Distinctive north Norfolk coastal flowers fail to bloom in man-made salt marshes, University of East Anglia study finds

The purple blooms that help give much of the north Norfolk coast its distinctive character are being threatened by the failure of man-made salt marshes to meet European conservation standards.

That was the conclusion of University of East Anglia scientists who found that the habitats created to replace those lost to coastal development or erosion are failing to reproduce the biodiversity of natural salt marshes.

Co-author Alastair Grant said poor drainage and a lack of creeks left the land waterlogged and, like over-watered pot plants, prevented enough oxygen entering the sediment.

The findings, published in the Journal of Applied Ecology today, showed that early-colonising plants like marsh samphire dominate the marshes at the expense of key species such as sea lavender, thrift, sea arrowgrass and sea plantain.

The researchers said their five-year study of 18 marshes created deliberately since 1991 showed that long-held assumptions that salt marshes were one of the easiest habitats to recreate were wrong.

Prof Grant said: 'We want the sites that are being created to be as close as possible to the natural sites to preserve the natural diversity. One of the reasons why north west Norfolk is so popular is that people do like the salt marsh habitat and seeing the sea lavender flowering.

'We want to make sure that these unique landscapes are preserved and, where they need to be recreated, are in a way that is as close as possible to the natural environment.'

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He said the main effect was on plant species and the specialised insects that feed on them, but there was also an impact on bird nesting sites.

He said it would not take 'impossible levels of expenditure' to make significant improvements to existing marshes, which could lead to net savings because less land would be needed to replace lost habitats.