Scientists Developing Robot to Explore Ocean 'Twilight Zone'

Scientists at the Woods Hole Oceanographic Institution are developing an underwater robot that analyzes ocean chemistry and biology, discovering insights on the role the ocean plays in global climate change.

In a lecture Wednesday at Harvard’s Wyss Institute for Biologically Inspired Engineering, Woods Hole senior scientist Dana R. Yoerger presented the team’s latest work on the Mesobot, which will be used to explore the ocean's mesopelagic zone—a depth of 200 to 1000 meters sometimes called the "twilight zone" because of the little light it receives.

The Mesobot is the fourth in a series of robots that Yoerger has worked on. Yoerger said that unlike the previous models which mainly mapped and photographed the ocean floor, the Mesobot will videotape and analyze the chemical and biological makeup of the shallower mesopelagic zone.

Yoerger and his fellow researchers are particularly interested in salps—small, previously little-known fish inhabiting this zone—and how they enable the ocean to process and store carbon.

“When conditions are right, and no one knows what that means, they can reproduce sexually... and they multiply at fantastic rates and then they all die and there’s literally a blizzard of dead salps hitting the sea floor,” Yoerger said. “It’s a tremendous flow of carbon to the sea floor and we don’t really understand that much about it.”

According to Yoerger, in recent years, growing salp populations—which link together to form long chains—have interfered with commercial fishermen by destroying their nets. Fishermen are also interest in harvesting salp as a replacement for krill to be used in nutritional supplements, he said, and this commercial interest is alarming to scientists who are just beginning to understand salps’ potential to store carbon.

"It’s urgent because now that people understand this biomass is there, you can bet people are figuring out how to exploit it," Yoerger said. "If that’s going to happen, it should be done in an informed, reasonable way."

Although the harvesting of salp is a critical issue, the Mesobot is still two years away from ocean testing, Yoerger said. In order to track and film salp, the Mesobot has to be able to move up and down with the salps’ migratory pattern while not scaring away the fish.

Attendee Javier Estrada, a postdoctoral student at Harvard Medical School, said he was enthusiastic about possible future revelations from the Mesobot.