This snail is local throughout its central and southern European range. It occurs in unpolluted, calcareous waters in well-vegetated marsh drains and is usually found with a number of other molluscs which are rare and vulnerable, including Segmentina nitida
In Britain, since 1965 it has been recorded at about fifteen sites, in Norfolk, Suffolk, Middlesex and Sussex, but living colonies have not been confirmed outside East Anglia for over ten years. In 1994, systematic sampling on the Pevensey Levels in Sussex, formerly a well known site, failed to produce any live records. The reasons for this decline are not clear. The species seems to have re-colonised at least one ditch system in Suffolk, possibly as a result of improved water quality.
This snail is listed as Vulnerable in the GB Red List.
Current factors causing loss or decline
The main threats possibly include over-frequent ditch clearance, nutrient enrichment due to fertiliser applications, and conversion of grazing levels to arable farming with associated water table lowering.
NE funded a survey of the molluscs of Pevensey Levels in 1994.
The Conchological Society of Great Britain and Ireland has surveyed most of the recent sites for this species.
Action plan objectives and targets
To maintain populations in at least 15 sites.
Proposed actions with lead agencies
Policy and legislation
Identify water quality requirements and take account of these standards when setting standards in watercourses occupied by this species, seeking to restore clear, unpolluted water to ditches to provide opportunities for expansion or re-colonisation. (ACTION: NE, IDBs, NRA)
Ensure the needs of this species are taken into account if considering extending ESAs over grazing marshes occupied by the snail. (ACTION: MAFF)
Site safeguard and management
Seek to ensure that management plans prepared for existing and newly discovered sites take into account the presence and requirements of the species on a case-by-case basis. (ACTION: NE)
Establish and implement a ditch management cycle that allows the re-colonisation of cleaned stretches from adjacent sections, taking into account the length of rotation necessary to avoid the ditch becoming choked with emergent vegetation. (ACTION: NE, IDBs, NRA,)
Seek to ensure that Water Level Management Plans take into account the ecological requirements of this species, where appropriate. (ACTION: IDBs, NRA)
Species management and protection
Following further research and monitoring, prepare advice on habitat management to favour this species, by the year 2000. (ACTION: NE)
Ensure that land managers are aware of the presence and vulnerability of this species, and appropriate methods of land and water management for its protection. (ACTION: NE)
Future Research and Monitoring
Within a single season, undertake a survey of all post-1965 live recorded sites to establish an accurate distributional baseline for the species. Then monitor using fixed point monitoring stations at each of the existing sites. (ACTION: NE)
Promote further study on the ecological requirements of this species, including the effects of changes in water quality on survival and current management of habitats containing healthy populations. (ACTION: NE)
Survey poorly recorded areas to discover if further colonies exist. (ACTION: NE)
Encourage research on the ecology and distribution of this species on an international level and use the information and expertise gained towards its conservation in the UK. (ACTION: NE, JNCC)
Pass information gathered during survey and monitoring of this species to JNCC or BRC so that it can be incorporated in national databases. (ACTION: NE)
Communications and Publicity
Maintain a network of contacts.
No action proposed.
Links with other action plans
Originally published in: Biodiversity: The UK Steering Group Report - Volume II: Action Plans (December 1995, Tranche 1, Vol 2, p156)