Distribution and conservation status of Perforatella rubiginosa (Pulmonata: Helicidae) in Britain

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In 1995 a survey was undertaken on behalf of the statutory conservation agency, English Nature as part of their Species Recovery Programme to determine the status of the known populations of Perforatella rubiginosa in England and to identify other populations within the known range.

The results demonstrated that P. rubiginosa was thriving at all of its known British sites which lie in the Thames basin, except Burham, Kent where only dead shells were found. Many of the populations are large and are more extensive than previously recognized. In addition, it was also found on Brentford Ait East, representing a new site for the species.

In Britain, P. rubiginosa is demanding in its habitat requirements. Most sites are within the flood zone of tidal freshwater rivers and are characterized by having areas of bare mud vegetated by tall herbs. Flood rubbish such as planks, logs, dead stems and plastic is a feature at all sites and represents an important refuge for the snail. Most sites are relatively sheltered and would be gently lapped by a significant proportion of high tides.

The restricted nature and extent of the habitat at all sites means that all populations are vulnerable. The principal threats come from industrial and urban development; inhibition of the tidal action by piling, barrages or locks and over-management such as clearance of the flood rubbish.

Conservation status.