Twenty nine sites were surveyed within or adjacent to the Bardsey/Lleyn Peninsula SAC including the areas between the Gwylan islands and Maen Mellt on the Lleyn peninsula (S to N) and around Bardsey Island and in Bardsey Sound. Several sites surveyed during the current study covered ground previously surveyed by Hiscock in 1983. The majority of biotopes surveyed were tide-swept bedrock and boulders with kelp forests in shallow water and hydroid, bryozoan and anthozoan turfs below, grading to cobbles and pebbles with scour-tolerant fauna particularly in Bardsey Sound. Extensive mobile sand plains were surveyed on Bastram shoal offshore to the south of Bardsey. Records currently considered sensitive have been removed from this dataset.
