The status and distribution of Lilljeborg’s Whorl Snail Vertigo lilljeborgi at Pont Croesor on the Afon Glaslyn in 2022
Results of a monitoring survey in August 2022 for the Near Threatened Lilljeborg’s Whorl Snail Vertigo lilljeborgi within Glaslyn SSSI are presented. The area surveyed is north of Pont Croesor on the Afon Glaslyn. Judged to be in Unfavourable condition after the last survey in July 2008 (Willing, 2009), the present survey over two days in August repeated the previous survey. The wetland habitats remain visually very similar to those described in 2008 and weather and river level conditions were similar. All 8 sites were revisited and sampled by visual search, beating vegetation, and collecting bulk samples of decaying plant matter. A 9th site was sampled near Site 7, the point at which V. lilljeborgi was last recorded in 2008. A suction sampler was used in 5 additional locations between sites on the east bank. A total of 12 adults of V. lilljeborgi was found at Site 7 and Site 8, confirming that the species survives on both sides of the Afon Glaslyn, although it is still apparently restricted to small areas. Two juvenile Vertigo were also found at Site 6. These could not be unambiguously identified as V. lilljeborgi, owing to the presence of another species, Vertigo antivertigo, nearby. All Vertigo specimens were found in large bulk samples that had been dried and sieved. No Vertigo were observed in the field, emphasising the importance of multiple sampling methods. Using the Conservation Objective Lower Limit of 10 individuals set by Willing (2009), V. lilljeborgi is judged to be in Favourable condition within Glaslyn SSSI in August 2022. Nonetheless, the population only just exceeds the Lower Limit, and remains small and potentially vulnerable. Further sampling in the areas around Pont Croesor could help determine whether V. lilljeborgi is more widespread on the Afon Glaslyn floodplain.
- Identification
- Extent
- Distribution
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- Spatial Reference System
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- Maintenance
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Identification
- Identifier
- NRW_DS125371
- Alternative Title
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- Statws a dosbarthiad Malwen Droellog Lilljeborg Vertigo lilljeborgi yn SoDdGA Glaslyn wrth Bont Croesor ar Afon Glaslyn yn 2022.
- Metadata Language
- English
- Lineage
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Sampling conducted by by visual search, beating vegetation, and collecting bulk samples of decaying plant matter.
- Additional Information
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Rowson, B. 2022. The status and distribution of Lilljeborg’s Whorl Snail Vertigo lilljeborgi at Pont Croesor on the Afon Glaslyn in 2022. NRW Evidence Report No. 649. Natural Resources Wales, Bangor
Extent
Extent
- Geographic Extent
- Wales (WLS)
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Distribution
- Format Type and Description
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Database
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- Specification
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A] Database - Welsh Invertebrate Database B] Documents - Digital versions of the contract report: Microsoft Word document; and an equivalent Adobe Portable Document Format version.
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Database
()
Quality
Data quality
- Quality Scope
- Dataset
- Lineage
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Sampling conducted by by visual search, beating vegetation, and collecting bulk samples of decaying plant matter.
Keywords
Keywords
- Type
- Theme
Citation
- Date (Publication)
- 2008-06-01
Keywords
- NRW Thesaurus
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- whorl snails
- vertigo moulinsiana
- snails
- river Glaslyn (afon Glaslyn)
- Pont Croesor
- Glaslyn
- Type
- Theme
Citation
- Date (Publication)
- 2023-12-31
Spatial Reference System
- Code
- NONE
Content
Content Information
NRW Profile
Custom Elements
Constraints
Constraints
Limitations on Public Access and Use
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Access Constraints Directive
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- no limitations
Access Constraints Text
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There are no access restrictions on this data. NRW may release, publish or disseminate it freely.
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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.
Attribution Statement
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- Open Government Licence (OGL)
Licence
- Other constraints
- Open Government Licence (OGL)
Metadata
Metadata
- File Identifier
- 4f4c4942-4343-5764-6473-313235333731 XML
- Metadata Language
- English
- Resource type
- Dataset
- Metadata Date
- 2024-05-31T09:41:00.365Z
- Metadata Standard Name
- NRW
- Metadata Standard Version
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1.0