They’re not as showy as coral reefs or as iconic as rainforests, but seagrasses are quietly doing some of the most important work on the planet. These underwater flowering plants form sprawling meadows along coastlines, supporting a staggering amount of life—and absorbing a surprising amount of carbon. Yet they’re disappearing at an alarming rate.
If we don’t start paying attention soon, the loss won’t just affect fish or marine biologists. It’ll hit all of us in ways we’re only just beginning to understand.
They’re one of the planet’s most efficient carbon sinks.
Seagrass meadows cover less than 0.2% of the seafloor, yet they store around 10% of the ocean’s carbon. That’s a staggering stat for a habitat many people have never even heard of. They capture carbon dioxide through photosynthesis and store it in the sediment, locking it away for thousands of years—far longer than most land-based ecosystems.
This “blue carbon” capacity is why scientists now place seagrasses alongside mangroves and salt marshes as essential ecosystems in the fight against climate change. A 2020 UNEP report called seagrasses one of the planet’s most effective natural carbon sinks. When these meadows are destroyed, all that stored carbon is released back into the ocean and atmosphere, accelerating the very climate crisis they were helping to slow.
They support incredible biodiversity.
Seagrass beds are biodiversity hotspots. They provide shelter and food for thousands of marine species, from tiny invertebrates to commercially important fish. Sea turtles, seahorses, dugongs, rays, and even sharks rely on seagrass meadows for part of their life cycle.
In fact, one square metre of healthy seagrass can host tens of thousands of tiny organisms. These ecosystems play a vital role in keeping ocean life balanced—and when they vanish, entire food webs collapse. According to Marine Conservation Society, around 30% of the world’s fish species depend on coastal seagrasses at some stage of their lives.
They’re essential to global food security.
If you’ve ever eaten seafood, chances are it was linked to seagrass in some way. Many commercially important species—including cod, pollock, scallops, and prawns—use seagrass meadows as spawning grounds, nurseries, or foraging areas.
When these habitats disappear, fish stocks plummet, affecting not only local ecosystems but global food chains. This is particularly critical in regions where coastal fishing provides both livelihoods and sustenance. Protecting seagrass is about more than just conservation—it’s about securing sustainable food for millions of people.
They act as natural coastal defences.
Seagrasses have dense root systems that anchor sediment and reduce wave energy, helping to stabilise the seafloor and prevent erosion. In doing so, they act as natural buffers against storm surges and sea-level rise.
In areas vulnerable to climate change and extreme weather events, seagrasses are among the most cost-effective defences available. According to research published in Nature Geoscience, coastal ecosystems like seagrass meadows could reduce wave heights by up to 50%, protecting communities and infrastructure in the process.
They improve water quality.
Seagrasses filter pollutants from water by trapping particles and absorbing nutrients like nitrogen and phosphorus. In doing so, they help prevent algal blooms, which can smother marine life and create “dead zones” with dangerously low oxygen levels.
Cleaner water doesn’t just benefit marine ecosystems—it improves recreational beaches, supports tourism, and reduces costs for water treatment facilities. In short, seagrass meadows quietly keep coastal waters breathable, swimmable, and fishable.
They’re vanishing at an alarming rate.
Despite their importance, seagrasses are among the fastest disappearing ecosystems on the planet. A study in PNAS found that they’re declining at about 7% per year—roughly a football field every 30 minutes. Causes include pollution, dredging, anchor damage, climate change, and disease.
These threats are often invisible to the public. Seagrasses exist underwater, out of sight and out of mind. But their decline is happening fast—and recovery is slow. In some regions, centuries-old meadows have vanished in a matter of decades.
Their loss releases massive amounts of stored carbon.
When seagrass meadows are damaged or destroyed, the carbon stored in their roots and sediment doesn’t just vanish—it gets released into the water and atmosphere. This can turn a natural carbon sink into a carbon source, adding to global emissions.
One square metre of seagrass can store up to 83,000 grams of carbon—compared to a terrestrial forest, which stores around 30,000 grams in the same area. That means protecting seagrass isn’t just about preventing future emissions—it’s about avoiding a potentially devastating release of carbon already stored safely below the surface.
Restoration works—but we need to move faster.
The good news is that damaged seagrass beds can be restored. Projects in the UK, the US, and Australia have shown that planting seagrass seeds and protecting vulnerable areas from further harm can help meadows regrow.
For example, the ReMEDIES project in southern England is restoring seagrass by reseeding degraded sites and working with local communities and boaters to minimise damage. But restoration is slow and labour-intensive. We need more funding, public awareness, and government support if we’re going to scale up these efforts in time.
Protecting seagrass is a global win.
Seagrasses might seem like a niche concern, but they punch well above their weight. They store carbon, feed people, protect coastlines, and support biodiversity—all in one. For countries facing the brunt of climate change, especially island nations and coastal communities, these meadows are a lifeline.
Investing in seagrass protection isn’t just an environmental choice—it’s an economic and humanitarian one. According to a 2021 report by the Global Ocean Accounts Partnership, seagrasses provide ecosystem services worth over £500 billion annually. That’s a figure that makes the case for protection crystal clear.
Seagrasses don’t have the glamour of coral reefs or the scale of rainforests, but they are no less vital.
They’re quiet powerhouses—cleaning our oceans, stabilising our shores, feeding our communities, and storing the carbon we’re all so desperate to reduce. And yet, they’re slipping away.
We still have time to change that, but it’ll take more than just admiration—it’ll take action. Because if we lose the world’s seagrasses, we’ll be giving up one of the best natural allies we’ve got.