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Seagrass: The Global Seafood Supermarket

How a Seafood Nursery Feeds Millions

Horseshoe crabs in seagrass.   ©Theodore Smith/Flickr
Horseshoe crabs in seagrass. ©Theodore Smith/Flickr

The word is out about the ways seagrass aids the environment, but more needs to be known about how this vital ecosystem boosts local economies.

For those who are not familiar with seagrass, the term covers the many species of the world’s only flowering underwater plant. Seagrass spreads along the ocean floor through rhizomes, often hugging shorelines in colonies that resemble the rolling, grassy meadows found on land.

Seagrasses are found globally in temperate and tropical waters where their biodiverse ecosystems rival those of coral reefs, protecting and nourishing wide varieties of marine prey and predator alike.

Seagrass Studies Ignore Local Economic Benefits

Environmentalists have spearheaded the call to protect and restore the seagrasses. Not only are fields of seagrass superior at carbon sequestration, they can slow, and even help rectify, ocean acidification, according to a 2021 study by the Monterey Aquarium Research Institute in California.

Researchers at Swansea University in Wales describe seagrass as a "nature-based solution for greenhouse gas mitigation," calling it "vital for biodiversity." But unfortunately, the immense ecological importance of seagrass beds doesn’t translate into wholesale preservation efforts.

Seagrass keeps communities from falling into poverty, or into greater poverty.

Often overlooked are seagrass beds’ significant economic importance to coastal communities.

In fact, seagrass keeps communities from falling into poverty, or into greater poverty, says Benjamin L.H. Jones, a professor in the department of Ecology, Environment, and Plant Sciences at Stockholm University in Sweden.

Jones is the lead author of a study that looked at the role seagrass plays in local economic income. The study, published in the June 2022 issue of the journal Ocean & Coastal Management, is one of the first of its kind to define the importance of seagrass to the coastal populations, Jones says.

"The support that seagrass meadows provide to communities can no longer be ignored; doing so would create further poverty for the most vulnerable in society," Jones says.

Vietnam: A local catch of snails.   ©Viethavvh/Wikimedia Commons
Seagrass allows Vietnamese villages to catch snails. ©Viethavvh/Wikimedia Commons

Food Security: On Par with Environmental Concerns

Efforts to restore and maintain fields of seagrass in oceans and seas mainly center around environmental arguments, Jones said. But how will the local populations that depend on seagrass for the fish and seafood they eat and for their livelihoods be affected by vanishing seagrass meadows? Their plights should also be a consideration in preservation efforts, Jones says.

When seagrass meadows are lost, household income goes down, Jones and his fellow researchers found.

  Crab in seagrass at low tide.   ©Arnica Backstram/Pixabay
Crab in seagrass at low tide. ©Arnica Backstram/Pixabay

In Southeast Asia and other tropical regions, plentiful fields of seagrass help alleviate poverty in local communities. That’s because many residents comb through the meadows to catch the fish, crab, turtles, and shrimp that live among the grass-like plants. Seagrass is a prominent food source for these households, the study finds.

Small-scale fisheries also rely on plentiful fields of seagrass because many types of fish—both large and small—live in the meadows, which proliferate relatively close to shore.

In fact, Jones and his colleagues discovered that, wealthy or poor, all the households they studied relied on seagrass to one degree or another.

By looking at income and other factors from 147 villages across four countries within the Indo-Pacific, the researchers were able to examine the ways the households depend on seagrass.

Even wealthy households that fish offshore with their own boats also fish within beds of seagrass, Jones says.

Net fishing near seagrass bed.   ©lena1/Pixabay
Net fishing near seagrass bed. ©lena1/Pixabay

Actually, seagrass meadows serve as a nursery habitat "to over 1/5th of the world's largest 25 fisheries," according to a 2018 study. That includes pollock (see video), "the most landed species on the planet," wrote the study authors.

But overfishing and pollution are rapidly diminishing seagrass meadows that these populations rely on. In fact, a football field of seagrass disappears every half hour, according to a study done last year by researchers at the University of California Davis and other institutions.

Jones and his colleagues join environmentalists, politicians and others in calling for the conservation of seagrass meadows. "Safeguarding seagrass meadows across the Indo-Pacific is vital to alleviate poverty," he says.

Push-Pull Needs of Fisheries and Seagrass Meadows

The depletion of seagrass can threaten food security in a number of ways other than impoverishment, says Mariana Herrera, a marine science researcher at the University of Vigo in Spain.

Particularly important is seagrass meadows’ role in supporting fisheries worldwide and bringing food to nearby populations, Herrera says.

People in tropical countries often rely on small-scale fisheries for their everyday food needs, she says. Small-scale fishers often operate without boats or with small boards. They’re not able to fish far from the shore, meaning seagrass meadows are important to support the shore life that creates their livelihood, Herrera says.

Korea: Fishing near shoreline seagrass.   ©Proman/Pixabay
In Korea, people fish near shoreline seagrass. ©Proman/Pixabay

Many marine species that live close to the shore "are easy to target using low-tech fishing gear or simply collection by hand [allowing] such fisheries to prevail across the tropics, more so in low-income and emerging economies," writes Jones and colleagues in their paper.

Small-scale fisheries are increasingly difficult to manage as they are tied to the fate of coastal habitats like seagrass meadows, which themselves are impacted by factors like poor water quality and coastal development, Herrera says.

Meanwhile, Jones and his colleagues found that, in the 147 households they studied, low-income households that depend on seagrass for income from fishing could be hit hardest by such factors as habitat loss and overfishing.

"If seagrass meadows are lost, the most vulnerable in society will have the most to lose," Jones says. "The support that seagrass meadows provide to communities can no longer be ignored, doing so would create further poverty for households that depend on seagrass for food and work."


*Jean Thilmany is a freelance writer living in St. Paul, MN, who writes frequently about science and engineering topics.


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