Azores Deep-sea Research — Cruise MapGES 2025 MT Physeter

MapGES 2025 MT Physeter

Mapping deep-sea biodiversity and “Good Environmental Status” in the Azores

Summary

Mapping deep-sea biodiversity and “Good Environmental Status” in the Azores

The MapGES 2025 cruise aboard MT Physeter consisted of 1 leg, divided in 3 parts, aimed at exploring and revisiting slopes, banks, ridges, and seamounts surrounding Faial, Pico, Graciosa and Terceira Islands. A total of 40 successful dives were conducted out of 41 planned, covering 11 sampling areas. During Leg 1a, on the 4th of June, we performed 2 successful dives with the Azor drift-cam. These first deployments surveyed the deep-sea benthic communities dwelling on the slopes of the geomorphological structures on the north flank of Faial Island. These first dives were also a practical test to experience some add-ons on our structure, such as the external feeding of the GoPro camera, the implementation of a second spotlight, the use of a 1500m umbilical cable and the USBL system. During the Leg 1b, from 21st June to 1st of July, we performed 35 successful dives with the Azor drift-cam around Graciosa and Terceira Island slopes and some adjacent geomorphological structures such as Vasco Gil, Ilha Azul E and João de Melo. Several deep dives (>1000 m) were performed during this leg with no major problems across the components of the drift-cam. During the Leg1c, on the 25th of July, we performed 3 successful dives with the Azor drift-cam on the deeper sectors of the NW slopes in Pico Island. During this year’s survey we observed diverse benthic and fish communities, from which we may highlight impressive and extensive aggregations of the primnoid corals Narella versluysi and N. bellissima, in Ilha Azul E, the notably large specimens of the octocoral Callogorgia verticillata, in Maçarico, the black corals Leiopathes expansa, in Beirada de Fora, and Antipathes dichotoma, in Vasco Gil. Also, an incredible and most likely record-breaking aggregation of anguilliform fishes Halosauridae was recorded at approximately 900 m depth in Graciosa S area.

MapGES 2025 continues our longstanding commitment to map deep-sea biodiversity and identifying Vulnerable Marine Ecosystems (VMEs) in the Azores with the Azor drift-cam imagery system. Our 2025 expedition aimed to enhance the data collected in previous surveys by conducting new video transects along the slopes of several islands in the archipelago, including Faial, Pico, Graciosa and Terceira. This fieldwork focused mostly on under-sampled areas and deeper strata. Additionally, we planned to explore one new area, specifically Vasco Gil seamount. 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 the previous contributions to 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) and new insights on how to sustainably manage deep-sea ecosystems.

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Statistics

Transits

829 km

Multibeam Bathymetry

km²

Filmed Seabed

30.8 km

Visited Areas

Stations

Dives

Video Footage Recorded

49 hours

Used Storage

2.3 Tb

Samples

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Highlights

During the MapGES 2025 survey conducted aboard the MT Physeter, 41 stations were completed using the Azor drift-cam. The stations spanned depths ranging from 205 to 1130 m, encompassing a broad spectrum of marine strata. The survey covered approximately 31 km of the seafloor and generated more than 49 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 and this year with several improvements on our system, including an umbilical cable of 1500m, the underwater positioning system (USBL), the external power feeding of the GoPro camera and the addition of a second spotlight.
This year’s survey aimed to complete the coverage of selected Island slopes around Faial, Graciosa, Terceira and Pico Islands. We successfully accomplished nearly all our objectives in each one of the areas re-visited and were also able to explore the Vasco Gil seamount for the first time.
For the third consecutive year of the MapGES survey onboard the MT Physeter, no Azor drift-cam structures were lost, despite that we were challenged by an entanglement on a lost fishing line, the unexpected encounter of the largest basaltic wall recorded with the Azor drift-cam dive (around 300m high) and an incident where the umbilical cable became entangled in the vessel’s propeller.
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 900 m and performed outstandingly with minimal issues across all components.
Ilha Azul E exhibited impressive and extensive aggregations of the primnoid corals Narella versluysi and N. bellissima.
Exploration of several areas East of Terceira Island continues to reveal interesting communities. Notably, large specimens of the octocoral Callogorgia verticillata and large black corals Leiopathes expansa were observed in the Maçarico area and Beirada de Fora areas, respectively.
The first exploration of Vasco Gil seamount revealed large black corals Antipathes dichotoma.
Remarkable geological features were observed across the surveyed areas: around the Vasco Gil seamount a heterogenous seafloor composed of contrasting black and white rock types suggests a complex geological origin in this geomorphological structure. Interesting geological patterns of the seafloor was sighted in Ilha Azul E and Beirada de Fora areas, where evidence of ancient stratification was recorded.
A deceased undetermined shark was observed on a sandy bottom in Graciosa S area, probably resulting from fisheries discards. This marks the first recorded shark carcass during an Azor drift-cam deployment. The rarity of such observations rise questions about the visibility and persistence of large organic falls in deep-sea environments.
An incredible and most likely record-breaking aggregation of anguilliform fishes Halosauridae was recorded at approximately 900 m depth in the southern area of Graciosa Island.
An unusually high number of angler fish (Lophius piscatorius) was repeatedly observed along the slopes of Graciosa Island.
The decapod Cancer bellianus was observed on top of the vase-shaped Characella pachastrelloides while holding another sponge. This behaviour is likely uncommon for this species of crustacean.