Monitoring the Health of the North Llyn Modiolus Reef

Modiolus Reefs are a feature of the Pen Llyn a'r Sarnau Special Area of Conservation (SAC). Information is gathered about the health of the reef through the recording of species present in fixed quadrats. Live horse mussels are hard to distinguish within the quadrat, however it is known that each live horse mussel supports one colony of the soft coral dead man's fingers Alcyonium digitatum and therefore these are used to count the number of live horse mussels present. This survey work is carried out as part of the Across Wales Diving Survey. The purpose of this data capture was to investigate the health of the reef. This contributes to reporting of favourable conservation status of the SAC feature. Data will be used in conjunction with acoustic data that looks at the extent of the feature (reef) and potential areas of damage.

Identifier: NRW_DS110271

Alternative Title

Monitro iechyd Riff Modiolus Gogledd Llyn
Quadrat monitoring of the North Llyn horse mussel Modiolus modiolus reef

Metadata Language: English

Lineage: Based on the monitoring trials see Marine Monitoring Report no. 1. Two sites were set up on the N. Llyn reef in order to monitor the health of the reef. An additional site is monitored on the Isle of Man as a comparison. In 2009 several sites of good condition were identified from multibeam and side-scan sonar images for possible additional monitoring. At these sites stratified random sampling is to be undertaken rather then marking permanent quadrats.At each of the original 2 sites on the Llyn permanent markers are in place that are used to position 0.5m by 0.5m quadrats. At each site 15 quadrats are placed on the crest of a Modiolus bioherm. Each quadrat is split into 25 cells of 100x100mm. The quadrat is filmed along each row from left to right using an underwater digital camera that stores footage on mini DV tapes. Detailed information about the setting up of the sites and standard operating procedures can be found in 'CCW Marine Monitoring Report 25b (draft): SOP 3'. Still images are extracted from the video processed and stitched into a mosaic. Live horse mussels are counted using the presence of Alcyonium digitatum as an indicator. Prior to analysis the quadrats are randomised to reduce any bias from the recorder. In addition to counting the presence of horse mussels trends in other easily recognizable species can be recorded to provide additional information about the quality and health of the reef. Other species recorded are live horse mussels common starfish Asterias rubens common brittlestar Ophiothrix fragilis sea urchin Psammechinus miliaris.

Additional Information: .

Dataset Reference Date (Publication): 2009-12-31

Temporal Extent

Begin date: 1999-01-01

End date: 2009-12-31

Topic category

Biota

Owner

Natural Resources Wales (NRW)

Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales

http://naturalresources.wales/?lang=en

Originator

CCW Marine Monitoring Team

Countryside Council for Wales, Maes y Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW

http://naturalresourceswales.gov.uk/splash?orig=/

Extent

Geographic Extent: Irish Sea

Geographic Extent: Cardigan Bay

Geographic Extent: Tremadog Bay

Geographic Extent: GWYNEDD - GWYNEDD

Map representing the geographic extent of the dataset

Vertical Extent

Medin Extent Keyword: benthic boundary layer

Vertical Extent

Minimum value (metres): -30

Maximum value (metres): -35

Vertical CRS

Format Type and Description

Documents ()

Specification

[A] Stitched mosaic images as TIFF files, video footage as mini DV tapes. [B] Analysed data in excel spreadsheet. [C] Summary of the data is held within Word Documents. [D] Photographs of quadrats held as .jpeg files.

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
Degree: false

Lineage: Based on the monitoring trials see Marine Monitoring Report no. 1. Two sites were set up on the N. Llyn reef in order to monitor the health of the reef. An additional site is monitored on the Isle of Man as a comparison. In 2009 several sites of good condition were identified from multibeam and side-scan sonar images for possible additional monitoring. At these sites stratified random sampling is to be undertaken rather then marking permanent quadrats.At each of the original 2 sites on the Llyn permanent markers are in place that are used to position 0.5m by 0.5m quadrats. At each site 15 quadrats are placed on the crest of a Modiolus bioherm. Each quadrat is split into 25 cells of 100x100mm. The quadrat is filmed along each row from left to right using an underwater digital camera that stores footage on mini DV tapes. Detailed information about the setting up of the sites and standard operating procedures can be found in 'CCW Marine Monitoring Report 25b (draft): SOP 3'. Still images are extracted from the video processed and stitched into a mosaic. Live horse mussels are counted using the presence of Alcyonium digitatum as an indicator. Prior to analysis the quadrats are randomised to reduce any bias from the recorder. In addition to counting the presence of horse mussels trends in other easily recognizable species can be recorded to provide additional information about the quality and health of the reef. Other species recorded are live horse mussels common starfish Asterias rubens common brittlestar Ophiothrix fragilis sea urchin Psammechinus miliaris.

Keywords

GEMET - INSPIRE themes, version 1.0

Type: Theme

Citation

Date (Publication): 2008-06-01

Code: geonetwork.thesaurus.external.theme.httpinspireeceuropaeutheme-theme

Keywords

NRW Thesaurus

marine monitoring (see also marine surveys)
Pen Llyn a'r Sarnau cSAC
modiolus modiolus
horse mussel
biogenic reef
reef
quadrats

Type: Theme

Citation

Date (Publication): 2023-12-31

Code: geonetwork.thesaurus.local.theme.converted_nrw-keywords

Keywords

SeaDataNet Parameter Discovery Vocabulary

Habitat characterisation

Type: Theme

Citation

Date (Revision): 2021-01-06

Code: geonetwork.thesaurus.external.theme.rdf+xml

Code: Latitude and Longitude (EPSG::4326)

Content Information

NRW Profile

Custom Elements

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

File Identifier: 4f4c4942-4343-5764-6473-313130323731 XML

Metadata Language: English

Parent Identifier: Across Wales Diving Monitoring Project (2004)
NRW_DS109743

Resource type: Dataset

Metadata Date: 2024-12-09T12:40:06.848Z

Metadata Standard Name: NRW

Metadata Standard Version: 1.0

pointOfContact

Natural Resources Wales (NRW)

Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales

http://naturalresources.wales/?lang=en

Publishing Body

Access the portal

Full access to the portal and metadata.

Monitoring the Health of the North Llyn Modiolus Reef

Identification

Temporal Extent

Extent

Extent

Vertical Extent

Vertical Extent

Distribution

Quality

Data quality

Keywords

Keywords

Citation

Keywords

Citation

Keywords

Citation

Spatial Reference System

Content

Content Information

NRW Profile

Custom Elements

Constraints

Constraints

Limitations on Public Access and Use

Access Constraints Directive

Access Constraints Text

Use Constraints

Metadata

Metadata

Publishing Body