Mudflats are composed of deposits of sand, silt & mud in sheltered, intertidal areas. They are usually uncovered at low tide but are submerged at high tide & range from soft mud to firm sands.
Intertidal flats cover an estimated 270,000 ha in the UK.
All larger areas of mudflats in Northern Ireland are located within sea loughs & estuaries. Mudflats are recorded at seven places in NI. Mudflats occur in Lough Foyle, primarily in the lower littoral zone & are covered at half tide, the mouth of the Bann Estuary, the southern end of Larne Lough, Belfast Lough, Strangford Lough, Carlingford Lough & Inner Dundrum Bay.
Mudflats are under threat from direct physical disturbances (e.g. capital or maintenance dredging for navigation), land claim, as they are usually found in sheltered regions near existing developments, making them economically attractive, construction of coastal defences, bait digging, mechanical cockle harvesting, introduced species (e.g. cord-grass Sparina anglica), sea level changes & climate change (higher summer temperatures may lead to increased level of desiccation in the intertidal area & increased storm frequency could increase the level of wave energy in the water column, preventing settlement of fine organic & inorganic materials). Pollution can be particularly damaging, as where there is nutrient enrichment, the green ephemeral seaweed Enteromorpha spp. can form macroalgal blooms which prevents light penetration to the mud surface below.