Saltmarshes are also regarded as a form of natural sea defence.

The Essex Wildlife Trust's Abbotts Hall Farm initiative on the Blackwater Estuary has won the RSPB/CIWEM Living Wetlands Award.

The scheme which also saves �500,000 in sea defences has boosted habitats for a range of birds, fish and plants.

The new wetland is providing a haven for thousands of species, including Brent geese, skylark and lapwing.

Four centuries ago, saltmarshes in Essex covered more than 115 square miles, supporting a huge range of species.

By 2002 this had shrunk by 90 per cent to an area of less than 3,000 hectares.

Five breaches were made in the sea wall at Abbotts Hall Farm, on the Blackwater Estuary near Colchester, to allow the tide through.

Ruth Davis, Head of Water Policy at the RSPB said: "Partnership schemes such as Abbotts Hall are showing the way forward.

"Many more of these projects will be needed in the future to maintain our coastal wildlife."