NORFOLK BIODIVERSITY ACTION PLAN SPECIES DATA AUDIT ...

Species Present
or
absent
in
Norfolk
Sandbowl Snail
Quickella arenaria
Shining Ram’s-horn Snail
Segmentina nitida
Witham Orb Mussel
Sphaerium solidum
Cylindrica Whorl Snail
Truncatellina cylindrica
Large-mouthed Valve Snail
Valvata macrostoma
No. of
records in
database
No. of
1km
squares
recorded
since
1980
Possible other
sources
of data sets
58
Other survey
work
completed or
in progress
Comments
A - - Not recorded in Norfolk
Current UK Species Action Plan
RDB Species
Known from only three UK sites, all sand
dune habitats.
Internationally threatened – Loss of dune
environments and falling water levels.
P 79 17 Current UK Species Action Plan
Found in unpolluted, usually calcareous
water in the ponds and drains of grazing
marshes.
Declining – Causes unclear but believed to
be over-frequent ditch clearance,
eutrophication due to fertiliser run-off, and
conversion of grazing levels to arable
farming, with associated water table
lowering.
Norfolk Action Plan published December
1998, revised January 2003.
A - - Not recorded in Norfolk
Little is known about the habitat
requirements of this species. However,
where it does occur the water bodies support
a wide range of molluscan fauna.
Marked decline in UK – Causes unclear but
may be linked to eutrophication and
pollution.
New to national list of BAP priority
species 2007
P ? ? County Recorder RDB Species
Associated with dry, calcareous grassland
and occasionally on sand dunes.
Marked decline in UK – Habitat loss and
degradation.
New to national list of BAP priority
species 2007
P 45 21 RDB Species
Quite widespread in suitable habitat.
Associated with coastal and floodplain
grazing marshes.
Internationally threatened – Habitat loss,
degradation and pollution.
New to national list of BAP priority
species 2007