A Cornwall Council project looking at the potential of seagrass in helping to tackle climate change has uncovered one of the biggest seagrass meadows ever found in UK waters.

The council commissioned the University of Exeter and environmental researchers Ecospan to carry out surveys off the coast near Penzance and Falmouth to assess how effective seagrass is at growing and storing ‘blue carbon’.

The term is used to describe the carbon captured by the world’s oceans and coastal habitats and is seen as a vital tool in helping to mitigate climate change.

Using cutting-edge surveying techniques scientists from Ecospan discovered a new seagrass bed in Mounts Bay covering the equivalent of nearly 300 rugby pitches and spanning 5km, all hidden beneath the water.

The bed is larger than all known seagrass beds in Cornwall combined and equates to 3.4 per cent of known seagrass areas nationally, representing one of the largest beds ever found in the country.

In the Fal and Helford Estuaries University of Exeter researchers were able to measure the full scale of the 172-hectare seagrass beds for the first time.

Councillor Martyn Alvey, Cornwall’s cabinet member for environment and climate change, said: "The ability of seagrass to draw down significant amounts of carbon has provided further evidence that natural climate solutions right here in Cornwall are vital to combating the climate emergency.

"While we knew there was some seagrass in Mount’s Bay, no one could have predicted the scale of these findings using new survey techniques.

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"We now need to work with partners to ensure that these vital blue carbon ecosystems are protected from threats such as poor water quality, recreational boating and nutrient loading.

"This will ensure these vital carbon sinks and homes for wildlife provided by seagrass can be protected now and into the future, and significantly aid our response to the climate and ecological emergencies."

Seagrass is a flowering plant that only grows in seawater and thrives as underwater meadows of green grass.

Seagrass meadows are a natural solution to a range of issues: they clean coastal waters and help to keep oceans healthy and climate stable.

They also provide a home and nursery for hundreds of species, including commercial fish which is vital to Cornwall’s economy.

Dr Chris Laing, Senior Lecturer in Marine Biology at the University of Exeter, said: "We are incredibly lucky to have such extents of seagrass and other important marine habitats in Cornwall, and our work with the council is bringing together stakeholders, water users and local communities to protect and preserve them for the future."

The council and harbour authorities in the Fal and Helford are already working to reduce pressures on seagrass beds. Harbour masters and moorings officers can advise boat owners where best to anchor to cause the least impact and all rubbish should be taken home.

Areas with the most seagrass in Cornwall are Mounts Bay, Fowey, Looe, Falmouth, St Mawes and the Helford.