NRW_DS109566 eng dataset Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en pointOfContact 2026-03-03T12:40:45 MEDIN 3.1.2 wel eng utf8 British National Grid (EPSG::27700) Non Native Species data - Distribution of Carpet Sea Squirt (Didemnum vexillum) in Holyhead Marina Non Native Species data - Distribution of Carpet Sea Squirt (Didemnum vexillum) in Holyhead Marina Dosbarthiad Didemnum vexillum ym Marina Caergybi 2011-02-28 publication 4f4c4942-4343-5764-6473-313039353636 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. 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. Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en owner Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en custodian Countryside Council for Wales (CCW) Countryside Council for Wales, Maes y Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW enquiries@naturalresourceswales.gov.uk http://naturalresourceswales.gov.uk/splash?orig=/ originator University of Wales, Bangor. School of Ocean Sciences Bangor, Gwynedd, LL57 2DG oss011@bangor.ac.uk http://www.bangor.ac.uk originator Marine Ecological Solutions Ltd Marine Ecological Solutions Ltd, 41 High Street, Menai Bridge, Ynys Mon, LL59 5EF, Wales info@marine-ecosol.com http://www.marine-ecosol.co.uk originator Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en distributor notPlanned Species distribution theme GEMET - INSPIRE themes, version 1.0 2008-06-01 publication geonetwork.thesaurus.external.theme.httpinspireeceuropaeutheme-theme Didemnum vexillum non-native species sea squirt theme NRW Thesaurus 2025-01-08 publication geonetwork.thesaurus.local.theme.converted_nrw-keywords Zoobenthos generic abundance theme SeaDataNet Parameter Discovery Vocabulary 2024-06-19 publication geonetwork.thesaurus.external.theme.rdf+xml otherRestrictions 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 no limitations otherRestrictions © 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. Contains Natural Resources Wales information © Natural Resources Wales and Database Right. All rights Reserved. Contains Ordnance Survey Data. Ordnance Survey Licence number AC0000849444. Crown Copyright and Database Right. vector eng utf8 biota NRW Geographic Identifiers Collection 2024-01-01 publication SIR YNYS MON - ISLE OF ANGLESEY -4.64356281 -4.63994764 53.31891361 53.32214656 SeaVoX Vertical Co-ordinate Coverages 2013-02-05 creation benthic boundary layer 2008-12-09 2008-12-10 0 5.8 Geographic Information System Abundance and distribution held as MapInfo Line layers and Location of video, photographs and specimen samples held as MapInfo point layers. Image Images held as digital video and digital photographs. dataset 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 2010-12-08 publication This dataset has not been assessed for conformance to the referenced INSPIRE regulation. false 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. 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.