Mud and sand flats
Intertidal mudflats and sandflats form a major component of both estuaries and embayments, but also occur on the open coast. They shelter large and diverse communities of animals and plants and so are particularly important as feeding grounds for wildfowl and waders.
Sandy beaches on the open coast, often battered by strong waves, contain burrowing sea urchins, bivalve shells, and worms, and support roaming starfish and many fish species.
Finer muddy sands occur where there is some shelter from wave action. Species commonly found here can include cockles, razor shells, lugworms and seagrass/eelgrass. Intertidal eelgrass is a nationally scarce marine flowering plant. Such areas are also important as nursery areas for fish such as bass and mullet.
Mudflats form in the most sheltered areas of the coast, usually in estuaries which have large supplies of silt from the rivers draining into them. Due to the sheltered nature of these areas the sediment is stable and dominated by polychaete worms, various bivalve shells and sea snails.
The flats of the Gann near Dale are the most biologically diverse intertidal sediment site within the SAC, despite being used heavily for bait digging. This area of very mixed substrate includes one of the richest muddy gravel communities in Wales. A Code of Conduct for bait digging at the Gann is in place following much research and engagement with stakeholders. See the marine code information on the projects page.