COUNTRYSIDE COUNCIL FOR WALES
SITE OF SPECIAL SCIENTIFIC INTEREST: CITATION
ANGLESEY CEMLYN BAY
National Grid Reference: SH331933
Site Area: 44.5 ha
The inner part of the bay is a tidal lagoon enclosed by a shingle ridge forming a "bay head barrier" of storm beach shingle. Saltmarsh communities occur around the lagoon. The shingle ridge, lagoon and brackish pools further inland support a number of uncommon plant species including sea kale Crambe maritima, sea radish Rapohanus maritimus, brackish water-crowfoot Ranunculus baudotii and Ruppia maritima.
There are colonies of common, arctic and sandwich terns which breed on low islands in the main lagoon. The number of breeding pairs of each species fluctuates from year to year but the site is particularly important for sandwich tern and often holds over 1% of the British breeding population.
The water level in the lagoon is maintained by a weir which is controlled to prevent the ternery from flooding at high spring tides. Wintering wildfowl, notably wigeon, shoveler, goldeneye, teal, mallard and tufted duck use the area.
(1) The shingle ridge and lagoon are leased from the National Trust and managed as a nature reserve by the North Wales Naturalists' Trust.