Restoring Cornwall’s Seagrass

Seagrass is the only flowering plant that can live in seawater. It often grows in large groups giving the appearance of terrestrial grassland – an underwater meadow. These meadows can be found in shallow coastal areas on sheltered sandy or muddy seabeds and can be exposed at low tide.

Seagrass is vital for the health of our oceans and the wider planet. These underwater meadows support a diverse ecosystem, acting as a nursey site for fish, providing food and shelter for tiny invertebrates, marine mammals and waterfowl and protecting our shorelines from coastal erosion.

Seagrasses also have the potential to store huge amounts of carbon and because of this are known as a natural solution to fighting climate change. Despite covering less than 1% of the ocean floor, seagrass beds are responsible for 15% of its total carbon capture.

In the UK, we have lost up to 90% of our seagrass meadows in the last 100 years. There are many factors that have led to the decline of seagrass: from physical pressures such as dredging and the use of mobile fishing gear; to pollution and even the increase of non-native species that outcompete our native seagrass. Seagrass meadows were also severely affected by a disease in the 1930s.

Although seagrass has suffered severe declines in the UK, we still have vital patches of it here in Cornwall, including off Falmouth, Mounts Bay and Looe.

There are two species of seagrass found in Cornwall, otherwise known as eelgrass species. The first, common seagrass (Zostera marina), has leaves up to 1m longer and is typically found on the lower shore. In contrast, dwarf seagrass (Zostera noltei) is shorter and thinner than common seagrass (with leaves up to 20cm long) and is found high up the shore in creeks and estuaries.

There are now only a few areas in the South West where dwarf seagrass remains in good condition. One of these places is Cornwall Wildlife Trust’s Fal Ruan nature reserve – the location of the Trust and Seasalt Cornwall’s new seagrass restoration project (see below).

In July 2022, Cornwall Wildlife Trust launched a new and exciting partnership project with Seasalt Cornwall to study and restore seagrass in the Fal Estuary. The three-year project aims to learn more about Cornwall’s dwarf seagrass beds by conducting on-site research, including aerial surveys and water quality tests. Marine experts will also trial restoration methods that have never previously been used in Cornwall before, with the hope of expanding the size of the seagrass bed at the Trust’s Fal-Ruan nature reserve.

Hear from our Marine Conservation Officer Matt Slater and the Seasalt Cornwall team on the launch of this exciting partnership project in the video below.

We have now completed our first round of seagrass planting trials in the River Fal as part of our Seeding Change Together project with Seasalt Cornwall. Our marine team have tested a variety of methods aimed at identifying the most effective ways of restoring and growing seagrass. A small group of volunteers – including employees from Seasalt Cornwall – have contributed over 120 hours to the project so far by helping us to collect and plant the seeds.

Watch the film with our Seagrass Project Officer Sophie to see what’s involved in the seagrass restoration process. Stay tuned for more exciting updates in the months ahead!