Expedition Galápagos Deep 2023
In late March 2023, the four-week "Galápagos Deep 2023" expedition was launched with 22 researchers, with the aim of learning more about the biodiversity and geology of the deep waters around the Galápagos. Alvin, the deep-sea submarine (DSV-2) which had already explored the wreck of the Titanic in 1986, was part of the expedition. Alvin can accommodate three people on board, can dive to depths of 6,500 meters and has two gripper arms capable of collecting samples with extreme precision and delicacy, as well as a high-resolution photo and video imaging system.
One remarkable discovery was a large accumulation of kelp. At around a meter long, it is the largest seaweed in the entire Ecuadorian marine area, and a plant not normally found in the tropics, which can only exist here thanks to cold-water currents such as the Humboldt Current. The kelp is an important habitat for key species that are essential to the survival of entire populations, particularly in the mesophilic zone, where very little daylight penetrates. After the violent El Niño season of 1982-83, kelp was only found off the west coasts of Isabela and Fernandina and was considered extinct in the rest of the archipelago. It now turns out that kelp forests the size of soccer fields exist at shallow depths of around 100 meters between Santa Cruz, Isabela and Floreana. They are different from the kelp of the western archipelago (Eisenia galapagensis) and probably constitute a distinct subspecies.
Kelp forest discovered with the ROV at around 55m depth. Image courtesy of Alize Bouriat, Charles Darwin Foundation
In addition to highly successful mapping and sampling dives, the expedition made a unique discovery: between the islands of Santa Cruz and San Cristóbal, at a depth of 400 to 600 meters, researchers found an intact coral reef full of life on the crest of a sunken volcano that had not been mapped until now. It stretches for several kilometers and consists of 50-60% living coral, in addition to numerous other marine species. The norm for deep-water coral reefs is a maximum of 10-20% live corals. Cold-water corals are among the oldest living organisms we know. They are an incredible 2,500 to 3,000 years old. At this depth, corals no longer have access to daylight. They live on "marine snow", a continuous rain of particles that allows large quantities of carbon to pass from the surface layers to the depths.
Ancient living deep coral reef (Mixed Madrepora sp. and Dendrophyllia sp. cold water coral) framework at 500m-400m depth. Image courtesy of L. Robinson (U. Bristol), D. Fornari (WHOI), M. Taylor (U. Essex), D. Wanless (Boise State U.) NSF/NERC/HOV Alvin/WHOI MISO Facility, 2023 ©Woods Hole Oceanographic Institution
The many images and samples collected are currently being analyzed in detail and promise to provide a wealth of new information on the deep seabed, climate change and environmental protection.
The following link will take you to an exciting webinar on this subject from the Charles Darwin Station. https://youtu.be/zcv85IH25-k
