1013 Geyer's whorl snail Vertigo geyeri
Description and ecological characteristics
Throughout its range the tiny Geyer’s whorl snail Vertigo geyeri is local and found in relatively exposed, constantly humid calcareous flush-fens (including the Annex I habitat type 7230 Alkaline fens) that are fed by tufa-depositing springs (including 7220 Petrifying springs with tufa formation (Cratoneurion)). These flushes are often only a few square metres in extent. Species that have been found with it at all sites in the UK are black bog-rush Schoenus nigricans and yellow sedge Carex viridula. It requires dense cover of low-growing grasses and sedges relatively free from Sphagnum and other mosses.
Vertigo geyeri flourished in post-glacial conditions, but climatic change led to a dramatic contraction of its range, and the species is vulnerable to drainage of the sites where it survives. Like all Annex II Vertigo species, it is highly dependent on maintenance of existing local hydrological conditions.
European status and distribution
Vertigo geyeri is found at widely-scattered localities in Europe between northern Scandinavia and the Swiss and Austrian Alps and Ireland, at a wide range of altitudes.
UK status and distribution
In the UK this species is currently known from north Wales, northern England, the Scottish Highlands, the Inner Hebrides, and Northern Ireland. In total it has been recorded from approximately 30 localities.
Site selection rationale
Sites have been selected to encompass the range of ecological situations in which V. geyeri is found in the UK (including both upland flushes and lowland fens), and to take account of its geographical distribution. The selected sites have ecological conditions that are considered to be particularly favourable for the species’ survival.
Sunbiggin Tarn represents Geyer’s whorl snail Vertigo geyeri in north-west England. It supports a large population of this species in upland calcareous flushes with a rich assemblage of arctic-alpine plants.
Corsydd Môn/ Anglesey Fens
West Wales and The Valleys
Cors Erddreiniog and Waun Eurad represent Geyer’s whorl snail Vertigo geyeri in north Wales. The site contains one of the largest known populations of V. geyeri in calcareous fen at low altitude.
Eller's Wood and Sand Dale
This site provides a lowland representation of Geyer’s whorl snail Vertigo geyeri in north-east England; the population exists at this site in a tufa-rich flush.
Tulach Hill and Glen Fender Meadows
Geyer’s whorl snail Vertigo geyeri is found at this central Scottish site in upland, base-rich flushed mires at an altitude of 170–345 m. It occurs in a rich assemblage of arctic-alpine plants, and at some flushes it has been recorded with another Annex II species, 1015 round-mouthed whorl snail Vertigo genesii.
SACs where this Annex II species is a qualifying feature, but not a primary reason for site selection
Many designated sites are on private land: the listing of a site in these pages does not imply any right of public access.