MBARI's Deep Sea Rover Aims to Help Scientists Study Carbon Cycling and Climate Change

Using technology to study the seafloor can be very challenging due to the extreme environment. Now, MBARI's autonomous robot rover, Benthic Rover II, collected data that gives insight into the seafloor. The rover also further reveals the deep sea's role in cycling carbon and provides scientists with a better understanding of how climate change affects the ocean.

Measuring 2.6 meters long, 1.7 meters wide, and 1.5 meters high, the Benthic Rover II can handle the deep sea's cold, corrosive, and high-pressure conditions. It's also made of corrosion-resistant titanium, plastic, and pressure-resistant syntactic foam, allowing it to survive 6,000 meters. Researchers lower the rover into the water, where it sinks for two hours before reaching the ocean's floor.

First, its sensors check for favorable currents. If the conditions are suitable, it moves up the current until it reaches an unaffected area to continue collecting data. From the rover's frontal cameras capture images of the seafloor and measure fluorescence. This glow of chlorophyll under blue light shows how much fresh phytoplankton and plant debris settled on the seafloor. Then, sensors record the waters' temperature and oxygen concentration above the bottom.

Afterward, the rover lowers two transparent respirometer chambers to measure the community of life's oxygen consumption in the mud for two days. Animals and microbes use up oxygen while consuming organic matter, releasing carbon dioxide in the process. Knowing exactly how much oxygen these microbes and animals consume is key to understanding carbon remineralization.

Once this sampling time passes, the rover lifts its respirometer chambers, moves ten meters forward, and chooses another sampling site. This pattern is repeated during its entire one-year deployment. When its deployment ends, the R/V Western Flyer retrieves the rover. Then, the team downloads its data, changes its battery, and sends it back to the seafloor for another year. However, the rover doesn't communicate with the team, so it doesn't tell them its location or condition. Instead, they deploy a Wave Glider robot, which uses its transmitter to ping the rover. Then, the rover transmits status updates and sample data to the glider overhead, which transmits that data to scientists via satellite.

"Data from the Benthic Rover II have helped us quantify when, how much, and what sources of carbon might be sequestered, or stored, in the abyssal seafloor," said MBARI Senior Research Specialist Crissy Huffard.