Why Seagrass Meadows Matter: The Ocean's Quiet Workhorses

Nobody plans a trip around seagrass. People ask about coral, about turtles, about whether they might see a shark from a respectful distance. Almost nobody asks about the plain green meadow swaying in the shallows on the way out to the reef. I include myself: for a long time I swam over it without a second thought.

So why do seagrass meadows matter? It comes down to a simple idea. They cover a very small part of the ocean, but they do several big jobs at once: they bury carbon in the mud, they shelter young fish, and they sit between the land and the reef. Here is what I could verify, and what is still uncertain.

What is seagrass, and is it the same as seaweed?

Seagrasses are flowering plants that live fully underwater. They are not seaweeds, which are algae. They grow roots in sandy or muddy seabed in shallow, sunlit coastal waters. The United Nations Environment Programme’s 2020 report Out of the Blue describes meadows in at least 159 countries, covering more than 300,000 square kilometres in total. Sources give slightly different numbers for the share of the ocean floor they cover, between 0.1 and 0.2 percent, which is a good reminder that mapping underwater plants is hard.

For a traveller, the practical point is this: seagrass is often right where boats anchor and where snorkellers wade in, which means we meet it more than we realise.

A small footprint, a big carbon job

The foundational study is a 2012 paper in Nature Geoscience by James Fourqurean and colleagues, who gathered data from 946 seagrass meadows around the world. They estimated that seagrass meadows store between 4.2 and 8.4 billion tonnes of organic carbon on a conservative approach, and up to 19.9 billion tonnes in the upper estimate. Press coverage of the work reported that seagrass beds are responsible for more than 10 percent of the carbon buried every year in the sea, and can hold per square kilometre far more carbon than a typical land forest, mostly in the soil. The same authors warned that if the meadows keep disappearing, up to 299 million tonnes of carbon could be released per year.

This kind of storage in coastal habitats is often called “blue carbon”. The carbon stays in waterlogged, low-oxygen mud, where it can remain for a very long time, as long as the seabed is not torn up. I want to be careful with comparisons that go viral, such as “seagrass stores carbon faster than rainforest”. The numbers differ by method and by place, so I prefer the original study’s ranges.

More than a carbon store: nurseries and healthy reefs

Carbon gets the headlines, but it is not the only reason seagrass matters, and for people who spend time in the water it is not the most visible one. According to summaries of the UNEP report, meadows provide nursery habitat for more than 20 percent of the world’s largest 25 fisheries. The exact wording differs between summaries, so please read it as a general sign of how many fish and fishing communities depend on these meadows. Young fish shelter among the blades before moving to reefs or open water.

Seagrass also sits between the land and the reef. We go deeper into this idea in our article on indicators of reef health and in the science of coral reef resilience: a reef does not live alone, and a damaged meadow can matter for the reef beside it. I want to stay honest here, though. The size of this effect depends on the place, and I do not have a single reliable number to give you.

Why it is disappearing quietly

Seagrass loss gets less attention than coral bleaching. It happens in shallow, muddy water that is not photogenic, and long-term monitoring is patchy in much of the world. A 2021 study in Global Change Biology by Jillian Dunic and colleagues combined 175 studies at 547 sites and found a net loss of 5,602 square kilometres, 19.1 percent of the surveyed meadow area, since 1880. In some regions the trend has recently stabilised or even reversed, but losses still outweigh gains. The authors note that their data represent only about one tenth of the known global seagrass extent, and that the sampling is biased towards some regions. Coastal development and poor water quality were the most commonly cited causes among twelve drivers.

So the honest summary is: loss is real and widespread, the exact speed in any one place is often unknown, and we should not fill that gap with invented numbers.

Anchors, moorings and the one habit that helps

There is a small, concrete thing anyone near the water can do: avoid anchoring on seagrass, and avoid standing or kneeling on it while snorkelling. A review of research on anchoring and mooring found that damage is worst where larger vessels anchor, with more than 100 square metres lost per anchoring, and that recovery may take decades to over a century. Small scars of less than one square metre can recover within a year. One study in Studland Bay, in the United Kingdom, found that each swinging chain mooring caused a loss of about 122 square metres of eelgrass.

There is also hopeful news. A 2026 study at the same site followed 39 damaged areas and found that every anchor scar showed signs of recovery once the disturbance stopped. Where eco-moorings were installed in 2021, bare patches shrank by an average of 93.6 percent by 2025. In Queensland, a programme in Moreton Bay has replaced more than 130 moorings in seagrass areas. Recovery is possible, but only if we stop the damage first.

What can a traveller do? Ask the boat crew where they anchor. Choose operators who use moorings, or anchor over sand and not over grass. Read our pieces on boat and anchor etiquette and on what happens to a reef when anchors drop in the wrong spot. And when you snorkel, float rather than stand: our guide to snorkelling without damaging coral shows how.

What this means for how we travel

On our hosted retreats we work with local operators in small groups of six guests at most, with unhurried plans, and anyone may skip any activity. That slow pace is what lets us look at quiet places like a meadow and not only at the famous reef. Travel has an environmental cost, including flights and boats, so we prefer fewer trips and longer stays.

A few small things help in the shallows: a well-fitting low-volume mask makes floating comfortable so you do not need to stand, a long-sleeved rash guard reduces how much sunscreen goes in the water, and a mineral option from a list like this mineral sunscreen selection is a gentler choice. If you would like to travel slowly enough to notice the meadow on the way to the reef, you can look at our upcoming retreats.

Questions people ask

Wildlife encounters are unpredictable and never forced. Ocean Calling works only with vetted, ethical local operators, and every animal is free to approach, or not, entirely on its own terms.