The status of Desmoulin’s Whorl Snail (Vertigo moulinsiana) at Rhos Goch National Nature Reserve (NNR) (2015)
This dataset comprises the results of a survey for Desmoulin's Whorl Snail (Vertigo moulinsiana) conducted in 2015. The survey confirmed the species' continued presence at Rhos Goch National Nature Reserve (NNR) following its discovery there in 2007, making it one of only three known sites for the species in Wales.
Despite being a small snail, Vertigo moulinsiana is the largest Vertigo species, with a shell height of up to approximately 2.6 mm. The species is known from only three localities in Wales: Cors Geirch and Afon Penrhos near Pwllheli on the Llŷn Peninsula, and Rhos Goch National Nature Reserve near Hay-on-Wye in Radnorshire. All Welsh V. moulinsiana sites are isolated and differ from the base-rich lake and riverside fens that are typically associated with the species across much of its English range.
The conservation importance of the species has led to its inclusion in various legislative schedules and Red Data Lists. It was categorised as Rare (Category 3) in the UK Red Data Books and has more recently been classified as Vulnerable in the IUCN-based UK Red List status review. The species is listed on Annex IIa of the European Community Habitats and Species Directive (92/43/EEC) and is also a Welsh Section 42 Species of Principal Importance (which replaced the UK Biodiversity Action Plan priority species list in 2006).
The purpose of this survey was to assess the presence and distribution of V. moulinsiana, focusing initially on areas where the species was recorded in 2007 and subsequently undertaking a wider search of potentially suitable habitat within the NNR and the adjoining Site of Special Scientific Interest (SSSI).
- Identification
- Extent
- Distribution
- Quality
- Keywords
- Spatial Reference System
- Content
- Constraints
- Maintenance
- Metadata
Identification
- Identifier
- NRW_DS116504
- Alternative Title
-
- Metadata Language
- English
- Lineage
-
Tray beating was undertaken in dry weather conditions using a gridded white beating tray measuring approximately 25 × 33 cm. Tray beating is a well-established survey technique that involves beating herbaceous fen vegetation over a gridded white plastic tray. At selected locations, this method enabled approximate V. moulinsiana abundance to be estimated, with six tray samples being approximately equivalent to 0.5 m².
In addition, the following information was recorded:
Dominant vegetation types, with particular note made of positive and negative V. moulinsiana habitat suitability indicators (for example, Carex spp. and Glyceria maxima as positive indicators, and Epilobium spp. and Urtica dioica as negative indicators).
Degree of site shading by overhead or overhanging trees and shrubs, recorded as an estimated percentage canopy cover where appropriate, as shading can negatively affect habitat suitability for V. moulinsiana.
Other potentially important environmental and site management factors, including grazing, ground poaching, recent cutting, human trampling, and pheasant release pens.
The presence of other mollusc species.
At four locations, bulk vegetation samples were collected, primarily from the open fen habitat on the western margins of the site. Where V. moulinsiana was recorded, numbers were counted from six-tray samples and converted to approximate densities per square metre, with adult and juvenile snails recorded separately. Twelve-figure GPS grid references and digital photographs were recorded for each principal sample location.
In addition to the formal sampling points, tray beating was undertaken throughout the survey as the surveyor moved around the site in order to identify localised V. moulinsiana populations that might otherwise have been overlooked.
- Additional Information
-
Willing, M.J. 2016 The status of Desmoulin’s Whorl Snail Vertigo moulinsiana at Rhos Goch NNR in 2015. NRW Evidence Report No: 157, 20pp. Natural Resources Wales, Bangor.
- Dataset Reference Date (Publication)
- 2016-03-31
Temporal Extent
- Begin date
- 2015-10-21
- End date
- 2015-10-22
- Topic category
-
- Biota
Extent
Extent
- Geographic Extent
- POWYS - POWYS
))
Distribution
Distribution
- Format Type and Description
-
-
Database
(
Unknown
)
- Specification
-
Species records held on the NRW Recorder 6 database.
-
Documents
(
Unknown
)
- Specification
-
The final report in Microsoft Word and Adobe PDF formats.
-
Database
(
Unknown
)
Quality
Data quality
- Quality Scope
- Dataset
- Conformity
- Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services
- Explanation
-
This dataset has not been assessed for conformance to the referenced INSPIRE regulation.
- Degree
- false
- Lineage
-
Tray beating was undertaken in dry weather conditions using a gridded white beating tray measuring approximately 25 × 33 cm. Tray beating is a well-established survey technique that involves beating herbaceous fen vegetation over a gridded white plastic tray. At selected locations, this method enabled approximate V. moulinsiana abundance to be estimated, with six tray samples being approximately equivalent to 0.5 m².
In addition, the following information was recorded:
Dominant vegetation types, with particular note made of positive and negative V. moulinsiana habitat suitability indicators (for example, Carex spp. and Glyceria maxima as positive indicators, and Epilobium spp. and Urtica dioica as negative indicators).
Degree of site shading by overhead or overhanging trees and shrubs, recorded as an estimated percentage canopy cover where appropriate, as shading can negatively affect habitat suitability for V. moulinsiana.
Other potentially important environmental and site management factors, including grazing, ground poaching, recent cutting, human trampling, and pheasant release pens.
The presence of other mollusc species.
At four locations, bulk vegetation samples were collected, primarily from the open fen habitat on the western margins of the site. Where V. moulinsiana was recorded, numbers were counted from six-tray samples and converted to approximate densities per square metre, with adult and juvenile snails recorded separately. Twelve-figure GPS grid references and digital photographs were recorded for each principal sample location.
In addition to the formal sampling points, tray beating was undertaken throughout the survey as the surveyor moved around the site in order to identify localised V. moulinsiana populations that might otherwise have been overlooked.
Keywords
Keywords
- Type
- Theme
Citation
- Date (Publication)
- 2008-06-01
Keywords
-
NRW Thesaurus
-
- snails
- Desmoulin's whorl snail
- vertigo moulinsiana
- Rhos Goch
- Rhos Goch NNR
- Type
- Theme
Citation
- Date (Publication)
- 2026-08-27
Spatial Reference System
Content
Content Information
NRW Profile
Custom Elements
Constraints
Constraints
Limitations on Public Access and Use
- Restriction type
- Other restrictions
Access Constraints Directive
- Limitations
- no limitations
Access Constraints Text
- Other constraints
-
There are no access restrictions on this data. NRW may release, publish or disseminate it freely.
Use Constraints
- Use constraints type
- Other restrictions
- Other constraints
-
© 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.
Attribution Statement
- Other constraints
-
Contains Natural Resources Wales information © Natural Resources Wales and Database Right. All rights Reserved.
Licence
- Other constraints
- Open Government Licence
Metadata
Metadata
- File Identifier
- 4f4c4942-4343-5764-6473-313136353034 XML
- Metadata Language
- English
- Parent Identifier
-
Welsh Invertebrate Database (WID)
NRW_DS23774
- Resource type
- Dataset
- Metadata Date
- 2026-10-07T12:18:46.462Z
- Metadata Standard Name
- NRW
- Metadata Standard Version
-
1.0