Seagrass meadows, often called the “lungs of the ocean,” play an essential role in combating climate change and supporting global food security. However, these vital ecosystems are rapidly disappearing. In British waters, a staggering 90% of natural seagrass meadows have been lost due to climate change, coastal development, pollution, and overfishing. To help restore these underwater habitats, two British inventors have developed an innovative solution: an aquatic lawnmower designed to harvest seagrass seeds more efficiently, potentially offering a lifeline to these vanishing meadows.
Why Seagrass Meadows Are Essential
Seagrass meadows may not be as famous as rainforests or coral reefs, but their contribution to the planet’s health is equally significant. These underwater meadows, covering just 0.2% of the world’s oceans, account for over 10% of the carbon stored in ocean sediments. This makes them 35 times more efficient at absorbing carbon than rainforests, a crucial trait in the fight against climate change.
Beyond their environmental benefits, seagrass meadows support marine ecosystems that directly contribute to the nutrition of three billion people worldwide. One hectare of seagrass alone can support up to 80,000 fish, making it a critical foundation for marine biodiversity and food chains.
The Threat Facing Seagrass
Despite their enormous importance, seagrass meadows are disappearing at an alarming rate. Since the late 19th century, around one-third of global seagrass meadows have vanished. The International Union for Conservation of Nature (IUCN) estimates that seagrass habitats are declining by 7% annually, making them the fastest-disappearing habitat on the planet. The situation is particularly dire in the United Kingdom, where a combination of factors has led to the loss of most natural seagrass meadows.
In response to this growing crisis, British entrepreneurs Sam Rogers and Ed Towler have developed a groundbreaking machine to address the decline. Their invention, an underwater “lawnmower,” aims to revolutionize the way seagrass seeds are harvested, making restoration efforts more efficient and scalable.
A New Invention: The Underwater ‘Lawnmower’
Until now, seagrass seed collection has been a time-consuming and labor-intensive process. Divers have traditionally harvested seagrass seeds by hand, which has limited the scale of restoration efforts. Previous projects involved volunteers donning snorkels and bodyboards to manually pick seed pods in the hope of preserving and replanting seagrass meadows.
However, the new invention by Rogers and Towler could change all that. Their underwater “lawnmower” moves along the seabed on skids, trimming seagrass with a large blade and collecting seeds in a process that is far more efficient than manual methods. The device was developed in partnership with the charity Project Seagrass, which focuses on the conservation and restoration of seagrass meadows around the world.
Towler explained the mechanics behind the machine: “This form factor allows for adjustable trimming height, and the mower body guides the cut seagrass gently toward the collector funnel at the rear, where it is then sucked up a pipe to the surface for the seeds to be separated from the seawater and collected.”
The machine’s design underwent multiple iterations before reaching its current form. Early tests using wet hay as a seagrass simulant faced challenges such as clogged filters and stalling pumps. However, after refining the system, the team successfully developed a functioning design that glides along the seafloor, trimming seagrass at just the right height and efficiently collecting seeds.
Testing and Next Steps
Testing the prototype was a tense experience for the inventors. Towler recalls the anxiety of watching the machine’s first real-world test, waiting to see if the seed-collection system would function as expected. “We waited in anxious silence once we started towing the mower, waiting to see if the seed-sucking systems would work. After a long 20 seconds, grass started flying through into the collector,” he said.
With the prototype now proven to be effective, Rogers and Towler are looking to scale up their invention. They are currently crowdfunding £30,000 to build the next version of the mower, which they hope will be robust enough to operate in a range of marine environments without corroding or suffering damage.
Global Efforts to Save Seagrass
Rogers and Towler’s underwater lawnmower is part of a broader effort to protect and restore seagrass meadows worldwide. One scientific study suggested that large-scale seagrass restoration could contribute as much as 1.43% to national efforts to offset carbon dioxide emissions by 2030.
In addition, Alphabet’s X division, also known as the “moonshot factory,” has been researching the potential of seagrass to absorb even more carbon dioxide from shallow waters. This project aims to develop ways to measure and quantify the carbon-storage capacity of seagrass meadows through advanced 3D mapping techniques. If successful, the project could help establish a market for carbon credits based on the carbon seagrass absorbs, further incentivizing its conservation.
The Future of Seagrass Restoration
While seagrass meadows are disappearing at an alarming rate, efforts like the underwater lawnmower offer hope for their restoration. As Rogers and Towler continue to refine their design and work with conservation organizations like Project Seagrass, their invention could play a critical role in helping to rebuild Britain’s lost seagrass meadows—and, by extension, support global efforts to combat climate change.
Towler expressed his motivation for the project: “Tools like the underwater seed harvester allow these teams to do more of the essential work they’re already doing, and that’s what motivates us.”
As the battle to preserve seagrass continues, Rogers and Towler’s invention is a timely and innovative solution that could make a significant difference in restoring one of the planet’s most valuable but endangered ecosystems.
