Modelling the Predicted Spread of a Carpet Sea Squirt ( Didemnum vexillum ) around the Welsh Coast (2011)
Didemnum vexillum is an invasive sea squirt that is not native to UK shores. It was first detected in Europe in 1991 and has since spread to several countries (including France, Ireland and the UK). The species has been located in Wales, Scotland and England and there is concern D. vexillum may have negative impacts on biodiversity and shellfish interests.
Predicting the spread of an invasive species is crucial when assessing possible management actions. The potential impacts of the species on both biodiversity and commercial interests need to be studied and a cost-benefit approach taken to decide on the best course of management for that species.
Geographic Information System (GIS) offers a fast, efficient way to map this predicted spread. The results of this mapping can then be used to focus on areas where D. vexillum may conflict with conservation and commercial interests.
- Identification
- Extent
- Distribution
- Quality
- Keywords
- Spatial Reference System
- Content
- Constraints
- Maintenance
- Metadata
Identification
- Identifier
- NRW_DS113445
- Metadata Language
- English
- Lineage
-
Countryside Council for Wales (CCW) has been investigating and controlling the spread of D. vexillum in Holyhead Marina since 2009. For this project, all the GIS spatial processing was carried out in ArcMAP 9.3 and used the ArcMAP toolbox along with Hawth's Tools and ET Geowizzards toolboxes. Data was used from 2009 - 2011 and a predictability model used which may have some limitations. In order to predict the potential spread of D. vexillum a simple modelling approach can be used, which uses the species biological limits and current known populations to estimate the positions of future colonies. Whilst this approach quickly produces results, it is limited as the model is not quantitative and can not be adequately tested.
- Dataset Reference Date (Publication)
- 2011-01-28
Extent
Extent
- Geographic Extent
- United Kingdom (UKM)
- Geographic Extent
- Wales (WLS)
))
Vertical Extent
- Medin Extent Keyword
- water column
Vertical Extent
- Minimum value (metres)
- -30
- Maximum value (metres)
- 0
- Vertical CRS
Distribution
Distribution
- Format Type and Description
-
-
Documents
(
)
- Specification
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[A] Summary report (electronic version - MS Word)
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Geographic Information System
(
)
- Specification
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[B] Map of locations of known presence of D.Vexillum (MapInfo table).
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Documents
(
)
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
-
Countryside Council for Wales (CCW) has been investigating and controlling the spread of D. vexillum in Holyhead Marina since 2009. For this project, all the GIS spatial processing was carried out in ArcMAP 9.3 and used the ArcMAP toolbox along with Hawth's Tools and ET Geowizzards toolboxes. Data was used from 2009 - 2011 and a predictability model used which may have some limitations. In order to predict the potential spread of D. vexillum a simple modelling approach can be used, which uses the species biological limits and current known populations to estimate the positions of future colonies. Whilst this approach quickly produces results, it is limited as the model is not quantitative and can not be adequately tested.
Keywords
Keywords
- Type
- Theme
Citation
- Date (Publication)
- 2008-06-01
Keywords
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NRW Thesaurus
-
- WALES
- non-native species
- Holyhead
- invasive species (alien species)
- colonial sea squirt
- Didemnum vexillum
- ascidians
- marinas and marine docks
- sea squirt
- Type
- Theme
Citation
- Date (Publication)
- 2025-01-08
Keywords
-
SeaDataNet Parameter Discovery Vocabulary
- Type
- Theme
Citation
- Date (Publication)
- 2024-06-19
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 to this data. NRW may release, publish or disseminate it freely.
Use Constraints
- Use constraints type
- Other restrictions
- Other constraints
-
© CNC/NRW 2011 There are no use restrictions on this data. Recipients may re-use, reproduce, disseminate this data free of charge in any format or medium, provided they do so accurately, acknowledging both the source and NRW's copyright, and do not use it in a misleading context. It is the recipient's responsibility to ensure the data is fit for the intended purpose, that dissemination or publishing does not result in duplication, and that it is fairly interpreted. Advice on interpretation should be sought where required. To avoid re-using old data, users should periodically obtain the latest version from the original source.
Metadata
Metadata
- File Identifier
- 4f4c4942-4343-5764-6473-313133343435 XML
- Metadata Language
- English
- Resource type
- Dataset
- Metadata Date
- 2026-03-03T16:06:50.645Z
- Metadata Standard Name
- NRW
- Metadata Standard Version
-
1.0