Intertidal Monitoring of Eelgrass (Zostera marina) Beds in Pen Llyn ar Sarnau Special Areas of Conservation (SACs) in 2004/2005 dataset https://portal.medin.org.uk/portal/start.php?tpc=007_NRW_DS102010 The Habitats Directive establishes that the management of Special Areas of Conservation (SACs) should aim to achieve the favourable conservation status of habitat and species features listed within its Annex I and Annex II. For SACs in Wales, the Countryside Council for Wales (CCW) is therefore required to report on a regular basis on whether features are in favourable conservation status. Seagrass beds develop in intertidal and shallow subtidal areas on sands and muds. They may be found in marine inlets and bays but also in other areas, such as lagoons and channels, which are sheltered from significant wave action. Eelgrass (Zostera marina), is considered to be scarce (present in 16-100 ten km squares) is protected through the EC Habitats Directive and is classed as a UK Biodiversity Action Plan (BAP) Priority Habitat. In particular, seagrass meadows are used as a refuge area by several juvenile commercially important fish species, and similarly provide an important food source for wildfowl such as Brent geese. As a result of their dense root networks, together with a certain degree of wave attenuation and the trapping of sediment particles which further encourages sedimentation, seagrass beds help to stabilise the underlying substratum, thereby playing an important role in terms of coastal defence and the reduction of coastal erosion (Davison and Hughes, 1998). As such, in addition to their biological function and conservation importance, they are also of considerable economic importance. Human activity in the coastal zone (pollution, dredging boat mooring etc) can affect seagrass distribution or even destroy the beds completely. The purpose of this data capture was to map the current known intertidal extent of the Zostera biotope, develop a survey methodology to determine grass density, record damage to the beds caused by physical impacts, develop an index of disease and record species (epibiota) on the Zostera and adjacent sediment. 20081231