The hidden superpowers of saltmarsh

Saltmarshes might look like grass and mud, but these spectacular coastal habitats are tackling some of the world’s most pressing crises.

They’re biodiversity-bursting, carbon-capturing, flood-busting, water-purifying, economy-boosting and mood-lifting ecosystems.

However, 85% of England’s saltmarshes have disappeared since 1860, lost to changes in land use and coastal squeeze – when sea defenses are placed close to tidal waters, limiting the space for saltmarshes to grow.

We must act now to protect one of our most effective tools in the fight against climate change.

Ready to discover how we can restore saltmarshes together?

Let’s dive in.

Contents

What are saltmarshes?

Saltmarshes are low-lying coastal wetlands where land meets the sea. These ever-changing landscapes are flooded and drained by the tides, creating a salty, boggy environment of mud and peat. Saltmarsh habitats are home to specialised salt-tolerant plants and diverse wildlife that adapt to seasonal changes. They’re found in temperate regions worldwide. In the tropics, saltmarshes are replaced by mangroves with salt-tolerant trees rather than low-growing plants.

How do saltmarshes form?

Saltmarshes form when mud and silt are deposited along sheltered coastlines. Small salt-tolerant ‘pioneer’ plants take root first, followed by larger plants, creating layers of diverse vegetation. When these plants die, they get buried in the sediment, locking away the carbon they absorbed. This process repeats: plants catch sediment, sediment buries plants and saltmarsh locks away carbon. Restoring these coastal habitats is essential for maintaining their ecological roles and benefits.

What are the benefits of saltmarsh?

Beneath the surface, saltmarshes are bursting with planet-protecting superpowers. These spectacular ecosystems offer a range of social, climate, economic and environmental benefits. They are:

Carbon-capturing: Saltmarshes can store carbon 40 times faster than temperate forests. Despite covering less than 2% of ocean area, they account for nearly 50% of carbon burial in marine sediments.

Flood-buffering: Saltmarshes act as buffers during heavy storms or high tides, protecting 60% of the world’s coastal population from rising flood risks.

Economy-boosting: Saltmarshes support local economies through fishing, tourism and sustainable agriculture. Creating 25,000 hectares of saltmarsh around the UK’s coastline would deliver estimated benefits valued at £1.7 billion over 60 years.

Biodiversity-bursting: Around 40% of the world’s wildlife depends on wetlands and saltmarshes, making them some of the most biodiverse habitats on earth.

Water-purifying: Saltmarshes act as natural filters, absorbing pollutants like pesticides, heavy metals and hydrocarbons, significantly improving water quality along coastlines.

Mood-lifting: Just 10 minutes in a wetland setting can increase positive feelings, making saltmarshes valuable resources for community wellbeing.

Wildlife in saltmarsh habitats

Saltmarshes are dynamic ecosystems that support an array of wildlife uniquely adapted to the conditions of these intertidal landscapes. Saltmarshes provide important breeding grounds, feeding areas and high-tide refuges for a diverse range of species, from birds and fish to invertebrates, mammals and even amphibians.

You can read more about the amazing wildlife on the UK’s saltmarshes.

Why are saltmarshes under threat?

Just 45,000 hectares of saltmarsh remain in the UK. This dramatic loss is due to land conversion and coastal squeeze, when infrastructure prevents habitats from moving inland in response to rising sea levels. However, there is hope. In England, saltmarsh habitat increased by 7% between 2009 and 2019, showing that with proper management and restoration efforts, we can help these coastal habitats burst back to life.

What is WWT doing to restore saltmarsh habitats?

Saltmarsh restoration is a powerful tool in fighting climate change and biodiversity loss.

At WWT we are taking action for saltmarshes here in the UK and worldwide, while working to empower others to do the same.

We are getting muddy, leading the way in saltmarsh restoration with pioneering large-scale projects and partnerships that demonstrate the power of these ecosystems.

We are also carrying out world-leading research into the benefits of these understudied habitats. We have already begun investigating the incredible value saltmarshes could bring to people and nature with our Wetland Potential Maps, but there is much more to learn.

Here are just some of the ways we're making a difference now (and how you can, too):

WWT Steart Marshes

In 2014, we partnered with the Environment Agency to create WWT Steart Marshes in Somerset, one of the UK’s largest new wetland reserves. This project showcases nature-based solutions for flood protection, biodiversity enhancement, community wellbeing and climate change mitigation.

In just 10 years, Steart Marshes has become a thriving ecosystem, attracting diverse wildlife like otters, egrets, owls and spoonbills. It also supports local agriculture, providing grazing land for saltmarsh beef and has been recorded capturing 70 tonnes of carbon dioxide equivalent per hectare per year.

The site boasts an incredible record when it comes to species diversity. In just ten years over 500 species of flora and fauna have been recorded on site. As well as its amazing biodiversity it is also a deeply valued community asset, providing a place for people to connect with nature, for farmers to produce the finest saltmarsh lamb and beef and capturing huge quantities of carbon in its first decade.

Saltmarsh Solutions at Awre

In December 2024, we announced our purchase of 148 hectares of low-lying land on the Awre peninsula for a pioneering saltmarsh restoration project using money donated by Aviva, the savings and insurance business.

We are using this £21 million to restore coastal saltmarsh at a landscape scale. This project will develop best practices for saltmarsh restoration and advocate for further investment in UK saltmarsh creation.

Our plan involves managed realignment, a process that will carefully breach the existing sea wall and allow controlled flooding of the land with salt water from the estuary. This will gradually re-establish the saltmarsh habitat that likely existed on the site centuries ago.

As well as being a haven for wildlife and a nature reserve for the local community, it will act as a hub for new research studying the superpowers of saltmarshes to store carbon, boost biodiversity and improve flood resilience.

How can I help with saltmarsh restoration?

Just like tiny ‘pioneer’ plants create marshland, even the smallest actions for saltmarsh restoration can yield extraordinary results. Here’s how you can be a part of saltmarsh creation and restoration:

Visit

Experience the wonder of saltmarshes up close at one of our Wetland Centres around the UK. Saltmarsh habitats can be found at WWT Steart Marshes, WWT Caerlaverock, WWT Slimbridge, WWT Castle Espie and WWT Llanelli.

Support

Join our mission to restore 100,000 hectares of wetlands in the UK, either by visiting your local Wetland Centre, donating to WWT or becoming a corporate partner.

Connect

Share the importance of saltmarshes with your community. Follow us on social media and help us spread the word about the super-powered ecosystems.