Biodiversity and Biogeography of the Abyssal and Hadal Aleutian Trench and Adjacent North Pacific Deep-Sea Regions
The scientific legacy of the AleutBio project
AleutBio (Aleutian Trench Biodiversity Studies), one of the earliest projects associated with the Challenger 150 programme, has now reached its final milestone with the publication of a landmark Special Issue bringing together the scientific outcomes of years of international deep-sea research and collaboration.
Led by Senckenberg Research Institute and Natural History Museum (Germany), and centred on the SO293 expedition aboard RV Sonne in 2022, the AleutBio project focused on advancing scientific understanding of biodiversity, species connectivity, and ecosystem dynamics across the eastern Bering Sea and Aleutian Trench region – a critical gateway between the Pacific and Arctic Oceans.
“Biodiversity and Biogeography of the Abyssal and Hadal Aleutian Trench and Adjacent North Pacific Deep-Sea Regions” is now available through ScienceDirect.
A multidisciplinary effort to explore the deep North Pacific
The AleutBio project was designed to investigate biodiversity and ecosystem connectivity across the eastern Bering Sea and the abyssal and hadal depths of the eastern Aleutian Trench – one of the least explored deep-sea regions in the North Pacific.
The deep sea represents approximately 95% of Earth’s habitable volume, yet only a tiny fraction has been directly observed. Prior to AleutBio, no abyssal or hadal samples had been collected from the eastern Aleutian Trench region, apart from a single box corer taken farther west in the 1970s.
Combining biodiversity research with microbiology, oceanography, bathymetric mapping, molecular biology, and biogeochemistry, AleutBio sought to better understand how species are distributed across deep-sea environments and how these ecosystems are responding to rapid environmental change.
Researchers studied life across every scale of the deep-sea ecosystem, from microbial communities and microscopic protists to meiofauna, macrofauna, and megafauna. The project also investigated:
- species connectivity between trench systems,
- environmental drivers shaping biodiversity,
- sediment composition and organic carbon dynamics,
- and ecological relationships between the Aleutian Trench, the Kuril-Kamchatka Trench, the Bering Sea, and the Arctic Ocean.
The Bering Sea and Aleutian region are undergoing rapid environmental change, including warming temperatures, sea-ice loss, shifting oxygen conditions, and altered deposition dynamics. AleutBio therefore provides critical baseline knowledge for understanding how deep-sea communities may respond to accelerating climate-driven change.
A Challenger 150-endorsed project
AleutBio was among the first projects to be endorsed by Challenger 150. The project strongly reflected Challenger 150’s wider mission:
- advancing deep-ocean biodiversity knowledge,
- strengthening international scientific partnerships,
- promoting interdisciplinary collaboration,
- and improving understanding of vulnerable deep-sea ecosystems.
The expedition also placed strong emphasis on public engagement and outreach through daily expedition blogs, social media updates, and wider science communication efforts that shared the realities of deep-sea exploration with global audiences.
The resulting Special Issue now makes many of the expedition’s scientific findings accessible to the wider research community while establishing an important foundation for future deep-sea studies in the North Pacific.
Scientific discoveries emerging from challenge
The AleutBio project unfolded during a period of significant geopolitical and logistical uncertainty, requiring substantial adjustments to planning, scientific personnel, logistics, and geographical focus throughout the expedition process.
As project lead Angelika Brandt explained in a quote published on the AleutBio website:
“AleutBio was an extremely challenging project due to the geopolitical situation, requiring considerable effort and numerous adjustments regarding logistics, scientific personnel, and the geographical focus of the research.
Nevertheless, we can say today that these challenges were met in an outstanding manner. In fact, the necessary geographical shift of the project even led to remarkable scientific surprises and highly encouraging data.
Although we collected only about one-tenth of the number of invertebrates compared to our previous expedition in the Kuril-Kamchatka Trench, we observed a comparable level of species diversity – a truly noteworthy finding. Particularly striking is the high connectivity of certain species from the eastern Aleutian Trench, which were also found in the Kuril-Kamchatka Trench and even in the Japan Trench.
My sincere thanks go to the Federal Ministry of Education and Research (BMBF) for its generous financial support, to the German Research Vessel Coordination Centre for their tireless and consistently reliable assistance, to Senckenberg for their institutional backing, and to my excellent scientific team. I would also like to thank all the researchers on board the expedition and our collaboration partners.
This was truly outstanding teamwork – thank you all!”
Despite these challenges, AleutBio produced an extraordinary volume of scientific data. The expedition expanded existing biogeographic datasets by adding more than 36,000 new records below 3,500 metres depth, compared with only 153 previously available for the region.
The findings also revealed unexpectedly high biodiversity and complex patterns of connectivity across deep-sea trench systems, helping reshape understanding of species distribution in the North Pacific deep sea.
Key scientific findings from the Special Issue
The AleutBio Special Issue presents the first comprehensive scientific results from this pioneering survey of the eastern Aleutian Trench and adjacent North Pacific deep-sea regions.
Together, the papers translate AleutBio’s expedition objectives into a cohesive picture of deep-sea discovery across one of the North Pacific’s least explored regions.
Among the major findings highlighted throughout the volume are:
- numerous species new to science,
- high levels of cryptic biodiversity,
- distinct benthic habitats shaped by sediment and organic carbon dynamics,
- evidence of significant species connectivity across trench systems,
- and new insights into how environmental gradients structure deep-sea communities.
The project documented remarkable biodiversity across multiple taxonomic groups. Approximately 77% of the isopod species collected in the Aleutian Trench were identified as new to science, while researchers identified 182 amphipod molecular operational taxonomic units (MOTUs), only six of which matched known species.
The Special Issue also documents:
- a newly established sponge family,
- the discovery of new kinorhynch, tanaid, ostracod, amphipod, and isopod species,
- the rediscovery of rare deep-sea fauna including the dumbo octopus Grimpoteuthis imperator,
- and the first Pacific record of the pennatulacean species Porcupinella profunda.
One of the most significant scientific themes emerging from the project is the unexpectedly high degree of connectivity between deep-sea trench systems. Several species collected in the eastern Aleutian Trench were also linked to populations in the Kuril-Kamchatka Trench, the Bering Sea, and other North Pacific deep-sea regions, suggesting more complex patterns of dispersal and ecological connectivity than previously understood.
The expedition also advanced methodological approaches in deep-sea biodiversity research through the use of DNA barcoding, metabarcoding, environmental DNA sequencing, proteomics, and integrative taxonomy combining molecular and morphological analyses.
Climate change and the future of deep-sea ecosystems
The AleutBio findings reinforce growing evidence that deep-sea ecosystems are vulnerable to climate-driven environmental change.
Researchers documented changing sediment deposition dynamics linked to glacial runoff, shifting environmental conditions across benthic habitats, and ecological patterns associated with warming waters and changing oxygen availability.
Species distribution modelling conducted through the project suggests that future environmental change may significantly alter the distribution of some deep-sea species across the North Pacific, potentially creating both ecological “winners” and “losers” as conditions continue to shift.
As Arctic systems continue to warm and human activity in northern marine regions increases, long-term biodiversity baselines such as those generated by AleutBio become increasingly important for future conservation, monitoring, and ocean stewardship efforts.
International collaboration at the centre of the project
Large-scale deep-sea science depends upon long-term international collaboration, interdisciplinary expertise, and extensive logistical coordination.
Throughout its duration, AleutBio brought together researchers, students, technicians, taxonomists, institutions, and collaboration partners from across the global scientific community. The project built upon earlier expeditions in the Northwest Pacific while expanding scientific understanding into previously underexplored regions of the eastern Aleutian Trench.
The completion of this Special Issue reflects years of collaborative work across biodiversity research, taxonomy, microbiology, geochemistry, oceanography, molecular biology, and environmental modelling.
It also reinforces the wider vision shared by Challenger 150 and the UN Ocean Decade – that understanding and protecting the deep ocean requires global scientific cooperation at an unprecedented scale.
A lasting scientific legacy
With the publication of this Special Issue, the AleutBio project achieves its final milestone, marking both the culmination of a major international research programme and the beginning of a lasting scientific legacy.
The biodiversity records, datasets, specimens, methodological advances, and international collaborations generated through AleutBio will continue to inform research into deep-sea biodiversity, species connectivity, climate-driven ecological change, and the protection of remote ocean ecosystems for years to come.
The full Special Issue can now be explored via ScienceDirect.
For more information about the project, visit the AleutBio project website.