Intertidal Monitoring of Eelgrass (Zostera marina) Extent and Density in Pen Llŷn a'r Sarnau Special Area of Conservation (SAC), 2004
A survey was undertaken in 2004 to map and assess the extent and density of intertidal eelgrass (Zostera marina) beds within the Pen Llŷn a'r Sarnau Special Area of Conservation (SAC). Seagrass beds occur in intertidal and shallow subtidal areas on sandy and muddy sediments in sheltered coastal environments and are recognised for their ecological and economic importance. Zostera marina is protected under the EC Habitats Directive and is recognised as a UK Biodiversity Action Plan Priority Habitat. Seagrass meadows provide nursery areas for juvenile fish, feeding grounds for wildfowl including Brent geese, and contribute to sediment stabilisation, coastal defence and erosion reduction.
The purpose of the survey was to map the current known intertidal extent of the Zostera biotope and develop a methodology for assessing seagrass density. The survey established a baseline dataset describing the distribution and density of eelgrass beds within the SAC, supporting future monitoring of their conservation status and vulnerability to human pressures such as pollution, dredging and boat moorings.
- Identification
- Extent
- Distribution
- Quality
- Keywords
- Spatial Reference System
- Content
- Constraints
- Maintenance
- Metadata
Identification
- Identifier
- NRW_DS102010
- Alternative Title
-
- 2004 CCW / IECS Pen Llyn a'r Sarnau SAC Zostera marina monitoring (MRCCW3020000000D)
- Metadata Language
- English
- Lineage
-
Under the Habitats Directive, CCW is required to assess the conservation status of SAC features on a regular basis. Zostera marina beds had previously been mapped during the intertidal Phase 1 survey undertaken in 1997, and the Institute of Estuarine and Coastal Studies (IECS) was contracted by CCW to undertake follow-up monitoring.
The extent of eelgrass beds was mapped on foot by walking the perimeter of the biotope and recording boundary positions using a portable differential GPS system. Representative photographs were taken throughout the survey. Seagrass density was assessed using twelve randomly selected sampling stations, each covering 0.07 m². At each station, the number of blades/leaves present was counted and used to calculate blade density per square metre. Differential GPS positions were recorded for every sampling location. The resulting dataset provides a baseline measure of eelgrass extent and density for future monitoring and condition assessment.
- Additional Information
-
Boyes, Hemingway, Allen (2008) Intertidal monitoring of Zostera marina in Pen Llyn a'r Sarnau SAC in 2004/2005. CCW Marine Monitoring Report No 28.
- Dataset Reference Date (Publication)
- 2008-12-31
Temporal Extent
- Begin date
- 2004-07-06
- End date
- 2005-08-07
- Topic category
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- Biota
))
Distribution
- Format Type and Description
-
-
Database
(
Marine Recorder Online - Version 2.09.02
)
- Specification
-
Marine Recorder
-
Database
(
Marine Recorder Online - Version 2.09.02
)
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
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This dataset has not been assessed for conformance to the referenced INSPIRE regulation.
- Degree
- false
- Lineage
-
Under the Habitats Directive, CCW is required to assess the conservation status of SAC features on a regular basis. Zostera marina beds had previously been mapped during the intertidal Phase 1 survey undertaken in 1997, and the Institute of Estuarine and Coastal Studies (IECS) was contracted by CCW to undertake follow-up monitoring.
The extent of eelgrass beds was mapped on foot by walking the perimeter of the biotope and recording boundary positions using a portable differential GPS system. Representative photographs were taken throughout the survey. Seagrass density was assessed using twelve randomly selected sampling stations, each covering 0.07 m². At each station, the number of blades/leaves present was counted and used to calculate blade density per square metre. Differential GPS positions were recorded for every sampling location. The resulting dataset provides a baseline measure of eelgrass extent and density for future monitoring and condition assessment.
Keywords
Keywords
- Type
- Theme
Citation
- Date (Publication)
- 2008-06-01
Keywords
-
NRW Thesaurus
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- Pen Llyn a'r Sarnau SAC
- Marine Recorder
- Zostera bed, extent quadrats
- Type
- Theme
Citation
- Date (Publication)
- 2026-08-27
Keywords
- Type
- Theme
Citation
- Date (Publication)
- 2024-06-19
Spatial Reference System
- Code
- WGS 84 (EPSG:4326)
Content
Content Information
NRW Profile
Custom Elements
- NRW Related Title
-
Intertidal Monitoring of Zostera marina in Pen Llyn a'r Sarnau SAC in 2004/2005
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 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
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Contains Natural Resources Wales information © Natural Resources Wales and Database Right. All rights Reserved.
Licence
- Other constraints
- Open Government Licence
Metadata
Metadata
- File Identifier
- 4f4c4942-4343-5764-6473-313032303130 XML
- Metadata Language
- English
- Parent Identifier
-
Across Wales Intertidal Monitoring Survey
NRW_DS109834
- Resource type
- Dataset
- Metadata Date
- 2026-10-19T08:04:14.449Z
- Metadata Standard Name
- NRW
- Metadata Standard Version
-
1.0