Deep ecosystems, a still largely unknown world: exploration campaigns launched in 2015

In 2014, a workshop of the Convention on Biological Diversity held in Malaga led to the identification of Ecologically or Biologically Significant Areas (EBSAs) in the Mediterranean, including waters within the RAMOGE area. Scientists involved in the Agreement then produced a map of sites with high biodiversity potential, identifying 67 areas, including Posidonia seagrass meadows and coralligenous habitats, as well as numerous canyons and seamounts, many of which remain largely unexplored.

RAMOGE subsequently launched a deep-sea exploration program, with campaigns conducted in 2015, 2018, and 2022. On board a research vessel, scientists carried out detailed bathymetric surveys and explored depths ranging from 50 to 2,200 meters using a remotely operated vehicle (ROV) capable of filming and collecting samples. In total, 33 dives were conducted across 18 sites, covering more than 80 km of transects and recording over 90 hours of video. The next campaign is scheduled for summer 2026 aboard the research vessel Alfred Merlin, operated by the DRASSM, part of the French Ministry of Culture.

These explorations reveal a rich biodiversity, specific to each type of environment (rocky and soft seabeds), and enable unique, sometimes unprecedented observations, including the presence of rare or threatened species and remains dating back to the last glacial period. During each campaign, around 120 different species and more than 30,000 individuals are recorded.

However, even in these deep areas, human impact remains evident: lost fishing gear and marine litter, 80% of which is plastic, disrupt marine life, causing entanglement, injuries, suffocation, or poisoning. These findings highlight the importance of collective awareness to protect these ecosystems, which are essential to the health of the Mediterranean.

The data collected make it possible to propose concrete management measures, such as the creation of an offshore Natura 2000 site protecting a complex of three Italian seamounts. The extension of the Bergeggi marine protected area is also currently under consideration. These initiatives fully support the countries of the Agreement in their international commitment to protect 30% of the Mediterranean by 2030, and reaffirm the importance of RAMOGE for cooperation, research, awareness, and protection.

Map of ecologically or biologically significant areas identified within the RAMOGE zone (polygons), sites explored using a remotely operated vehicle (ROV) during the 2015, 2018, and 2022 campaigns (red points), and the Natura 2000 site established at the Ulisse-Doria-Janua complex of three Italian seamounts (1,126 km², depths ranging from 450 to 2,056 m). RAMOGE Archives.

Diagram of a deep-sea exploration mission workflow. RAMOGE Archives.

The Astrea, an Italian research vessel of the Institute for Environmental Protection and Research (ISPRA), used for the 2015 and 2022 exploration campaigns, photograph, August 2015. RAMOGE Archives.

The Atalante, a French research vessel of the French Research Institute for Exploitation of the Sea (IFREMER), used for the 2018 exploration campaign, La Seyne-sur-Mer, photograph, September 17, 2018. RAMOGE Archives.

The ROV Victor 6000 (a remotely operated underwater vehicle capable of reaching depths of up to 6,000 m), aboard the Atalante, photograph, September 18, 2018. RAMOGE Archives.

Transect of an exploration dive carried out by a remotely operated vehicle (ROV) on September 22, 2018, at the Janua seamount (Italy). RAMOGE Archives.

Mapping of the Cannes Canyon and the Méjean shoal, 2018. RAMOGE Archives.

Basket star (Gorgonocephalus mediterraneus) on a violescent sea-whip (Paramuricea clavata), part of a coralligenous ecosystem (Monaco, –55 m), photograph, 2015. RAMOGE Archives.

Coralligenous ecosystem (Nioulargue Bank, –100 m), characterized by several species of gorgonians, including the violescent sea-whip (Paramuricea clavata) and fish such as Swallowtail seaperch (Anthias anthias), photograph, 2015. RAMOGE Archives.

Skeletal remains of Paragorgia arborea (Janua seamount, –1,008 m), a cold-water gorgonian whose presence in the Mediterranean was previously unknown. Dating of a sample showed that the colony lived in the Mediterranean 10,000 years ago. The species thrived during the last glacial period before becoming extinct. Photograph, 2018. RAMOGE Archives.

Placogorgia sp., a species of gorgonian very rare in the Mediterranean (Janua seamount, –995 m), photograph, 2018. RAMOGE Archives.

Widehead brotula (Cataetyx laticeps) (Monaco, –2,147 m). This is the first recorded observation of this species in the Mediterranean since 1974. This fish is one of the few viviparous species in the Mediterranean, with females giving birth to live young rather than laying eggs. Photograph, 2018. RAMOGE Archives.

Blackmouth catshark (Galeus melastomus) (Arma di Taggia, –362 m). This small shark, measuring 50 to 80 cm in length, lives in the Mediterranean and the northeastern Atlantic, at depths ranging from 50 to 1,200 m. Photograph, 2015. RAMOGE Archives.

Ocean sunfish (Mola mola) entangled in a fishing line (Nioulargue Bank, –260 m), photograph, 2015. RAMOGE Archives.

Violescent sea-whip (Paramuricea clavata) entangled in a fishing net (Bordighera, –75 m), photograph, 2015. RAMOGE Archives.

Accumulation of debris at a depth of 2,200 m in the Monaco Canyon, photograph, 2018. RAMOGE Archives.

Published results of the three deep-sea exploration campaigns of 2015, 2018, and 2022, covers. A.P.M., A/655/17, and RAMOGE Archives.

RAMOGE conference at the Oceanographic Museum of Monaco dedicated to deep-sea exploration campaigns, delivered by scientists from the three countries of the Agreement. Photograph, February 26, 2025. RAMOGE Archives.