Back on March 26, 2012, National Geographic Explorer-in-Residence James Cameron piloted a submersible nearly 11 kilometers (7 miles) down to the Challenger Deep, the deepest known part of the ocean. While that feat generated excitement around the world, enthusiasm continues to grow within the scientific community as the initial findings from the expedition are released. Cameron’s expedition, the DEEPSEA CHALLENGE, actually explored two ocean trenches: the Challenger Deep and the Sirena Deep in the Mariana Trench (both southwest of Guam), and the New Britain Trench (south of Papua New Guinea). Almost a year later, scientists have had time to study video and samples collected on the expedition. “People here at Scripps [Institution of Oceanography] and elsewhere at the University of Hawaii have looked over that video data just to see what they can identify and what is happening with regard to biodiversity in the New Britain Trench and in the Challenger Deep,” says marine microbiologist and DEEPSEA CHALLENGE Chief Scientist Dr. Douglas Bartlett. Bartlett notes that the New Britain Trench was rich in biodiversity—including spoon worms, acorn worms, cutthroat eels, rattail fish, eelpouts, and the deepsea lizardfish. He also describes sea anemones that look like white flowers, attached to a trench wall 8 kilometers (5 miles) down. The expedition also documented amphipods, a kind of crustacean, as long as 17 centimeters (6.7 inches). “That is the deepest example of this phenomenon, referred to as gigantism, ever seen,” Bartlett says.
It’s Lonely at the Bottom Far fewer organisms populate the Challenger Deep. “You look at the video from Jim’s deep dive to the Challenger Deep, and it’s dramatically different,” Bartlett says. “In the Challenger Deep, unlike the New Britain Trench, we’re not seeing worm trails all over the place . . . It’s a really forlorn, alien-like environment.” Among the few, hardy species in the Challenger Deep are amphipods, a possible new species of sea cucumber, and single-celled organisms known as xenophyophores. “[Xenophyophores] just look like these crinkly little globs on the seafloor,” Bartlett says. “But they are incredible organisms, because they are among the largest single-celled organisms on the planet.” Dr. Paul Yancey, a biologist at Whitman College in Walla Walla, Washington, made a striking discovery while doing laboratory work on some of the amphipods collected on the expedition. “[Dr. Yancey] found in the deep-sea amphipods from the Challenger Deep this compound, scyllo-inositol, that it turns out is currently being fast-tracked by the FDA [U.S. Food and Drug Administration] for the treatment of Alzheimer’s disease,” Bartlett says. Another exciting find was made while astrobiologist and National Geographic Emerging Explorer Kevin Hand was viewing video of the Sirena Deep dive. Hand discovered rocks covered in microbial mats—sheets of tiny organisms. Dr. Patricia Fryer, a marine geologist and member of the DEEPSEA CHALLENGE team, explains the discovery. “The primary thing that caught all of our attention was the fact that . . . there are actual outcroppings right on the inner trench wall at 10,800 meters [35,433 feet], mantle rock that had interacted with seawater and created the sort of processes that could seed microbial life,” Fryer says. These deep-ocean chemical reactions could have been instrumental to the origin of life on Earth. “We are thinking now about the possibilities and places on the earth where life may have evolved,” Fryer says. “Some geologists are very excited about the ocean ridges, because everyone is seeing black smokers and all of the ecology that surrounds them. That is what has started people thinking about the oceans, the deep oceans, as a place where life may have evolved.”
Protecting Our Future as well as the Past Deep-sea trenches like the Challenger Deep may hold important information for our future as well as our shared past. Learning about the trenches could help people to better protect coastal communities during tsunamis. DEEPSEA CHALLENGE research may “help modeling of tsunami genesis during earthquakes,” Fryer says. Tsunamis form from earthquakes on the seafloor. Modeling such “tsunami genesis” may be tremendously helpful for people being able to predict not only the potential run-up of the tsunami, she continues, but the direction in which it might be most focused. Both Fryer and Bartlett are very excited about the possibility of another DEEPSEA CHALLENGE mission to further explore these deep-sea trenches. Bartlett hopes to collect more samples in the future—possibly sea cucumbers, the material around cold seep environments, or the remains of a large vertebrate on the ocean floor—if one is found. Meanwhile, Fryer hopes to learn more about the extent of the deep-sea chemical reactions and the processes that formed Earth’s lithosphere, the rocky, outermost shell of our planet. “Keep in mind that these great trenches, these environments deeper than 6 kilometers, are almost unexplored,” Bartlett says, “and they represent an amount of area that is equivalent to that of pretty much the continental United States.”