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. "

Identifier: NRW_DS110926

Alternative Title

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

Metadata Language: English

Lineage: 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: Detailed methodologies in use at Holden's Reef can be found in Marine Monitoring Report 25b (standard operating procedures 11 12 and 13)

Dataset Reference Date (Publication): 2010-12-31

Temporal Extent

Begin date: 2004-05-18

End date: 2010-12-31

Topic category

Oceans
Biota

Owner

Natural Resources Wales (NRW)

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

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

Originator

Various contractors

See Natural Resources Wales, Maes y Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales

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

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: water column; benthic boundary layer

Vertical Extent

Minimum value (metres): -6.2

Maximum value (metres): -9.5

Vertical CRS

Format Type and Description

Database ()

Specification

[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)

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: 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

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)
Special Area of Conservation Monitoring
Pen Llyn a'r Sarnau cSAC
Holden's Reef
fish ecology
methane
carbonate reef

Type: Theme

Citation

Date (Publication): 2023-12-31

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

Keywords

SeaDataNet Parameter Discovery Vocabulary

Fish abundance in water bodies
Fish taxonomy-related counts
Habitat characterisation
Habitat extent

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 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

File Identifier: 4f4c4942-4343-5764-6473-313130393236 XML

Metadata Language: English

Parent Identifier: Natural Resources Wales (NRW) Marine Benthic Species and Habitat Collation Held in Marine Recorder
NRW_DS114501

Resource type: Dataset

Metadata Date: 2024-05-31T09:41:20.848Z

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 of Carbonate Reef Extent and Fish Population at Holden's Reef (2003 - 2010)

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