They can strengthen coastlines, break the force of crashing waves, shelter migrating fish, shellfish and birds, clean water, store up to 5% of the world’s carbon dioxide and pump oxygen into the ocean. , making it partly possible for life on Earth as we know it.
These miracle machines are not the latest brilliant technological invention. On the contrary, they are one of nature’s first floral creations: sea grasses. Anchored to the shores of every continent except Antarctica, these plants (and they are plants, not algae, that grow, flower, fruit and go to seed) are one of the most powerful but unprecedented that already exist on the planet.
Seagrass restoration is a tool that coastal communities can use to fight climate change, both by capturing emissions and mitigating their effects, which is among the topics discussed as leaders in business, science , culture and politics meet Thursday and Friday in Busan, South Korea, to a New York Times conference, A New Climate.
Around the world, scientists, non-governmental organizations and volunteers are working to restore seagrasses, if not to their original glory, at least to something far larger and more majestic than the arid, muddy bottoms left behind. behind them when damaged or destroyed.
In Virginia, parts of Britain and Western Australia, among others, with the help of committed researchers and citizen scientists, seagrasses are making a comeback. They bring with them clearer waters, more stable shorelines, and animals and other organisms that once thrived there. And yet, herbaria don’t get the attention they deserve, say its proponents.
It’s impossible to know exactly how many seagrasses were lost, because scientists don’t know how many there were in the first place.
Only about 16% of the world’s coastal ecosystems are considered intact, and seagrass beds are among the hardest hit. It is estimated that a third of seagrass beds worldwide have disappeared in recent decades, according to Matthew Long, a research associate in marine chemistry and geochemistry at the Woods Hole Oceanographic Institution. “Globally, a football pitch of seagrass is lost every 30 minutes,” Dr. Long said, “and we’re losing about 5-10% at an accelerating rate every year.”
“Seagrass beds are affected by global stressors: deoxygenation, ocean acidification and warming temperatures,” Dr. Long said. But local stressors have also played a role in their wilting, primarily in the form of nutrient pollution, largely from agricultural runoff and sewage, as well as algal bloom and death. which ensue, which first smothers other plants such as seagrasses (a process called eutrophication). then, as they decompose, they absorb all the oxygen in the water (hypoxia).
Although the effects of climate change and increasing human impacts have accelerated the loss of seagrass beds in recent decades, this is not a new story.
On the east coast of Virginia, a severe storm in August 1933 that followed debilitating disease and overharvesting of bay scallops wiped out what remained of ancient vast eelgrass meadows. (Eelgrass is a type of seagrass.) For decades, there was no eelgrass on the ocean side, said Bo Lusk, a scientist from nature conservation Volgenau Virginia Coast Reservealthough some remained on the part of the coast washed by the Chesapeake Bay.
Dr Lusk, who grew up in the area, heard stories of lush green carpets of seagrass from his grandmother, who remembered the shores teeming with life – until they weren’t anymore . But then, in 1997, someone reported seeing patches of eelgrass on the shore, likely from seeds that drifted south from Maryland and settled in a hospitable neighborhood in Virginia.
After several years of experiments, Robert J. Orth, a scientist from the Virginia Institute of Marine Sciencehas developed a very effective method of seagrass restoration, similar to methods used around the world: in the spring, scientists and hundreds of volunteers collect seeds, which they count and process during the summer and plant them in the sediments in the fall.
Since 2003, when the restoration effort in the Volgenau Virginia Coast Reserve began, scientists and others planted about 600 acres of seeds, and the seagrass now covers 10,000 acres, according to Dr. Lusk. Later this year, the Nature Conservancy hopes to sell the first validated blue carbon credits for seagrasses, based on this restoration effort, said Jill Bieri, director of the reserve.
However, the success of Project Virginia has been somewhat difficult to recreate around the world. “You can’t do this just anywhere,” Dr. Lusk said. “If the Nature Conservancy hadn’t started this land protection work 50 years ago, buying up parts of the coast to preserve it, chances are we wouldn’t have the water quality we have now, and it wouldn’t have been so successful.”
Restoring the seagrass will take decades of commitment, Dr Lusk said. Richard Unsworth, Associate Professor of Biosciences at Swansea University in Wales and Founder and Scientific Director of Seagrass Projecta UK NGO that works on seagrass restoration, said an important part of the work was the long-term promise made to the whole ecosystem – the seagrass, but also community members.
“The actions of fishermen, the views of boat owners, water quality issues – all of this can be part of a complex socio-cultural situation, and in the long run it will be incredibly successful, but it is a slow process, not a quick fix where you plant something and then you save it,” Dr Unsworth said.
Community engagement has been a necessary component to the success of the herbaria because it takes a lot of work to collect and plant millions of seeds. For Project Seagrass, this also meant developing a website and app, Seagrass Watcherwhich allows users to upload photos of seagrass in the wild (which are then verified by scientists), to help researchers fully map the extent and types of seagrass around the world, as the mapping of seagrass beds globally is rather patchy.
But one well-mapped location is Shark Bay, a remote part of Australia’s western coast, where seagrass beds from 10 different grasslands have been found to actually be a single plantperhaps the largest in the world.
There, seagrasses have been growing and accumulating carbon in their plant matter, but also in the sediments, for more than 3,000 years, said Elizabeth Sinclairevolutionary biologist at the University of Western Australia.
But during an extreme marine heat wave from 2010 to 2011, about a third of the seagrass canopy (which is visible above the sand) died, releasing up to nine million tons of carbonaccording to an estimate.
For the past decade or so, Dr Sinclair and his colleagues have been studying the recovery of seagrasses – the places where they naturally return and where they are unlikely to ever return, without the help of scientists as well as the Malgana people, Australians indigenous. who work as rangers.
Despite warming temperatures and changing ocean chemistry making full restoration impossible, the work is worth it, Dr. Lusk said, whether on the winding waterways of the Virginia coast, the the rocky coasts of Wales or the vast endless bays of the West. Australia.
“There are so many logical reasons why we should do this,” Dr. Lusk said. “Carbon storage is great, shoreline protection, all these other things are great, and you can know that in your head, but until you’re in the water and you really spend time in that system, you don’t have the emotional connection.
“I would continue to do this if there was no carbon stored. It just feels good to be there.