Monitoring of a Maerl Bed in the Milford Haven Waterway, Pembrokeshire 2010 dataset https://portal.medin.org.uk/portal/start.php?tpc=007_NRW_DS114753 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. 20111201