Monitoring of Carbonate Reef Extent and Fish Population at Holden's Reef (2003 - 2010)
Holden's Reef is a small (approximately 40 m diameter), roughly circular reef situated in the northern sector of Cardigan Bay. It is unusual in being formed as a result of a chemical reaction between seawater and the escape of natural gas from the seabed, a phenomenon generally found in much deeper waters. Holden's Reef is one of an assemblage of methanogen-precipitated calcium carbonate reefs and was the first of the group to be discovered. This dataset contains the results of a programme of monitoring established to study fish populations and reef extent. It also includes data from an in-house survey carried out at Holden's Reef in 2003, initiated following the reef's discovery, and Marine Nature Conservation Review (MNCR) phase 2 surveys carried out in 2005 of \Little\" and \"Big\" Reef. Holden's Reef is monitored for fish abundance and diversity extent and rugosity (the link between rugosity and fish abundance has been seen in several studies). This will contribute to condition assessment of the reef feature in the Pen Llyn a'r Sarnau Special Area of Conservation (SAC). Holden's Reef is situated more than 10 km off shore north west of Barmouth and is approximately 40 m in diameter. "
- Identification
- Extent
- Distribution
- Quality
- Keywords
- Spatial Reference System
- Content
- Constraints
- Maintenance
- Metadata
Identification
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DynodyddIdentifier
- NRW_DS110926
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Teitl AmgenAlternative Title
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- 2003 CCW Holden's Reef initial survey MRCCW30000000030
- 2005 CCW/Pelagial/Sea-Scope Holden's Reef, Pen Llyn a'r Sarnau sublittoral survey MRCCW3010000000D
- Monitro poblogaeth y pysgod a maint y riff carbonad yn Riff Holden
- Carbonate reef extent and rugosity, Holden's Reef
- Fish abundance and diversity at Holden's Reef
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Laith MetadataMetadata Language
- English
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Lineage
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A site marker (a single road pin) has been established at the centre of the reef in its shallowest part. An additional marker is located due north from the centre at the edge of the reef. The extent of the reef is measured by divers who swim along a bearing from the central marker to the edge of the reef and the distance recorded. The distance from the centre to the edge of the reef is measured at 12 bearings 30 degrees apart. The rugosity of the reef is measured by splitting the reef into an inner and outer zone radiating from the central marker. The distance between the centre and zone boundary is measured using a taut tape measure. This distance is then repeated allowing the tape measure to rest along the contours if the reef. The rugosity is determined to be the ratio between the two measurements. Fish abundance and diversity is measured by a pair of divers undertaking 3 consecutive timed counts of 5 minute duration. These counts take place in up to 4 zones that represent different topography and depths on the reef. To aid recording slates are pre-marked with species likely to be observed.
- Additional Information
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Detailed methodologies in use at Holden's Reef can be found in Marine Monitoring Report 25b (standard operating procedures 11 12 and 13)
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Dyddiad cyfeirnod y set ddata (Cyhoeddiad)Dataset Reference Date (Publication)
- 2010-12-31
Extent
Extent
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HydGeographic Extent
- Irish Sea
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HydGeographic Extent
- Cardigan Bay
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HydGeographic Extent
- Tremadog Bay
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HydGeographic Extent
- GWYNEDD - GWYNEDD
))
Vertical Extent
- Medin Extent Keyword
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water column; benthic boundary layer
Maint Fertigol
Vertical Extent
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Gwerth lleiafMinimum value (metres)
- -6.2
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Gwerth uchafMaximum value (metres)
- -9.5
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System Gyfeirio Cydlynu FertigolVertical CRS
Distribution
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Fformat - Math a DisgrifiadFormat Type and Description
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Database
()
- Specification
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[A] Reports in word and pdf format. [B] Species and Abundance data available as excel spreadsheets and formatted for PRIMER. [C] Extent of reef available as MapInfo TAB files. [D] Transect length used to measure extent and rugosity values available as excel spreadsheet. [E] Incidental video available as mini dv tapes, incidental images available as JPGs. Survey data from initial survey in 2003 and phase 2 surveys in 2005 are on Marine Recorder (MRCCW30000000030, MRCCW3010000000D)
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Database
()
Quality
Ansawdd Data
Data quality
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Cwmpas AnsawddQuality Scope
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DatasetDataset
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CydymffurfiadConformity
- 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
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A site marker (a single road pin) has been established at the centre of the reef in its shallowest part. An additional marker is located due north from the centre at the edge of the reef. The extent of the reef is measured by divers who swim along a bearing from the central marker to the edge of the reef and the distance recorded. The distance from the centre to the edge of the reef is measured at 12 bearings 30 degrees apart. The rugosity of the reef is measured by splitting the reef into an inner and outer zone radiating from the central marker. The distance between the centre and zone boundary is measured using a taut tape measure. This distance is then repeated allowing the tape measure to rest along the contours if the reef. The rugosity is determined to be the ratio between the two measurements. Fish abundance and diversity is measured by a pair of divers undertaking 3 consecutive timed counts of 5 minute duration. These counts take place in up to 4 zones that represent different topography and depths on the reef. To aid recording slates are pre-marked with species likely to be observed.
Keywords
Allweddair
Keywords
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MathType
-
ThemeTheme
Dyfyniad
Citation
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Dyddiad (Cyhoeddiad)Date (Publication)
- 2008-06-01
Allweddair
Keywords
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NRW Thesaurus
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- marine monitoring (see also marine surveys)
- Special Area of Conservation Monitoring
- Pen Llyn a'r Sarnau cSAC
- Holden's Reef
- fish ecology
- methane
- carbonate reef
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MathType
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ThemeTheme
Dyfyniad
Citation
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Dyddiad (Cyhoeddiad)Date (Publication)
- 2023-12-31
Allweddair
Keywords
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SeaDataNet Parameter Discovery Vocabulary
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- Fish abundance in water bodies
- Fish taxonomy-related counts
- Habitat characterisation
- Habitat extent
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MathType
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ThemeTheme
Dyfyniad
Citation
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Dyddiad (Adolygu)Date (Revision)
- 2021-01-06
Spatial Reference System
Content
Gwybodaeth Cynnwys
Content Information
Proffil CNC
NRW Profile
Elfennau CNC
Custom Elements
Constraints
Constraints
Limitations on Public Access and Use
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Math o GyfyngiadRestriction type
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Other restrictionsOther restrictions
Access Constraints Directive
- Limitations
- no limitations
Access Constraints Text
- Other constraints
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There are no access restrictions to this data. NRW may release, publish or disseminate it freely.
Use Constraints
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Cyfyngiadau DefnyddioUse constraints type
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Other restrictionsOther restrictions
- Other constraints
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© CNC/NRW 2010. 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
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Dynodydd FfeilFile Identifier
- 4f4c4942-4343-5764-6473-313130393236 XML
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Laith MetadataMetadata Language
- English
- Parent Identifier
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Natural Resources Wales (NRW) Marine Benthic Species and Habitat Collation Held in Marine Recorder
NRW_DS114501
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Math o adnoddResource type
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DatasetDataset
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Dyddiad MetadataMetadata Date
- 2024-05-31T09:41:20.848Z
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Enw Safonol MetadataMetadata Standard Name
- NRW
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Fersiwn MetadataMetadata Standard Version
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1.0