Seagrasses are one of the most widespread marine ecosystems on Earth, covering around 300,000 km2 of seabed in 159 countries.
Monochromatic seagrass meadows may not be as colourful as coral reefs or as mysterious as mangrove forests. But they are havens for fish, protect coasts from storms and are key stores of carbon, making them some of the world’s most valuable natural spaces.
Despite their importance, these ecosystems are in danger. A football field worth of seagrass disappears every 30 minutes and an estimated 7 per cent of meadows are being lost worldwide per year. Ocean acidification, coastal development and rising ocean temperatures due to climate change are the prime drivers of seagrass loss.
To raise awareness about the threats to these ecosystems, the United Nations has designated 1 March as World Seagrass Day.
“The seagrass ecosystem is a perfect example of nature in action, where habitats and the delicate web of life are intertwined in perfect harmony,” said Leticia Carvalho, Head of the Marine and Freshwater Branch of the United Nations Environment Programme (UNEP). “On this, International Seagrass Day, let us shine a light on the magic of seagrass meadows and the species, human and non-human alike, who depend on them,” she added.
Carvalho said the world must prioritize timely, ambitious and coordinated actions that conserve, restore and sustainably manage seagrasses. As that happens, countries need to ensure that local communities, who have been living in harmony with nature for thousands of years, benefit. Ramping up these efforts is integral to reaching the Paris Agreement and many of the United Nations’ Sustainable Development Goals, says Carvalho.
It’s also considered crucial for helping countries meet the goals of the Kunming-Montreal Global Biodiversity Framework, a landmark pact signed last year to protect nature. That agreement was signed amid a biodiversity crisis which is seeing 1 million of the planet’s 8 million species being pushed towards extinction.
Here are five surprising ways seagrasses can safeguard wildlife, benefit people and help lay the groundwork for a more sustainable future.
- Seagrass is a haven for marine species
Seagrass meadows are nurseries for 20 per cent of the world’s largest fisheries, found a 2020 report from UNEP and partners titled Out of the Blue: The Value of Seagrass to the Environment and to People. The survival of many species, such as turtles, seahorses, manatees and dugongs, depend on these meadows.
Thanks to its leafy underwater canopy, seagrass also provides shelter for countless small invertebrates, such as crabs and shrimp, as well as many species of algae and bacteria.
- Seagrass filters water for corals, a biodiversity hotspot
Often called ‘nature’s water filter’, seagrass meadows were described as a super ecosystem in the Out of the Blue report. They help clean water by trapping carbon-rich sediments and absorbing nutrients and pathogens. Seagrass-dominated systems oxygenate water through photosynthesis, improving water quality and stoking coral growth.
Seagrass meadows create biodiversity hotspots by providing habitat and nutrients for countless species.
Due to its sensitivity to a range of stressors and contaminants, seagrass is an early indicator of the ecological health of coastal areas. When seagrass suffers, so does biodiversity.
- Seagrass supports fisheries and livelihoods around the world
Seagrass is similar to terrestrial plants in that it has leaves, flowers, seeds, roots, and connective tissues. As such, it is an important food source for fish, octopuses, shrimp, oysters, clams and squid, underpinning fisheries that support hundreds of millions of people around the world, according to the Out of the Blue report.
In Tanzania, for instance, a decline in seagrass was found to have a negative impact on the livelihoods of women who collect invertebrates, such as clams, sea snails and sea urchins.
- Seagrass is important for non-marine species, too
During their autumn migration, some geese and ducks graze on seagrasses poking out from coastal sediments. Other birds forage for invertebrates in the often shallow waters that surround the plants.
In December 2022, world leaders agreed to the Montreal-Kunming Global Biodiversity Framework, a pact designed to protect the diversity of life on Earth and ward off a looming extinction crisis. Carvalho said that as countries develop their national targets under the agreement, they must include protection for seagrass meadows.
“Seagrass meadows support a stunning array of life and safeguarding them is vital if we’re going to meet our global goals on biodiversity – and we have to,” she said.
- Seagrass is an antidote to climate change
Often referred to as a type of blue forest, seagrass meadows, much like their terrestrial counterparts, help to counter climate change. Even though these meadows cover only 0.1 per cent of the ocean floor, they are highly efficient carbon sinks, storing up to 18 per cent of the world’s oceanic carbon, found the Out of the Blue report.
Seagrass also acts as the first line of defense along coasts by reducing wave energy, protecting people from the increasing risk of floods and storms.
The UN Decade on Ecosystem Restoration 2021–2030, led by the United Nations Environment Programme, the Food and Agriculture Organization of the United Nations and partners covers terrestrial as well as coastal and marine ecosystems. A global call to action, it will draw together political support, scientific research and financial muscle to massively scale up restoration.
