A Survey for Desmoulin’s Whorl Snail Vertigo moulinsiana on Cors Geirch National Nature Reserve / Site of Special Scientific Interest and the Afon Penrhos Floodplain (2016)
A survey for Desmoulin's Whorl Snail Vertigo moulinsiana on Cors Geirch National Nature Reserve (NNR)/ Site of Special Scientific Interest (SSSI) and the Afon Penrhos floodplain was undertaken in October 2016 to determine its current status and distribution. Sampled locations were based upon the results of previous surveys at Cors Geirch (1999-2008) and Afon Penrhos (2002-2008). The population at Cors Geirch was found to have declined considerably, with a complete loss of the snail from former stronghold areas and just 17 shells recorded from two small areas at the southern end of the site. Assessments in 2003 and 2008 had considered the population to be in favourable condition. With an eight-year monitoring hiatus, the causes of the sharp decline are unclear but are likely to include the spread of uncut and un-grazed rank, fen vegetation combined with encroaching birch and sallow. Dense vegetation growth at the site was such that the former ditch-lines, used as features for site monitoring, were almost completely obscured and difficult to reach. At Afon Penrhos, the snail was found in large numbers in short, mechanically-cut and lightly horse-grazed 'fen-meadow'; tall uncut fen supported significantly lower numbers. Elsewhere in the UK, the snail is typically associated with tall fen. Vertigo moulinsiana was recorded on about 19 acres (8 hectares) of the site, but population boundaries were not established on the eastern and south-east borders of the surveyed area. It is estimated that a further 75 acres (30 hectares) of potentially-suitable habitat exists which should be surveyed to determine if it supports the snail. The Afon Penrhos population is not only the largest in Wales, but also probably one of the largest in mainland Britain. The significance of the population here is further enhanced by recent considerable population losses at several Special Areas of Conservation(SAC) in southern England. Once the full extent of the population on Afon Penrhos is determined, it is recommended that the site should be notified as a SSSI to reduce any risk of loss or damage due to changes in site management. In light of the snail's association with short 'fen-meadow' at Afon Penrhos, it is recommended that rank areas which previously supported Vertigo moulinsiana on Cors Geirch are opened up to provide short fen habitat to assist the recovery of the remnant population.
- Dull adnabod
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- Arolwg Falwen Droellog Desmoulin Vertigo moulinsiana ar Warchodfa Natur Genedlaethol/Safle o Ddiddordeb Gwyddonol Arbennig Cors Geirch a Gorlifdir Afon Penrhos (2016)
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Surveys were by visual searches and the collection of samples of suitable vegetation for drying and sieving.
- Gwybodaeth ychwanegol
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Willing, MJ., (2017), A survey for Desmoulin’s Whorl Snail Vertigo moulinsiana on Cors Geirch NNR/SSSI and the Afon Penrhos floodplain in 2016, NRW Evidence Report No: 210, 36pp., Natural Resources Wales, Bangor.
- Dyddiad cyfeirnod y set ddata (Cyhoeddiad)
- 2017-03-31
Ystod amser
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- 2016-10-03
- Dyddiad gorffen
- 2016-10-05
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Rhychwant
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[A] The final report in Microsoft Word and Adobe PDF formats. [B] Species records, which are held on the NRW Recorder 6 database.
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Surveys were by visual searches and the collection of samples of suitable vegetation for drying and sieving.
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Dyfyniad
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- 2008-06-01
Allweddair
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- vertigo moulinsiana
- whorl snails
- Desmoulin's whorl snail
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Dyfyniad
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- 2023-12-31
System Cyfeirio Gofodol
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A survey of Desmoulin's Whorl Snail Vertigo moulinsiana on Cors Geirch NNR/SSSI and the Afon Penrhos flood in 2016
Cyfyngiadau
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© CNC/NRW Data may be re-used under the terms of the Open Government Licence providing it is done so, acknowledging both the source and NRW's copyright. It is the recipient's responsibility to ensure the data is fit for the intended purpose.
Metadata
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- 4f4c4942-4343-5764-6473-313138383938 XML
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Welsh Invertebrate Database (WID)
NRW_DS23774
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- 2024-05-31T09:41:17.886Z
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1.0