Archaeological heritage and biodiversity hotspots : mutualisation of technological innovation and investigation strategies to improve knowledge and protection in poorly explored deep-sea regions

Deep-sea exploration is recent and its cultural and biodiversity heritage remains largely unknown. Human activities increasingly developing at great depths threaten the richest of these sites, and massive destruction occurs sometimes even before they are discovered and inventoried. Investigating and establishing effective protection measures for deep-sea biodiversity and cultural heritage sites is a critical challenge, requiring urgent and collaborative exploration efforts.

Mutualistic approaches integrating deep-sea biodiversity and archeological investigations hold great potential to support this effort. Underwater archaeology and deep-sea ecology share similar requirements in terms of instrumentation for accessing sites, for observation and sampling at scales ranging from centimetres to tens-of-meters. Furthermore, the investigation of shipwrecks provides unique opportunities for advancing knowledge in terms of spatial and temporal dynamics of deep-sea communities and highlights the potential role of archaeological sites as habitats for protected species, of relevance to conservation strategies and to anthropogenic impact assessments at depth.

Certain priority areas for underwater archaeology exploration, such as historical maritime routes, represent hotspots of this cultural and ecological heritage. This is the case of the Corsica Channel, between the east coast of the island and Italy, where the seabed reaches depths of several hundred meters within a short distance from the coast of Corsica, marked by a narrow shelf and steep margin, in addition to be host a large number of shipwrecks from more than a 2000-year time period. The development of « lightweight » deep-sea robotic technologies has opened access to these depths to explorers and researchers. The Département des Recherches Archéologiques Subaquatiques et Sous-marines (Drassm) of the French Ministry of Culture pioneered this effort through its programme of research and innovation on the deep-sea shipwrecks off-shore Corsica, fostering tight collaboration between archaeologists and roboticists for the development of dedicated instrumentation.

This strategy and these tools are also highly valuable for deep-sea ecological research and biodiversity conservation programs. The development of collaborations between the Drassm and the Museum National d’Histoire Naturelle (Paris, France), since 2021, has notably provided new information on the distribution of protected taxa, such as scleractinian and gorgonian corals, in this region of the western Mediterranean sea under particular stress from climate disturbance. The data acquired provide insights to the growth rate and favourable habitat conditions of these foundation species and, more broadly, on the diverse fauna hosted by deep-sea shipwrecks, expanding deep-sea ecological knowledge, in alignment with the objectives of protection and conservation in the area (Parc Naturel Marin du Cap Corse et de l’Agriate, Natura 2000 Habitats Directive). This program triggered joined-efforts for the characterisation of settlements on different archaeological sites, their structuring species and associated fauna, using deep-sea imagery. The presentation will illustrate the value of this collaborative effort and its contribution to of the investigation of poorly explored sites, cultural and biological hotspot of unique richness, through different examples, ranging from the Roman-era to World War II shipwrecks.