Intertidal Monitoring of Tide-swept Boulder Habitat in the Menai Strait and Conwy Bay Special Areas of Conservation (SACs) 2008 dataset https://portal.medin.org.uk/portal/start.php?tpc=007_NRW_DS112289 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. Rocky reefs (hard substrata) are of considerable conservation importance due the high diversity of the communities they support and, as such, are included under Annex 1 of the EU Habitats Directive (92/43/EEC) (Hill et al. 1998). They are an abundant feature of the UK coastline, especially on western coasts where exposed bedrock predominates. In some areas, the substratum may be composed entirely of bedrock whilst on less steeply shelving / gently shelving shores, large boulders, cobbles, gravel, sand and mud may be present (Hill et al., 1998). Rocky reefs are extremely variable in terms of their structure and the communities they support with reef communities being influenced by the type of rock and the microhabitats available, sediment availability, degree of shelter, shore height, and temperature regime. Communities in exposed areas are usually dominated by sponges, anemones and foliose red algae with ascidians, delicate filamentous algae and fan worms being more common in sheltered areas (JNCC, 2005). 20080606