Non Native Species data - Distribution of Carpet Sea Squirt (Didemnum vexillum) in Holyhead Marina

Didemnum vexillum is an invasive colonial ascidian that has become established world-wide having been identified in Japan, North America, northern Europe, and New Zealand, following a global expansion since the 1970’s. It forms sheet like colonies on natural and artificial hard substrata as well as benthic organisms including other ascidians and algae. The serious ecological and economic damage experienced in New Zealand and other temperate regions has led to a large investment in on-going research into the biological tolerances and spread of D. vexillum as well as rapid response, monitoring and management following introductions. In summer 2008 an MSc student from Bangor University carrying out a survey of non native species in marinas in North Wales found a sea squirt in Holyhead Harbour that looked like the invasive non native species D. vexillum. A specimen was sent to a UK expert, who confirmed in November 2008 that it was very likely to be D. vexillum. Specimens were confirmed by Gretchen Lambert (pers. com. University of Washington, USA) as being D. vexillum. The purpose of this data capture was to assess the distribution and spread of the non-native species and possible threat to native species and biodiversity of the area.

Identification

Identifier
NRW_DS109566
Alternative Title
  • Dosbarthiad Didemnum vexillum ym Marina Caergybi
Metadata Language
English
Lineage

A rapid assessment diver survey was completed by systematically surveying each of the pontoons. Data was collected by divers and communicated to the surface where it was mapped. Presence/Absence of Didemnum vexillum was recorded. Still images and video were also taken at random locations. Specimen samples were taken at various locations on each of the pontoon for further identification and confirmation by an expert.
Dataset Reference Date (Publication)
2011-02-28
Owner
  Natural Resources Wales (NRW)
Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales
http://naturalresources.wales/?lang=en
Originator
  Countryside Council for Wales (CCW)
Countryside Council for Wales, Maes y Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW
http://naturalresourceswales.gov.uk/splash?orig=/
Originator
  University of Wales, Bangor. School of Ocean Sciences
Bangor, Gwynedd, LL57 2DG
http://www.bangor.ac.uk
Originator
  Marine Ecological Solutions Ltd
Marine Ecological Solutions Ltd, 41 High Street, Menai Bridge, Ynys Mon, LL59 5EF, Wales
http://www.marine-ecosol.co.uk
 

Extent

Extent

Geographic Extent
SIR YNYS MON - ISLE OF ANGLESEY
N
W
E
S
Map representing the geographic extent of the dataset


 

Vertical Extent

Medin Extent Keyword
benthic boundary layer

Vertical Extent

Minimum value (metres)
0
Maximum value (metres)
5.8
Vertical CRS
 
 

Distribution

Format Type and Description
  • Documents ()

    Specification

    [A] Abundance and distribution held as MapInfo Line layers. [B] Location of video, photographs and specimen samples held as MapInfo point layers. [C] Images held as digital video and digital photographs.

 

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
Degree
false
Lineage

A rapid assessment diver survey was completed by systematically surveying each of the pontoons. Data was collected by divers and communicated to the surface where it was mapped. Presence/Absence of Didemnum vexillum was recorded. Still images and video were also taken at random locations. Specimen samples were taken at various locations on each of the pontoon for further identification and confirmation by an expert.
 

Keywords

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
  • Didemnum vexillum
  • non-native species
  • sea squirt
Type
Theme

Citation

Date (Publication)
2023-12-31
Code
geonetwork.thesaurus.local.theme.converted_nrw-keywords

Keywords

SeaDataNet Parameter Discovery Vocabulary
  • Zoobenthos generic abundance
Type
Theme

Citation

Date (Revision)
2021-01-06
Code
geonetwork.thesaurus.external.theme.rdf+xml
 

Spatial Reference System

Code
British National Grid (EPSG::27700)
 

Content

Content Information

NRW Profile

Custom Elements

NRW Related Title

Survey of a non-native ascidian (sea squirt) didemnum vexillum in Holyhead harbour January 2009
 

Constraints

Constraints

Limitations on Public Access and Use

Restriction type
Other restrictions
 

Access Constraints Directive

Limitations
no limitations
 

Access Constraints Text

Other constraints

The following data is considered OS derived data and is therefore jointly owned by NRW and the Ordnance Survey. NRW may release, publish or disseminate this data freely; providing recipients are made aware of use restrictions
 

Use Constraints

Use constraints type
Other restrictions
Other constraints

© CNC/NRW and © Crown copyright [2011]. All rights reserved. Natural Resources Wales, AC0000849444 Third parties seeking to re-use this data require a Licence issued by NRW. It allows re-use, reproduction and dissemination in any format or medium but only for non-commercial purposes, according to the terms and conditions of the Licence. Those seeking commercial re-use require a commercial licence available from the OS.
 
 
 

Metadata

Metadata

File Identifier
4f4c4942-4343-5764-6473-313039353636 XML
Metadata Language
English
Resource type
Dataset
Metadata Date
2024-12-09T12:31:53.599Z
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

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