Osvaldo Ulloa, a Chilean scientist, led an expedition 8,000 metres beneath the sea to an area where no human had ever been, and his team discovered microscopic organisms that raised more questions than answers. The submarine expedition in January descended into the Atacama Trench, formed by the collision of two tectonic plates in the eastern Pacific Ocean.
"We accomplished the feat of taking humans into the trench where no other human had gone before," said Ulloa, director of the Millennium Institute of Oceanography at the University of Concepcion.
On the 12-week journey off Chile's northern coast in the 5,900-kilometer (3,650-mile) long trench that extends up to Ecuador, he was joined by American explorer Victor Vescovo and Millennium assistant director Ruben Escribano.
By the time the Atacama Hadal expedition reached a depth of 100 metres, it was pitch black, with the crew members' vision limited to what the submarine's powerful LED light could capture. Out of the darkness, remarkable examples of deep-sea life emerged.
"We came across geological structures and saw a type of holothurians or translucent sea cucumbers, like jelly, that we hadn't recorded and were most likely new species," Ulloa explained. "We also discovered bacterial communities that feed on chemical and inorganic compounds and had filaments that we didn't even know existed in the Atacama Trench."
"That raised a slew of questions: What are those compounds? Which kind of bacteria are they? We have no idea; we'll have to go back there."
The expedition also discovered amphipods, which are crustaceans related to shrimp and are scavenging crustaceans, segmented worms, and translucent fish. They were discovered in the same location in 2018 by an unmanned expedition.
Extremely Ambitious
The Atacama Trench, also known as the Peru-Chile Trench, is formed by the meeting of the Nazca and South American tectonic plates. It is an area that has seen a number of earthquakes and tsunamis.
"We'll place three sensors on the South American Plate and two on the Nazca Plate to see how the ocean floor is deformed," Ulloa explained. For the time being, "these types of sensors are only available on land."
The devices will allow scientists to observe where energy is building in areas that have not experienced an earthquake, assisting in predicting where the next tremor will occur.
"It is an incredibly ambitious project," Ulloa said, adding that it is "the largest experiment in underwater geology that has been done here in Chile." The sensors are scheduled to be installed in the second half of this year. "The international community is very interested in putting more sensors in this region to study all of the processes associated with the collision of these two plates."
