A �1MILLION scheme that protects the RSPB's highly acclaimed Minsmere nature reserve from the ravages of the North Sea has been hailed as a vitally important support system that also protects Suffolk's green economy.

The Environment Agency's major rebuilding of the flagship reserve's North Wall, a now-completed project that was unveiled yesterday, ensures that about 250 hectares of Minsmere is safeguarded from sea flooding – a disaster that would rob the reserve of much of its international importance for wildlife.

Freshwater reedbeds, the habitat of rare bitterns and other highly specialised species, as well as the shallow saline lagoons of the reserve's famous Scrape area, where the society's logo bird the avocet breeds, would be destroyed.

It would be a catastrophe for wildlife – but also a serious body blow to Suffolk's tourism industry. About 90,000 people visit the reserve each year, largely lured by the wildlife thriving on the habitats that would be under threat, and such an influx generates millions of pounds for business in the area.

If such vital habitats were ever lost to the sea, Minsmere's massive contribution to the local economy would be diminished.

Dr Charles Beardall, the agency's Anglia region eastern area manager, said Suffolk's was one of the fastest-eroding coastlines in Europe and the agency's duty of protection was likely to become ever more challenging in the face of sea level rise.

Many properties were in East Anglia's at-risk coastal areas but the Dunwich/Minsmere area was among Suffolk's most vulnerable stretches and contained an internationally important nature reserve.

'It is really important to protect such a site that has international designations, and the small handful of properties in this area, and so we have made a really important investment – one that is very significant in terms of Suffolk's green economy and one that protects Minsmere,' he said.

Under the scheme, Minsmere's North Wall – a raised bank on which visitors access the beach and which defines the southern fringe of the reserve's North Marsh freshwater reedbed – has been strengthened and a new sluice has been installed.

The marsh is vulnerable to incursions by the sea through a beach weak spot near the foot of Minsmere Cliffs. Incursions are likely to become more regular in future years and, as a result, the marsh's character is likely to change, with the area possibly becoming a brackish lagoon.

Adam Rowlands, the RSPB's senior sites manager for the area, said there would be a 'managed transition.' The new sluice would allow beneficial management of freshwater levels in the North Marsh.

When sea incursion takes place, the sluice could be closed and the new wall would become an impenetrable barrier preventing sea flooding on the rest of the reserve.