by “It should be more like pancake batter,” says Nastasia Winey as she prepares a seed mix solution for Grasshopper – a seaweed planting robot. Winey is a robotics engineer at ReefGen, a company that works to repopulate lost seagrass habitats worldwide.
Seagrass meadows are found on seafloors from Alaska to Australia and are one of the most widespread coastal habitats on Earth. Although they cover only a thousandth of the seafloor, these marine plants play important roles in aquatic ecosystems – from providing breeding grounds for marine species to storing up to 18% of the ocean’s carbon.
However, this vital underwater habitat is in decline due to factors such as coastal development, climate change, overfishing and pollution – with a global loss of around 7% per year.
There are about 72 species of seagrass worldwide, and although they cover about 0.1% of the seafloor, they play an important role in maintaining a healthy ocean. – BORIS HORVAT/AFP via Getty Images
“There were once about 18 million hectares of seagrass beds on the planet, and we have lost between 30 and 40%,” says Chris Oakes, CEO of ReefGen.
For Oakes, who is also a marine biologist, this is a disturbing statistic.
“Without seagrass beds, we will see more coastal erosion, loss of coral reefs, loss of fish stocks and poorer water quality,” he tells CNN.
Five years ago, ReefGen was founded by Tom Chi, co-founder of Google
Robots for restoration
During seagrass restoration projects, divers often plant seeds or sprouts on the ocean floor. This process can be slow and result in low yields, says Oakes. It can also be risky for divers who work on the seabed for long periods of time.
“Manual planting works, but robots are really good when things are boring, dirty, dangerous or far away – the four Ds,” says Oakes.
As technology has improved over the past two decades and parts costs have fallen, underwater robots are increasingly playing an important role in exploring and working in harsh water conditions.
“The amazing thing about where we are today in terms of robotics technology is that there are a lot of off-the-shelf parts that are affordable, allowing us to move into these new applications like restoration,” Oakes explains.
ReefGen initially developed a robot called Cora that plants coral plugs in reefs to regenerate them. Cora provided the basis for Grasshopper – the startup’s seaweed planting variant.
Chris Oakes, CEO of ReefGen, is seen here on the southern end of the Outer Banks, North Carolina, preparing to place Grasshopper, a seagrass planting robot, on the ocean floor to plant eelgrass seeds. -CNN
Weighing just 23 kilograms (50 pounds), Grasshopper – adorned with pink skis, a few cameras and lots of technology – can currently sow up to 60 seeds per minute and holds up to 20,000 seeds in a 20 liter bag.
The previously prepared seaweed seed and mud solution is injected into the sediments in the seabed.
After releasing about four seeds through its planting shaft, it hops about 30 centimeters to the next injection site so as not to disturb its surroundings.
Grasshopper is not yet fully autonomous. Still controlled by a human through a controller interface on a boat, it follows a transect line – a long tape measure that a diver places across the seafloor for plotting and orientation.
“Right now we are focusing on planting, biology and mechanical aspects,” says Oakes. “Once we’re sure everything is designed correctly, we’ll overlay other semi-autonomous functions like navigation so you don’t actually have to control it or lay those transect lines.”
Comparative studies
The seagrass planting robots have been used in North America, Europe and Southeast Asia. In July this year, Grasshopper planted 25,000 seeds in Wales.
While Oakes says it takes time to see results, he adds that their first seaweed pilot project in 2022 grew the same quality and quantity of seaweed as the hand-planted control plot. This effort helped prove that mechanized planting was feasible at both speed and scale.
In October, ReefGen partnered with the University of North Carolina (UNC) Institute of Marine Sciences to conduct comparative studies examining various seed-based seagrass restoration methods, including robotic planting.
The North Carolina coast has a large seagrass population that is slowly declining annually.
“Many of our grasslands have gone from very contiguous areas to more patchy areas, so we’re really trying to find ways to reverse those trends,” Professor Joel Fodrie, director of the UNC Institute of Marine Sciences, tells CNN.
Fodrie’s team collected seeds from seaweed donor sites that had a surplus last spring and stored them in their wet lab until fall, where they typically germinate and are ready for planting.
“We will plant these seeds in the places that we think can grow new grass meadows, or at least grow meadows again where we used to have them,” says Fodrie.
An aerial photo off the coast of Morehead City, North Carolina, where Professor Joel Fodrie of UNC’s Institute of Marine Sciences says they’ve seen a slow annual decline in seagrass beds. -CNN
Over the course of a few days, Grasshopper planted 1,000 seeds in a 1,000-square-foot quadrant offshore on the southern end of the Outer Banks, which will be compared to the control sites that Fodrie’s team planted by hand.
Oakes says scientific studies like this help them extrapolate data like how quickly they can plant over time or what they can improve for the next expedition.
“So far, what we do to collect and then scatter seeds again still relies on many hands,” says Fodrie, “so the ability to automate and the ability to use technology can certainly make things much more practical. “Much larger scales.”
Monitoring is the key to success
While the ReefGen team is encouraged by Grasshopper’s potential to expand restoration, Oakes says monitoring and maintaining restored meadows will be key to success.
“It is important to view restoration as an ongoing process; It’s not a finished program – there will be other seagrass-killing events,” he says.
To capture changes over time, ReefGen works with companies that provide specialized field technology for seagrass monitoring, reporting and validation.
Oakes said local communities play a central role in the long-term care of seagrass.
“It’s important that we don’t just show up with expensive robots and flashy things and say, ‘We have all the answers,'” he says. “We are creating more habitat for fish, cleaner water, more jobs – everything we want as humans; That’s why we want to do this and make it affordable and available.”
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