The Arctic seabed contains significant reserves of oil and natural gas, as well as strategic resources such as rare earths and metals. Accelerated melting of the ice, catalysed by climate change, seems to be paving the way for their exploitation. But above all, it raises major ecological concerns at a time when scientific knowledge remains limited.
by Laurie Henry
Cover photo: The amphipod Amathillopsis aff. spinigera is one of the many organisms living at the bottom of the Arctic Ocean. © Lydia A. Schmidt and Carolin Uhlir/Senckenberg
Occupying a central position in the global climatic and oceanographic balance, the Arctic Ocean is connected to the Atlantic and Pacific by currents that influence marine ecosystems far beyond high latitudes. Its depths, long considered hostile and deserted, nevertheless play a key role in the regulation of nutrient flows and global ocean circulation. But this region, essential to the stability of the oceans, is today under pressure from economic and geopolitical issues, particularly with the prospect of new shipping routes.
Far from being an icy desert, these abysses harbour a biodiversity that is still largely unknown. A study conducted by researchers from the Senckenberg Research Institute, the Alfred Wegener Institute and the University of Bergen, published in the journal Elementa, draws up a new inventory of the unsuspected richness of these ecosystems, but also of the threats they face. This work invites us to rethink research priorities and the measures to be taken to conserve the treasures of this region.
Exceptional diversity at the bottom of the abyss
The researchers based their work on an analysis of 75,404 data sets, compiled from accessible databases such as OBIS (Ocean Biodiversity Information System) and GBIF (Global Biodiversity Information Facility), as well as non-digitised scientific publications. These data, centred on the region north of 66°N and at depths exceeding 500 metres, have made it possible to identify 2,637 benthic species.
Arthropods are the dominant group, with 21,405 occurrences mainly comprising crustaceans such as copepods and isopods, adapted to the loose sediments and rocky structures of oceanic ridges. The annelids, recorded in 13,763 occurrences, mainly colonise continental slopes and submarine canyons where organic matter accumulates, favouring their development. Sponges, with 12,591 occurrences, are particularly abundant in areas with strong currents, such as cold-water coral reefs and seamounts, where they play an essential role in water filtration and habitat structuring. Species diversity and distribution are strongly influenced by local conditions, including depth and nutrient availability.
Arctic Ocean (66–90°N) maps showing the records in the compiled dataset by geomorphological feature. (A) Each point represents the occurrence of a record at a water depth > 500 m. (B) Map showing taxon density reported by hexagon, each hexagon being approximately 50,000 km2 in size. (C) Map showing the density of occurrence records reported by hexagon of equal size of 50,000 km2. © Eva Ramirez-Llodra et al., 2024The results also show a significant disparity in the distribution of species according to underwater structures. The Gakkel Ridge, which crosses the centre of the Arctic Ocean, is home to a specialised fauna around hydrothermal vents, where chemosynthetic organisms exploit the elements dissolved in the water to survive in the absence of light. In contrast, abyssal basins, such as the Eurasian and Canadian basins, are characterised by more homogeneous and nutrient-poor environments, limiting biological diversity to highly specialised, often endemic species.
The study also revealed significant gaps in the data, particularly in the central Arctic basins, where the lack of sampling, due to logistical constraints and extreme conditions, prevents a full understanding of these ecosystems. This lack of information represents a major challenge for the conservation and sustainable management of these fragile habitats.
Innovative tools to unlock the mysteries of the deep
Thanks to new advanced technologies such as remotely operated (ROV) or autonomous underwater vehicles (AUV), the seabed has been mapped and biological and geological samples collected using robotic arms. These vehicles, equipped with high-definition cameras, offer real-time visualisation of deep habitats, revealing complex structures such as sponge reefs or hydrothermal vents. During recent missions, these technologies have made it possible to document the unique ability of certain sponges to move, a discovery that redefines our understanding of benthic life.
Rarefaction curves of the number of taxa in relation to the number of records for the depths of the Arctic Ocean. Rarefaction curves (A) by 5-degree latitudinal bands and (B) by geomorphological characteristics. © Eva Ramirez-Llodra et al., 2024
At the same time, environmental DNA (eDNA) analysis has emerged as a powerful tool for mapping biodiversity without disturbing habitats. By collecting water or sediment samples, this method detects the genetic traces left by marine organisms, providing a quick and comprehensive overview of the species present.
This technique has thus revealed unsuspected diversity in remote and difficult-to-access areas, where conventional sampling methods are ineffective. Combined with the capabilities of ROVs, eDNA considerably enriches global databases.
But the challenge for the future remains the harmonisation and centralisation of these efforts on an international scale. According to Dr Saeedi, ‘international cooperation and access to modern infrastructure, through initiatives such as the United Nations Decade of Ocean Science, have been essential in filling some knowledge gaps, but increased efforts are still needed’.
An economic treasure under pressure
Unfortunately, the Arctic also harbours major strategic resources, with 13% of the world’s untapped oil reserves and 30% of its natural gas reserves. These reserves, combined with rare metals and rare earths, are fuelling the interest of global industries. The melting of the ice, aggravated by global warming, has not only made these riches more accessible, but has also opened up new strategic maritime routes. According to the authors, these dynamics could accelerate the exploitation of these regions, even though scientific knowledge about these environments remains insufficient to ensure their sustainable management.
Data availability for the deep Arctic Ocean by 100-m depth interval. (A) Total number of records. (B) Total number of taxa (solid bars) and species (hatched bars) by depth interval. © Eva Ramirez-Llodra et al., 2024
This economic pressure is taking place in a tense geopolitical context, where certain nations such as the United States or Denmark are expressing growing ambitions. Faced with these challenges, Professor Brandt warns of the ecological impacts. The exploitation of the Arctic could threaten an ecosystem that is still poorly understood, and which is essential for global biodiversity. Without a framework for solid international cooperation, these resources risk being plundered to the detriment of the environmental balance, while the available data already reveals gaps in the mapping and study of deep ecosystems.
Indeed, despite progress, explorations remain fragmented and depend on international collaborations. To go beyond one-off initiatives, the scientific community must combine technology and diplomacy to protect these ecosystems from growing economic pressures. One avenue for the future lies in the development of permanent observatories on the seabed, capable of continuously monitoring these extreme environments. These infrastructures could not only strengthen research, but also serve as warning tools for environmental impacts, thus enabling proactive and sustainable management of Arctic resources.
Source : Eva Ramirez-Llodra et al, “The emerging picture of a diverse deep Arctic Ocean seafloor: From habitats to ecosystems”, Elementa (2024).