A study of the Milford Haven maerl bed (2005) dataset https://portal.medin.org.uk/portal/start.php?tpc=007_NRW_DS101780 Maerl beds are a UK Biodiversity Action Plan (BAP) habitat and are also included in the biodiversity duty of public bodies introduced by the NERC Act 2006. 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. Maerl beds are an important habitat for many different types of marine life, which live amongst or are attached to the surface of Maerl, or burrow in the coarse gravel of dead maerl beneath the top living layer. Maerl beds can be of importance to sustainable fisheries, providing nursery grounds for commercial species of fish and shellfish. In Milford Haven the maerl species Phymatolithon calcareum forms the only living maerl bed in Wales. P. calcareum is listed in the EC Habitats Directive Annex Vb. The aim of this project was to collate high quality images of the Milford Haven maerl bed to create a base line for long term monitoring for Biodiversity Action Plan reporting. There is high confidence in this dataset as the surveyors are amongst the most experienced marine biologists in the UK. 20070228