4f4c4942-4343-5764-6473-313134373533 English NRW_DS114501 Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en 2026-10-26T11:10:26.848Z NRW 1.0 wel utf8 Latitude and Longitude (EPSG::4326) (Draft) Monitoring of a Maerl Bed in the Milford Haven Waterway, Pembrokeshire 2010 (Draft) Monitoring of a Maerl Bed in the Milford Haven Waterway, Pembrokeshire 2010 (Drafft) Monitro Gwely Marl yn nyfrffordd Aberdaugleddau, Sir Benfro, 2010 2010 DRAFT CCW Monitoring of a Maerl Bed in the Milford Haven Waterway, Pembrokeshire, 2010 (MRCCW31200000003) 2011-12-01 NRW_DS114753 http://naturalresources.wales/ Maerl is a collective term for several species of red seaweed, with hard, chalky skeletons. It is rock hard and, unlike other seaweeds, it grows as unattached rounded nodules or short, branched shapes on the seabed. Like all seaweeds, maerl needs sunlight to grow, and it only occurs to a depth of about 20 m. Maerl can form large beds, when the conditions are right – a fast tidal flow or sufficient wave action to remove fine sediments, but not strong enough to break the brittle maerl branches. Within these beds, layers of dead maerl build up with a thin layer of pink, living maerl on the top. Maerl beds are classed as a UK Biodiversity Action Plan (BAP) priority habitat, listed under the Annex 1 of the Habitats Directive, is on the list of OSPAR's List of Threatened and/or Declining Species and Habitats (Region 3 - Celtic Sea), and the habitat supports a number of UKBAP priority species, and species of principal important for the purpose of conservation of biodiversity under the Natural Environment and Rural Communities Act 2006. This data contains the results of a monitoring exercise undertaken to assess the status of the maerl bed in the Haven for the reporting purposes, and also to compare with baseline data gathered in 2005 to identify any trends. The information contributes to UK BAP monitoring and reporting obligations and to the management of the Pembrokeshire Marine Special Area of Conservation (SAC). This dataset forms part of repeated monitoring of 6 sites within the maerl bed in the Milford Haven waterway. The initial surveys were carried out in 2005. Maerl is a collective term for several species of red seaweed, with hard, chalky skeletons. It is rock hard and, unlike other seaweeds, it grows as unattached rounded nodules or short, branched shapes on the seabed. Like all seaweeds, maerl needs sunlight to grow, and it only occurs to a depth of about 20 m. Maerl can form large beds, when the conditions are right – a fast tidal flow or sufficient wave action to remove fine sediments, but not strong enough to break the brittle maerl branches. Within these beds, layers of dead maerl build up with a thin layer of pink, living maerl on the top. Maerl beds are classed as a UK Biodiversity Action Plan (BAP) priority habitat, listed under the Annex 1 of the Habitats Directive, is on the list of OSPAR's List of Threatened and/or Declining Species and Habitats (Region 3 - Celtic Sea), and the habitat supports a number of UKBAP priority species, and species of principal important for the purpose of conservation of biodiversity under the Natural Environment and Rural Communities Act 2006. This data contains the results of a monitoring exercise undertaken to assess the status of the maerl bed in the Haven for the reporting purposes, and also to compare with baseline data gathered in 2005 to identify any trends. The information contributes to UK BAP monitoring and reporting obligations and to the management of the Pembrokeshire Marine Special Area of Conservation (SAC). This dataset forms part of repeated monitoring of 6 sites within the maerl bed in the Milford Haven waterway. The initial surveys were carried out in 2005. 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 MarineSeen Estuary Cottage, Bentlass, Hundleton, Pembrokeshire, SA71 5RN, Wales fbunker@marineseen.com http://www.marineseen.com/ 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 Milford Haven Pembrokeshire Marine SAC Maerl beds Milford Haven Waterway Marine Recorder NRW Thesaurus 2026-10-19 geonetwork.thesaurus.local.theme.converted_nrw-keywords Macroalgae generic abundance in water bodies SeaDataNet Parameter Discovery Vocabulary 2024-06-19 geonetwork.thesaurus.external.theme.rdf+xml There are no access restrictions to 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. Contains Natural Resources Wales information © Natural Resources Wales and Database Right. All rights Reserved. Open Government Licence English biota SeaVoX Vertical Co-ordinate Coverages 2021-01-06 benthic boundary layer Irish Sea Carmarthen Bay Wales (WLS) -5.10687735 -5.06633182 51.69526632 51.71291344 2010-08-18 2010-10-01 3.6 7 Database Marine Recorder Online - Version 2.09.02 Marine Recorder 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 This project was the first repeat of a long term monitoring study (by divers) of the epibiota, infauna and sediment characteristics at six sites within the Milford Haven maerl bed. The following methods were used: - In situ quadrat cell frequency counts. - In situ cores for Particle Size Analysis. - In situ cores for infaunal analysis. - In situ surface sampling for microscopic identification of epiflora. The data quality if considered to be high. There is a high confidence in taxonomic skills of contractor and management of sub-contractors with regards to standards in taxonomy throughout the survey. This project was the first repeat of a long term monitoring study (by divers) of the epibiota, infauna and sediment characteristics at six sites within the Milford Haven maerl bed. This project was the first repeat of a long term monitoring study (by divers) of the epibiota, infauna and sediment characteristics at six sites within the Milford Haven maerl bed. The following methods were used: - In situ quadrat cell frequency counts. - In situ cores for Particle Size Analysis. - In situ cores for infaunal analysis. - In situ surface sampling for microscopic identification of epiflora. The data quality if considered to be high. There is a high confidence in taxonomic skills of contractor and management of sub-contractors with regards to standards in taxonomy throughout the survey. This project was the first repeat of a long term monitoring study (by divers) of the epibiota, infauna and sediment characteristics at six sites within the Milford Haven maerl bed.