Morfa Gwyllt Lagoon Soft Sediment Infauna Survey (2006 - 2012) dataset https://portal.medin.org.uk/portal/start.php?tpc=007_NRW_DS110467 Coastal lagoons are areas of shallow, coastal salt water, wholly or partially separated from the sea by sandbanks, shingle or, less frequently, rocks. Lagoons show a wide range of geographical and ecological variation; five main sub-types have been identified in the UK, on the basis of their physiography, as meeting the definition of the Annex I habitat type. Annex 1 habitat types are those habitats which are listed under the EC Habitats Directive and form part of Special Area of Conservation (SAC) interest features. Morfa Gwyllt lagoon in classed as one of these features within the Pen Llyn a`r Sarnau/ Lleyn Peninsula and the Sarnau SAC. Morfa Gwyllt lagoon is a small percolation lagoon that consists of a depression in a shingle bar across the mouth of the Afon Dysynni in mid Wales. This is the only example of a percolation lagoon in Wales. The substrate is a mosaic of medium sand over/amongst shingle, with muddier patches within the deeper pockets, and scattered larger pebbles. Three lagoonal specialists have been found at this site: the amphipod Sphaeroma hookeri, the bryozoan Conopeum seurati and the alga Chaetomorpha linum. This dataset is a collation of data from subtidal benthic soft sediment sampling carried out within Morfa Gwyllt lagoon collected to aid the monitoring and condition assessment of this Annex 1 feature. 20121231