By Alessandra Prentice and Christophe Van Der Perre
Saya DE MALHA BANK, Indian Ocean (Dan Tri) – Hundreds of miles from the nearest shore, ribbons are like shaky foliage in currents sweeping across a mountain plateau under water the size of Switzerland.
A remotely assisted camera glided across this sunny, turquoise waters in this western corner of the Indian Ocean, capturing rare footage of what scientists believe to be the world’s largest sea meadow.
According to the United Nations Environment Program (UNEP), human activity is helping to destroy a football field of these seagrass beds every 30 minutes around the world. And scientists are now racing to collect what’s left.
Oxford University earth-observing scientist Gwilym Rowlands, who is helping the Seychelles government map the island nation’s seagrass, said: “There is a lot of unknown – even simple things like we have. how much seagrass ”.
“If you look at the map data for seagrass, there are huge holes” in what we know.
According to a 2012 study in the journal Nature Geoscience, seagrass plays a big role in regulating the oceanic environment, storing carbon from carbon dioxide (CO2) that warms the planet (CO2) per square mile. more than twice as much as land-based forests.
Countries hoping to get credit for reducing their CO2 emissions can tally their seagrass and the carbon they store, a first step to recognizing how much carbon makes up for the final transaction. on the open market.
Grass also limits the acidity of the surrounding water – a function especially important when the ocean absorbs more CO2 from the atmosphere and becomes more acidic.
But seagrass provides some buffer from acidification, which can damage an animal’s shell and disrupt fish behavior. In a study published March 31 in the journal Global Change Biology, scientists at the University of California, Davis, found that seagrass scattered along the California coast could reduce local acid levels. up to 30% in the long run.
Plants also help clean up polluted water, support fisheries, and protect shorelines from erosion and micro-plastic traps, said Aurora Ricart, lead author of the study.
“What’s even better is that these habitats are ubiquitous,” she said.
CHART AS CLIMATE
While most seagrass species are on the edge of coastlines around the world, the Saya de Malha’s shallowness allows sunlight to filter down to the seabed, creating an underwater grassland in the Indian Ocean, providing the place where shelters, nurseries and feeding grounds for thousands of marine species.
The bank’s isolation has helped protect it from coastal threats, including pollution and dredging. But even such remote international waters face increasing intrusions from maritime and industrial fishing.
In March, scientists from organizations including the UK University of Exeter accompanied Greenpeace on an expedition to collect some of the first field data on wildlife in the area, including including less well-studied seagrass beds.
With the boat floating for days on the plateau, the researchers collected pieces of grass floating in the water, rolled them into bottles for analysis back to shore.
Data on seagrass grassland is patchy, but research so far estimates the grass covers more than 300,000 square kilometers (115,000 square miles), distributed across continents except Antarctica, according to UNEP. That would be an area the size of Italy.
It is not known how much carbon is trapped in the Saya de Malha, but globally, the tangled roots of seagrass are estimated to retain more than 10% of the carbon buried in ocean sediments each year.
“It makes sense,” said Dimos Traganos, principal scientist at the German Aerospace Center project that develops software to improve seagrass tracking using satellite imagery and other data. of great significance to the world climate change mitigation efforts. That effort, he says, has been aided by recent advances in cloud computing and data storage. “We’re in an exciting phase.”
Seagrass meadows are thought to be receding around 7% annually globally, according to the most recent seagrass population survey published in a 2009 study in the journal Proceedings of the National Academy of Sciences. It is noted that the estimate is based on incomplete data available at the time.
More thoroughly studied areas illustrate the harm human activities can cause. According to a March 4 study in the journal Frontiers in Plant Science, fishing pollution and fishing losses may have helped remove 92% of seagrass in mainland England over the past century.
The study says if left intact, these fish could feed about 400 million fish and store up to 11.5 million tons of carbon – equivalent to 3% of UK CO2 emissions in 2017, the study said. said rescue.
This year, the Seychelles began assessing coastal seagrass carbon stocks for the first time, and at least 10 countries say seagrass will play a role in their climate action plans, according to UNEP.
Mr. James Michel, who served 12 years as chairman of the Seychelles until 2016, the Seychelles and Mauritius, have joint jurisdiction over the Saya de Malha seabed, should calculate and take into account the wealth of seagrasses above the threshold. their common door.
“Then we’ll be in a better position to know how to not only preserve it but also manage it to make sure it’s protected for the future.”