Can Scientists Map the Entire Seafloor by 2030?

Science
دوشنبه 7 تیر 1400 ساعت 16:12
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Smith sonian mag
For nearly a decade, scientists at Monterey Bay’s Aquarium Research Institute (MBARI) have studied the topography and ecology of Sur Ridge, an underwater expanse the size of Manhattan located 37 miles off the coast of California.
While Sur Ridge, a submarine seamount made up of a series of peaks and valleys, had been known to scientists for decades, its abundant potential for aquatic life wasn’t realized until recently. “The first time somebody actually put a [remotely operated vehicle] down there and looked at what was there was 2013 ,” says David Caress, principal engineer at MBARI. “What they were doing was essentially exploration and sampling, but they discovered a spectacular ecological community." Researchers found forests of bubblegum corals, swathes of yellow coral, white sponges and a vampire squid.
“Sur Ridge is blanketed with really dense communities” says Caress, “It was clear that mapping would be useful to provide context to the ecology, and that’s where I come in.” Determining the topography would help scientists understand currents that carry plankton to deep-water corals and sponges, which serve as the basis for the ecosystem.
MBARI owns remotely operated vehicles (ROVs) capable of exploring cold, dark ocean depths. Between 2015 and 2020, the MBARI team carried out expeditions to map Sur Ridge, starting with lower resolution surveys and increasing in detail. First, researchers used ship-based multibeam SONAR to survey the area at 25-meter resolution. Then they used a Mapping Autonomous Underwater Vehicle to scan the topography at one-meter resolution. Finally, an ROV flew three meters from the surface of Sur Ridge and used lasers, sonar, strobe lights and stereo cameras to create five-centimeter and one-centimeter resolution maps with millimeter-scale photography.
MBARI and Frame 48, a Los Angeles-based post-production company used the data to create a video depicting Sur Ridge in high definition. This underwater arena, of which little was known eight years ago, was now available for observation. MBARI’s reconstruction was the most detailed visualization of a large underwater feature in the deep sea.
While the Sur Ridge project, with mapping completed on a grid with cells just a centimeter in size, represents the upper echelon of targeted seafloor mapping, just 20 percent of the world’s seafloor has been mapped to an adequate resolution—with grid cells of 100 meters or more across, depending on depth.
To combat this lack of information, two nonprofit organizations came together in 2018 to found the Nippon Foundation-GEBCO Seabed 2030 Project, an international effort aimed at mapping 100 percent of the ocean floor by 2030. “In 2017, only 6 percent of the world’s oceans floor had been adequately mapped,” says Jamie McMichael-Phillips, the project’s director. “Seabed 2030 was designed to accelerate this mapping, using data from academia, government, the maritime industry and citizens themselves.”
The Nippon Foundation, a Japanese philanthropic outfit that has projects focused on the future of the oceans, and GEBCO, a group focused on understanding the bathymetry, or depth measurement, of the oceans, want to build a comprehensive, publicly accessible map of the world’s seafloors—the GEBCO Grid. To complete the map, the project will rely on research organizations, government entities, citizens and others to submit data. These groups are already collecting seabed data for scientific, navigational, or nautical reasons and the GEBCO Grid provides a place where all of their data can be combined in one detailed map.
Seafloor mapping is expensive and technologically intensive, but it holds value to a wide range of fields. Scientists can use information on the shape of the seafloor to understand a myriad of climate change processes, such as sea-level increases. Bathymetric maps also help researchers predict the path and strength of tsunamis and enable ecologists to better understand underwater ecosystems.
“Data is used in coastal ocean science, habitat characterization, wave models, flooding models, wind energy development, all kinds of things,” says Ashley Chappell, integrated ocean and coastal mapping coordinator at the U.S. National Oceanic and Atmospheric Administration (NOAA).
While the modern incarnation of seafloor mapping is technologically intensive, measuring depth is not a new pursuit. Over 3,000 years ago, weighted lines and sounding poles—rods lowered into the water—were used to measure the depth of the ocean off Egypt. In the 1870s, the HMS Challenger , a repurposed Royal Navy warship cast rope weighted with lead overboard to measure depth. Its findings included the first recordings of the Challenger Deep, the deepest known point of the Earth’s oceans.
In the 1950s, academics produced the first physiographic map of the Atlantic Ocean floor using single-beam echo soundings, which determine water depth by measuring the travel time of a sonar pulse. Researchers discovered a worldwide volcanic ridge system on the ocean floor, where lava emerged to form large plates that moved—helping confirm the theory that Earth’s continents drift over time. During the late 1970s, more effective multibeam sonars became available for civilian use and were installed on academic research vessels, accelerating the field further. Modern bathymetry now has a range of tools in its cartographic arsenal, from aircrafts using laser imaging technology ( LIDAR ) that map coastline areas to submersible ROVs, such as those used by MBARI.
Still, seafloor mapping is technically difficult and consequently expensive. “An oceanographic research ship with work class deep diving ROV can easily cost $35,000 per day and rise to more than double that depending on ship size,” says Caress. “And there’s ship and crew costs on top of that”.
Moreover, vessels using sonar have to travel fairly slowly, which is an issue when about 140 million square miles of water need to be covered.
In the last few years, though, efforts have accelerated to streamline the process and close the knowledge gap, in part thanks to Seabed 2030, which has set a tangible goal for the bathymetric community. The project has brought together research institutions and increased citizen awareness of the importance of the seabed . “While we were collaborating before, the project has certainly driven more collaboration,” says Chappell. “And from my perspective, it really reinvigorated this desire we all share: to get our oceans mapped.”
Research laboratories, government entities, private companies and other organizations are contributing data to the GEBCO grid, with the understanding that it will help others across the world in a range of industries.
Hundreds of thousands of cargo vessels, fishing boats and yachts are equipped with on-board echosounders, and take routes that research organizations do not. Utilizing data from these ships will be crucial to the project’s success. While some citizens are already onboard and contributing data, McMichael-Phillips is counting on others to join the effort as awareness of the project grows. Seabed 2030 is running field trials in Palau, South Africa and Greenland, where citizen vessels have been provided with inexpensive data loggers with the expectation that they will provide useful data and encourage others to do the same.
McMichael-Phillips hopes that by the end of this year the GEBCO Grid should be able to display 21 percent of the ocean seafloor to an adequate resolution. Collaboration is key if the 100 percent figure is to be achieved by 2030. If the project had a fleet of 200 ships patrolling and mapping the oceans 24/7, it could achieve its goal in a year. “There are more than 200 vessels capable of deploying sonar systems,” says McMichael-Phillips, “but the cost of such a feat would be somewhere between $3 billion and $5 billion, which isn’t easy to find in the maritime domain.” Crowdsourced data is thus of utmost importance to the project.
Still, the future of seafloor mapping is looking hopeful, thanks to new technologies and increased collaboration. For example, the Schmidt Ocean Institute, a private research organisation with a sophisticated research vessel and ROV, has pledged to share all of its mapping data with Seabed 2030. The nonprofit is currently working with Australian research institutions to map the Tasman and Coral seas off the east coast of Australia.
And new autonomous vessels are mapping the seafloor more efficiently than crewed vessels . In August 2020, a SEA-KIT vessel mapped over 350 square miles of ocean floor in the Atlantic Ocean while remotely controlled by a team located in Essex, England. Such efforts are also cheaper than sending crewed vessels out, and they will need to be adopted more widely if Seabed 2030’s goal is to be reached.
“People can run uncrewed, low-carbon mapping systems from the safety of the shore,” says McMichael-Phillips. “We’re only just seeing that technology accelerate through the maritime sector; it’s a big game changer.”
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