Volunteer Diver Seagrass Zostera marina Surveys, Llyn Peninsula and Milford Haven (2008)
Arolygon gan ddeifars gwirfoddol ar wellt y gamlas Zostera marina, Pen Llyn ac Aberdaugleddau

  • English
  • wel
  • All

In areas where conditions are suitable seagrass beds form and these are considered nationally important in the UK. Seagrasses are thought to help stabilising the seabed in addition to providing organic matter, shelter and food for a variety of fish, birds and invertebrates. Seagrass beds are vital nursery grounds for flatfish, and in some areas also for cephalopods. They are also known to be sensitive to changes in water quality and human disturbance. Seagrass beds have been designated as a UK Biodiversity Action Plan Habitat (underpinned by the Convention of Biological Diversity, Rio Earth Summit 1992), and as a Habitat of Principal Importance for the Conservation of Biological Diversity in Wales (NERC Act 2006: Section 42). The survey was due to be expanded in 2009 to other areas within the Pen Llyn a'r Sarnau Special Area of Conservation (SAC) and methodologies refined. 1. Develop methods to look at damage to seagrass beds caused by anchor chains compared to permanent moorings. 2. 'Ground-truth' aerial photographs of Porth Dinllaen and Milford Haven subtidal seagrass beds. 3. Test methods of measuring extent of large seagrass beds using volunteers. 4. Estimate density and measure depth of live seagrass in different parts of the bed. 5. Make note of any unusual feature of the seagrass bed.

Identification

Dynodydd
Identifier
NRW_DS110284
Teitl Amgen
Alternative Title
  • 2008 Seasearch Survey of the Entrances of Milford Haven, Pembrokeshire, Wales MRMCS01200000011
  • Seagrass surveys in Porth Dinllaen and the Milford Haven
Laith Metadata
Metadata Language
English
Lineage

Data is captured by using Volunteer divers who are CMAS 2 star qualified or equivalent with a minimum of 60 dives each. Anchor and density of seagrass shoots are captured by placing quadrats at 5 m intervals along a series of transects that are laid from the centre of the anchor point or seagrass bed. Transects are carried out in a north, south, west and east direction and where time allows also on NE, SW, NW and SE bearings. The number of shoots is counted in each 30 by 30 cm quadrat. In addition the condition of shoot and presence of seeds, black spot disease, snake pipefish and Sargassum muticum (and other non-native species), all of which are believed to be good indicators of the condition of the seagrass bed were recorded. The extent of the beds was also ground-truthed from aerial photographs. Areas (polygons) of suspected seagrass habitats were identified from the photos. An acoustic marker was deployed to the centroid of the polygon, divers were then deployed to the suspected outer edge of the seagrass bed and swam to the acoustic marker using a hand held acoustic homing device. Divers recorded where seagrass started and stopped, changed in seabed types, distance, depth and bearing. The method was repeated until all 8 cardinal points of the compass were complete (time allowing). Methods were tested at Porth Dinllaen as well as measures of extent, density and damaged from anchoring, whereas work in the Milford Haven concentrated on confirming the existence of seagrass beds and their deepest extent. All work carried out contributed to reporting on the features Favourable Conservation Status.
Dyddiad cyfeirnod y set ddata (Cyhoeddiad)
Dataset Reference Date (Publication)
2008-12-31

Temporal Extent

Begin date
2008-06-14
End date
2008-09-12
 
Categori pwnc
Topic category
  • Biota
    Biota
Perchennog
Owner
  Natural Resources Wales (NRW) -
Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales
http://naturalresources.wales/?lang=en
Perchennog
Owner
  Marine Conservation Society (MCS) -
Unit 3,Wolf Business Park,, Alton Road, Ross-on-Wye, Herefordshire, HR9 5NB
http://www.mcsuk.org/
Cychwynnwr
Originator
  CCW Marine Monitoring Team -
Countryside Council for Wales, Maes y Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW
http://naturalresourceswales.gov.uk/splash?orig=/
Cychwynnwr
Originator
  Sea-Search Volunteers -
Sea-Search c/o Marine Conservation Society, Unit 3 Wolf Business Park, Alton Road, Ross-on-Wye, Herefordshire, HR9 5NB
http://www.seasearch.co.uk
 

Extent

Extent

Hyd
Geographic Extent
GWYNEDD - GWYNEDD
Hyd
Geographic Extent
SIR BENFRO - PEMBROKESHIRE
N
W
E
S
Map representing the geographic extent of the dataset


 

Vertical Extent

Medin Extent Keyword

benthic boundary layer

Maint Fertigol
Vertical Extent

Gwerth lleiaf
Minimum value (metres)
1.28
Gwerth uchaf
Maximum value (metres)
-5.6
System Gyfeirio Cydlynu Fertigol
Vertical CRS
 
 

Distribution

Fformat - Math a Disgrifiad
Format Type and Description
  • Documents ( )

    Specification

    [A] Transects, density data and anchor data are MapInfo TAB files. [B] Species data held in excel spreadsheets. [C] Seasearch data held in Marine Recorder MRMCS01200000011. [D] Images as JPGs [E] Interim report as word and PDF file.

 

Quality

Ansawdd Data
Data quality

Cwmpas Ansawdd
Quality Scope
Dataset
Dataset
Cydymffurfiad
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

Data is captured by using Volunteer divers who are CMAS 2 star qualified or equivalent with a minimum of 60 dives each. Anchor and density of seagrass shoots are captured by placing quadrats at 5 m intervals along a series of transects that are laid from the centre of the anchor point or seagrass bed. Transects are carried out in a north, south, west and east direction and where time allows also on NE, SW, NW and SE bearings. The number of shoots is counted in each 30 by 30 cm quadrat. In addition the condition of shoot and presence of seeds, black spot disease, snake pipefish and Sargassum muticum (and other non-native species), all of which are believed to be good indicators of the condition of the seagrass bed were recorded. The extent of the beds was also ground-truthed from aerial photographs. Areas (polygons) of suspected seagrass habitats were identified from the photos. An acoustic marker was deployed to the centroid of the polygon, divers were then deployed to the suspected outer edge of the seagrass bed and swam to the acoustic marker using a hand held acoustic homing device. Divers recorded where seagrass started and stopped, changed in seabed types, distance, depth and bearing. The method was repeated until all 8 cardinal points of the compass were complete (time allowing). Methods were tested at Porth Dinllaen as well as measures of extent, density and damaged from anchoring, whereas work in the Milford Haven concentrated on confirming the existence of seagrass beds and their deepest extent. All work carried out contributed to reporting on the features Favourable Conservation Status.
 

Keywords

Allweddair
Keywords

GEMET - INSPIRE themes, version 1.0
Math
Type
Theme
Theme

Dyfyniad
Citation

Dyddiad (Cyhoeddiad)
Date (Publication)
2008-06-01
Code
geonetwork.thesaurus.external.theme.httpinspireeceuropaeutheme-theme

Allweddair
Keywords

NRW Thesaurus
  • anchor damage
  • Pen Llyn a'r Sarnau cSAC
  • Pembrokeshire Marine SAC
  • Milford Haven
  • eelgrass
  • Porth Dinllaen
  • zostera marina
Math
Type
Theme
Theme

Dyfyniad
Citation

Dyddiad (Cyhoeddiad)
Date (Publication)
2026-08-27
Code
geonetwork.thesaurus.local.theme.converted_nrw-keywords

Allweddair
Keywords

SeaDataNet Parameter Discovery Vocabulary
Math
Type
Theme
Theme

Dyfyniad
Citation

Dyddiad (Cyhoeddiad)
Date (Publication)
2024-06-19
Code
geonetwork.thesaurus.external.theme.rdf+xml

Allweddair
Keywords

IPSV Subjects List
  • Volunteers
Math
Type
Theme
Theme

Dyfyniad
Citation

Dyddiad (Cyhoeddiad)
Date (Publication)
2020-11-18
Code
geonetwork.thesaurus.external.theme.subjects
 

Spatial Reference System

Code
Latitude and Longitude (EPSG::4326)
 

Content

Gwybodaeth Cynnwys
Content Information

Proffil CNC
NRW Profile

Elfennau CNC
Custom Elements

 

Constraints

Constraints

Limitations on Public Access and Use

Math o Gyfyngiad
Restriction type
Other restrictions
Other restrictions
 

Access Constraints Directive

Limitations
no limitations
 

Access Constraints Text

Other constraints

This data is jointly owned by NRW and Marine Conservation Society. In addition to this the following data is also considered OS derived data and is therefore jointly owned by NRW and the Ordnance Survey. There are no access restrictions on this data. However there are third party use restrictions. There are no access restrictions to this data. NRW may release, publish or disseminate it freely.
 

Use Constraints

Cyfyngiadau Defnyddio
Use constraints type
Other restrictions
Other restrictions
Other constraints

© CNC/NRW and Marine Conservation Society © Crown copyright. All rights reserved. Natural Resources Wales, AC0000849444 Data may be re-used under provision and in line with the terms of a NRW licence. Those seeking commercial re-use require a commercial licence available from the OS.
 
 
 

Metadata

Metadata

Dynodydd Ffeil
File Identifier
4f4c4942-4343-5764-6473-313130323834 XML
Laith Metadata
Metadata Language
English
Parent Identifier
Across Wales Diving Monitoring Project (2004)

NRW_DS109743
Math o adnodd
Resource type
Dataset
Dataset
Dyddiad Metadata
Metadata Date
2026-09-28T13:50:40.702Z
Enw Safonol Metadata
Metadata Standard Name
NRW
Fersiwn Metadata
Metadata Standard Version

1.0

Pwynt Cyswllt
pointOfContact
  Natural Resources Wales (NRW) -
Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales
http://naturalresources.wales/?lang=en
 
 

Publishing Body

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