Seagrass, Solent - 35442 - Theo Vickers

We're working to protect and recover seagrass meadows in UK seas, a vital habitat for animals and a key tool in the fight to combat climate change.

What is seagrass?

Seagrass is a flowering plant that lives underwater around the UK’s coast in shallow, sheltered areas. It forms marine meadows which are highly productive ecosystems and biodiversity hotspots. The oldest seagrass meadows are thought to be hundreds of thousands of years old.

Seagrass meadows are one of the most important natural solutions to the climate crisis.

It plays an important role in absorbing and storing carbon, which can help us battle the climate crisis. It can absorb 10% of the carbon buried in ocean sediment every year, but only covers 0.1% of the ocean floor.



of the carbon buried in ocean sediment each year is absorbed by seagrass

Why is seagrass important?

  • Carbon storage: seagrass is the single most important species in the sea for locking in CO2. As a habitat it is far more carbon-rich and effective at absorbing carbon than an equivalent area of rainforest.
  • Protecting coasts: with rising sea levels causing coastal erosion, healthy seagrass blades – often up to 1m high – can reduce the power of waves washing away our sheltered coves and beaches.
  • Biodiversity hotspots: the UK’s seagrass meadows are home to the two species of seahorse which live in UK waters - the spiny seahorse and the short snouted seahorse. They're also breeding grounds for cuttlefish and sharks, and nurseries for cod, plaice and pollock.
  • A forest shelter: seagrass is a complex ‘forest’ that supports and protects many animals, and increases the organic enrichment of the sand and muds around the root systems. This is a vital shelter and food source for molluscs, shrimp, crustaceans, anemones and other invertebrates to thrive in.

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Threats to seagrass

The majority of UK seagrass beds - an estimated 92% - have been lost or damaged in the past century. Worldwide, at least 35% have been lost over the last 40 years.

The decline has been caused by industrial growth, modification of ports and sheltered harbours, boat traffic, and increasing, stronger storm events. Pollution within the water column also affects the light getting to the seagrass beds and increases the amount of ‘fouling’ algae on the seagrass strands.

Seagrass beds are massive carbon sinks but have been severely reduced in English waters since the industrial revolution.

Dr Jean-Luc Solandt, Marine Protected Area Specialist



of UK marine meadows may have been destroyed as a result of pollution, disease and damage caused by people



more CO2 is thought to be absorbed by seagrass than rainforests



of the carbon buried in ocean sediment each year is absorbed by seagrass

Alongside the loss of seagrass habitat over time, remaining meadows are damaged by anchoring, and the recreational use of our seas. The south coast, a tourist hotspot, is subject to the pressures and effects of large numbers of visitors, alongside the anchoring and mooring of vessels.

Anchoring has been found to rip up seagrass, damaging the grasses and their root systems as the anchors drag along the seabed. Moored boats also attract boats from outside the harbour which are looking for somewhere safe to anchor; more boats mooring and dropping anchors ultimately causes further damage to the seagrass.

Conservation and restoration

Through numerous collaborative projects, focussed on the south coast of England, we're working to protect, restore and conserve seagrass habitats.

Seagrass bed Georgie Bull

Credit: Georgie Bull


Since 2019, we've been working to support the replacement of traditional block-and-chain moorings with sophisticated Advanced Mooring Systems. So far, we’ve replaced five traditional block and chain systems that scraped across the seabed, ripping up seagrass, with mooring ‘riser’ chains which are suspended above the seabed using submerged buoys.

An additional significant benefit is that we’ve used screw piles to secure the riser chain to the seabed rather than the concrete-filled tyres commonly used to hold down moorings. Already there are signs of seagrass regeneration close to the moorings themselves since installation in Spring 2019.

Water quality

The Marine Conservation Society has long been campaigning for significantly improved water quality in our seas. When waters are polluted there is less light for photosynthesis to take place in marine plants such as seagrass. Polluted waters also mean an increase in the amount of algae growing on seagrass blades and in the water column – both of which are bad for the health of seagrass.

More needs to be done over combined sewage overflows and farming practices which can leach nitrogen, pesticides and other chemicals into our rivers and ultimately into our coastal waters.


Since 2009, we've been working to get damaging fishing (trawling, scallop dredging) out of seagrass beds in English Marine Protected Areas (MPAs). In 2014 we were successful in getting regulators, like the local inshore fishing authorities, to protect all English seagrass beds in MPAs.

Trawlers and dredgers sometimes ‘cleaned their gear’ by towing it through seagrass – thankfully that is now illegal. However, there is still an issue with recreational fishers digging out bait from muds and intertidal seagrass beds in places such as Essex and the Solent. It’s essential that this sort of activity is stopped through the use of measures like no access zones, voluntary codes, and information to fishers.

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