British scientists are attempting to recreate a 20-hectare salt marsh that has undergone massive marine erosion.

Scientists from the Institute of Terrestrial Ecology are focussing on a salt marsh at Tollesbury near Colchester, Essex. Laurie Boorman, senior coastal ecologist at the institute, said that if this work was not undertaken the marsh would disappear, and the sea wall behind it would come under attack and require substantial and expensive reinforcement.

Salt marshes not only provide valuable protection for sea walls along much of Britain's coastline, they also have a highly productive ecosystem producing organic matter to feed shellfish and fish in shallow water and provide wintering grounds for wild fowl including ducks and geese. And they often boast unique or rare plant and animal life.

Dr Boorman said that the plan at Tollesbury is to sow cores of vegetation from existing salt marsh as well as plants that have been raised artificially. He said: "It is important that colonisation of the area is rapid enough to prevent erosion as thriving vegetation is essential for stabilising the mud."

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Salt marshes were extensive along the seaward edges of low-lying coastal areas such as the outer Thames estuary, in north Kent, Essex and Suffolk, but much of this area has been reclaimed over the past 500 years.

The Tollesbury project, which is backed by the Ministry of Agriculture, Fisheries and Food, is an example of the new strategies being developed by ecologists to help prevent the loss of salt marshes and other wetlands. It is making use of a much better understanding of salt marsh processes that has resulted from a major Brussels-backed project - in which the institute is involved - looking into future management techniques for marshes throughout Europe.

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Dr Boorman said that the plight of existing salt marshes is being worsened by the continual slow subsidence of land in south-east England. The resulting reduction in area of salt marsh is being exacerbated by rises in sea level due to global warming.

He explained that as the effective water level rises the seaward edges of the marshes erode. The natural response of a salt marsh ecosystem to this is to migrate inland - a move that is now prevented by sea walls. "Over the coming years this loss of salt marsh will increase markedly, necessitating expensive reinforcement of sea walls. It is estimated that 40 per cent of the salt marshes in the outer Thames estuary could be lost over the next 60 years."