Unexplored Seamounts of the Salas y Gómez Ridge

Understanding seamount biodiversity
Experts believe the ridge provides a protective corridor for numerous organisms traveling between the central Pacific and the South American coast, and the area almost certainly harbors species new to science. Marine mammals and seabirds migrate across the ridge to feed. This region harbors 82 threatened or endangered species, and there is strong evidence that biodiversity along these seamounts warrants robust protections.

The connections and environmental drivers between the seamounts of the Salas y Gómez Ridge are understudied. A key objective of this expedition is to identify biogeographic boundaries at different scales. The team will examine how currents flowing between and around the mountains impact the distribution of vital food sources and the genetic diversity among the organisms living there. Their work will inform future conservation efforts and advance our understanding of oceanic processes around seamounts.

People and science at sea
The international, multidisciplinary team includes engineers, marine ecologists, and physical, geological, chemical, and biological oceanographers, half of whom come from Chilean scientific institutions. The Rapa Nui Sea Council (koro Nui o te Vaikava) elected Artist-at-Sea Tauroa Aguilera and Berth of Opportunity participant Serafina Moulto to join the expedition to bring their perspectives as Rapanui community members to the expedition.

To better assess the biodiversity and oceanic processes, the team will collect multibeam and backscatter data to generate maps of ridges and identify locations for exploration with the ship’s remotely operated vehicle, ROV SuBastian. They’ll also collect meteorological, acoustic, and oceanic data while surveying surface waters for seabirds, marine mammals, and marine debris. Water samples collected with the ship’s CTD rosette and baited traps will allow the scientists to look at productivity in the water column and compare that to wildlife sightings above and deep below the Ocean’s surface.

Video surveys and sampling with the ROV dives in three depth zones (<600, 600-1000, and 1000-1500 m) will help scientists describe what sort of animals and organisms exist along these seamounts and within potential biogeographic boundaries. Holotypes, the single physical examples of an organism used when the species is formally described, will remain at the Chilean National History Museum to build capacity for future scientific study and advocacy efforts in the region.

A stereo, laser, and hyperspectral camera system, currently under development and testing, will be integrated onto the ROV. The camera will allow the team to capture color arrays invisible to the human eye within each image pixel. The minute color differences will enable the identification of tiny organisms, different types of sand, and potentially whether or not animals are healthy or sick. Together, this data and imagery will paint a detailed portrait of biodiversity on the ridge.

Informing a high-seas marine protected area
In February of 2023, the United Nations adopted the High Seas Treaty and pledged to protect 30% of the world’s Ocean by 2030. Currently, less than 1% of the high seas are protected. While recent marine protected areas, or MPAs, have been established in Chile, they are limited to the country’s territorial waters. Rapa Nui leadership and Chilean policymakers have championed international efforts to designate the ridge as a large-scale marine protected area. Previous studies strongly suggest that the Salas y Gómez Ridge is a critical area to protect in international waters, and this expedition will provide solid evidence to support and advance this effort.

Furthermore, because there is little to no fishing or commercial activity around the ridge, scientists and policymakers are optimistic that it is a bastion for oceanic biodiversity. Due to the lack of human exploitation, a small window of opportunity exists for protecting the Salas y Gómez Ridge without impacting industry, which could galvanize support for international cooperation to preserve the ridge for future generations.