As published last week by the Monterey Bay Aquarium Research Institute(MBARI), a new robot spent most of July traveling across the muddy ocean bottom, about 40 kilometers (25 miles) off the California coast. The Benthic Rover has been providing scientists with an entirely new view of life on the deep seafloor and is meant to give scientists a way to document the effects of climate change on the deep sea.
The Benthic Rover moves very slowly across the seafloor taking photographs of the animals and sediment in its path. Every three to five meters (10 to 16 feet) the Rover stops and makes a series of measurements on the community of organisms living in the seafloor sediment. These measurements will help scientists understand one of the ongoing mysteries of the ocean—how animals on the deep seafloor find enough food to survive.
Most life in the deep sea feeds on particles of organic debris, known as marine snow, which drift slowly down from the sunlit surface layers of the ocean. But even after decades of research, marine biologists have not been able to figure out how the small amount of nutrition in marine snow can support the large numbers of organisms that live on and in seafloor sediment.
This new robot carries two experimental chambers called “benthic respirometers” that are inserted a few centimeters into the seafloor to measure how much oxygen is being consumed by the community of organisms within the sediment. This, in turn, allows scientists to calculate how much food the organisms are consuming. At the same time, optical sensors on the Rover scan the seafloor to measure how much food has arrived recently from the surface waters.
MBARI researchers have been working on the Benthic Rover since 2005. One of their challenges was designing the Rover to survive at depths where the pressure of seawater is about 420 kilograms per square meter (6,000 pounds per square inch). They also had to keep it from sinking into the soft seafloor mud as well as solve other engineering challenges that required less high-tech solutions, like it picking up mud and depositing it in front where it was contaminating the measurement samples or stirring up a cloud of sediment.
The Benthic Rover is designed to operate on batteries, without any human input. However, on its July trip, the Rover was connected by a long extension cord to a newly-completed underwater observatory. This observatory, known as the Monterey Accelerated Research System (MARS), provided power for the robot, as well as a high-speed data link back to shore. The observatory connection allowed MBARI researchers to fine tune the Rover’s performance and view its data, videos, and still images in real time.
Later this fall, the Rover will be sent back down to the undersea observatory site in Monterey Bay for a two-month deployment. Next year then it will be sent on its own for six months 4,000 meters down to the seafloor about 220 km (140 miles) offshore of Central California. The team is also considering taking the Rover to Antarctica to study the unique seafloor ecosystem there as well as hooking it up to a proposed deep-water observatory several hundred miles off the coast of Washington State.
The Bentic Rover will answer some key questions of oceanography, as well as help researchers study the effects of climate change in the ocean. As the Earth’s atmosphere and oceans become warmer, even life in the deep sea will be affected. The Benthic Rover, and its possible successors, will help researchers understand how deep-sea communities are changing over time.
The Robot is the result of four years of hard work by a team of engineers and scientists led by MBARI project engineer Alana Sherman and marine biologist Ken Smith.
Copyright © 2009 by Marine Science Today, a publication of OceanLines LLC