4f4c4942-4343-5764-6473-313136353038 English NRW_DS109834 Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en 2026-03-03T12:01:38.011Z NRW 1.0 wel British National Grid (EPSG::27700) Intertidal Monitoring Pen Llyn a’r Sarnau Special Area of Conservation (SAC) 2013 Intertidal Monitoring Pen Llyn a’r Sarnau Special Area of Conservation (SAC) 2013 Monitro rhynglanwol Ardal Cadwraeth Arbennig (ACA) Pen Llŷn a’r Sarnau 2013 2016-03-31 NRW_DS116508 Pen Llyn a’r Sarnau Special Area of Conservation (SAC) is designated for its estuaries and their constituent mudflats, sandflats and reefs; large shallow inlets and bays with intertidal Zostera beds; populations of the shingle-dwelling amphipod Pectenogammarus, piddocks in intertidal clay and lower shore boulder communities and reefs, particularly the biogenic reefs of Sabellaria alveolata. These features are monitored by ASML on behalf of Natural Resources Wales (NRW), which has a statutory duty to produce advice under Regulation 35 (formerly Regulation 33) of the Habitats Regulations 1994. This dataset is a compilation of a number of intertidal research and monitoring programmes conducted in 2013. This included, intertidal surveying of the honeycomb reef worm Sabellaria alveolata at West Afon Dwyfor and Llandanwg; the surveying of the population status of Pectenogammarus populations (LGS.Pec), a scarce, shingle shore specific amphipod found near Pwllheli; sediment analyses of biotopes of the Dyfi and Glaslyn/Dwyryd estuaries were conducted, and subsequently the Glaslyn/Dwyryd infaunal samples were analysed; and finally a species list was created using fixed monitoring quadrats in the upper, mid and lower shore at Porth Oer, the results of which were compared to 2012 survey results. Pen Llyn a’r Sarnau Special Area of Conservation (SAC) is designated for its estuaries and their constituent mudflats, sandflats and reefs; large shallow inlets and bays with intertidal Zostera beds; populations of the shingle-dwelling amphipod Pectenogammarus, piddocks in intertidal clay and lower shore boulder communities and reefs, particularly the biogenic reefs of Sabellaria alveolata. These features are monitored by ASML on behalf of Natural Resources Wales (NRW), which has a statutory duty to produce advice under Regulation 35 (formerly Regulation 33) of the Habitats Regulations 1994. This dataset is a compilation of a number of intertidal research and monitoring programmes conducted in 2013. This included, intertidal surveying of the honeycomb reef worm Sabellaria alveolata at West Afon Dwyfor and Llandanwg; the surveying of the population status of Pectenogammarus populations (LGS.Pec), a scarce, shingle shore specific amphipod found near Pwllheli; sediment analyses of biotopes of the Dyfi and Glaslyn/Dwyryd estuaries were conducted, and subsequently the Glaslyn/Dwyryd infaunal samples were analysed; and finally a species list was created using fixed monitoring quadrats in the upper, mid and lower shore at Porth Oer, the results of which were compared to 2012 survey results. Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en Aquatic Survey and Monitoring Ltd (ASML) Whitfield Brow, Bollihope, Frosterley, Weardale, Co. Durham, DL13 2SZ, England tom@aquatic-environments.co.uk http://www.marineseen.com/aquatic_survey_and_monitoring.htm Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en Habitats and biotopes GEMET - INSPIRE themes, version 1.0 2008-06-01 geonetwork.thesaurus.external.theme.httpinspireeceuropaeutheme-theme marine biology (subtidal biology) (littoral biology) (sublittoral biology)(intertidal biology)(see also seashore) marine sediments (coastal sediments) (intertidal sediments) (subtidal sediments) marine ecology (intertidal ecology)(subtidal ecology) (littoral communities) (intertidal habitat)(see also seashore) Intertidal monitoring seashore (intertidal) (littoral) (see also beaches) marine wildlife (marine fauna)(marine flora)(intertidal fauna)(see also marine species,marine algae,marine mammals marine surveys (intertidal & subtidal surveys) (littoral survey) (sublittoral surveys) (bathymetric survey) (see also marine monitoring and MNCR) intertidal sabellaria spinulosa ross worm sabellaria alveolata polychaete worms honeycomb worm biotopes sediment infauna Infauna mudflats sandflats estuarine rock NRW Thesaurus 2023-12-31 geonetwork.thesaurus.local.theme.converted_nrw-keywords Habitat extent Habitat characterisation SeaDataNet Parameter Discovery Vocabulary 2021-01-06 geonetwork.thesaurus.external.theme.rdf+xml Integrated Public Sector Vocabulary 2013-04-03 geonetwork.thesaurus.external.theme.subjects NRW SMNR Vocabulary 2023-12-27 geonetwork.thesaurus.local.theme.converted_nrw-smnr-keywords There are no access restrictions on this data. NRW may release, publish or disseminate it freely. no limitations © CNC/NRW Data may be re-used under the terms of the Open Government Licence providing it is done so, acknowledging both the source and NRW's copyright. It is the recipient's responsibility to ensure the data is fit for the intended purpose. English biota SeaVoX Vertical Co-ordinate Coverages 2021-01-06 water column boundary layer; water column; unknown Irish Sea Cardigan Bay Tremadog Bay Menai Strait -4.92166202 -3.87062856 52.38079346 53.01432522 2016-08-10 2016-08-10 Mercer, T.S. 2016. Intertidal monitoring, Pen Llyn a’r Sarnau SAC August 2013. NRW Evidence Report No. 58, pp 68 + x, Aquatic Survey & Monitoring Ltd. Harehope Quarry, Co. Durham. Documents Sabellaria Quadrat Data: [A] Digital versions of the contract report: Microsoft Word document(s); and an equivalent Adobe Portable Document Format version. [B] MapInfo GIS layer in MapInfo Native format (Tables): - Position of the sample stations - Translations from the above MapInfo Tables are retained in ESRI Shapefile and MapInfo Interchange formats. [C] Excel spreadsheets with station details and species data [D] Photographs of the stations [E] Marine Recorder file Porth Oer Bedrock Data: [A] Digital versions of the contract report: Microsoft Word document(s); and an equivalent Adobe Portable Document Format version. [B] Excel spreadsheets with species data from quadrat surveys. [C] Photographs of the quadrats. [D] Marine Recorder file. Dwyryd/Glaslyn sediment Data: [A] Digital versions of the contract report: Microsoft Word document(s); and an equivalent Adobe Portable Document Format version. [B] MapInfo GIS layer in MapInfo Native format (Tables): - Position of the sample stations - Translations from the above MapInfo Tables are retained in ESRI Shapefile and MapInfo Interchange formats. [C] Excel spreadsheets with station details and species data [D] Photographs of the stations [E] Marine Recorder file Dyfi sediment data: [A] Digital versions of the contract report: Microsoft Word document(s); and an equivalent Adobe Portable Document Format version. [B] MapInfo GIS layer in MapInfo Native format (Tables): - Position of the sample stations - Translations from the above MapInfo Tables are retained in ESRI Shapefile and MapInfo Interchange formats. [C] Excel spreadsheets with station details and species data [D] Photographs of the stations [E] Marine Recorder file 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 This dataset has not been assessed for conformance to the referenced INSPIRE regulation. false A number of surveying techniques were used: - Intertidal reefs, characterised by biogenic reef formed by the honeycomb reef worm Sabellaria alveolata were surveyed at West Afon Dwyfor and Llandanwg with multiple quantitative quadrats. - Pectenogammarus populations (LGS.Pec), a scarce, shingle shore specific amphipod, was surveyed near Pwllheli and its abundance compared to previous years. - The sediment biotopes of the Dyfi & Glaslyn/Dwyryd estuaries were surveyed both qualitatively and quantitatively respectively. - The Dyfi sediment biotopes were assessed qualitatively in situ and quantitatively. - The Glaslyn/Dwyryd quantitative infaunal samples were analysed and a range of univariate community statistics were calculated. - The fixed monitoring quadrats in the upper, mid and lower shore stations at Porth Oer were surveyed and compared to 2012’s results. A species list was produced for the fixed monitoring quadrats. A number of surveying techniques were used: - Intertidal reefs, characterised by biogenic reef formed by the honeycomb reef worm Sabellaria alveolata were surveyed at West Afon Dwyfor and Llandanwg with multiple quantitative quadrats. - Pectenogammarus populations (LGS.Pec), a scarce, shingle shore specific amphipod, was surveyed near Pwllheli and its abundance compared to previous years. - The sediment biotopes of the Dyfi & Glaslyn/Dwyryd estuaries were surveyed both qualitatively and quantitatively respectively. - The Dyfi sediment biotopes were assessed qualitatively in situ and quantitatively. - The Glaslyn/Dwyryd quantitative infaunal samples were analysed and a range of univariate community statistics were calculated. - The fixed monitoring quadrats in the upper, mid and lower shore stations at Porth Oer were surveyed and compared to 2012’s results. A species list was produced for the fixed monitoring quadrats.