata. The survey covered approximately 22 km of the seafloor and generated more than 55 hours of video footage for analysis. These numbers represent a big achievement considering that we successfully operated, once again, the Azor drift-cam for deep-sea exploration on board a small vessel.
  2. This year’s survey aimed to complete the coverage of selected Island slopes around Santa Maria Islands. We accomplished nearly all our objectives in each one of the areas re-visited, even with the challenging sea conditions we faced most of the days.
  3. For the fourth consecutive year of the MapGES survey onboard the MT Physeter, no Azor drift-cam structures were lost, even though we were challenged by an entanglement on basaltic rock that took more than 8 hours to retrieve.
  4.  As one of our key objectives this year was to explore deeper strata previously unsampled in certain areas, the drift-cam was repeatedly deployed at depths exceeding 1000 m and performed outstandingly with no issues across all components and showing the remarkable resilience of the system.
  5. We performed the longest dive ever deploying the Azor drift-cam, with a bathymetric range that went from around 900 to 60 m, a total duration of nearly three and a half hours and covered more than 2.5 km of seabed.
  6. The transects conducted on the west and east slopes of Santa Maria Island reaffirmed the predominantly depositional nature of these sectors, in contrast with the prevailing erosional environment in the other sectors. Depositional areas were characterized by extensive surficial sand strata of different thickness covering relatively steep slopes, rocky outcrops and shallow sectors.
  7. A high-density patch of unidentified shrimps was recorded with the Azor drift-cam, found in a basaltic outcrop in Santa Maria West slope. The reason for the aggregation of these individuals could not be established. 
  8. We may have reached the depth limit of the current work capabilities of the Azor drift-cam. We experienced problems receiving the live-view image signal with a brand-new umbilical cable of 1700m.
  9. Deep hard substrates on the north slopes of Santa Maria revealed a large diversity of antipatharians, displaying sometimes large colonies of Leiopathes expansa, Antipathes dichotoma and Phanopathes erinaceus.
  10. Lytocarpia myriophyllum interestingly displayed infrequently seen associated fauna, such as the decapod Anamathia rissoana, commonly observed on top of the whip coral Viminella flagellum in shallower sectors.
  11. The primnoid coral Candidella imbricata was commonly spotted on the transition between outcropping rocks and mixed substrate of the deep sectors. The bird’s nest sponge Pheronema carpenteri was also frequently observed in the same sectors. These species were frequent but rarely co-occurring.

 

Authors

DOI: 10.5281/zenodo.21537924

Publication Date: 2026-07-28

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