Seamounts of the Southeast Pacific

Exploring biogeographic boundaries
Physical and biological forces interact, creating distinct biogeographic regions that influence what can live there and how much life an area can support. Scientists have observed and studied a biogeographic boundary impacting what organisms, or fauna, live between the Indo-West Pacific and the East Pacific. A key objective of this expedition is to determine if such a boundary is also present at greater depths and if the deep-sea organisms on the lower slope are related to intensively studied ecosystems elsewhere in the Pacific.

Using the R/V Falkor (too)’s multibeam sonar and subbottom profiler, researchers will create detailed maps of the terrain in order to identify the best locations for ROV dives and sampling. The science team intends to focus on previously unstudied biodiversity — deep-sea corals, sponges, and associated invertebrates, and fishes — along the deep slopes of the seamounts and compare them to known communities between the Indo-West and East Pacific. The team will conduct non-destructive surveys on 10 seamounts of Salas y Gómez, Nazca, and Juan Fernández Ridges, representing complex topographic features with potentially sensitive organisms on the seafloor.

Understanding impact
With less than 1% of the Earth’s seamounts thoroughly mapped and sampled, this research will help scientists better understand how human and oceanic forces are influencing life at some of the least studied seamounts in the Southeast Pacific. Communities living on seamounts usually include long-lived, slow-growing, slow-to-reproduce, and fragile habitat-forming invertebrates. This makes seamounts particularly sensitive and vulnerable to human disturbance and exploitation.

In 2016, Chile banned bottom trawling on seamounts — one of the most destructive fishing methods — because it involves dragging a net along the seafloor or seamount slope to capture fish or crustaceans. The process destroys entire seafloor habitats. Exploring Chile’s seamounts will help scientists examine ecosystem recovery following the ban.

Furthermore, a global alliance of partners whose objective is to protect coral reefs in areas beyond national jurisdiction, the Coral Reefs of the High Seas Coalition or CRHSC, has been working since 2019 to synthesize scientific information and propose conservation measures to protect the Salas y Gómez and Nazca ridges. This work led to the publication of a large number of scientific papers and educational materials over the last four years.

In April 2021, Chile launched an effort to create a high seas marine protected area, known as an MPA, in the Salas y Gómez and Nazca ridges, as a priority measure to address the climate crisis; this was the first political action carried out by a government to protect this area. After the announcement, the proposal was presented to the scientific committee of the South Pacific Regional Fisheries Management Organization in September and in June 2022 it was announced during the UN Ocean Conference in Lisbon. In November 2022, Chile and CRHSC co-hosted the workshop, Pathway to Protect Salas y Gómez and Nazca Ridges, and more recently, in February 2023, they hosted Pathway to Protect Critical High Seas Areas during the International Marine Protected Areas Congress in Vancouver.

The coordinated efforts of Chile and CRHSC include building international political support for the creation of the first High Seas large-scale marine protected area in the waters of the Salas y Gómez and Nazca ridges. The data collected during the expedition will help further clarify challenges and opportunities for future protection. A detailed understanding of biodiversity in and outside Chile’s marine protected areas will give scientists and officials tools for protecting and managing this vital resource, while supporting future marine management plans for the Southeast Pacific.