Seagrass: The Ocean’s Hidden Meadows

Hidden beneath the ocean’s surface lies one of Earth’s most important ecosystems. Seagrass is a marine plant that grows in shallow coastal waters, forming underwater meadows known as seagrass beds. These landscapes feed sea turtles, dugongs, and even sharks, while sheltering a diverse array of fish and small organisms. These flowering plants aren’t seaweed but true plants that have adapted to life entirely underwater, taking root in the seafloor and thriving where few others can survive. 

But what happens in the grassy meadows is only half the story. Below the seafloor, their roots and saltwater-saturated soils hold impressive reserves of carbon.

Read on as we dive into what makes seagrass so extraordinary, from the adaptations that let it flourish to the animals that eat it and the carbon it buries away. 

Key Takeaways Seagrass meadows are plants, not seaweed, that grow in shallow coastal waters and are uniquely adapted to the moving tides and sandy seafloors. As one of the ocean’s blue carbon ecosystems, seagrass meadows store large amounts of carbon in their soils. They also feed animals, filter water, and support fisheries and tourism Nearly one-third of the world’s seagrass meadows have been lost. Restoration and conservation efforts are helping replant seagrass and protect existing meadows. Sustainable tourism practices can help mitigate damage to these ecosystems.

What is Seagrass and How is It Different from Seaweed?

Seagrass is an aquatic flowering plant that grows fully submerged in shallow coastal waters. Despite its name, it isn’t actually a type of grass, but it’s not seaweed either.

While seaweed is an algae, seagrass is a plant with roots, leaves, flowers, and seeds, much like the plants found on land. Its closest relatives are lilies and orchids. Seagrass absorbs nutrients from the seafloor through its roots, whereas seaweed lacks roots and instead takes in nutrients directly from the surrounding water through its entire surface.

Though not true grasses, seagrass gets its name from its green grass-like leaves. There are approximately 72 known species of seagrass, commonly referred to by names such as eelgrass, turtle grass, shoal grass, and manatee grass. While some seagrass leaves look like flat blades of grass, others are shaped like ovals, fern fronds, or even long spaghetti noodles.

In some places, seagrass grows densely clumped together and carpets large areas of the seafloor. These ecosystems are known as seagrass beds or meadows.

Seagrass Adaptations: How These Plants Survive Underwater

Seagrasses are the only flowering plants that spend their life completely submerged in the ocean. Several adaptations enable them to do this, including an extensive network of roots and rhizomes, flexible leaves, air-filled tissues, high salt-tolerance, and a combination of asexual and sexual reproduction. 

Adaptation	Function
Roots and rhizomes	Anchor the plants in soft, unstable sediments, such as sand. Rhizomes are underground stems that spread sideways, sending out new roots and shoots, helping seagrass form large meadows. Together, roots and rhizomes account for approximately 60% of the plant’s biomass, demonstrating just how important they are to seagrass survival.
Flat, ribbon-like, flexible leaves and stems	Allow seagrass to move and bend with water movement, rather than breaking.
Air-filled tissues	Store oxygen and help leaves stay upright in the water.
Salt tolerance	Allows seagrass to live fully submerged in seawater.
Sexual and asexual reproduction	Reproduce using water currents to carry their pollen and through the spread of rhizomes, which turn into independent clones of the parent plant. This enables some species to grow over large areas for thousands of years.

Where Seagrass Beds Are Found

Seagrass beds are found in coastal waters around the world, from tropical lagoons to temperate bays. Because seagrass relies on sunlight for photosynthesis, it only grows in clear, shallow areas where sunlight can reach the seafloor.”

Seagrass meadows occur in marine and brackish environments along coastlines worldwide, except in Antarctica. Together, they cover about 116,000 square miles (300,000 square kilometers), which is around 0.1% of the ocean floor.

Life in Seagrass Meadows

Animals of all shapes and sizes can be found in and around seagrass beds.

Tiny pipefish and seahorses hide among the blades, using their camouflage to avoid predators. Seahorses grip the slender grass with their monkey-like tails, holding steady as currents drift past.

Seagrass beds are bustling cafeterias of the sea. An abundance of small creatures, such as worms, crabs, and shrimp draws in larger hunters like stingrays, sawfish, and snappers. 

Gentle grazers like dugongs, manatees, and sea turtles feed directly on seagrass leaves. As these grazers eat, they disperse seagrass seeds, acting as gardeners of the meadow. 

Even sharks are part of this community. Lemon and nurse sharks often patrol seagrass habitats in search of prey, while the Bonnethead Shark—the world’s only known omnivorous shark— eats the seagrass itself, which can make up to 60% of its diet.

The benefits of seagrass extend well beyond the meadow. Many larger marine species feed on the smaller animals that live in these habitats, linking seagrass meadows to the wider ocean food web. Seagrass meadows also act as natural water filters by trapping sediment and absorbing nutrients. Their presence keeps the water clearer and supports the health of coral reefs. Their influence even reaches the skies, as shorebirds touch down to feed among the shallows. 

Seagrass and People: Coastal Livelihoods and Tourism

Seagrass meadows are also linked to coastal livelihoods. They serve as fish nurseries for one-fifth of the world’s largest fisheries, contributing to global food production and providing income for small-scale fishers. The waters around seagrasses attract visitors for snorkeling, diving, and wildlife watching, creating additional job opportunities. 

Florida’s Nature Coast, just north of Tampa Bay, offers an example of how healthy seagrass meadows support local economies. Each year, more than half a million visitors come to view manatees grazing in the grass and enjoy scalloping, fishing, snorkeling, and paddle sports in its clear, spring-fed waters. Tourism and recreation in the region generate more than $250 million annually, supporting approximately 8,000 jobs.

Seagrass and Climate: Blue Carbon Storage

Like land-based grasses, seagrasses pull carbon from the atmosphere through photosynthesis. Their dense blades also slow currents, causing carbon-rich particles to settle. However, seagrasses’ real strength lies in the hidden root and rhizome networks that anchor them to the seafloor. The underground structures stabilize the sediments, trapping carbon in the seafloor as it steadily accumulates. In fact, seagrass meadows store over 95% of their total carbon below ground. 

The waterlogged, low-oxygen soils in which these plants grow further set seagrass apart. These conditions slow decay, allowing carbon to build up over time. Because decomposition occurs so slowly, seagrass meadows can lock carbon away for millennia. Through this process, seagrass meadows are dubbed “blue carbon” ecosystems — coastal habitats that store carbon in the ocean rather than on land.

Seagrass works at remarkable speed, capturing and burying carbon up to 35 times faster than tropical rainforests. This extraordinary efficiency is why, despite covering less than 1% of the ocean floor, these underwater meadows still absorb roughly 18% of the world’s oceanic carbon. 

What’s Threatening Seagrass?

Nearly a third of seagrass meadows have vanished since records began. Throughout the past century, human pressures have driven steady declines of approximately 1–2% per year, with the rate of loss accelerating to 7% in recent decades. While some areas are seeing an increase in seagrass, the total amount lost was nearly 12 times greater than the area gained.

The IUCN categorizes 21% of species as Near Threatened, Vulnerable, or Endangered. Together, this makes seagrass one of the most vulnerable and least protected coastal ecosystems globally.

Several threats are driving this loss:

• Water Pollution: Runoff from agriculture and urban development introduces excess nutrients and sediment that fuel algal blooms, reducing water clarity and blocking sunlight, which in turn smother seagrass beds. The massive sargassum invasions in the Caribbean and Mexico are an example of this. These large blooms often wash up in thick mats along beaches, discoloring the shoreline and emitting an unpleasant odor. In popular swimming areas, sunscreen chemicals can also accumulate, adding further stress to seagrass ecosystems.
• Coastal Development & Habitat Destruction: Coastal construction and land modification remove or bury seagrass habitat, stir up sediment, and replace natural coastal environments with man-made infrastructure. At some resorts and beach clubs, seagrass is also viewed as a nuisance and cleared to make swimming areas look more inviting. However, this often has the opposite effect, turning vibrant underwater meadows into barren stretches of seafloor. In Mauritius, one hotel removed a seagrass bed to enhance the guest experience, but the result was far less appealing. Without the seagrass, the water grew murkier, and the marine life that once thrived there disappeared.
• Boating, Fishing, & Recreation Impacts: Boat propellers, hulls, and anchors tear up seagrass and leave scars on the seafloor that can take years to recover. In Chesapeake Bay, boat propellers caused more than 3 miles (5 kilometers) of damage to seagrass meadows in a single year. Fishing nets dragged along the bottom also damage seagrass, stirring up sediment that clouds the water and blocks the sunlight. In shallow coastal areas, swimmers, snorkelers, and divers may crush the blades and kick up the sediment, making it harder for seagrass to grow. 
• Climate Change: Rising ocean temperatures slow seagrass growth and fuel algal blooms, while sea-level rise alters their natural range. These pressures are compounded by stronger storms that cause additional damage as the powerful waves uproot seagrass and heavy sediment plumes bury meadows or cloud the water. For example, when Hurricanes Irma and María hit Puerto Rico, more than 10% of the seagrass cover around Culebra Island was destroyed.

Seagrass Protection and Restoration

When seagrass disappears, so do the many benefits it provides. A recent study estimated that Caribbean seagrass delivers around USD 255 billion in ecosystem services each year, with $88 billion attributed to carbon storage alone. 

Recognizing their immense value, seagrass restoration and conservation efforts are emerging worldwide to protect and rehabilitate these ecosystems. Projects are replanting seagrass in degraded coastal zones, improving water quality, and preventing further damage to existing meadows.

Here are a few examples of seagrass protection and restoration in action: 

• Kenya: The Vanga Blue Forest Project is helping to reduce pressure on seagrass by working with local fishers and beach management units to address destructive fishing practices.
• Mexico: In the coastal hotspot of Playa del Carmen, a project is collecting sargassum seaweed from beaches before it decays. The harvested seaweed is transformed into compost and biochar, which is distributed to women-led farms.
• Maldives: Six Senses Laamu stopped removing seagrass for aesthetic reasons and launched the #ProtectMaldivesSeagrass campaign to inspire other resorts to follow suit. The campaign has since gained national support, with dozens of resorts pledging to leave their meadows intact.
• Mauritius: The Four Seasons Resort Mauritius at Anahita is establishing the Indian Ocean’s first resort-based seagrass nursery. The project is growing seedlings for transplanting to help re-establish healthy habitats.

How You Can Help Protect Seagrass

Seagrass may grow quietly beneath the waves, but its impact stretches far above and beyond. Every traveler can help protect seagrass meadows by reducing their carbon footprint and respecting marine life.

Here are three ways you can take action today:

• Travel responsibly: Download our Sustainable Marine Tourism Tips to learn how to enjoy the ocean without harming its fragile ecosystems.
• Take climate action: Offset your carbon footprint through our carbon calculator to support projects that curb climate change.
• Join the movement: Become a member of Sustainable Travel International to access more tools and resources that will help your company transform its impact on the planet.