deep-submergence vehicle

The Woods Hole Oceanographic Institution’s deep-submergence vehicle Nereus, will collect samples and stream live video. (photo credit: WHOI.

Jeffrey Drazen, a University of Hawaiʻi at Mānoa oceanography associate professor, joins an international team of researchers led by deep-sea biologist Tim Shank of the Woods Hole Oceanographic Institution to use the world’s only full-ocean depth, hybrid remotely operated vehicle, Nereus, and other advanced technology to explore life in the depths of the Kermadec Trench.

The 40-day expedition, which began on April 12, kicks off an ambitious three-year collaborative effort funded by the National Science Foundation. The goal of the program, known as Hadal Ecosystem Studies, is to conduct the first-ever systematic study of life in ocean trenches, comparing it to the neighboring abyssal plain—flat areas of the seafloor usually found at depths between 3,000 and 6,000 meters.

Due to the extreme pressures of these deep-sea environments and the technical challenges involved in reaching them, ocean trenches remain among the least explored environments on the planet.

“We know relatively little about life in our ocean trenches—the deepest marine habitat on Earth. We didn’t have the technology to do these kind of detailed studies before,” said Shank. “This will be a first-order look at community structure, adaptation, and evolution—how life exists in the trenches.”

The Kermadec Trench, off the northeastern tip of New Zealand’s North Island, is the fifth deepest trench in the world with a maximum depth of 10,047 meters (32,963 feet or 6.24 miles). It is also one of the coldest trenches due to the inflow of deep-water originating from Antarctica.

The team will use the deep-submergence vehicle, Nereus, which can remain deployed for up to 12 hours, to collect both biological and sediment samples. Nereus will stream imagery from its video camera to the ship via a fiber-optic filament about the width of human hair.

What marine animals live in the trench and how do they survive the crushing pressures found at that depth— about 15,000 pounds per square inch? These are some of the questions the science team will be trying to answer.

“The energy requirements of hadal animals have never been measured before,” said Drazen, who will lead the efforts to study distribution of food supply and the energetic demands of the trench organisms.

“The bulk of our knowledge of trenches is only from snapshot visits using mostly trawls and camera landers,” Shank said. “Only detailed systematic studies will advance our biological understanding and also reveal the role trenches may play as the final location of where most of the carbon and other chemicals get sequestered in our ocean, which ultimately impacts the global carbon budget and climate.”

Read the full UH Mānoa news release for more on the expedition.

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