Seafloor robot sets world record while collecting climate data

Washington: An autonomous robotic seafloor crawler has set a new world record for the longest distance travelled and duration sustained under the sea, while collecting climate data for an entire year. Benthic Rover, developed by the Monterey Bay Aquarium Research Institute (MBARI) in the US, is the only untethered, entirely autonomous seafloor crawler in existence.

The Rover operates at Station M - an area of flat, muddy, abyssal seafloor 4,000 meters deep and about 220 kilometres from the California coastline. MBARI marine ecologist Ken Smith and his colleagues have been studying Station M since 1989. Some of their instruments measure sinking particulate organic carbon (POC) in the form of marine snow - bits of phytoplankton and zooplankton detritus, as well as faecal matter - that drifts down to the seafloor.

One of the most significant findings from the last few years of the Rover's deployments involved several large pulses of marine snow that rapidly sank to the seafloor. These pulses may be related to stronger along-shore winds that drive the upwelling of nutrients in coastal waters. The nutrients spur the growth of phytoplankton and zooplankton, which increases the amount of marine snow that rains down to the seafloor.

Organisms in this abyssal realm rely upon marine snow as their primary source of food. The Benthic Rover records how much of the marine snow is consumed by the seafloor community. The Rover detected several brief, two- to four-week events when nearly an entire year's worth of chlorophyll-rich detritus landed on the seafloor. These events would have gone undetected without the long-term presence of the Benthic Rover.

In documenting such events, the Rover helped solve an important piece of Earth's carbon-cycle puzzle - showing that a much larger percentage of carbon than previously expected can sink rapidly from the surface into deeper water. These periodic events can now be factored into global climate change models.

When marine snow arrives on the seafloor, some is eaten and respired as carbon dioxide while some is buried in seafloor sediment. Information about how much carbon is respired and how much is sequestered is important data for climate science. In November 2016, the Rover was retrieved after its record run - operating for one year and two days, and travelling a distance of 1.6 kilometres.

The Rover has been operating autonomously since 2009 and has been steadily increasing its duration of deployment and distance travelled before needing to be brought onboard a research vessel for maintenance.